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The enormous burden of the COVID-19 pandemic in economic and healthcare terms has cast a shadow on the serious threat of antimicrobial resistance, increasing the inappropriate use of antibiotics and shifting the focus of drug discovery programmes from antibacterial and antifungal fields. Thus, there is a pressing need for new antimicrobials involving innovative modes of action (MoAs) to avoid cross-resistance rise. Thiosemicarbazones (TSCs) stand out due to their easy preparation and polypharmacological application, also in infectious diseases. Recently, we reported a small library of TSCs ( 1-9 ) that emerged for their non-cytotoxic behaviour. Inspired by their multifaceted activity, we investigated the antibacterial, antifungal, and antidermatophytal profiles of derivatives 1-9 , highlighting a new promising research line. Furthermore, the ability of these compounds to inhibit selected microbial and human carbonic anhydrases (CAs) was assessed, revealing their possible involvement in the MoA and a good selectivity index for some derivatives.

Thiosemicarbazones 5a-j were synthesized with yields of 45-68% by condensation of 3-acetylcoumarins 3a-j and tetra-O-acetyl-β-d-thiosemicarbazide 4. All obtained thiosemicarbazones were screened for anti-microorganic activities against bacteria (B. subtilis, S. aureus, S. epidermidis, E. coli, P. aeruginosa, K. pneumoniae, S. typhimurium) and fungi (A. niger, C. albicans, S. cerevisiae, and A. flavus). Some compounds had significant inhibitory activity with MICs of 0.78-3.125 μM in comparison with 5a, including 5e,h,i for S. aureus, and 5c,f,i for S. epidermidis (Gram-(+) bacteria), 5c,f,g for E.coli, 5f for K. pneumoniae, 5b,c,g for P. aeruginosa, and 5i for S. typhimurium (Gram-(-) bacteria), 5d,h,i for A. niger, 5i for A. flavus, 5b,d,e,h for C. albicans, and 5i for S. cerevisiae. Compounds exhibited excellent activity against tested microorganism with MIC = 0.78 μM, including 5h,i (against S. aureus), 5h (against C. albicans), and 5i (against S. cerevisiae)., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Background: Various analogues of benzimidazole are found to be biologically and therapeutically potent against several ailments. Benzimidazole when attached with heterocyclic rings has shown wide range of potential activities. So, from the above provided facts, we altered benzimidazole derivatives so that more potent antagonists could be developed. In the search for a new category of antimicrobial and anticancer agents, novel azomethine of 2-mercaptobenzimidazole derived from 3-(2- (1H-benzo[d]imidazol-2-ylthio)acetamido)benzohydrazide were synthesized., Results and Discussion: The synthesized analogues were characterized by FT-IR, 1 H/ 13 C-NMR and MS studies as well C, H, N analysis. All synthesized compounds were evaluated for in vitro antibacterial activity against Gram-positive (B. subtilis), Gram-negative (E. coli, P. aeruginosa, K. pneumoniae and S. typhi) strains and in vitro antifungal activity against C. albicans and A. niger strains by serial dilution method, the minimum inhibitory concentration (MIC) described in μM/ml. The in vitro anticancer activity of synthesized compounds was determined against human colorectal carcinoma cell line (HCT- 116) using 5-fluorouracil as standard drug., Conclusion: In general, most of the synthesized derivatives exhibited significant antimicrobial and anticancer activities. Compounds 8, 10, 15, 16, 17, 20 and 22 showed significant antimicrobial activity towards tested bacterial and fungal strains and compound 26 exhibited significant anticancer activity., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

The azo-azomethine dyes with a different substitution have been designed from the reaction of 4,4'-diaminodiphenyl sulfone with 2-hydroxy-5-(aryldiazenyl)benzaldehyde. The compounds have been characterized by elemental analysis, Mass, IR, UV-Vis, TGA-DTA and NMR spectroscopy. The solvatochromism behaviors, effects of substitution and pH on the electronic absorption spectra of dyes were evaluated. The in vitro antimicrobial activities were also screened for their potential for antibiotic activities by broth micro dilution method. Also, the optimum molecular geometries, molecular electrostatic potential (MEP), nucleus-independent chemical shift (NICS) and frontier molecular orbitals (FMO), vibrational spectra (IR ) and electronic absorption (UV-Vis) spectra of the title compounds have been investigated with the help of DFT and TDDFT methods with 6-311++G(d,p) basis sets and PCM calculations. The results of the calculations show excellent agreement with the experimental value., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Four novel ligands derived from 2,3-butanedione have been synthesized, two dissymmetric thiosemicarbazone/3-hydroxy-2-naphthohydrazone ligands, H 2 L 1 (bearing 4-isopropyl-3-thiosemicarbazone) and H 2 L 2 (containing 4-cyclohexyl-3-thiosemicarbazone) and the symmetric H 2 L 3 , diacetyl bis(3-hydroxy-2-naphthohydrazone), and H 2 L 4 , diacetyl bis(4-cyclohexyl-3-thiosemicarbazone). Their reactivity with SnR 2 Cl 2 (R=methyl, n-butyl and phenyl) was explored and the resulting complexes were characterized by elemental analysis, molar conductivity, mass spectrometry, IR, 1 H, 13 C and 119 Sn NMR and seven of them also by single crystal X-ray diffraction. The results showed that the reactivity of the dissymmetric ligands is strongly different and while the cyclohexyl derivative is very stable, with isopropyl easily undergoes a symmetrization reaction to yield the corresponding symmetric ligands. The antimicrobial activity of the ligands and the corresponding diorganotin(IV) complexes was investigated in vitro against seven species of microorganisms and minimum inhibitory concentrations (MICs) were determined. The results showed that the ligand H 2 L 2 and several of its derivatives, together with methyl and phenyl complexes of H 2 L 1 , have the ability of inhibiting the growth of tested bacteria and fungi to different extents. Bacillus subtilis and Staphylococcus aureus Gram positive strains were the most sensitive microorganisms., (Copyright © 2016 Elsevier Inc. All rights reserved.)

A new diamine, (dimethylsilanediyl)bis(methylene)bis(4-aminobenzoate) (1), containing dimethylsilane spacer, was prepared by the condensation of p-aminobenzoic acid with bis(chloromethyl)dimethylsilane. This was subsequently reacted with salicylaldehyde, 3-hydroxy-salicylaldehyde, and 3-methoxy-salicyladehyde, when corresponding Schiff bases (E)-(dimethylsilanediyl)bis(methylene)bis(4-((E)-(2-hydroxybenzilidene)amino)benzoate (2), (E)-(dimethylsilanediyl)bis(methylene)bis(4-((E)-(2-hydroxybenzilidene)amino)benzoate (3), and (E)-(dimethylsilanediyl)bis(methylene) bis(4-((E)-(2-hydroxy-3-methoxybenzilidene)amino)benzoate (4), respectively were formed. All the obtained compounds were structurally characterized by spectral (FT-IR, (1)HNMR, (13)CNMR) analyses and single crystal X-ray diffraction. Photophysical studies revealed that the new prepared Schiff bases are good UV light absorbing and fluorescent materials. Thus, they exhibit strong UV/Vis-absorption at 250-400nm and violet or orange emission, in sensitive dependence on the polarity of the solvents and the nature of the substituent (H, OH and OCH3) at the aromatic ring. The antimicrobial activity of these compounds was first studied in vitro by the disk diffusion assay against two species of bacteria and three fungi. The minimum inhibitory concentration was then determined with the reference of standard compounds. The results displayed that Schiff bases 3 and 4 having hydroxy- and methoxy-substituents on the aromatic ring were better inhibitors of both types of species (bacteria and fungi) than standard compounds, Caspofungin and Kanamycin., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Complexes of copper(II) and nickel(II) of general composition M(L)2X2, have been synthesized with the ligand 1-Tetralone thiosemicarbazone (where L=1-Tetralone thiosemicarbazone and X=Cl(-),1/2SO4(2-)). The molar conductance of the complexes in fresh solution of DMSO lies in the range of 10-20Ω(-1)cm(2)mol(-1) indicating their non-electrolytic behavior. Thus, the complexes may be formulated as [M(L2)X2]. Ligand was characterized by mass, NMR, IR and single crystallographic studies. All the complexes were characterized by elemental analyses, magnetic moments, IR, electronic and EPR spectral studies. The IR spectral data of ligand indicated the involvement of sulfur and azomethine nitrogen in coordination to the central metal ion. The copper(II) and nickel(II) complexes were found to have magnetic moments1.93-1.96BM and 2.91-2.94BM corresponding to one and two unpaired electrons respectively. On the basis of molar conductance, EPR, electronic and infrared spectral studies, a tetragonal geometry has been assigned for Cu(II) chloride complex and trigonal bipyramidal to Cu(II) sulfate complex but an octahedral geometry for Ni(II) complexes. Newly synthesized ligand and its Cu(II) and Ni(II) complexes have also been screened against different bacterial and fungal species., (Copyright © 2012 Elsevier B.V. All rights reserved.)

A series of mono and bis 2-2-(arylidineaminophenyl)indole azomethines have been synthesized by a condensation reaction of 2-(2-amino phenyl) indole with various mono and diketones R-CO-R(l) /R-CO-X-CO-R(l) (1:1/2:1 ratio) in ethanol media. The synthesized azomethines were characterized via IR, (1)H-NMR, (13)C-NMR, MS and elemental analysis. The antimicrobial activity of these compounds against different bacteria and fungi was also evaluated.

A series of 2,6-diaryltetrahydropyran-4-one thiosemicarbazones (11-27) were synthesized and characterized for evaluation of potential antibacterial activity against Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Salmonella typhi, Bacillus subtilis and Klebsiella pneumonia and antifungal activity against Cryptococcus neoformans, Candida albicans, Rhizopus sp., Aspergillus niger and Aspergillus flavus were evaluated. Compounds 21 and 22 showed maximum inhibition potency at low concentration (6.25 μg/ml) against P. aeruginosa. For antifungal activity, 20 and 21 were effective against C. neoformans and 22-24 against C. albicans at minimum concentration. Further, the results of QSAR studies of these synthesized compounds indicated the importance of weakly polar component of surface area, hydrophobicity and ionization potential parameters in defining their antimicrobial activity., (Copyright © 2011 Elsevier Masson SAS. All rights reserved.)

Thiosemicarbazones of p-aminobenzoic acid (PABA) were synthesized and tested for their antimicrobial and anticancer activity. Hydroxamate derivatives 4a-4l were found to have better antimicrobial and anticancer activity than their acid counterpart. Compound 4d was found to have good antimicrobial activity against Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus, Vibrio cholerae, and Bacillus subtilis with IC(50) value of about 1 µM. Compound 4f showed potent antifungal activity against Candida albicans (IC(50)  = 1.29 µM) and compound 4h showed potent anticancer activity (IC(50)  = 0.07 µM)., (Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

New series of 2,4-diaryl-3-azabicyclo[3.3.1]nonan-9-one thiosemicarbazones (9-16) obtained from the corresponding 2,4-diaryl-3-azabicyclo[3.3.1]nonan-9-ones (1-8) upon cyclization with ethylbromoacetate in the presence of sodium acetate-acetic acid buffer afforded novel 2-[(2,4-diaryl-3-azabicyclo[3.3.1]nonan-9-ylidene)hydrazono]-1,3-thiazolidin-4-ones (17-24). The synthesized compounds have been characterized by their elemental, analytical and spectral studies. Besides, the reported compounds were screened for their antibacterial and antifungal activities against a spectrum of microbial organisms. These studies proved that compounds 11/18/20/23 against Staphylococcus aureus, 19/20/24 against Salmonella typhi show maximum inhibition potency at low concentration (6.25microg/ml) whereas 18/19 against Candida albicans and 19/20/21 against Rhizopus sp. showed beneficial antifungal activity at minimum concentration.

Eight different newly synthesised aldehyde Schiff base N-aryl thiosemicarbazones, differing in R, R' groups, are tested on 25 clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA) and a standard strain. Antibacterial activity was carried out by a well-diffusion method in concentrations of 15-500 microg/well. Compounds 1, 2, 3, 4 and 6 showed good inhibition of MRSA. Increasing concentration of the test compounds enlarged the inhibition zone. Determination of minimum inhibitory concentration (MIC) was carried out using a dilution susceptibility test in concentrations of 4-512 microg/mL of the medium. The lowest MIC value (16 microg/mL) was produced by compound 4.

In the present communication, a new series of 2-[(phenylmethylene)hydrazono]-4-oxo-3-phenyl-5-thiazolidineacetic acids (2a-p) have been synthesized. Benzaldehyde 4-phenyl-3-thiosemicarbazones substituted (1a-p) were also obtained and used as intermediate to give the title compounds. All synthesized compounds were characterized by IR, (1)H and (13)C NMR. The in vitro anti-Toxoplasma gondii activity of 1a-p and 2a-p was evaluated. The 4-thiazolidinones (2a-p) were screened for their in vitro antimicrobial activity. For anti-Toxoplasma gondii activity, in general, all compounds promoted decreases in the percentage of infected cells leading to parasite elimination. These effects on intracellular parasites also caused a decrease in the mean number of tachyzoites. In addition, most of the 4-thiazolidinones showed more effective toxicity against intracellular parasites, with IC(50) values ranging from 0.05 to 1 mM. According to results of antimicrobial activity, compounds 2f, 2l, and 2p showed best activity against Mycobacterium luteus, 2c was more active against Mycobacterium tuberculosis, and 2g, 2l, and 2n showed same activity as nistatin (standard drug) against Candida sp. (4249).

The chelating behavior of the thiosemicarbazone derivatives of 2-hydroxy-8-R-tricyclo[7.3.1.0.(2,7)]tridecane-13-one (where R = H, CH3, C6H5) towards Co(II), Ni(II) and Cu(II) has been investigated by elemental analysis, molar conductivity measurements, UV-VIS, IR, ESR spectroscopy and thermal studies. It was deduced from the experiments performed that the ligands coordinate to metal ions in different ways--neutral bidentate or mononegative bidentate--depending on the nature of R. Also, if metal acetates are used instead of metal chlorides, the ligands coordinate in a mononegative bidentate fashion, regardless of the nature of R or the thiosemicarbazone type ligand. The antimicrobial activity of the ligands and of the complexes towards samples of Acinetobacter boumanii, Klebsiella pneumoniae, Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa was determined.

A series of eight new azomethine derivatives were synthesized by reacting 2-formylphenoxyacetic acid with aromatic amines. The chemical structures of these compounds were confirmed by means of 1H-NMR, 13C-NMR, MS and elemental analysis. The compounds were assayed by the disc diffusion method for antibacterial against Staphylococcus aureus and Escherichia coli. Among the compounds tested, 2a, 2b, 2e, 2g and 2h exhibited good antibacterial activity, almost equal to that of Ciprofloxacin used as standard.

Twelve zinc(II) complexes with thiosemicarbazone and semicarbazone ligands were prepared and characterized by elemental analysis, thermogravimetric and differential thermal analysis (TG/DTA), FT-IR and 1H and 13C NMR spectroscopy. Seven three-dimensional structures of zinc(II) complexes were determined by single-crystal X-ray analysis. Their antimicrobial activities were evaluated by MIC against four bacteria (B. subtilis, S. aureus, E. coli and P. aeruginosa), two yeasts (C. albicans and S. cerevisiae) and two molds (A. niger and P. citrinum). The 5- and 6-coordinate zinc(II) complexes with a tridentate thiosemicarbazone ligand (Hatsc), ([Zn(atsc)(OAc)](n) 1, [Zn(Hatsc)(2)](NO(3))(2).0.3H(2)O 2, [ZnCl(2)(Hatsc)] 3 and [Zn(SO(4))(Hatsc)(H(2)O)].H(2)O 4 [Hatsc=2-acetylpyridine(thiosemicarbazone)]), showed antimicrobial activities against test organisms, which were different from those of free ligands or the starting zinc(II) compounds. Especially, complex 2 showed effective activities against P. aeruginosa, C. albicans and moderate activities against S. cerevisiae and two molds. These facts are in contrast to the results that the 5- or 6-coordinate zinc(II) complexes with a tridentate 2-acetylpyridine-4N-morpholinethiosemicarbazone, ([Zn(mtsc)(2)].0.2EtOH 5, the previously reported catena-poly [Zn(mtsc)-mu-(OAc-O,O')](n) and [Zn(NO(3))(2)(Hmtsc)] [Hmtsc=2-acetylpyridine (4N-morpholyl thiosemicarbazone)]), showed no activities against the test microorganisms. The 5- and 6-coordinate zinc(II) complexes with a tridentate 2-acetylpyridinesemicarbazone, ([Zn(OAc)(2)(Hasc)] 6 and [Zn(Hasc)(2)](NO(3))(2) 7 [Hasc=2-acetylpyridine(semicarbazone)]), showed no antimicrobial activities against bacteria, yeasts and molds. Complex [ZnCl(2)(Hasc)] 8, which was isostructural to complex 3, showed modest activity against Gram-positive bacterium, B. subtilis. The 1:1 complexes of zinc(II) with pentadentate thiosemicarbazone ligands, ([Zn(dmtsc)](n) 9 and [Zn(datsc)](n) 10 [H(2)dmtsc=2,6-diacetylpyridine bis(4N-morpholyl thiosemicarbazone) and H(2)datsc=2,6-diacetylpyridine bis(thiosemicarbazone)]), did not inhibit the growth of the test organisms. On the contrary, 7-coordinate zinc(II) complexes with one pentadentate semicarbazone ligand and two water molecules, ([Zn(H(2)dasc)(H(2)O)(2)](OAc)(2).5.3H(2)O 11 and [Zn(H(2)dasc)(H(2)O)(2)](NO(3))(2).H(2)O 12 [H(2)dasc=2,6-diacetylpyridine bis(semicarbazone)]), showed modest to moderate activities against bacteria. Based on the X-ray structures, the structure-activity correlation for the antimicrobial activities was elucidated. The zinc(II) complexes with 4N-substituted ligands showed no antimicrobial activities. In contrast to the previously reported nickel(II) complexes, properties of the ligands such as the ability to form hydrogen bonding with a counter anion or hydrated water molecules or the less bulkiness of the 4N moiety would be a more important factor for antimicrobial activities than the coordination number of the metal ion for the zinc(II) complexes.

An interesting series of new platinum complexes has been synthesized by the reaction of Na(2)PtCl(4) with 2-acetyl pyridine thiosemicarbazone, HAcTsc. The new complexes, [Pt(AcTsc)Cl], [Pt(HAcTsc)(2)]Cl(2) and [Pt(AcTsc)(2)], have been characterized by elemental analyses and spectroscopic studies. The crystal structure of the complex [Pt(AcTsc)Cl] has been solved by single-crystal X-ray diffraction. The anion of HAcTsc coordinates in a planar conformation to the central platinum(II) through the pyridyl N, azomethine N and thiolato S atoms. Double intermolecular hydrogen bonds (NH-Cl), pi-pi and weak Pt-Pt and Pt-pi contacts lead to aggregation and to a two-dimensional supramolecular assembly. The antibacterial and antifungal effect of the novel platinum(II) complexes and the related palladium(II) complexes, [Pd(AcTsc)Cl], [Pd(HAcTsc)(2)]Cl(2) and [Pd(AcTsc)(2)], were studied in vitro. The complexes were found to have a completely lethal effect on Gram+ bacteria, while the same complexes showed no bactericidal effect on Gram- bacteria. Additionally, the complexes [Pt(AcTsc)(2)] and [Pd(AcTsc)(2)] showed effective antifungal activity towards yeast. Among these compounds [33], the most effective in inducing antitumour and cytogenetic effects are the complexes [Pt(AcTsc)(2)] and [Pd(AcTsc)(2)] while the rest, display marginal cytogenetic and antitumour effects.

[N-(2-pyridyl)-N'-(4-(un) substituted] thioureas and (substitutedaryl)thiosemicarbazones were synthesised and evaluated for their antibacterial activity. All aryl thiosemicarbazones showed good activity against Aeromonas hydrophilia and Salmonella typhimurium. But none of the pyridyl thioureas showed any prominent activity against tested bacteria.

To investigate the relationship between antimicrobial activities and the molecular structures of nickel(II) complexes with thiosemicarbazone and semicarbazone ligands, nickel(II) complexes with ligands Hmtsc, Hatsc, Hasc and H2dmtsc, were prepared and characterized by elemental analysis, FT-IR, 1H and 13C NMR spectroscopies, magnetic susceptibility measurements, UV-Vis absorption spectra, TG/DTA and single-crystal X-ray analysis. Their antimicrobial activities were evaluated by the MIC against four bacteria (B. subtilis, S. aureus, E. coli and P. aeruginosa), two yeasts (C. albicans and S. cerevisiae) and two molds (A. niger and P. citrinum). The 4-coordinate, diamagnetic nickel(II) complexes showed antimicrobial activities which were different from those of free ligands or the starting nickel(II) compounds; [Ni(mtsc)(OAc)] 1 showed selective and effective antimicrobial activities against two Gram-positive bacteria (B. subtilis and S. aureus) and modest activities against a yeast (S. cerevisiae), [Ni(mtsc)Cl] 3 exhibited moderate activities against a Gram-positive bacterium (S. aureus), and [Ni(atsc)(OAc)] 5 showed modest activities against two Gram-positive bacteria (B. subtilis and S. aureus). On the other hand, the 6-coordinate, paramagnetic nickel(II) complexes with two protonated or deprotonated ligands ([Ni(mtsc)2] 2, [Ni(atsc)(mtsc)] 4, [Ni(atsc)2] 6, [Ni(Hatsc)2](NO3)(2)7, [Ni(Hatsc)2]Cl(2)8 and [Ni(Hasc)2](OAc)(2)9) and the sterically crowded 4-coordinate, diamagnetic nickel(II) complex ([Ni(dmtsc)] 10) did not inhibit the growth of the test organisms. The structure-activity correlation in this series of nickel(II) complexes was discussed based on their ligand-replacement abilities.

Arylidenimidazoles bearing a thioethereal function in the position 2 of the imidazole ring show good antimicrobial activity. We now report on the synthesis and the biological properties of some novel arylidenisothiosemicarbazones, structurally related to the arylideneiminoimidazoles of which they can be considered the linear precursors. Particular attention has been put on the influence of structural modifications on the biological activity.

Some Mannich bases of 1-cyclohexylidene-N(1,2-dihydro-2-oxo-3H-indol-3- ylidene) thiosemicarbazones have been prepared by employing formaldehyde and morpholine and piperidine as secondary amines. These Mannich bases have been characterised on the basis of different physico chemical evidences. Like some alkaloids, they also form reineckate complexes which serve for their estimation. Antibacterial activity of the synthesised Mannich bases has been studied by employing nine bacterial strains. Chloro group at position 5 broadened the spectrum of activity. Compounds with piperidine showed better activity than the compounds with morpholine, against almost all the organisms used (except 1 or 2 occasions).

o-Vanillin-(4-methylthiosemicarbazone), o-Vanillin-(4-phenylthiosemicarbazone) and some of their metal complexes of the platinum group have been synthesized, characterized by chemical and spectral methods and studied for their antibacterial, antifungal and amoebicidal activity in vitro. The platinum group metal chelates exibited significant activity against a wide spectrum of microorganisms at different concentrations. The Pt(II) and Ru(III) chelates derived from o-vanillin-(4-phenylthiosemicarbazone) seem to be the most efficient inhibitors. Evaluation of the antimalarial activity of the compounds in mice infected with Plasmodium berghei indicated that cures were attainable at dose levels of 40-160 mg/kg but with toxic death prevalence at higher dose levels.

Various new 1,4-disubstituted thiosemicarbazide and 2,5-disubstituted-1,3,4-thiadiazole derivatives were synthesized and evaluated for their in vitro antimicrobial activity. The structure of compounds was confirmed by elemental analyses and spectroscopic techniques. Some of the synthesized compounds were found to be active against C. Albicans.

2-Acetylpyridine-(2-methylthiosemicarbazone), 2-acetylpyridine-(4-methylthiosemicarbazone), 2-acetylpyridine-(4-phenylthiosemicarbazone) and some of their metal complexes of the platinum group have been synthesized, characterized by chemical and spectral methods and studied for their antibacterial, antifungal and amoebicidal activity in vitro. They were studied also for their antimalarial activity and for toxicity in vivo. The platinum metal chelates exhibited significant activity against a wide spectrum of microorganisms at different concentrations. The Ru (III) chelates derived from 2-acetylpyridine-(4-methylthiosemicarbazone) seem to be the most efficient inhibitors. Evaluation of the antimalarial activity of the complexes in mice infected with Plasmodium berghei indicated that cures were attainable at dose levels of 20-160 mg/kg.

The metal (II) complexes of benzyl and benzoin thiosemicarbazones have been synthesized and characterized. They were studied for their antibacterial, antifungal and amoebicidal activity in vitro and for their toxicity in vivo. The ligands and their metal complexes exhibited low antibacterial and amoebicidal activity. The metal chelates of benzoin thiosemicarbazone seem to be the most active compounds.

2-Acetylpyridine-(4-methylthiosemicarbazone), 2-acetylpyridine-(2- methylthiosemicarbazone) and their metal (II) complexes have been synthesized and characterized by chemical and spectral methods. They were studied for their antibacterial, antifungal and amoebicidal activity in vitro and for their toxicity in vivo. The ligands and their metal (II) complexes exhibited significant activity against a wide spectrum of microorganisms. The metal (II) complexes derived from 2-acetylpyridine-(4-methylthiosemicarbazone) seem to be the most active compounds.

2-Acetylpyridine-(4-phenylthiosemicarbazone) and its metal (II) complexes have been synthesized and characterized by chemical and spectral methods. They were studied for their antibacterial and antifungal activities in vitro. The ligand and its metal (II) complexes exibited significant activity against a wide spectrum of bacteria and fungi.

Two novel series of thiosemicarbazide derivatives were synthesized: 2-[4-(substituted thiocarbamoylhydrazinocarbonyl) phenoxymethyl]-1H-benzimidazoles and 1-benzyl-2-[4-(substituted thiocarbamoylhydrazinocarbonyl) phenoxymethyl]-1H-benzimidazoles, and cyclised to 2-[4-(4-substituted-4H-1,2,4-triazole-5-thion-3-yl)phenoxymethy ]-1H-benzimidazoles and 1-benzyl-2-[4-(4-substituted-4H-1,2,4-triazole-5- 5-thion-3-yl)phenoxymethyl]-1H-benzimidazoles, respectively. The antimicrobial activity of the prepared compounds was tested.

The title compounds were prepared by reacting [(4,5-diphenyl-1H-imidazol-2-yl)thio]acetic acid hydrazides 6 and 7 with aromatic aldehydes to give the corresponding hydrazones 6a-m and 7a-d or with isothiocyanates to afford the corresponding thiosemicarbazides 8a-c and 9. 8a-c and 9 were cyclized into triazoline-5-thiones 10a-c and 11 in the presence of sodium hydroxide or into 1,3,4-thiadiazoles 14a-c and 15 in the presence of sulfuric acid. On the other hand, 10c and 11 were also reacted with alkyl halides to obtain their thioether derivatives, 12a,b and 13. All the synthesized compounds were characterized by their elementary analysis and by using UV, IR, NMR and mass spectrometry. 6b, c, f, h-k, m, 7, 7d, 8c, 9, 10c, 11, 12a-b, 13, 14 and 15 were tested for antimicrobial activity, but no significant activity was observed.

Two novel series of 3-benzylthiazolidine-2,4-dione-4-thiosemicarbazones (V - IX) and 3-benzyl-4-[(3,4-diaryl-3H-thiazol-2-yl)azo]thiazolidin-2-on es (X - XXII) were synthesized as potential antimicrobial and anticancer agents. The products were found to be inactive against a variety of microorganisms and the preliminary antileukemic evaluation of some representative compounds against P 388 lymphocytic leukemia indicated insignificant activity.

A series of thiosemicarbazones and thioureas having an open-chain analogue of the ribosyl group, the 2-acetoxyethoxymethyl moiety, has been synthesized. Significant growth inhibitory activity versus gram-positive and gram-negative organisms, a yeast, and a mold has been found with the 2-acetoxyethoxymethyl derivatives of N-alkyl-, aryl-, and heteroaryl-thiosemicarbazones and thioureas. The molecules may function as inhibitors of ribonucleotide reductase or in utilization of the carbamyl group in pyrimidine biosynthesis.