although   ligands having oxygen and nitrogen as donor atoms are by far the most 
 extensively studied , interest in sulfur donor chelating agents has grown over 
 the years   and the number of chemical studies in this area has increased considerably .
interest in complexes of these ligand systems now covers several areas , ranging from general considerations of the effect of sulfur and electron delocalization in transition metal complexes to potential biological 
 activity and practical application [ 24 ] . 
 
the aim of the present work is to synthesize new thiocarbohydrazone ligand , and to study its coordination behavior with co(ii ) , ni(ii ) , cu(ii ) , and zn(ii ) ions .
n , n-thiocarbohydrazide condenses easily with two molecules of carbonyl compounds viz . , isatin , on the nh2 and nh2 hydrazine amino groups to produce the desired ligand shown in figure 1 .
the tautomerism in this ligand and also the well - known tendency of oxygen and sulfur donors to act as bridging sites [ 5 , 6 ] allows various structural possibilities for the corresponding metal complexes . 
 
a   considerable number of metal complexes are now known to possess antitumor activity   .
there are reports that 
 sulphur - containing ligands   and platinum complexes of sulphur - containing amino acids were found to have inhibitory action against tumors . 
 
however , since the class of sulphur - containing compounds such as thiosemicarbazones , an structural analogue of the thiocarbohydrazone , have been reported to have anticancer activity owing to the specific and unique 
 properties of their metal chelate , it is suggested    that the present compounds , being similar in structure and character , may be acting by virtue of their chelating properties at the cellular level thereby exerting their anticancer activity .
hence , it was considered worthwhile to subject the 
 presently studied complexes for evaluation of their anticancer activity . 
 
the antimicrobial properties of metals have been recognized for centuries and have represented some of the most fundamental breakthroughs in medicinal history .
many studies stressed the role of metal ions in important biological processes , whereas the inorganic pharmacology started to be an important field with more than 25 inorganic compounds , being used in therapy as antibacterial , antiviral , and anticancer drugs [ 12 , 13 ] .
kirschner et al .   have suggested that the transfer of the metal ion from the ligand to the cancer - associated viruses was an important mechanism for designing new anticancer therapies . the inverse process ,
that is , coordinating a metal ion from 
 an important biomolecule , such as , for instance , a zinc finger protein , has recently been used to design novel antiviral therapies , targeted against human immunodeficiency ( hiv ) and human papilloma virus ( hpv ) infections .
we have already drawn attention to the strong relationship between metals or their complexes [ 1618 ] , and 
 antibacterial , antitumour , and anticancer   activities .
a number of in vivo studies have indicated   that biologically active compounds become more bacteriostatic and carcinostatic upon chelation . 

the metal content of the complexes were estimated after decomposition with mixture of hcl and hclo4 by gravimetric method ( copper and nickel ) and edta titration method ( cobalt and zinc ) .
magnetic susceptibility of complexes were 
 measured at room temperature on a faraday balance using hg[co(scn)4 ] as a calibrant .
electronic spectra were recorded using varian cary 50 bio uv - visible spectrophotometer in dmso .
the ir spectra of ligand and its complexes were recorded as kbr pellets in the region 4000400  cm on nicolet 170 sx ft - ir spectrometer .
the h - nmr spectra of ligand and its zinc ( ii ) complex were recorded in dmso - d6 on bruker 300  mhz spectrometer using tms as an internal standard .
the cyclic voltammetry 
 experiments were carried out with a three - electrode apparatus using a chi1110a electrochemical analyzer ( usa ) .
the epr spectra of copper ( ii ) complexes were recorded at room temperature on varian e-4 x - band spectrometer using tcne as g - marker .
conductivity measurements were made on 10  m solutions of complexes in dmso using elico - cm82 
 conductivity bridge provided with a cell having cell constant 0.51 . 
 
a solution of isatin 5.8  g ( 0.04  mol ) in ethanol ( 30  ml ) was added drop wise to a refluxing solution of thiocarbohydrazide 2.1  g ( 0.02  mol ) in the same solvent ( 40  ml ) .
few drops of glacial acetic acid were added to the reaction mixture and was refluxed for 2  hours . at the end of the reaction , monitored by tlc ( n - hexane / ethyl acetate 2:3 ) ,
a yellow - orange powder was filtered and washed with warm ethanol and then with diethyl ether .
the complex was prepared by the addition of ethanolic solution of metal ( ii ) chloride or aqueous ethanolic solution of metal ( ii ) acetates ( 0.003  mol ) with constant stirring to the corresponding amount of the ligand ( 0.003  mol ) in the same solvent .
the product was filtered off , washed several times with ethanol , and dried in vacuum over p2o5 
 ( scheme 2 ) . 
 
the   brine shrimp lethality test was used to predict the presence of cytotoxic activity . 

the brine shrimp eggs were hatched in artificial sea water at room temperature under constant aeration for 48  hours . after hatching ,
10 larvae were placed in a vial containing 5  ml of artificial sea water .
a drop of dry yeast suspension ( 3  mg in 5  ml sea water ) was added to each vial as food for shrimps .   
test compounds in different concentrations ( 10 , 100 , and 1000  ppm ) were added to the vials before making up the final volume to 5  ml with sea water .
the experiments were done in triplicate and mean of three readings was taken as final result .
after 24 hours , the survivors were counted using a 3x magnifying glass , and the percent deaths and lc50 ( lethal concentration for half the population ) values wear calculated by using finney computer program .
ehrlich ascitic carcinoma ( eac ) , to induce cancer in animal model 
 ( mice ) were obtained from ( amala cancer research 
 center , amala nagar , kerala , india . )  
the cells were maintained as ascites tumor in swiss albino mice by 
 intraperitoneal inoculation of 1106 viable cells .
six - to - eight week old female swiss albino mice ( 255  g body weight ) were selected 
 from ( central animal facility , manipal academy of higher education , manipal , karnataka , india . )
the animals were acclimatized to the experimental room having temperature 232c , controlled humidity conditions , and 12:12 hour light and dark cycle .
the mice were housed in sterile polypropylene cages containing sterile paddy husk as 
 bedding material with a maximum of 4 animals in each cage .
the mice were fed on autoclaved standard mice food pellets ( hindustan lever ) and had access to water   ad libitum .
the animal experiments were performed according to the rules and regulations of the institutional animal ethics committee ( iaec ) . 
  the   compounds
( dose 50  mg / kg ) , suspended in 4  % gum acacia ( gummy exudates from the 
 bark of acacia senegal , an inactive substance , which forms a mucilage with water ) were administrated 
 intraperitoneally , daily once for 5 days from day 10 posttumor inoculation in a volume of 0.1  ml/10  g mouse .
the eac cells that were collected from the animal peritoneum by aspiration were washed repeatedly with phosphate buffered saline ( pbs ) to free it from blood .
the viability of the cells was checked in a haemocytometer . the cells ( 1106 in 0.1  ml pbs ) were incubated in clean sterile tubes with the test compounds ( 0.01  ml , 150  g / ml in dimethyl sulfoxide ( dmso ) ) for 3 hours at 37c , keeping the final volume at 0.9  ml . the volume of dmso was pegged below 0.1  % of the total volume .
the live ( without stain ) and dead ( with blue stain ) cells were counted using haemocytometer and percent cell death was calculated using the formula : 
 ( 1)%cytotoxicity=100(tdeadcdead)/ttot , 
 where tdead is the number of dead cells in the treated group , cdead is that in the 
 control group , and ttot is the total number of dead and live cells in the test 
 compound treated group .
antitumor activity of the compounds was determined using ehrlich ascites carcinoma ( eac ) tumor model in mice .
( ( a ) normal mice for 
 hematological studies , ( b ) tumor - bearing mice , ( c ) 
 tumor - bearing mice treated with one dose of cisplatin , ( d ) 
 tumor - bearing mice groups treated with compounds for 5 days . ) .
the ascitic carcinoma - bearing mice ( donor ) were used for the study , 15 days after tumor transplantation . the ascitic fluid
tumor viability was determined by tryphan blue exclusion test and cells were counted using haemocytometer .
the ascitic fluid 
 was suitably diluted in normal saline to get a concentration of 10 cells / ml of tumor cell suspension .
the mice were weighed on the day of tumor inoculation and then once in three days thereafter .
the compounds were administered from tenth day for 5 days intraperitoneally . after the administration of last dose followed by 18-hour fasting , six mice from 
 each group were sacrificed for the study of antitumor activity and hematological parameters .
the remaining animals in each of the groups were kept to check the mean survival time ( mst ) of the tumor - bearing hosts .
antitumor 
 effects of compounds were assessed by observation of following parameters . 
  upon   weighing the animal on the day of inoculation and after once in three days in the postinoculation period , the percentage increase in weight was calculated using the formula : % increase in weight = [ ( animal weight on respective 
 day / animal weight on day-0 ) 1 ] 100 .
total number of days an animal survived from the day of tumor inoculation was counted .
the percentage increase in lifespan ( %  ils ) was 
 calculated using the formula : ils ( % ) = [ ( mean survival time of treated group / mean survival time of control group ) 1]100 . 
  in order to detect the influence of compounds on the hematological status of eac - bearing 
 mice , comparison was made amongst groups of mice for each compound on the fourteenth day 
 after transplantation .
blood was drawn from each mouse from retro orbital under ether anesthesia and the white blood cell ( wbc ) total count , differential leukocyte counts , red blood cell ( rbc ) total count , and hemoglobin content 
 parameters were evaluated . 
 
results were analyzed by one - way anova by scheffe 's posthoc test using spss computer package . 

antibacterial activity of test compounds was assessed against bacillus cirroflgellosus by 
 cup - plate method . 
 
the definite volumes of peptone ( 0.5  % ) , yeast extract ( 0.15  % ) , beef extract ( 0.15  % ) , 
 sodium chloride ( 0.35  % ) , dipotassium phosphate ( 0.36  % ) , and potassium 
 dihydrogen phosphate ( 0.13  % ) were dissolved in distilled water and the 
 ph was adjusted to 7.2 .
one day prior to these tests , inoculation of above bacterial cultures was made in the 
 inoculation medium as described above and incubated at 37c for 1824 hours .
base - layer medium was prepared by dissolving definite volumes of peptone ( 0.6  % ) , yeast 
 extract ( 0.3  % ) , beef extract ( 0.13  % ) , and agar ( 2.5  % ) in distilled water .
the ph of this medium was also adjusted to 7.2 and sterilized by autoclaving at 15 p.s.i . for 20 minutes . 
 
each test compounds ( 5  mg ) was dissolved in dimethylformamide ( 5  ml ) to give a solution 
 of 1000  g / ml . out of this
base - layer was obtained by pouring about 1015  ml of base - layer medium into each sterilized petridishes and were allowed to attain room temperature . this solid layer after attaining room temperature is called 
 base - layer . over - night
grown sub - cultures of bacteria were mixed with seed 
 layer medium and immediately poured into petridishes containing the base - layer 
 and then allowed to attain room temperature . 
 
the cups were made by scooping out nutrient agar with a sterile cork borer . to these 
 cups , solutions of test compounds ( 0.1  ml )
were added using sterile pipettes 
 and these plates were subsequently incubated at 37c for 36 hours .
the zone of 
 inhibitions , if any , was measured in mm for the particular compound .
norfloxacin 
 was used as positive - control and solvent - control was also used to know the 
 activity of the solvent .
fungicidal activity of test compounds was assessed against aspergillus niger and candida albicans by cup - plate method . 
 
inoculation medium was prepared by dissolving definite volumes of peptone ( 1.0  % ) , yeast 
 extract ( 0.6  % ) , sodium chloride ( 0.5  % ) , potassium dihydrogen phosphate 
 ( 0.3  % ) , and glucose ( 1.0  % ) in distilled water .
the ph of the medium was adjusted to 6.0 and sterilized at 15 p.s.i . for 20 minutes .
one day before testing , inoculation of fungi , were made in the inoculation medium and 
 incubated at 37c for 1824 hours .
the definite volumes of peptone ( 4.0  % ) , yeast extract ( 0.6  % ) , sodium chloride 
 ( 0.5  % ) , potassium dihydrogen phosphate ( 0.3  % ) , glucose ( 1.0  % ) , and agar ( 2.5 
 % ) were dissolved in distilled water .
the ph of the medium was adjusted 
 to 6.0 and sterilized by autoclaving at 15 p.s.i . for 20 minutes .
the definite volumes of peptone ( 4.0  % ) , yeast extract ( 0.6  % ) , sodium chloride 
 ( 0.5  % ) , potassium dihydrogen phosphate ( 0.3  % ) , glucose ( 1.0  % ) and agar ( 2.5  % ) were dissolved in distilled water .
the ph of medium was adjusted to 
 6.0 and was sterilized separately by autoclaving at 15 p.s.i . for 20 minutes . 
 
the method of testing for antifungal activity is the same as that adopted for assessing antibacterial activity .
grisofulvin was used as a positive control and solvent content was also used to know the activity of the solvent .
the ligand was synthesized by acid catalysed condensation of thiocarbohydrazide with the 
 isatin in ethanol ( scheme 1 ) ; the condensation proceeds , as usual , selectively on the carbonyl in position 3 in the isatin ring .
the ligand is characterized by means of ir , h nmr spectroscopy , and elemental analysis . in the h nmr spectrum of the ligand
there is only one set of signals for the aromatic protons , while the nh of isatin and nh of hydrazone give rise to two different singlets in the 1114  ppm range .
the presence of the nh groups is confirmed in the ir spectra by a broad peak around 3200  cm ; the c = o groups absorb near 1690  cm . 
 
the reactions between the metal(ii ) chlorides / acetates and the ligand 
 ( 1:1 ) lead to 
 formation of complexes , ( scheme 1 ) .
the growth of single crystals of 
 these complexes for x - ray studies is very difficult owing to their amorphous 
 nature and we were unsuccessful in our attempts to do so .
the elemental 
 analyses of these complexes reveal 1:1 ligands to metal stoichiometry in case 
 of cu(ii ) and ni(ii ) .
copper forms the complexes of the type 
 [ cu(l)cl]2h2o with cu(ii ) chloride and    [ cu(l)oac]2h2o   in case of cu(ii ) acetate .
nickel forms [ ni(l)cl ] 
 type complex with ni(ii ) chloride and [ ni(l)oac ]   with acetate .
both cobalt and zinc chloride 
 and acetates form the same complexes with the 2:1 ligand to metal stoichiometry , with general formula , [ m(l2 ) ] .
the 
 complexes are found to be soluble in dimethylformamide , dimethylsulphoxide , and 
 acetonitrile but insoluble in common organic solvents such as ethanol , 
 methanol , benzene , acetone , and so forth .
the composition and coordination geometry of 
 these complexes has been established on the following 
 experimental observations .
the molar conductance values in 
 dimethylsulphoxide fall in the expected range ( 1032 cmmol ) of 
 nonelectrolytes .
the complexes were analyzed for metal , nitrogen , carbon , 
 hydrogen and chloride .
the analytical , conductivity , and magnetic moment data of 
 the complexes are summarized in table 1 . 
  the ir spectral data of the ligand n
, n-bis(isatin)thiocarbohydrazone shows a sharp 
 absorption band around 3200  cm attributed to the presence of nh group and a very strong band near 1690  cm assigned to ( c = o ) stretching vibration .
the band at 1619  cm is assigned to the azomethine ( c = n ) stretching .   
the ir spectral assignment of metal complexes was aided by comparison with the 
 vibration frequencies of the free ligand .
the broad band that appears in the range of 31603210  cm is assigned to the stretching vibration of ring ( nh ) .
there is only one band in the   v(c = o ) region and it does not differ significantly from the band in the ligand ; suggesting that the carbonyl groups are weakly involved in the coordination .
although there is coordination of nitrogen atom of the azomethine group to the central metal atom , we could not appreciably conclude from the ir data , because of remaining uncoordinated azomethine group that absorbs at a just lower frequency near 1614 - 1615  cm as compared to their ligand .
the band corresponding to the stretching vibration of the c = s group appears at 12001194  cm in the ligand .
the absence of this band in the ir spectra of the metal complexes can be explained by the tautomerism of the c = s group with one of the imino groups to form the csh and the coordination of sulphur after deprotonation . the band that appears in the range of 690750  cm is 
 thus assigned to the    ( cs ) in the ir spectra of the metal complexes .
the ir spectra of the complexes derived from copper and nickel acetate , show an absorption bands in the region 16651650  cm which is assigned to   8 ( co ) antisymmtric stretching of acetate group and another in the region 12971258  cm and which can be assigned to   3 ( co ) symmetric stretching vibration of 
 acetate .
difference   83 which 
 is around 407493  cm indicates the unidentate coordination of the acetate group .
the complexes show a broad band around 3400  cm , 
 which is assigned to the   (h2o ) absorption .
the   (mn ) and   (mo ) stretching vibrations are observed at 
 about 490 and 455  cm , respectively , in the spectra of the complexes 
 . 
 
the h nmr spectrum of the ligand shows only one set of signals for the aromatic 
 protons around 6.937.60  ppm , while the nh of isatin and nh of hydrazone give rise to two different singlets in the 1114  ppm range .
the h nmr spectrum of the zn(ii ) complex is less informative , the presence of the 
 hydrazonic proton is confirmed by a peak at about 13  ppm , which is slightly shifted to down field after complexation .
peak due to ring nh and remaining signals of the ligand remain substantially unchanged upon complexation . 
 
electronic spectral data of the ligand and their transition metal complexes were recorded 
 in dmf solutions . in the electronic spectrum of the ligand ,
three prominent absorption bands at 266 , 382 , and 670  nm were characterized .
the band at 266  nm corresponds to the  * transition of the c = s group .
the band at 382  nm corresponds to the transition of azomethine group and the band at 670  nm corresponds to the n * transition from the amide oxygen 
 of the isatin moiety to the azomethine group . 
  in case of complexes
, the bands appeared in the almost same position as they were appeared 
 in ligand .
followed by these , the bands displayed at 485 , 485 and 495  nm in case of cu(ii ) , ni(ii ) and co(ii ) complexes respectively are assigned to ligand to metal charge transfer transitions ( lmct ) .
apart from these , the bands around 899 , 780  nm in case of cu(ii ) and ni(ii ) complexes were assigned as d - d 
 transition bands . 
 
the electrochemical behavior of copper(ii ) complex has been investigated in dmso containing 0.1  m tetraethyl ammonium chloride supporting electrolyte , using glassy carbon working electrode and ag / agcl , pt 
 electrodes as reference and counter electrodes , respectively .
the complex involves single redox step corresponding to cu(ii)cu(i ) , quasireversible electrode process at epc = 0.659  v and the associated anodic peak at epa = 0.504  v 
 suggesting the tetrahedral environment of the copper ion . 
 
the magnetic moments of the complexes were recorded at room temperature and the observed magnetic moment value for the co(ii ) complex is 4.98 bm , which is in the range of 4.4 to 5.5 bm observed 
 for the octahedral co(ii ) complexes
. 
  the ni(ii ) complexes derived from chloride and acetate salts exhibit the magnetic moment values   3.55 and 2.92 bm suggesting tetrahedral environment around metal ion .
the value of 1.91 bm for cu(ii ) chloride and 1.89 
 bm for cu(ii ) acetate complex suggests the four coordinated tetrahedral complexes , which further supported by their electronic spectral data   and cv studies . 
 
x - band esr spectra of the polycrystalline cu(ii ) complex were recorded at room temperature .
the esr spectra of the mononuclear copper chloride and acetate complexes show a giso value 
 in the range of 2.066 and 2.092 respectively . 
 
the brine shrimp lethality bioassay has been chosen to assess the in vitro cytotoxic effects of the compounds , as it is an inexpensive , reliable , and quick method for the purpose .
all the tested compounds showed considerable cytotoxic activity in the brine shrimp lethality bioassay . 

the compounds were tested using the short - term in vitro cytotoxicity towards eac cells 
 as a preliminary screening technique of tryphan blue exclusion method ( cell viability test ) for their cytotoxic potential .
this test is based on the principle that living cell membrane has the ability to prevent the entry of 
 dye .
hence , they remain unstained and can be easily distinguished from dead cells , which take the dye .
results of the short - term in vitro cytotoxicity of the compounds are shown in table 3 .
all the compounds were found to be cytotoxic and produced 50% cell death at or below a concentration 19.1  g / ml . at 50  g / ml concentration , the standard ( cisplatin ) showed 98  % cell death . at 50  g / ml concentration , the [ cu(l)oac]2h2o , 
 [ cu(l)cl]2h2o showed more than 80  % cell death .  
all the compounds were found to have considerable 
 cytotoxicity in the cell viability test . 

cisplatin administration ( on tenth postinoculation day ) significantly ( p<.05 ) reduced weight gain as compared to control on day-15 .
the compounds also significantly ( p<.05 ) reduced the 
 weight gain on day-15 as compared to control ( table 4 ) .
comparative 
 effects of treatments versus cisplatin on reduction of body weights in 
 tumor - induced mice are given in table 5 . 

 
cisplatin administration ( on tenth postinoculation day ) significantly ( p<.05 ) reduced weight gain as compared to control on day-15 .
the compounds also significantly ( p<.05 ) reduced the 
 weight gain on day-15 as compared to control ( table 4 ) .
comparative 
 effects of treatments versus cisplatin on reduction of body weights in 
 tumor - induced mice are given in table 5 . 
 
the effect of compounds on survival of tumor - bearing mice is 
 shown in table 6 .
cisplatin significantly prolonged the median and mean 
 survival times ( p<.05 ) with respect to its control .
it showed a significant 
 increase in the percentage lifespan of animals ( ils > 50 ) . on the other hand , 
 all the compounds significantly prolonged the mean survival times .
the 
 influence of all the compounds on %  ils was more than 25  % . by convention ,
a 25  % 
 increase in lifespan is considered as possible anticancer activity of a test 
 compound . 
 
tumor 
 induction significantly ( p<.05 ) increased the total number of wbc by almost 4 times .
all the compounds significantly ( p<.05 ) reversed the 
 tumor - induced rise in total counts of wbc .
however , they were not as efficacious as cisplatin in reversing the tumor - induced total counts . on differential counts ,
tumor - induction caused a significant reduction in lymphocyte and a significant ( p<.05 ) increase in neutrophil counts .
this was significantly ( p<.05 ) reversed towards normal by cisplatin and the test compounds .
tumor induction caused significant decrease in rbc and hb almost to the half of the normal animals .
this was significantly ( p<.05 ) reversed towards normal by cisplatin and the test compounds . 
  in the light of interesting antimicrobial activities of the coordination complexes , 

the ligands and their corresponding complexes were screened for antifungal and 
 antibacterial activity against aspergillus niger , candida albicans , and bacillus 
 cirroflagellosus , respectively , by the cup plate method using nutrient agar . 

the radial growth of the colony was recorded on completion of the incubation 
 and the mean diameter for each complex at a single concentration was recorded . 

the average percentage inhibition of the fungicidal growth medium compared 
 using the vincent   equation : i=100(ct)/c ,   where   i=   percentage inhibition , t = average   diameter   of   the fungal and bacterial growth on the tested plates , and c= average diameter of the growth on the control plates .
the screening data of the inhibition of the fungi and bacteria are given in table 8 .  
from the data , it is clear that the free ligand n , n-bis(isatin)thiocarbohydrazone 
 is moderately active against b. cirroflagellosus where as highly active against fungi a. niger and c. albicans .
on complexation , there is a notable enhancement of both antibacterial as well as antifungal activity .
the promising results were observed for the co(ii ) complex against both the fungi . the higher fungi toxicity exhibited by the complexes
may be ascribed to the fact that the metal complexes are more susceptible to fungal cells than bacterial cells . 

from the elemental analysis , molar conductivity , uv - visible , magnetic , 
 ir and h nmr spectral data it was possible to determine the type of 
 coordination of the ligand in their metal complexes .
in all the complexes , only one 
 part of the ligand is coordinated to the metal ion resulting mononuclear 
 complexes .
the ligand coordinates essentially through the carbonyl oxygen of 
 the isatin fragment , the nitrogen atom of the azomethine group and sulfur atom 
 after deprotonation to give five membered rings .
the   compounds showed considerable cytotoxic activity in the trypan blue exclusion 
 method . in the in vivo cancer model ( ehrlich ascitic carcinoma model )
, the compounds significantly ( p<.05 ) reversed the tumor - induced 
 changes in the parameters monitored viz . , percentage 
 increase in body weight , percentage increase in lifespan , 
 tumor - viable count , 
 and hematological parameters ( total and dlc of wbc , total rbc , and hemoglobin 
 count ) .
these 
 effects were almost comparable to cisplatin  the standard drug used in the 
 study .
the compounds , however , were found to have good effect in prolonging the 
 lifespan ( ils ) as compared to standard drug cisplatin .
based on the data of the present study , it is very difficult to suggest the possible 
 mechanism of these compounds for anticancer effects .
the compounds tested in our 
 present study have shown promising cytotoxic activity when screened using the 
 in vitro method and at the same time were shown to have good activity when 
 tested using the ehrlich ascites carcinoma model .  
though it is very difficult to conclude 
 anything at this stage , it can be assumed that after testing against various 
 other cancer models and at different doses these compounds may prove to be 
 safer drugs for tomorrow . 
 
further , the promising results were observed for the antimicrobial screening especially for 
 the co(ii ) complex against both the fungi and what may be attributed to the 
 fact that the metal complexes are potentially active against fungal cells than 
 bacterial cells . 

 the synthesis , structure , electrochemistry , and biological studies of co(ii ) , ni(ii ) , cu(ii ) , and zn(ii ) complexes of thiocarbohydrazone ligand are described . 
 the ligand is synthesized starting from thiocarbohydrazide and isatin . 
 it is evident from the ir data that in all the complexes , only one part of the ligand is coordinated to the metal ion resulting mononuclear complexes . 
 the ligand coordinates essentially through the carbonyl oxygen of the isatin fragment , the nitrogen atom of the azomethine group , and sulfur atom after deprotonation to give five membered rings . 
 h1 
 nmr spectrum of the ligand shows only one set of signals for the aromatic protons , while the nh of isatin and nh of hydrazone give rise to two different singlets in the 1114 ppm range . 
 the formulations , [ cu(l)cl]2h2o , [ cu(l)(ch3coo)]2h2o , [ ni(l)cl ] , [ ni(l)(ch3coo ) ] , [ co(l2 ) ] , and [ zn(l2)]2h2o are in accordance with elemental analyses , physical , and spectroscopic measurements . 
 the complexes are soluble in organic solvents . 
 molar conductance values in dmf indicate the nonelectrolytic nature of the complexes . 
 copper complex displays quasireversible cyclic voltametric responses with ep near 0.659 v and 0.504 v vs ag / agcl at the scan rate of 0.1 v / s . 
 copper(ii ) complexes show a single line epr signals . for 
 the observed magnetic moment and electronic spectral data possible explanation has been discussed . from all the available data , 
 the probable structures for the complexes have been proposed . 
 the compounds synthesized in present study have shown promising cytotoxic activity when screened using the in vitro method and at the same time were shown to have good activity when tested using the ehrlich ascites carcinoma ( eac ) model . 
 the antimicrobial screening showed that the cobalt complex possesses enhanced antimicrobial activity towards fungi . 
1. INTRODUCTION
2. EXPERIMENTAL
3. ANTITUMOR ACTIVITY
4. EVALUATION OF ANTIBACTERIAL AND  ANTIFUNGAL ACTIVITIES
5. RESULT AND DISCUSSION
6. CONCLUSION