the present invention relates to compounds of the general formula which are inhibitors of purine nucleoside phosphorylases , purine phosphoribosyltransferases , 5 ′- methylthioadenosine phosphorylases , 5 ′- methylthioadenosine nucleosidases and / or nucleoside hydrolases . the invention also relates to the use of these compounds in the treatment of diseases and infections including cancer , bacterial infections , protozoal infections , and t - cell mediated disease and to pharmaceutical compositions containing the compounds .