Antituberculosis agents. V: Alpha-[5-(5-nitro-2-furyl)-1,3,4-oxadiazol-2-ylthio]acethydrazide and related compounds

Synthesis, antimicrobial activity and cytotoxicity of novel oxadiazole derivatives

In the present study, 5-substituted-1,3,4-oxadiazolin-2-thiones (1a-b) were synthesized via the ring closure reactions of appropriate acid hydrazides with carbon disulphide. N-(Benzothiazol-2-yl)-2-[[5-substituted-1,3,4-oxadiazol-2-yl]sulfanyl]acetamide derivatives (3a-j) were obtained by the nucleophilic substitution reactions of 5-substituted-1,3,4-oxadiazolin-2-thiones (1a-b) with N-(benzothiazol-2-yl)-2-chloroacetamides. The chemical structures of the compounds were elucidated by IR, (1)H NMR, (13)C NMR and FAB(+)-MS spectral data and elemental analyses. The synthesized compounds were screened for their antimicrobial activities against Micrococcus luteus, Bacillus subtilis, Pseudomonas aeruginosa, Staphylococcus aureus, Escherichia coli, Listeria monocytogenes and Candida albicans. All compounds except compound 3h exhibited the highest antibacterial activity against P. aeruginosa. Among all compounds (3a-j), the compounds bearing 4-methoxyphenoxymethyl moiety on oxadiazole ring (3a-e) exhibited the highest inhibitory activity against C. albicans. Although compound 3j did not possess 4-methoxyphenoxymethyl moiety on oxadiazole ring, this derivative also exhibited the same level of anti-candidal activity. The compounds were also investigated for their cytotoxic effects using MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. Compound 3a exhibited the highest cytotoxic activity, whereas compound 3g possessed the lowest cytotoxic activity against NIH/3T3 cells.

Synthesis and antitubercular activity of 6-chloro (unsubstituted)-2-methoxy-9-substituted acridine derivatives

Several analogues of the general formulae 2-methoxy-9-substituted acridine and 6-chloro-2-methoxy-9-substituted acridine were synthesized and evaluated in vitro at 6.25 microg/mL against M. tuberculosis H37Rv. Compounds 15 and 17 showed potential antitubercular activity with 100% inhibition to the virulent mycobacterium.

Antituberculosis agents. V. Synthesis, evaluation of in vitro antituberculosis activity and cytotoxicity of some 2-(5-nitro-2-furyl)-1,3,4-thiadiazole derivatives

A new series of 2-(5-nitro-2-furyl)-1,3,4-thiadiazole-2-sulfide, sulfoxide and sulfones were synthesized and evaluated for in vitro antituberculosis activity against Mycobacterium tuberculosis strain H37Rv using the radiometric BACTEC 460-TB methodology. Active compounds were also screened by serial dilution to assess toxicity to a VERO cell line. The results indicate that some compounds exhibited a good antituberculosis activity and the ethylthio analogue (5b) was the most active compound (MIC = 0.78 microg ml(-1)). Also, the cytotoxic effects indicate that compound 5b was the least toxic compound.

Antituberculosis agents II. Evaluation of in vitro antituberculosis activity and cytotoxicity of some 2-(1-methyl-5-nitro-2-imidazolyl)-1,3,4-thiadiazole derivatives

Using the radiometric BACTEC 460-TB methodology, the minimum inhibitory concentration (MIC) of a series of 2-(1-methyl-5-nitro-2-imidazolyl-1,3,4-thiadiazole-5-alkylsulfides, alkylsulfoxides and alkylsulfones which had been reported previously as antifungal agents, were determined. Active compounds were also screened by serial dilution to assess toxicity to a VERO cell line. The results indicate that compounds bearing a primary alkylthio substitution displayed good antituberculosis activity (MIC = 3.13-6.25 microg/ml). Oxidation to sulfone abolished the antituberculosis activity in methyl and propyl derivatives while the ethylsulfonyl analogue was active (MIC = 1.56 microg/ml). The cytotoxic effects indicate that 2-(1-methyl-5-nitro-2-imidazolyl)-5-methylthio-1,3,4-thiadiazole was the least toxic compound (IC50 > 10 microg/ml). Generally, all compounds showed a low selectivity index.

Synthesis of new 7-substituted 4-methylcoumarin derivatives of antimicrobial activity

New cyclic derivatives derived from 4-methyl-7-coumarinyloxyacetic acid hydrazide have been synthesized. Some representative examples were screened for antimicrobial activity.

Antibacterial organophosphorus compounds: phosphoranilidohydrazones of 5-nitro-2-furaldehyde

A series of phosphoranilidohydrazones of 5-nitro-2-furaldehyde was synthesized and evaluated for antibacterial activity. The series was prepared to examine the applicability of phosphoramidic hydrazones as carriers for the antibacterial nitrofuran moiety. Designed as analogues of nitrofurantoin, members of the series were chosen according to the Topliss approach to analogue design. The title compounds were devoid of gram-negative activity but possessed moderate antistaphylococcal activity. The most potent members of the series were equipotent with nitrofurantoin against Staphylococcus aureus. The relationship between structure and antistaphylococcal activity is discussed.