in one embodiment of the present invention , the mch receptor antagonist is a compound of formula i , or a pharmaceutically - acceptable salt , tautomer or prodrug thereof , having the following structure : a is selected from the group consisting of heteroaryl , — c (═ o )—, and — c (═ o ) nh —; w is selected from the group consisting of a bond , — c (═ o )—, alkyl , alkenyl , aryl , aralkenyl and heterocyclo ; z is selected from the group consisting of a bond , alkyl , cycloalkyl , aryl , aralkyl , heteroaryl , and heterocyclo ; r 1 is selected from the group consisting of alkyl , aryl , aralkyl , alkoxycarbonyl , heterocyclo , aryloxy , heteroaryl , and alkylphosphonate , wherein r 1 is optionally substituted by one or more substituents selected from the group consisting of alkyl , hydroxy , carboxyl , halo , cyano and keto ; r 2 is selected from the group consisting of hydrogen , alkyl , cycloalkyl , aryl , aralkyl , aroyl , heterocyclo , heteroaryl , and aralkoxy , or r 2 and r 8 together with the atom to which they are both attached form a 5 - or 6 - membered cycloalkyl or heterocyclo group , wherein r 2 or the cycloalkyl or heterocyclo group formed with r 8 is optionally substituted by one or more substituents selected from the group consisting of alkoxy , aryloxy , haloalkyl , halo , aryl , aralkenyl , aralkyl , alkyl , haloalkylaryl , haloaryloxy , alkylaryloxy , heteroaryl , cyano , hydroxy , hydroxyalkoxy , alkoxycarbonyl , alkylthio , n -( alkylcarbonyl ) amino , and nitro ; r 3 is selected from the group consisting of hydrogen , aryl , alkoxy , aralkoxy , heteroaryl and heterocyclocarbonyl , wherein r 3 is optionally substituted by one or more substituents selected from the group consisting of halo , aryl , haloaryl , alkoxy , alkyl , carboxyl , aryloxy , keto , and hydroxy ; r 4 , r 5 , r 6 , r 7 , and r 9 are independently selected from the group consisting of hydrogen , alkyl , and halo ; and r 8 is hydrogen or alkyl , or r 2 and r 8 together with the atom to which they are both attached form a 5 - or 6 - membered cycloalkyl or heterocyclo group ; provided that z is not methyl when x is xb or xc , further provided that w is not pyrrolidyl when x is xc , and further provided that r 3 is not aryl - or haloaryl - substituted indolyl . in another embodiment , the mch receptor antagonist consists of compounds of formula i , or a pharmaceutically - acceptable salt , tautomer or prodrug thereof , wherein a is selected from the group consisting of 5 - or 6 - membered heteroaryl , — c (═ o )—, and — c (═ o ) nh —; w is selected from the group consisting of a bond , — c (═ o )—, lower alkyl , lower alkenyl , aryl , aralkenyl and 3 - to 10 - membered heterocyclo ; z is selected from the group consisting of a bond , lower alkyl , lower cycloalkyl , aryl , aralkyl and 3 - to 10 - membered heterocyclo ; r 1 is selected from the group consisting of lower alkyl , aryl , aralkyl , lower alkoxycarbonyl , 3 - to 10 - membered heterocyclo , aryloxy , 3 - to 10 - membered heteroaryl , and lower alkylphosphonate , wherein r 1 is optionally substituted by one or more substituents selected from the group consisting of lower alkyl , hydroxy , carboxyl , halo , cyano and keto ; r 2 is selected from the group consisting of hydrogen , lower alkyl , lower cycloalkyl , aryl , aralkyl , aroyl , 3 - to 10 - membered heterocyclo , 3 - to 10 - membered heteroaryl , and aralkoxy , or r 2 and r 8 together with the atom to which they are both attached form a 5 - or 6 - membered cycloalkyl or heterocyclo group , wherein r 2 or the cycloalkyl or heterocyclo group formed with r 8 is optionally substituted by one or more substituents selected from the group consisting of lower alkoxy , aryloxy , lower haloalkyl , halo , aryl , aralkenyl , aralkyl , lower alkyl , haloalkylaryl , haloaryloxy , alkylaryloxy , 5 - or 6 - membered heteroaryl , cyano , hydroxy , lower hydroxyalkoxy , lower alkoxycarbonyl , lower alkylthio , n -( lower alkylcarbonyl ) amino , and nitro ; r 3 is selected from the group consisting of hydrogen , aryl , lower alkoxy , aralkoxy , furyl , thienyl , pyrrolyl , pyrazolyl , imidazolyl , triazolyl , isoxazolyl , oxazolyl , indolyl , benzofuryl , thiazolyl , isothiazolyl , oxadiazolyl , oxatriazolyl , dioxazole , tetrazolyl , benzodioxolyl , and ( 3 - to 10 - membered heterocyclo ) carbonyl , wherein r 3 is optionally substituted by one or more substituents selected from the group consisting of halo , aryl , haloaryl , lower alkoxy , lower alkyl , carboxyl , aryloxy , keto , and hydroxy ; r 4 , r 5 , r 6 , r 7 , and r 9 are independently selected from the group consisting of hydrogen , lower alkyl , and halo ; and r 8 is hydrogen or lower alkyl , or r 2 and r 8 together with the atom to which they are both attached form a 5 - or 6 - membered cycloalkyl or heterocyclo group . in another embodiment , the mch receptor antagonist consists of compounds of formula i , or a pharmaceutically - acceptable salt , tautomer or prodrug thereof , wherein a is selected from the group consisting of furyl , thienyl , pyrrolyl , pyrazolyl , imidazolyl , triazolyl , isoxazolyl , oxazolyl , indolyl , thiazolyl , isothiazolyl , oxadiazolyl , oxatriazolyl , dioxazole , tetrazolyl , benzodioxolyl , — c (═ o )—, and — c (═ o ) nh —; w is selected from the group consisting of a bond , — c (═ o )—, methyl , ethyl , propyl , butyl , pentyl , hexyl , ethenyl , propenyl , allyl , butenyl , pentenyl , phenyl , naphthyl , tetrahydronaphthyl , biphenyl , phenylethenyl , phenylpropenyl , phenylallyl , phenylbutenyl , phenylpentenyl , pyrrolidinyl , imidazolidinyl , piperidinyl , piperazinyl , morpholinyl , thiazolidinyl , dihydrothienyl , dihydropyranyl , dihydrofuryl , dihydrothiazolyl , and tetrahydrofuryl ; z is selected from the group consisting of a bond , methyl , ethyl , propyl , butyl , pentyl , hexyl , cyclopropyl , cyclobutyl , cyclopentyl , cyclohexyl , phenyl , naphthyl , tetrahydronaphthyl , biphenyl , benzyl , diphenylmethyl , triphenylmethyl , phenylethyl , diphenylethyl , pyrrolidinyl , imidazolidinyl , piperidinyl , piperazinyl , morpholinyl , thiazolidinyl , dihydrothienyl , dihydropyranyl , dihydrofuryl , dihydrothiazolyl , and tetrahydrofuryl ; r 1 is selected from the group consisting of methyl , ethyl , propyl , butyl , pentyl , hexyl , phenyl , naphthyl , tetrahydronaphthyl , biphenyl , benzyl , diphenylmethyl , triphenylmethyl , phenylethyl , diphenylethyl , methoxycarbonyl , ethoxycarbonyl , propoxycarbonyl , butoxycarbonyl , pentyloxycarbonyl , hexyloxycarbonyl , pyrrolidinyl , imidazolidinyl , piperidinyl , piperazinyl , morpholinyl , thiazolidinyl , dihydrothienyl , dihydropyranyl , dihydrofuryl , dihydrothiazolyl , tetrahydrofuryl , phenoxy , naphthyloxy , tetrahydronaphthyloxy , biphenylyloxy , furyl , thienyl , pyrrolyl , pyrazolyl , imidazolyl , triazolyl , isoxazolyl , oxazolyl , indolyl , thiazolyl , isothiazolyl , oxadiazolyl , oxatriazolyl , dioxazole , tetrazolyl , benzodioxolyl , monomethylphosphonate , dimethylphosphonate , monoethylphosphonate , diethylphosphonate , monopropylphosphonate , and dipropylphosphonate , wherein r 1 is optionally substituted by one or more substituents selected from the group consisting of methyl , ethyl , propyl , butyl , pentyl , hexyl , hydroxy , carboxyl , fluoro , chloro , bromo , iodo , cyano and keto ; r 2 is selected from the group consisting of hydrogen , methyl , ethyl , propyl , butyl , pentyl , hexyl , cyclopropyl , cyclobutyl , cyclopentyl , cyclohexyl , phenyl , naphthyl , tetrahydronaphthyl , biphenyl , benzyl , diphenylmethyl , triphenylmethyl , phenylethyl , diphenylethyl , phenylcarbonyl , naphthylcarbonyl , tetrahydronaphthylcarbonyl , biphenylcarbonyl , pyrrolidinyl , imidazolidinyl , piperidinyl , piperazinyl , morpholinyl , thiazolidinyl , dihydrothienyl , dihydropyranyl , dihydrofuryl , dihydrothiazolyl , tetrahydrofuryl , furyl , thienyl , pyrrolyl , pyrazolyl , imidazolyl , triazolyl , isoxazolyl , oxazolyl , indolyl , benzofuryl , thiazolyl , isothiazolyl , oxadiazolyl , oxatriazolyl , dioxazole , tetrazolyl , benzodioxolyl , phenylmethoxy , phenylethoxy , phenylpropoxy , phenylbutoxy , phenylpentyloxy , and phenylhexyloxy , or r 2 and r 8 together with the atom to which they are both attached form a 5 - or 6 - membered cycloalkyl or heterocyclo group selected from the group consisting of cyclopentyl , cyclohexyl , pyrrolidinyl , imidazolidinyl , piperidinyl , piperazinyl , morpholinyl , thiazolidinyl , dihydrothienyl , dihydropyranyl , dihydrofuryl , dihydrothiazolyl , and tetrahydrofuryl , wherein r 2 or the cycloalkyl or heterocyclo group formed with r 8 is optionally substituted by one or more substituents selected from the group consisting of methoxy , ethoxy , propoxy , butoxy , pentyloxy , hexyloxy , phenoxy , naphthyloxy , tetrahydronaphthyloxy , biphenylyloxy , fluoromethyl , difluoromethyl , trifluoromethyl , chloromethyl , dichloromethyl , trichloromethyl , trichloromethyl , pentafluoroethyl , heptafluoropropyl , difluorochloromethyl , dichlorofluoromethyl , difluoroethyl , difluoropropyl , dichloroethyl , dichloropropyl , fluoro , chloro , bromo , iodo , phenyl , naphthyl , tetrahydronaphthyl , biphenyl , phenylethenyl , phenylpropenyl , phenylallyl , phenylbutenyl , phenylpentenyl , benzyl , diphenylmethyl , triphenylmethyl , phenylethyl , diphenylethyl , methyl , ethyl , propyl , butyl , pentyl , hexyl , fluoromethylphenyl , difluoromethylphenyl , trifluoromethylphenyl , chloromethylphenyl , dichloromethylphenyl , trichloromethylphenyl , trichloromethylphenyl , bis ( fluoromethyl ) phenyl , bis ( difluoromethyl ) phenyl , bis ( trifluoromethyl ) phenyl , bis ( chloromethyl ) phenyl , bis ( dichloromethyl ) phenyl , bis ( trichloromethyl ) phenyl , bis ( trichloromethyl ) phenyl , chlorophenoxy , bromophenoxy , fluorophenoxy , dichlorophenoxy , dibromophenoxy , difluorophenoxy , chlorobromophenoxy , chlorofluorophenoxy , bromofluorophenoxy , methylphenoxy , ethylphenoxy , propylphenoxy , dimethylphenoxy , diethylphenoxy , dipropylphenoxy , methylnaphthyloxy , ethylnaphthyloxy , propylnaphthyloxy , dimethylnaphthyloxy , diethylnaphthyloxy , dipropylnaphthyloxy , methylbiphenylyloxy , ethylbiphenylyloxy , propylbiphenylyloxy , dimethylbiphenylyloxy , diethylbiphenylyloxy , dipropylbiphenylyloxy , furyl , thienyl , pyrrolyl , pyrazolyl , imidazolyl , triazolyl , isoxazolyl , oxazolyl , indolyl , thiazolyl , isothiazolyl , oxadiazolyl , oxatriazolyl , dioxazole , tetrazolyl , benzodioxolyl , cyano , hydroxy , hydroxymethoxy , hydroxyethoxy , hydroxypropoxy , hydroxybutoxy , hydroxypentyloxy , hydroxyhexyloxy , methoxycarbonyl , ethoxycarbonyl , propoxycarbonyl , butoxycarbonyl , pentyloxycarbonyl , hexyloxycarbonyl , methylthio , ethylthio , propylthio , butylthio , pentylthio , hexylthio , n -( methylcarbonyl ) amino , n -( ethylcarbonyl ) amino , n -( propylcarbonyl ) amino , n -( butylcarbonyl ) amino , n -( pentylcarbonyl ) amino , n -( hexylcarbonyl ) amino , and nitro ; r 3 is selected from the group consisting of hydrogen , phenyl , naphthyl , tetrahydronaphthyl , biphenyl , methoxy , ethoxy , propoxy , butoxy , pentyloxy , hexyloxy , phenylmethoxy , phenylethoxy , phenylpropoxy , phenylbutoxy , phenylpentyloxy , phenylhexyloxy , furyl , thienyl , pyrrolyl , pyrazolyl , imidazolyl , triazolyl , isoxazolyl , oxazolyl , indolyl , thiazolyl , isothiazolyl , oxadiazolyl , oxatriazolyl , dioxazole , tetrazolyl , benzodioxolyl , pyrrolidinylcarbonyl , imidazolidinylcarbonyl , piperidinylcarbonyl , piperazinylcarbonyl , morpholinylcarbonyl , thiazolidinylcarbonyl , dihydrothienylcarbonyl , dihydropyranylcarbonyl , dihydrofurylcarbonyl , dihydrothiazolylcarbonyl , and tetrahydrofurylcarbonyl , wherein r 3 is optionally substituted by one or more substituents selected from the group consisting of fluoro , chloro , bromo , iodo , phenyl , naphthyl , tetrahydronaphthyl , biphenyl , chlorophenyl , bromophenyl , fluorophenyl , dichlorophenyl , dibromophenyl , difluorophenyl , chlorobromophenyl , chlorofluorophenyl , bromofluorophenyl , methoxy , ethoxy , propoxy , butoxy , pentyloxy , hexyloxy , methyl , ethyl , propyl , butyl , pentyl , hexyl , carboxyl , phenoxy , naphthyloxy , tetrahydronaphthyloxy , biphenylyloxy , keto , and hydroxy ; r 4 , r 5 , r 6 , r 7 , and r 9 are independently selected from the group consisting of hydrogen , methyl , ethyl , propyl , butyl , pentyl , hexyl , fluoro , chloro , bromo , and iodo ; and r 8 is selected from the group consisting of hydrogen , methyl , ethyl , propyl , butyl , pentyl , and hexyl , or r 2 and r 8 together with the atom to which they are both attached form a 5 - or 6 - membered cycloalkyl or heterocyclo group selected from the group consisting of cyclopropyl , cyclobutyl , cyclopentyl , cyclohexyl , pyrrolidinyl , imidazolidinyl , piperidinyl , piperazinyl , morpholinyl , thiazolidinyl , dihydrothienyl , dihydropyranyl , dihydrofuryl , dihydrothiazolyl , and tetrahydrofuryl . in another embodiment , the mch receptor antagonist consists of compounds of formula i , or a pharmaceutically - acceptable salt , tautomer or prodrug thereof , wherein a is selected from the group consisting of furyl , thienyl , pyrrolyl , pyrazolyl , imidazolyl , triazolyl , isoxazolyl , oxazolyl , indolyl , thiazolyl , isothiazolyl , oxadiazolyl , oxatriazolyl , dioxazole , tetrazolyl , benzodioxolyl , — c (═ o )—, and — c (═ o ) nh —; w is selected from the group consisting of a bond , — c (═ o )—, alkyl , alkenyl , aryl , aralkenyl and heterocyclo ; z is selected from the group consisting of a bond , alkyl , cycloalkyl , aryl , aralkyl , heteroaryl , and heterocyclo ; r 1 is selected from the group consisting of alkyl , aryl , aralkyl , alkoxycarbonyl , heterocyclo , aryloxy , heteroaryl , and alkylphosphonate , wherein r 1 is optionally substituted by one or more substituents selected from the group consisting of alkyl , hydroxy , carboxyl , halo , cyano and keto ; r 2 is selected from the group consisting of hydrogen , alkyl , cycloalkyl , aryl , aralkyl , aroyl , heterocyclo , heteroaryl , and aralkoxy , or r 2 and r 8 together with the atom to which they are both attached form a 5 - or 6 - membered cycloalkyl or heterocyclo group , wherein r 2 or the cycloalkyl or heterocyclo group formed with r 8 is optionally substituted by one or more substituents selected from the group consisting of alkoxy , aryloxy , haloalkyl , halo , aryl , aralkenyl , aralkyl , alkyl , haloalkylaryl , haloaryloxy , alkylaryloxy , heteroaryl , cyano , hydroxy , hydroxyalkoxy , alkoxycarbonyl , alkylthio , n -( alkylcarbonyl ) amino , and nitro ; r 3 is selected from the group consisting of hydrogen , aryl , alkoxy , aralkoxy , heteroaryl and heterocyclocarbonyl , wherein r 3 is optionally substituted by one or more substituents selected from the group consisting of halo , aryl , haloaryl , alkoxy , alkyl , carboxyl , aryloxy , keto , and hydroxy ; r 4 , r 5 , r 6 , r 7 , and r 9 are independently selected from the group consisting of hydrogen , alkyl , and halo ; and r 8 is hydrogen or alkyl , or r 2 and r 8 together with the atom to which they are both attached form a 5 - or 6 - membered cycloalkyl or heterocyclo group ; provided that z is not methyl when x is xb or xc , further provided that w is not pyrrolidyl when x is xc , and further provided that r 3 is not aryl - or haloaryl - substituted indolyl ; in another embodiment , the mch receptor antagonist consists of compounds of formula i , or a pharmaceutically - acceptable salt , tautomer or prodrug thereof , wherein a is selected from the group consisting of furyl , thienyl , pyrrolyl , pyrazolyl , imidazolyl , triazolyl , isoxazolyl , oxazolyl , indolyl , thiazolyl , isothiazolyl , oxadiazolyl , oxatriazolyl , dioxazole , tetrazolyl , benzodioxolyl , — c (═ o )—, and — c (═ o ) nh —; w is selected from the group consisting of a bond , — c (═ o )—, lower alkyl , lower alkenyl , aryl , aralkenyl and 3 - to 10 - membered heterocyclo ; z is selected from the group consisting of a bond , lower alkyl , lower cycloalkyl , aryl , aralkyl and 3 - to 10 - membered heterocyclo ; r 1 is selected from the group consisting of lower alkyl , aryl , aralkyl , lower alkoxycarbonyl , 3 - to 10 - membered heterocyclo , aryloxy , 3 - to 10 - membered heteroaryl , and lower alkylphosphonate , wherein r 1 is optionally substituted by one or more substituents selected from the group consisting of lower alkyl , hydroxy , carboxyl , halo , cyano and keto ; r 2 is selected from the group consisting of hydrogen , lower alkyl , lower cycloalkyl , aryl , aralkyl , aroyl , 3 - to 10 - membered heterocyclo , 3 - to 10 - membered heteroaryl , and aralkoxy , or r 2 and r 8 together with the atom to which they are both attached form a 5 - or 6 - membered cycloalkyl or heterocyclo group , wherein r 2 or the cycloalkyl or heterocyclo group formed with r 8 is optionally substituted by one or more substituents selected from the group consisting of lower alkoxy , aryloxy , lower haloalkyl , halo , aryl , aralkenyl , aralkyl , lower alkyl , haloalkylaryl , haloaryloxy , alkylaryloxy , 5 - or 6 - membered heteroaryl , cyano , hydroxy , lower hydroxyalkoxy , lower alkoxycarbonyl , lower alkylthio , n -( lower alkylcarbonyl ) amino , and nitro ; r 3 is selected from the group consisting of hydrogen , aryl , lower alkoxy , aralkoxy , furyl , thienyl , pyrrolyl , pyrazolyl , imidazolyl , triazolyl , isoxazolyl , oxazolyl , indolyl , benzofuryl , thiazolyl , isothiazolyl , oxadiazolyl , oxatriazolyl , dioxazole , tetrazolyl , benzodioxolyl , and ( 3 - to 10 - membered heterocyclo ) carbonyl , wherein r 3 is optionally substituted by one or more substituents selected from the group consisting of halo , aryl , haloaryl , lower alkoxy , lower alkyl , carboxyl , aryloxy , keto , and hydroxy ; r 4 , r 5 , r 6 , r 7 , and r 9 are independently selected from the group consisting of hydrogen , lower alkyl , and halo ; and r 8 is hydrogen or lower alkyl , or r 2 and r 8 together with the atom to which they are both attached form a 5 - or 6 - membered cycloalkyl or heterocyclo group . in another embodiment , the mch receptor antagonist is selected from a subclass of compounds of formula i represented by formula ii : a is selected from the group consisting of furyl , thienyl , pyrrolyl , pyrazolyl , imidazolyl , triazolyl , isoxazolyl , oxazolyl , indolyl , thiazolyl , isothiazolyl , oxadiazolyl , oxatriazolyl , dioxazole , tetrazolyl , benzodioxolyl , — c (═ o )—, and — c (═ o ) nh —; w is selected from the group consisting of a bond , — c (═ o )—, alkyl , alkenyl , aryl , aralkenyl and heterocyclo ; z is selected from the group consisting of a bond , alkyl , cycloalkyl , aryl , aralkyl , heteroaryl , and heterocyclo ; r 1 is selected from the group consisting of alkyl , aryl , aralkyl , alkoxycarbonyl , heterocyclo , aryloxy , heteroaryl , and alkylphosphonate , wherein r 1 is optionally substituted by one or more substituents selected from the group consisting of alkyl , hydroxy , carboxyl , halo , cyano and keto ; r 2 is selected from the group consisting of hydrogen , alkyl , cycloalkyl , aryl , aralkyl , aroyl , heterocyclo , heteroaryl , and aralkoxy , or r 2 and r 8 together with the atom to which they are both attached form a 5 - or 6 - membered cycloalkyl or heterocyclo group , wherein r 2 or the cycloalkyl or heterocyclo group formed with r 8 is optionally substituted by one or more substituents selected from the group consisting of alkoxy , aryloxy , haloalkyl , halo , aryl , aralkenyl , aralkyl , alkyl , haloalkylaryl , haloaryloxy , alkylaryloxy , heteroaryl , cyano , hydroxy , hydroxyalkoxy , alkoxycarbonyl , alkylthio , n -( alkylcarbonyl ) amino , and nitro ; r 3 is selected from the group consisting of hydrogen , aryl , alkoxy , aralkoxy , heteroaryl and heterocyclocarbonyl , wherein r 3 is optionally substituted by one or more substituents selected from the group consisting of halo , aryl , haloaryl , alkoxy , alkyl , carboxyl , aryloxy , keto , and hydroxy ; r 4 , r 5 , r 6 , and r 7 are independently selected from the group consisting of hydrogen , alkyl , and halo ; and r 8 is hydrogen or alkyl , or r 2 and r 8 together with the atom to which they are both attached form a 5 - or 6 - membered cycloalkyl or heterocyclo group ; provided that r 3 is not aryl - or haloaryl - substituted indolyl ; in another embodiment , the mch receptor antagonist consists of compounds of formula ii , or a pharmaceutically - acceptable salt , tautomer or prodrug thereof , wherein a is selected from the group consisting of 5 - or 6 - membered heteroaryl , — c (═ o )—, and — c (═ o ) nh —; w is selected from the group consisting of a bond , — c (═ o )—, lower alkyl , lower alkenyl , aryl , aralkenyl and 3 - to 10 - membered heterocyclo ; z is selected from the group consisting of a bond , lower alkyl , lower cycloalkyl , aryl , aralkyl and 3 - to 10 - membered heterocyclo ; r 1 is selected from the group consisting of lower alkyl , aryl , aralkyl , lower alkoxycarbonyl , 3 - to 10 - membered heterocyclo , aryloxy , 3 - to 10 - membered heteroaryl , and lower alkylphosphonate , wherein r 1 is optionally substituted by one or more substituents selected from the group consisting of lower alkyl , hydroxy , carboxyl , halo , cyano and keto ; r 2 is selected from the group consisting of hydrogen , lower alkyl , lower cycloalkyl , aryl , aralkyl , aroyl , 3 - to 10 - membered heterocyclo , 3 - to 10 - membered heteroaryl , and aralkoxy , or r 2 and r 8 together with the atom to which they are both attached form a 5 - or 6 - membered cycloalkyl or heterocyclo group , wherein r 2 or the cycloalkyl or heterocyclo group formed with r 8 is optionally substituted by one or more substituents selected from the group consisting of lower alkoxy , aryloxy , lower haloalkyl , halo , aryl , aralkenyl , aralkyl , lower alkyl , haloalkylaryl , haloaryloxy , alkylaryloxy , 5 - or 6 - membered heteroaryl , cyano , hydroxy , lower hydroxyalkoxy , lower alkoxycarbonyl , lower alkylthio , n -( lower alkylcarbonyl ) amino , and nitro ; r 3 is selected from the group consisting of hydrogen , aryl , lower alkoxy , aralkoxy , furyl , thienyl , pyrrolyl , pyrazolyl , imidazolyl , triazolyl , isoxazolyl , oxazolyl , indolyl , benzofuryl , thiazolyl , isothiazolyl , oxadiazolyl , oxatriazolyl , dioxazole , tetrazolyl , benzodioxolyl , and ( 3 - to 10 - membered heterocyclo ) carbonyl , wherein r 3 is optionally substituted by one or more substituents selected from the group consisting of halo , aryl , haloaryl , lower alkoxy , lower alkyl , carboxyl , aryloxy , keto , and hydroxy ; r 4 , r 5 , r 6 , and r 7 are independently selected from the group consisting of hydrogen , lower alkyl , and halo ; and r 8 is hydrogen or lower alkyl , or r 2 and r 8 together with the atom to which they are both attached form a 5 - or 6 - membered cycloalkyl or heterocyclo group . in another embodiment , the mch receptor antagonist consists of compounds of formula ii , or a pharmaceutically - acceptable salt , tautomer or prodrug thereof , wherein a is selected from the group consisting of furyl , thienyl , pyrrolyl , pyrazolyl , imidazolyl , triazolyl , isoxazolyl , oxazolyl , indolyl , thiazolyl , isothiazolyl , oxadiazolyl , oxatriazolyl , dioxazole , tetrazolyl , benzodioxolyl , — c (═ o )—, and — c (═ o ) nh —; w is selected from the group consisting of a bond , — c (═ o )—, methyl , ethyl , propyl , butyl , pentyl , hexyl , ethenyl , propenyl , allyl , butenyl , pentenyl , phenyl , naphthyl , tetrahydronaphthyl , biphenyl , phenylethenyl , phenylpropenyl , phenylallyl , phenylbutenyl , phenylpentenyl , pyrrolidinyl , imidazolidinyl , piperidinyl , piperazinyl , morpholinyl , thiazolidinyl , dihydrothienyl , dihydropyranyl , dihydrofuryl , dihydrothiazolyl , and tetrahydrofuryl ; z is selected from the group consisting of a bond , methyl , ethyl , propyl , butyl , pentyl , hexyl , cyclopropyl , cyclobutyl , cyclopentyl , cyclohexyl , phenyl , naphthyl , tetrahydronaphthyl , biphenyl , benzyl , diphenylmethyl , triphenylmethyl , phenylethyl , diphenylethyl , pyrrolidinyl , imidazolidinyl , piperidinyl , piperazinyl , morpholinyl , thiazolidinyl , dihydrothienyl , dihydropyranyl , dihydrofuryl , dihydrothiazolyl , and tetrahydrofuryl ; r 1 is selected from the group consisting of methyl , ethyl , propyl , butyl , pentyl , hexyl , phenyl , naphthyl , tetrahydronaphthyl , biphenyl , benzyl , diphenylmethyl , triphenylmethyl , phenylethyl , diphenylethyl , methoxycarbonyl , ethoxycarbonyl , propoxycarbonyl , butoxycarbonyl , pentyloxycarbonyl , hexyloxycarbonyl , pyrrolidinyl , imidazolidinyl , piperidinyl , piperazinyl , morpholinyl , thiazolidinyl , dihydrothienyl , dihydropyranyl , dihydrofuryl , dihydrothiazolyl , tetrahydrofuryl , phenoxy , naphthyloxy , tetrahydronaphthyloxy , biphenylyloxy , furyl , thienyl , pyrrolyl , pyrazolyl , imidazolyl , triazolyl , isoxazolyl , oxazolyl , indolyl , thiazolyl , isothiazolyl , oxadiazolyl , oxatriazolyl , dioxazole , tetrazolyl , benzodioxolyl , monomethylphosphonate , dimethylphosphonate , monoethylphosphonate , diethylphosphonate , monopropylphosphonate , and dipropylphosphonate , wherein r 1 is optionally substituted by one or more substituents selected from the group consisting of methyl , ethyl , propyl , butyl , pentyl , hexyl , hydroxy , carboxyl , fluoro , chloro , bromo , iodo , cyano and keto ; r 2 is selected from the group consisting of hydrogen , methyl , ethyl , propyl , butyl , pentyl , hexyl , cyclopropyl , cyclobutyl , cyclopentyl , cyclohexyl , phenyl , naphthyl , tetrahydronaphthyl , biphenyl , benzyl , diphenylmethyl , triphenylmethyl , phenylethyl , diphenylethyl , phenylcarbonyl , naphthylcarbonyl , tetrahydronaphthylcarbonyl , biphenylcarbonyl , pyrrolidinyl , imidazolidinyl , piperidinyl , piperazinyl , morpholinyl , thiazolidinyl , dihydrothienyl , dihydropyranyl , dihydrofuryl , dihydrothiazolyl , tetrahydrofuryl , furyl , thienyl , pyrrolyl , pyrazolyl , imidazolyl , triazolyl , isoxazolyl , oxazolyl , indolyl , benzofuryl , thiazolyl , isothiazolyl , oxadiazolyl , oxatriazolyl , dioxazole , tetrazolyl , benzodioxolyl , phenylmethoxy , phenylethoxy , phenylpropoxy , phenylbutoxy , phenylpentyloxy , and phenylhexyloxy , or r 2 and r 8 together with the atom to which they are both attached form a 5 - or 6 - membered cycloalkyl or heterocyclo group selected from the group consisting of cyclopentyl , cyclohexyl , pyrrolidinyl , imidazolidinyl , piperidinyl , piperazinyl , morpholinyl , thiazolidinyl , dihydrothienyl , dihydropyranyl , dihydrofuryl , dihydrothiazolyl , and tetrahydrofuryl , wherein r 2 or the cycloalkyl or heterocyclo group formed with r 8 is optionally substituted by one or more substituents selected from the group consisting of methoxy , ethoxy , propoxy , butoxy , pentyloxy , hexyloxy , phenoxy , naphthyloxy , tetrahydronaphthyloxy , biphenylyloxy , fluoromethyl , difluoromethyl , trifluoromethyl , chloromethyl , dichloromethyl , trichloromethyl , trichloromethyl , pentafluoroethyl , heptafluoropropyl , difluorochloromethyl , dichlorofluoromethyl , difluoroethyl , difluoropropyl , dichloroethyl , dichloropropyl , fluoro , chloro , bromo , iodo , phenyl , naphthyl , tetrahydronaphthyl , biphenyl , phenylethenyl , phenylpropenyl , phenylallyl , phenylbutenyl , phenylpentenyl , benzyl , diphenylmethyl , triphenylmethyl , phenylethyl , diphenylethyl , methyl , ethyl , propyl , butyl , pentyl , hexyl , fluoromethylphenyl , difluoromethylphenyl , trifluoromethylphenyl , chloromethylphenyl , dichloromethylphenyl , trichloromethylphenyl , trichloromethylphenyl , bis ( fluoromethyl ) phenyl , bis ( difluoromethyl ) phenyl , bis ( trifluoromethyl ) phenyl , bis ( chloromethyl ) phenyl , bis ( dichloromethyl ) phenyl , bis ( trichloromethyl ) phenyl , bis ( trichloromethyl ) phenyl , chlorophenoxy , bromophenoxy , fluorophenoxy , dichlorophenoxy , dibromophenoxy , difluorophenoxy , chlorobromophenoxy , chlorofluorophenoxy , bromofluorophenoxy , methylphenoxy , ethylphenoxy , propylphenoxy , dimethylphenoxy , diethylphenoxy , dipropylphenoxy , methylnaphthyloxy , ethylnaphthyloxy , propylnaphthyloxy , dimethylnaphthyloxy , diethylnaphthyloxy , dipropylnaphthyloxy , methylbiphenylyloxy , ethylbiphenylyloxy , propylbiphenylyloxy , dimethylbiphenylyloxy , diethylbiphenylyloxy , dipropylbiphenylyloxy , furyl , thienyl , pyrrolyl , pyrazolyl , imidazolyl , triazolyl , isoxazolyl , oxazolyl , indolyl , thiazolyl , isothiazolyl , oxadiazolyl , oxatriazolyl , dioxazole , tetrazolyl , benzodioxolyl , cyano , hydroxy , hydroxymethoxy , hydroxyethoxy , hydroxypropoxy , hydroxybutoxy , hydroxypentyloxy , hydroxyhexyloxy , methoxycarbonyl , ethoxycarbonyl , propoxycarbonyl , butoxycarbonyl , pentyloxycarbonyl , hexyloxycarbonyl , methylthio , ethylthio , propylthio , butylthio , pentylthio , hexylthio , n -( methylcarbonyl ) amino , n -( ethylcarbonyl ) amino , n -( propylcarbonyl ) amino , n -( butylcarbonyl ) amino , n -( pentylcarbonyl ) amino , n -( hexylcarbonyl ) amino , and nitro ; r 3 is selected from the group consisting of hydrogen , phenyl , naphthyl , tetrahydronaphthyl , biphenyl , methoxy , ethoxy , propoxy , butoxy , pentyloxy , hexyloxy , phenylmethoxy , phenylethoxy , phenylpropoxy , phenylbutoxy , phenylpentyloxy , phenylhexyloxy , furyl , thienyl , pyrrolyl , pyrazolyl , imidazolyl , triazolyl , isoxazolyl , oxazolyl , indolyl , thiazolyl , isothiazolyl , oxadiazolyl , oxatriazolyl , dioxazole , tetrazolyl , benzodioxolyl , pyrrolidinylcarbonyl , imidazolidinylcarbonyl , piperidinylcarbonyl , piperazinylcarbonyl , morpholinylcarbonyl , thiazolidinylcarbonyl , dihydrothienylcarbonyl , dihydropyranylcarbonyl , dihydrofurylcarbonyl , dihydrothiazolylcarbonyl , and tetrahydrofurylcarbonyl , wherein r 3 is optionally substituted by one or more substituents selected from the group consisting of fluoro , chloro , bromo , iodo , phenyl , naphthyl , tetrahydronaphthyl , biphenyl , chlorophenyl , bromophenyl , fluorophenyl , dichlorophenyl , dibromophenyl , difluorophenyl , chlorobromophenyl , chlorofluorophenyl , bromofluorophenyl , methoxy , ethoxy , propoxy , butoxy , pentyloxy , hexyloxy , methyl , ethyl , propyl , butyl , pentyl , hexyl , carboxyl , phenoxy , naphthyloxy , tetrahydronaphthyloxy , biphenylyloxy , keto , and hydroxy ; r 4 , r 5 , r 6 , and r 7 are independently selected from the group consisting of hydrogen , methyl , ethyl , propyl , butyl , pentyl , hexyl , fluoro , chloro , bromo , and iodo ; and r 8 is selected from the group consisting of hydrogen , methyl , ethyl , propyl , butyl , pentyl , and hexyl , or r 2 and r 8 together with the atom to which they are both attached form a 5 - or 6 - membered cycloalkyl or heterocyclo group selected from the group consisting of cyclopropyl , cyclobutyl , cyclopentyl , cyclohexyl , pyrrolidinyl , imidazolidinyl , piperidinyl , piperazinyl , morpholinyl , thiazolidinyl , dihydrothienyl , dihydropyranyl , dihydrofuryl , dihydrothiazolyl , and tetrahydrofuryl . in another embodiment , the mch receptor antagonist is selected from a subclass of compounds of formula i represented by formula iii : w is selected from the group consisting of a bond , — c (═ o )—, alkyl , alkenyl , aryl , aralkenyl and heterocyclo ; z is selected from the group consisting of a bond , alkyl , cycloalkyl , aryl , aralkyl , heteroaryl , and heterocyclo ; r 1 is selected from the group consisting of alkyl , aryl , aralkyl , alkoxycarbonyl , heterocyclo , aryloxy , heteroaryl , and alkylphosphonate , wherein r 1 is optionally substituted by one or more substituents selected from the group consisting of alkyl , hydroxy , carboxyl , halo , cyano and keto ; r 2 is selected from the group consisting of hydrogen , alkyl , cycloalkyl , aryl , aralkyl , aroyl , heterocyclo , heteroaryl , and aralkoxy , or r 2 and r 8 together with the atom to which they are both attached form a 5 - or 6 - membered cycloalkyl or heterocyclo group , wherein r 2 or the cycloalkyl or heterocyclo group formed with r 8 is optionally substituted by one or more substituents selected from the group consisting of alkoxy , aryloxy , haloalkyl , halo , aryl , aralkenyl , aralkyl , alkyl , haloalkylaryl , haloaryloxy , alkylaryloxy , heteroaryl , cyano , hydroxy , hydroxyalkoxy , alkoxycarbonyl , alkylthio , n -( alkylcarbonyl ) amino , and nitro ; r 3 is selected from the group consisting of hydrogen , aryl , alkoxy , aralkoxy , heteroaryl and heterocyclocarbonyl , wherein r 3 is optionally substituted by one or more substituents selected from the group consisting of halo , aryl , haloaryl , alkoxy , alkyl , carboxyl , aryloxy , keto , and hydroxy ; r 4 , r 5 , r 6 , and r 7 are independently selected from the group consisting of hydrogen , alkyl , and halo ; and r 8 is hydrogen or alkyl , or r 2 and r 8 together with the atom to which they are both attached form a 5 - or 6 - membered cycloalkyl or heterocyclo group ; provided that r 3 is not aryl - or haloaryl - substituted indolyl ; in another embodiment , the mch receptor antagonist consists of compounds of formula iii , or a pharmaceutically - acceptable salt , tautomer or prodrug thereof , wherein each of r 4 , r 5 , r 6 and r 7 are hydrogen . in another embodiment , the mch receptor antagonist consists of compounds of formula iii , or a pharmaceutically - acceptable salt , tautomer or prodrug thereof , wherein each of r 4 , r 5 , r 6 and r 7 are hydrogen , and wherein w is selected from the group consisting of a bond , — c (═ o )—, lower alkyl , lower alkenyl , aryl , aralkenyl and 3 - to 10 - membered heterocyclo ; z is selected from the group consisting of a bond , lower alkyl , lower cycloalkyl , aryl , aralkyl and 3 - to 10 - membered heterocyclo ; r 1 is selected from the group consisting of lower alkyl , aryl , aralkyl , lower alkoxycarbonyl , 3 - to 10 - membered heterocyclo , aryloxy , 3 - to 10 - membered heteroaryl , and lower alkylphosphonate , wherein r 1 is optionally substituted by one or more substituents selected from the group consisting of lower alkyl , hydroxy , carboxyl , halo , cyano and keto ; r 2 is selected from the group consisting of hydrogen , lower alkyl , lower cycloalkyl , aryl , aralkyl , aroyl , 3 - to 10 - membered heterocyclo , 3 - to 10 - membered heteroaryl , and aralkoxy , or r 2 and r 8 together with the atom to which they are both attached form a 5 - or 6 - membered cycloalkyl or heterocyclo group , wherein r 2 or the cycloalkyl or heterocyclo group formed with r 8 is optionally substituted by one or more substituents selected from the group consisting of lower alkoxy , aryloxy , lower haloalkyl , halo , aryl , aralkenyl , aralkyl , lower alkyl , haloalkylaryl , haloaryloxy , alkylaryloxy , 5 - or 6 - membered heteroaryl , cyano , hydroxy , lower hydroxyalkoxy , lower alkoxycarbonyl , lower alkylthio , n -( lower alkylcarbonyl ) amino , and nitro ; r 3 is selected from the group consisting of hydrogen , aryl , lower alkoxy , aralkoxy , furyl , thienyl , pyrrolyl , pyrazolyl , imidazolyl , triazolyl , isoxazolyl , oxazolyl , indolyl , benzofuryl , thiazolyl , isothiazolyl , oxadiazolyl , oxatriazolyl , dioxazole , tetrazolyl , benzodioxolyl , and ( 3 - to 10 - membered heterocyclo ) carbonyl , wherein r 3 is optionally substituted by one or more substituents selected from the group consisting of halo , aryl , haloaryl , lower alkoxy , lower alkyl , carboxyl , aryloxy , keto , and hydroxy ; r 8 is hydrogen or lower alkyl , or r 2 and r 8 together with the atom to which they are both attached form a 5 - or 6 - membered cycloalkyl or heterocyclo group . in another embodiment , the mch receptor antagonist consists of compounds of formula iii , or a pharmaceutically - acceptable salt , tautomer or prodrug thereof , wherein each of r 4 , r 5 , r 6 and r 7 are hydrogen , and wherein w is selected from the group consisting of a bond , — c (═ o )—, methyl , ethyl , propyl , butyl , pentyl , hexyl , ethenyl , propenyl , allyl , butenyl , pentenyl , phenyl , naphthyl , tetrahydronaphthyl , biphenyl , phenylethenyl , phenylpropenyl , phenylallyl , phenylbutenyl , phenylpentenyl , pyrrolidinyl , imidazolidinyl , piperidinyl , piperazinyl , morpholinyl , thiazolidinyl , dihydrothienyl , dihydropyranyl , dihydrofuryl , dihydrothiazolyl , and tetrahydrofuryl ; z is selected from the group consisting of a bond , methyl , ethyl , propyl , butyl , pentyl , hexyl , cyclopropyl , cyclobutyl , cyclopentyl , cyclohexyl , phenyl , naphthyl , tetrahydronaphthyl , biphenyl , benzyl , diphenylmethyl , triphenylmethyl , phenylethyl , diphenylethyl , pyrrolidinyl , imidazolidinyl , piperidinyl , piperazinyl , morpholinyl , thiazolidinyl , dihydrothienyl , dihydropyranyl , dihydrofuryl , dihydrothiazolyl , and tetrahydrofuryl ; r 1 is selected from the group consisting of methyl , ethyl , propyl , butyl , pentyl , hexyl , phenyl , naphthyl , tetrahydronaphthyl , biphenyl , benzyl , diphenylmethyl , triphenylmethyl , phenylethyl , diphenylethyl , methoxycarbonyl , ethoxycarbonyl , propoxycarbonyl , butoxycarbonyl , pentyloxycarbonyl , hexyloxycarbonyl , pyrrolidinyl , imidazolidinyl , piperidinyl , piperazinyl , morpholinyl , thiazolidinyl , dihydrothienyl , dihydropyranyl , dihydrofuryl , dihydrothiazolyl , tetrahydrofuryl , phenoxy , naphthyloxy , tetrahydronaphthyloxy , biphenylyloxy , furyl , thienyl , pyrrolyl , pyrazolyl , imidazolyl , triazolyl , isoxazolyl , oxazolyl , indolyl , thiazolyl , isothiazolyl , oxadiazolyl , oxatriazolyl , dioxazole , tetrazolyl , benzodioxolyl , monomethylphosphonate , dimethylphosphonate , monoethylphosphonate , diethylphosphonate , monopropylphosphonate , and dipropylphosphonate , wherein r 1 is optionally substituted by one or more substituents selected from the group consisting of methyl , ethyl , propyl , butyl , pentyl , hexyl , hydroxy , carboxyl , fluoro , chloro , bromo , iodo , cyano and keto ; r 2 is selected from the group consisting of hydrogen , methyl , ethyl , propyl , butyl , pentyl , hexyl , cyclopropyl , cyclobutyl , cyclopentyl , cyclohexyl , phenyl , naphthyl , tetrahydronaphthyl , biphenyl , benzyl , diphenylmethyl , triphenylmethyl , phenylethyl , diphenylethyl , phenylcarbonyl , naphthylcarbonyl , tetrahydronaphthylcarbonyl , biphenylcarbonyl , pyrrolidinyl , imidazolidinyl , piperidinyl , piperazinyl , morpholinyl , thiazolidinyl , dihydrothienyl , dihydropyranyl , dihydrofuryl , dihydrothiazolyl , tetrahydrofuryl , furyl , thienyl , pyrrolyl , pyrazolyl , imidazolyl , triazolyl , isoxazolyl , oxazolyl , indolyl , benzofuryl , thiazolyl , isothiazolyl , oxadiazolyl , oxatriazolyl , dioxazole , tetrazolyl , benzodioxolyl , phenylmethoxy , phenylethoxy , phenylpropoxy , phenylbutoxy , phenylpentyloxy , and phenylhexyloxy , or r 2 and r 8 together with the atom to which they are both attached form a 5 - or 6 - membered cycloalkyl or heterocyclo group selected from the group consisting of cyclopentyl , cyclohexyl , pyrrolidinyl , imidazolidinyl , piperidinyl , piperazinyl , morpholinyl , thiazolidinyl , dihydrothienyl , dihydropyranyl , dihydrofuryl , dihydrothiazolyl , and tetrahydrofuryl , wherein r 2 or the cycloalkyl or heterocyclo group formed with r 8 is optionally substituted by one or more substituents selected from the group consisting of methoxy , ethoxy , propoxy , butoxy , pentyloxy , hexyloxy , phenoxy , naphthyloxy , tetrahydronaphthyloxy , biphenylyloxy , fluoromethyl , difluoromethyl , trifluoromethyl , chloromethyl , dichloromethyl , trichloromethyl , trichloromethyl , pentafluoroethyl , heptafluoropropyl , difluorochloromethyl , dichlorofluoromethyl , difluoroethyl , difluoropropyl , dichloroethyl , dichloropropyl , fluoro , chloro , bromo , iodo , phenyl , naphthyl , tetrahydronaphthyl , biphenyl , phenylethenyl , phenylpropenyl , phenylallyl , phenylbutenyl , phenylpentenyl , benzyl , diphenylmethyl , triphenylmethyl , phenylethyl , diphenylethyl , methyl , ethyl , propyl , butyl , pentyl , hexyl , fluoromethylphenyl , difluoromethylphenyl , trifluoromethylphenyl , chloromethylphenyl , dichloromethylphenyl , trichloromethylphenyl , trichloromethylphenyl , bis ( fluoromethyl ) phenyl , bis ( difluoromethyl ) phenyl , bis ( trifluoromethyl ) phenyl , bis ( chloromethyl ) phenyl , bis ( dichloromethyl ) phenyl , bis ( trichloromethyl ) phenyl , bis ( trichloromethyl ) phenyl , chlorophenoxy , bromophenoxy , fluorophenoxy , dichlorophenoxy , dibromophenoxy , difluorophenoxy , chlorobromophenoxy , chlorofluorophenoxy , bromofluorophenoxy , methylphenoxy , ethylphenoxy , propylphenoxy , dimethylphenoxy , diethylphenoxy , dipropylphenoxy , methylnaphthyloxy , ethylnaphthyloxy , propylnaphthyloxy , dimethylnaphthyloxy , diethylnaphthyloxy , dipropylnaphthyloxy , methylbiphenylyloxy , ethylbiphenylyloxy , propylbiphenylyloxy , dimethylbiphenylyloxy , diethylbiphenylyloxy , dipropylbiphenylyloxy , furyl , thienyl , pyrrolyl , pyrazolyl , imidazolyl , triazolyl , isoxazolyl , oxazolyl , indolyl , thiazolyl , isothiazolyl , oxadiazolyl , oxatriazolyl , dioxazole , tetrazolyl , benzodioxolyl , cyano , hydroxy , hydroxymethoxy , hydroxyethoxy , hydroxypropoxy , hydroxybutoxy , hydroxypentyloxy , hydroxyhexyloxy , methoxycarbonyl , ethoxycarbonyl , propoxycarbonyl , butoxycarbonyl , pentyloxycarbonyl , hexyloxycarbonyl , methylthio , ethylthio , propylthio , butylthio , pentylthio , hexylthio , n -( methylcarbonyl ) amino , n -( ethylcarbonyl ) amino , n -( propylcarbonyl ) amino , n -( butylcarbonyl ) amino , n -( pentylcarbonyl ) amino , n -( hexylcarbonyl ) amino , and nitro ; r 3 is selected from the group consisting of hydrogen , phenyl , naphthyl , tetrahydronaphthyl , biphenyl , methoxy , ethoxy , propoxy , butoxy , pentyloxy , hexyloxy , phenylmethoxy , phenylethoxy , phenylpropoxy , phenylbutoxy , phenylpentyloxy , phenylhexyloxy , furyl , thienyl , pyrrolyl , pyrazolyl , imidazolyl , triazolyl , isoxazolyl , oxazolyl , indolyl , thiazolyl , isothiazolyl , oxadiazolyl , oxatriazolyl , dioxazole , tetrazolyl , benzodioxolyl , pyrrolidinylcarbonyl , imidazolidinylcarbonyl , piperidinylcarbonyl , piperazinylcarbonyl , morpholinylcarbonyl , thiazolidinylcarbonyl , dihydrothienylcarbonyl , dihydropyranylcarbonyl , dihydrofurylcarbonyl , dihydrothiazolylcarbonyl , and tetrahydrofurylcarbonyl , wherein r 3 is optionally substituted by one or more substituents selected from the group consisting of fluoro , chloro , bromo , iodo , phenyl , naphthyl , tetrahydronaphthyl , biphenyl , chlorophenyl , bromophenyl , fluorophenyl , dichlorophenyl , dibromophenyl , difluorophenyl , chlorobromophenyl , chlorofluorophenyl , bromofluorophenyl , methoxy , ethoxy , propoxy , butoxy , pentyloxy , hexyloxy , carboxyl , phenoxy , naphthyloxy , tetrahydronaphthyloxy , biphenylyloxy , keto , and hydroxy ; r 8 is selected from the group consisting of hydrogen , methyl , ethyl , propyl , butyl , pentyl , and hexyl , or r 2 and r 8 together with the atom to which they are both attached form a 5 - or 6 - membered cycloalkyl or heterocyclo group selected from the group consisting of cyclopropyl , cyclobutyl , cyclopentyl , cyclohexyl , pyrrolidinyl , imidazolidinyl , piperidinyl , piperazinyl , morpholinyl , thiazolidinyl , dihydrothienyl , dihydropyranyl , dihydrofuryl , dihydrothiazolyl , and tetrahydrofuryl . in another embodiment , the mch receptor antagonist is selected from a subclass of compounds of formula i represented by formula iv : z is selected from the group consisting of a bond , alkyl , aryl , aralkyl , heteroaralkyl , and heterocyclo ; r 1 is selected from the group consisting of alkoxycarbonyl , alkyl , cycloalkyl , aralkyl , aryl , heteroaryl , and heterocyclo , wherein r 1 is optionally substituted by one or more substituents selected from the group consisting of alkyl , halo , and keto ; r 2 is selected from the group consisting of alkyl , aryl , heterocyclo , and heteroaryl , or r 2 and r 8 together with the atom to which they are both attached form a 5 - or 6 - membered cycloalkyl or heterocyclo group , wherein r 2 or the cycloalkyl or heterocyclo group formed with r 1 is optionally substituted by one or more substituents selected from the group consisting of alkoxy , alkyl , alkylaryloxy , alkylthio , aralkenyl , aralkoxy , aralkyl , aryloxy , cyano , halo , haloalkyl , haloalkylaryl , haloaryloxy , heteroaryl , hydroxy , hydroxyalkoxy , n -( alkylcarbonyl ) amino , and nitro ; r 4 , r 5 , r 6 , and r 7 are independently selected from the group consisting of hydrogen , alkyl and halo ; and r 10a , r 10b , r 10c , r 10d , and r 10e are independently selected from the group consisting of hydrogen , alkyl , hydroxy , and alkoxy ; in another embodiment , the mch receptor antagonist consists of compounds of formula iv , or a pharmaceutically - acceptable salt , tautomer or prodrug thereof , wherein z is selected from the group consisting of a bond , lower alkyl , aryl , lower aralkyl , lower heteroaralkyl , and 3 - to 10 - membered heterocyclo ; r 1 is selected from the group consisting of lower alkoxycarbonyl , lower alkyl , lower cycloalkyl , lower aralkyl , aryl , 3 - to 10 - membered heteroaryl , and 3 - to 10 - membered heterocyclo , wherein r 1 is optionally substituted by one or more substituents selected from the group consisting of lower alkyl , halo , and keto ; r 2 is selected from the group consisting of lower alkyl , aryl , 3 - to 10 - membered heterocyclo , and 3 - to 10 - membered heteroaryl , or r 2 and r 8 together with the atom to which they are both attached form a 5 - or 6 - membered cycloalkyl or heterocyclo group , wherein r 2 or the cycloalkyl or heterocyclo group formed with r 8 is optionally substituted by one or more substituents selected from the group consisting of lower alkoxy , lower alkyl , lower alkylaryloxy , lower alkylthio , lower aralkenyl , lower aralkoxy , lower aralkyl , aryloxy , cyano , halo , lower haloalkyl , lower haloalkylaryl , haloaryloxy , 3 - to 10 - membered heteroaryl , hydroxy , lower hydroxyalkoxy , n -( lower alkylcarbonyl ) amino , and nitro ; r 4 , r 5 , r 6 , r 7 , and r 9 are independently selected from the group consisting of hydrogen , lower alkyl , and halo ; and r 10a , r 10b , r 10c , r 10d , and r 10e are independently selected from the group consisting of hydrogen , lower alkyl , hydroxy , and lower alkoxy . in another embodiment , the mch receptor antagonist consists of compounds of formula iv , or a pharmaceutically - acceptable salt , tautomer or prodrug thereof , wherein z is selected from the group consisting of a bond , methyl , ethyl , propyl , t - butyl , phenyl , tetrahydronaphthyl , biphenyl , naphthyl , phenylpropyl , indolylethyl , and piperidyl ; r 1 is selected from the group consisting of methoxycarbonyl , ethoxycarbonyl , t - butoxycarbonyl , isopropyl , n - butyl , t - butyl , cyclopropyl , cyclobutyl , cyclopentyl , cyclohexyl , benzyl , phenyl , tetrahydronaphthyl , indolyl , tetrahydrofuryl , pyrrolidinyl , and morpholinyl , wherein r 1 is optionally substituted by one or more substituents selected from the group consisting of methyl , ethyl , propyl , bromo , fluoro , chloro , and keto ; r 2 is selected from the group consisting of methyl , phenyl , biphenyl , naphthyl , tetrahydrofuryl , pyrrolidinyl , morpholinyl , piperidyl , thienyl , pyrrolyl , and pyridyl , or r 2 and r 8 together with the atom to which they are both attached form a piperidyl or cyclohexyl group , wherein r 2 or the piperidyl or cyclohexyl group formed with r 8 is optionally substituted by one or more substituents selected from the group consisting of methoxy , ethoxy , methyl , ethyl , isopropyl , isobutyl , methylphenoxy , methylthio , phenylethenyl , benzyloxy , phenylethoxy , benzyl , phenoxy , cyano , fluoro , chloro , bromo , trifluoromethyl , trifluoromethylphenyl , dichlorophenoxy , imidazole , benzodioxole , hydroxy , hydroxyethoxy , n -( methylcarbonyl ) amino , and nitro ; r 4 , r 5 , r 6 , r 7 , and r 9 are independently selected from the group consisting of hydrogen , methyl , ethyl , n - propyl , isopropyl , fluoro , chloro , and bromo ; and r 10a , r 10b , r 10c , r 10d , and r 10e are independently selected from the group consisting of hydrogen , methyl , hydroxy , and methoxy . in another embodiment , the mch receptor antagonist is selected from a subclass of compounds of formula i represented by formula v : z is selected from the group consisting of a bond , alkyl , aralkyl , heteroaralkyl , and heterocyclo ; r 1 is selected from the group consisting of alkoxycarbonyl , alkyl , aralkyl , aryl , heteroaryl , and heterocyclo , wherein r 1 is optionally substituted by one or more substituents selected from the group consisting of alkyl , halo , and keto ; r 2 is selected from the group consisting of alkyl , aryl , and heteroaryl , or r 2 and r 8 together with the atom to which they are both attached form a 5 - or 6 - membered cycloalkyl or heterocyclo group , wherein r 2 or the cycloalkyl or heterocyclo group formed with r 8 is optionally substituted by one or more substituents selected from the group consisting of alkoxy , alkyl , alkylaryloxy , alkylthio , aralkenyl , aralkoxy , aralkyl , aryloxy , cyano , halo , haloalkyl , haloalkylaryl , haloaryloxy , heteroaryl , hydroxy , hydroxyalkoxy , n -( alkylcarbonyl ) amino , and nitro ; r 10a , r 10b , r 10c , r 10d , and r 10e are independently selected from the group consisting of hydrogen , alkyl , hydroxy , and alkoxy ; in another embodiment , the mch receptor antagonist consists of compounds of formula v , or a pharmaceutically - acceptable salt , tautomer or prodrug thereof , wherein z is selected from the group consisting of a bond , lower alkyl , lower aralkyl , lower heteroaralkyl , and 3 - to 10 - membered heterocyclo ; r 1 is selected from the group consisting of lower alkoxycarbonyl , lower alkyl , lower aralkyl , aryl , 3 - to 10 - membered heteroaryl , and 3 - to 10 - membered heterocyclo , wherein r 1 is optionally substituted by one or more substituents selected from the group consisting of lower alkyl , halo , and keto ; r 2 is selected from the group consisting of lower alkyl , aryl , and 3 - to 10 - membered heteroaryl , or r 2 and r 8 together with the atom to which they are both attached form a 5 - or 6 - membered cycloalkyl or heterocyclo group , wherein r 2 or the cycloalkyl or heterocyclo group formed with r 8 is optionally substituted by one or more substituents selected from the group consisting of lower alkoxy , lower alkyl , lower alkylaryloxy , lower alkylthio , lower aralkenyl , lower aralkoxy , lower aralkyl , aryloxy , cyano , halo , lower haloalkyl , lower haloalkylaryl , haloaryloxy , 3 - to 10 - membered heteroaryl , hydroxy , lower hydroxyalkoxy , n -( lower alkylcarbonyl ) amino , and nitro ; r 10a , r 10b , r 10c , r 10d , and r 10e are independently selected from the group consisting of hydrogen , lower alkyl , hydroxy , and lower alkoxy . in another embodiment , the mch receptor antagonist consists of compounds of formula v , or a pharmaceutically - acceptable salt , tautomer or prodrug thereof , wherein z is selected from the group consisting of a bond , methyl , ethyl , propyl , t - butyl , phenylpropyl , indolylethyl , and piperidyl ; r 1 is selected from the group consisting of methoxycarbonyl , ethoxycarbonyl , t - butoxycarbonyl , isopropyl , n - butyl , t - butyl , benzyl , phenyl , tetrahydronaphthyl , indolyl , tetrahydrofuryl , pyrrolidinyl , and morpholinyl , wherein r 1 is optionally substituted by one or more substituents selected from the group consisting of methyl , chloro , and keto ; r 2 is selected from the group consisting of methyl , phenyl , biphenyl , naphthyl , thienyl , pyrrolyl , and pyridyl , or r 2 and r 8 together with the atom to which they are both attached form a piperidyl or cyclohexyl group , wherein r 2 or the piperidyl or cyclohexyl group formed with r 8 is optionally substituted by one or more substituents selected from the group consisting of methoxy , ethoxy , methyl , ethyl , isopropyl , isobutyl , methylphenoxy , methylthio , phenylethenyl , benzyloxy , phenylethoxy , benzyl , phenoxy , cyano , fluoro , chloro , bromo , trifluoromethyl , trifluoromethylphenyl , dichlorophenoxy , imidazole , benzodioxole , hydroxy , hydroxyethoxy , n -( methylcarbonyl ) amino , and nitro ; r 10a , r 10b , r 10c , r 10d , and r 10e are independently selected from the group consisting of hydrogen , methyl , hydroxy , and methoxy . in another embodiment , the compound of formula i is selected from the group of compounds listed in table 1 . the compounds of formulas i , ii , iii , iv , and v are mch receptor antagonists , as demonstrated by the ligand binding assays described hereinbelow . mch receptor antagonist activity has been correlated with pharmaceutical activity for the treatment of eating disorders such as obesity and hyperphagia , and diabetes . compounds of formula i exhibit good activity in standard in vitro mch calcium mobilization assays and / or receptor binding assays , specifically in the assays described hereinbelow , see examples 6 and 7 . generally , compounds of formula i have a k i of about 10 μm or less , preferably about 1 μm or less , more preferably about 100 nm or less , or even more preferably about 10 nm or less , as determined by a standard in vitro mch receptor mediated calcium mobilization assay as exemplified by example 6 , hereinbelow . generally compounds of formula i are mch receptor antagonists and exhibit ic 50 values of about 10 μm or less , preferably about 1 μm or less , more preferably about 100 nm or less , or even more preferably about 10 nm or less , as determined by a standard in vitro mch receptor binding assay such as is described hereinbelow in example 7 . preferably , the mch receptor antagonists of formula i bind specifically , and still more preferably with high affinity , to mch receptors . the compounds described herein may be synthesized according to the following procedures of schemes 1 - 3 , wherein a , w , x , z , and r 1 - r 8 are as defined for formulas i - v , above . compounds of formula i can be prepared by the methods of generic scheme 1 . coupling of carbonyl compounds such as aldehydes or ketones 1 with amines 2 and compounds 3 ( where a ′ is a ring precursor ) forms an intermediate precursor that is then cyclized to form the compounds 4 of formula i . compounds of formula ii - v can be prepared by general scheme 2 . using a modified ugi synthesis , [( a ) ugi , i ., angew . chem . int . ed . engl . 1962 , 1 , 8 ; ( b ) ugi , i . and steinbruckner , c ., chem . ber . 1961 , 94 , 734 ; ( c ) ugi , i . et al ., endeavor 1994 , 18 , 115 ; ( d ) domling , a ., combinatorial chemistry & amp ; high throughput screening 1998 , 1 , 1 ] carbonyl compounds such as aldehydes or ketones 1 with piperazines 5 and isocyanides 6 forms an intermediate precursor that is cyclized , such as with tmsn 3 , to form tetrazoles 7 . isoxazoles compounds can be prepared by general scheme 3 . cycloaddition reactions of substituted propynyl piperazines 8 , such as with nitrile oxide , form isoxazoles 9 . benzaldehyde ( 102 ml , 1 mmol ), trans - cinnamylpiperazine ( 202 mg , 1 mmol ), 2 , 6 - dimethylphenylisocyanide ( 131 mg , 1 mmol ), and tmsn 3 ( 132 ml , 1 mmol ) were added to 40 ml methanol in order of their participation in the ugi reaction . after 18 hours the solution was concentrated to yield a colorless oil . the product was purified by fcc ( 2 % meoh / chcl 3 ) to yield a colorless oil . biphenylcarboxaldehyde ( 182 mg , 1 mmol ), tmsn 3 ( 132 ml , 1 mmol ), 2 , 6 - dimethylphenylisocyanide ( 131 mg , 1 mmol ) and trans - cinnamylpiperazine ( 202 mg , 1 mmol ) were added to 40 ml methanol in order of their participation in the ugi reaction . after 18 hours , the solution was concentrated to yield a colorless oil , which was purified by fcc ( 1 % meoh / chcl 3 ). because of rapid elution of product in 1 % meoh / chcl 3 , only one fraction was pure . other fractions were combined and evaporated . the product was a light yellow oil , which was briefly a white solid during evaporation . the compound of example 2 ( 168 mg , 0 . 359 mmol ) was dissolved in 5 ml dcm and 1 . 0 m hcl / ether ( 0 . 72 ml ) was added . after 1 hour , the resulting white precipitate was filtered . amine ( 0 . 93 g , 5 mmol ), aldehyde ( 0 . 51 ml , mmol ), tmsn 3 ( 0 . 66 ml , 5 mmol ) and isocyanide ( 0 . 66 g , mmol ) were dissolved in 200 ml meoh in order of participation in the ugi reaction . after 4 days , the reaction solution was about 75 % evaporated , and the white precipitate was filtered , washed with cold meoh , and air dried . the compound of example 4 ( 37 mg ) and 2 ml 10 % tfa / dce were shaken for 18 hours and concentrated to give a colorless oil . the product was purified by lc . human embryonic kidney cells ( 293 total ) expressing either human , rat , or mouse mch receptor were harvested from 150 mm culture dishes using pbs . spinning at 1500 rpm for 2 minutes initially pelleted cells . the resulting pellet was then homogenized in 15 ml ice cold sucrose buffer ( 25 mm hepes , 0 . 3 m sucrose , ph 7 . 4 ) with a motorized , glass fitted , teflon ® homogenizer . the homogenate was centrifuged at 48 , 000 × g at 4 ° c . for 10 minutes , resuspended in 15 ml assay buffer ( 25 mm hepes , 10 mm mgcl 2 , 0 . 2 % bsa , 0 . 1 mg / ml sti , 0 . 1 mg / ml pefabloc ®, 1 μm phosphoramidon , ph 7 . 4 ) with a tissue - tearor ® ( biospec products ) and centrifuged again at 48 , 000 × g for 10 minutes . the pellet was homogenized for a third time in 15 ml assay buffer using the tissue - tearor ® and again centrifuged at 48 , 000 × g for 10 minutes . the resulting pellet was resuspended in assay buffer at a wet weight concentration of 10 - 20 mg / ml . pharmacological analyses were conducted using either a ht - ps100 device ( axiom biotechnologies , san diego , calif . ), which provides high - resolution dose - response fluorometric measurements of [ ca ++ ] i mobilization , or using a flipr ® device ( molecular devices , sunnyvale , calif .). materials : hek 293 cells were stably transfected with the rat mch1 receptor and maintained under g418 antibiotic pressure . ht - ps100 assay buffer consisted of physiological saline solution ( 145 mm nacl , 5 . 4 mm kcl , 1 . 0 mm nah 2 po 4 , 1 . 8 mm cacl 2 , 0 . 8 mm mgso 4 , 15 . 0 mm hepes , ph 7 . 4 , 11 . 2 mm glucose )+ 50 μm pluronic - f127 . mch peptide ( amgen , inc .) was reconstituted in assay buffer and served as the positive agonist control for all experiments . test compounds were prepared as 10 mm stocks in 100 % dmso and diluted to a top end working concentration of 100 μm in 96 well plates . methods : hek 293 stably expressing mch1r were maintained in dulbeco &# 39 ; s modified eagle &# 39 ; s medium ( gibco / life technologies , rockville , md .) supplemented with 2 mm glutamine and 10 % dialyzed fetal bovine serum ( hyclone , logan , utah ) at 37 ° c ., 5 % co 2 . cells were harvested by 10 ′ treatment with versene ( gibco / life technologies ) followed by trituration , washing twice with cold ( 4 ° c .) hybridoma medium ( serum / protein free , with l - glutamine , sodium bicarbonate , mops buffer ) ( sigma - aldrich corp , st . louis , mo .) and resuspended at 2 × 10 6 cells / ml in the same medium . the resuspended cells were loaded with the fluorescent calcium indicator fura - 2 by incubating with fura - 2am ( molecular probes , eugene , oreg .) at 1 . 6 μm for 60 ′ at room temperature . the loaded cells were then washed twice with hybridoma medium , adjusted to 2 × 10 5 cells / ml and kept at ambient temperature in a spinner flask under gentle stirring for up to 6 hours during the experiment . receptor - stimulated intracellular calcium responses were detected in the flow - through detector cuvette of the ht - ps100 by monitoring increases in the ratio of fura - 2 fluorescence intensities r 340 / 380 measured at alternating 340 / 380 nm excitation and 510 nm emission . preliminary static experiments , conducted to determine the kinetics of mch1r &# 39 ; s dose response to mch peptide , indicated the optimum time point to capture the maximum ca ++ transients was 30 s . no interference with dmso was seen up to 1 %. based on these observations , subsequent experiments were conducted on the ht - ps100 to generate high resolution dose response curves , characterize agonist / antagonist properties , and evaluate antagonist potencies via schild experiments . during ht - ps100 validation , reproducible ec 50 s for mch of 10 nm were generated within a broad range of cell passage and harvest density . ht - ps100 gradient generation was calibrated with a standardized stock of fluorescein . test compounds were screened for mch1r activity in the ht - ps100 for both agonist and antagonist action . agonist mode challenges were conducted at a maximum gradient concentration of 100 μm . antagonist activity was tested by 30 s pre - incubation of cells at a compound concentration of 100 μm , with subsequent introduction of mch at a concentration 5 - fold of ec 50 as determined in preliminary experiments . compounds that showed inhibition of the mch - induced ca ++ response were automatically tagged for re - interrogation , ic 50 generation , and schild analysis . schild experiments were conducted on the ht - ps100 for selected compounds by 30 s pre - incubation of cells with antagonist compounds prior to administering mch peptide . several fixed concentrations of antagonist compounds were prepared in 10 - fold increments , and presented to the cells 30 s before introducing a gradient of increasing mch concentration . values for compound pa 2 were calculated by linear regression of log ( dr − 1 ) mch ec 50 as a function of log ( antagonist concentration ), where dr is the dose ratio of mch ec 50 values determined in the presence and absence of antagonist . the following compounds had k i values of 100 nm or less in the ht - ps100 assay : compound nos . 1 , 4 , 48 , 53 , 55 , 56 , 57 , 60 , 61 , 62 , 64 , 70 , 76 , 77 , 78 , 79 , 82 , 83 , and materials : pharmacological analysis was conducted using a flipr ® device ( molecular devices , sunnyvale , calif .). chok1 - gqi cells were stably transfected with the rat mch1 receptor and maintained under g418 antibiotic pressure . flipr ® assay buffer consisted of phenol red - free dmem + 2 . 5 mm probenecid . mch peptide ( amgen , inc .) was reconstituted in assay buffer and served as the positive agonist control for all experiments . test compounds were prepared as 10 mm stocks in 100 % dmso and diluted to a top end working concentration of 10 μm in 96 well black , flat bottom , collagen - i coated plates ( becton dickinson , bedford , mass .). methods : chok1 - gqi cells stably expressing mch1r were maintained in dulbeco &# 39 ; s modified eagle &# 39 ; s medium ( gibco / life technologies , rockville , md .) supplemented with 2 mm glutamine and 10 % dialyzed fetal bovine serum ( hyclone , logan , utah ) at 37 ° c ., 5 % co 2 . cells were harvested by 10 ′ treatment with versene ( gibco / life technologies ) followed by trituration , washing twice with cold ( 4 ° c .) hybridoma medium ( serum / protein free , with l - glutamine , sodium bicarbonate , mops buffer ) ( sigma - aldrich corp , st . louis , mo .) and replated onto 96 well black , flat bottom , collagen - i coated plates to a density of 10 , 000 cells / well . the cells were then loaded with the fluorescent calcium indicator fura - 2 ( molecular probes , eugene , oreg .) at 1 . 6 μm for 60 ′ at room temperature . the loaded cells were then washed twice with 90 μl / well of wash buffer ( 1 × hbss , 20 mm hepes , 2 . 5 mm probenecid ). receptor - stimulated intracellular calcium responses were detected using flipr ® by monitoring increases in the fura - 2 fluorescence response . test compounds were screened for mch1r activity in the flipr ® for both agonist and antagonist action . agonist mode challenges were conducted at a maximum gradient concentration of 1 μm . antagonist activity was tested by 10 min pre - incubation of cells at a compound concentration of defined to be 300 × the ec 50 of mch ( typically 1 μm ), with subsequent introduction of mch at a concentration 5 - fold of ec 50 as determined in preliminary experiments . compounds that showed inhibition of mch induced mch1r dependant ca ++ responses were automatically tagged for re - interogation , ic 50 generation , and schild analysis . schild experiments were conducted on the flipr ® for selected compounds by co - administering antagonist compounds together with mch peptide . several fixed concentrations of antagonist compounds were prepared in 10 - fold increments , and presented to the cells in a gradient of increasing mch concentration . values for compound pa 2 were calculated by linear regression of mch ec 50 s as a function of antagonist concentration . the following compounds had k i values of 100 μm or less in the rmch flipr ® assay : compound nos . 1 , 4 , 11 , 12 , 20 , 48 , 53 , 55 , 56 , 57 , 60 , 61 , 62 , 64 , 70 , 76 , 77 , 78 , 79 , 82 , 83 , 84 , 86 , 87 , 92 , 133 , 134 , 135 , 143 , 144 , 145 , 145 , 147 , 148 , 150 , and 151 . of these , compound nos . 11 and 56 had k i values of 100 nm or less in this assay . the following compounds had k i values of 100 μm or less in the hmch flipr ® assay : compound nos . 1 , 4 , 20 , 48 , 53 , 55 , 56 , 57 , 60 , 61 , 62 , 70 , 77 , 78 , 79 , 82 , 83 , 84 , 86 , 87 , 133 , 134 , 135 , 143 , 144 , 145 , 147 , 148 , 150 , and 151 . of these , compound nos . 4 , 48 , 53 , 55 , 56 , 70 , 79 , and 82 had k i values of 100 nm or less in this assay . binding assays were determined as described below using mouse , rat or human mch 1 receptors ( mmch1r , rmch1r , and hmch1r , respectively ) expressed in hek 293 ; ic 50 values were calculated . binding assays were performed in 96 - well u - bottom plates . membranes ( 100 μg tissue ) were incubated at 30 ° c . for 90 minutes in assay buffer with various peptides in the presence of 0 . 2 nm 125 i native - mch ( perkin - elmer life sciences , boston , mass .) in 100 μl total volume . non - specific binding was assessed in the presence of 1 μm cold native - mch . the reaction was terminated by rapid filtration through unfilter - 96 gf / c glass fiber filter plates ( filtermate ® 196 harvester , packard instrument co ., meriden , conn .) pre - soaked in pbs / 0 . 5 % bsa , followed by three washes with 300 μl ice - cold water . bound radioactivity was determined using a topcount ® microplate scintillation and luminescence counter ( packard instrument co ., meriden , conn .). nonlinear regression analyses of drug concentration curves were performed using graphpad prism ® ( graphpad software , inc ., san diego , calif .). the following compounds had ic 50 values of 100 μm or less in the rmch assay : compound nos . 1 , 4 , 11 , 12 , 14 , 15 , 19 , 20 , 21 , 22 , 24 , 26 , 27 , 28 , 29 , 29 , 30 , 31 , 33 , 35 , 36 , 37 , 38 , 39 , 46 , 48 , 52 , 53 , 55 , 56 , 57 , 58 , 60 , 61 , 62 , 63 , 64 , 68 , 69 , 70 , 71 , 72 , 73 , 74 , 75 , 76 , 77 , 78 , 79 , 80 , 81 , 82 , 83 , 84 , 92 , 99 , 118 , 122 , 123 , 124 , 125 , 126 , 127 , 128 , 129 , 130 , 131 , 133 , 134 , 135 , 136 , 137 , 138 , 139 , 140 , 142 , 143 , 144 , 145 , 147 , 148 , 150 , 151 , 154 , 156 , 162 , 163 , and 164 . of these , compound nos . 1 , 11 , 56 , 70 , 79 , 84 , 129 , 134 , 136 , 137 , 138 , 139 , 140 , 142 , 144 , and 163 had ic 50 values of 100 nm or less in the rmch assay . the following compounds had ic 50 values of 100 μm or less in the hmch assay : compound nos . 1 , 4 , 11 , 12 , 14 , 15 , 16 , 17 , 19 , 20 , 21 , 22 , 26 , 29 , 30 , 31 , 33 , 35 , 36 , 37 , 38 , 39 , 42 , 46 , 48 , 52 , 53 , 55 , 56 , 57 , 58 , 60 , 61 , 62 , 63 , 64 , 66 , 67 , 68 , 69 , 70 , 71 , 72 , 73 , 74 , 76 , 77 , 78 , 79 , 80 , 81 , 82 , 83 , 84 , 85 , 86 , 87 , 91 , 92 , 133 , 134 , 135 , 142 , 143 , 144 , 145 , 147 , 148 , 150 , 151 , and 164 . of these , compound nos . 1 , 4 , 20 , 55 , 56 , 62 , 64 , 70 , 76 , 77 , 78 , 84 , 134 , 142 , and 144 had ic 50 values of 100 nm or less in the hmch assay . in view of the above , it will be seen that the several objects of the invention are achieved . the above description of the embodiments and examples are intended only to acquaint others skilled in the art with the invention , its principles , and its practical application , so that others skilled in the art may adapt and apply the invention in its numerous forms , as may be best suited to the requirements of a particular use . the present invention , therefore , is not limited to the above embodiments , and may be variously modified . with reference to the use of the word ( s ) “ comprise ” or “ comprises ” or “ comprising ” or “ including ” or “ having ” in the above description and / or in the following claims , it should be noted that unless the context requires otherwise , those words are used on the basis and clear understanding that they are to be interpreted inclusively , rather than exclusively , and that each of those words is to be so interpreted in construing the above description and / or the following claims . when introducing elements of the present invention or the preferred embodiment ( s ) thereof , the articles “ a ,” “ an ,” “ the ,” and “ said ” are intended to mean that there are one or more of the elements . in view of the above , it will be seen that the several objects of the invention are achieved and other advantageous results attained . as various changes could be made in the above compounds and methods without departing from the scope of the invention , it is intended that all matter contained in the above description shall be interpreted as illustrative and not in a limiting sense . the entire texts of all u . s . patents and other references cited herein are hereby incorporated by reference into this patent .