Discovery of novel antitubercular 2,10-dihydro-4aH-chromeno[3,2-c]pyridin-3-yl derivatives.

Twenty two novel 2,10-dihydro-4aH-chromeno[3,2-c]pyridin-3-yl derivatives were synthesized by reacting 3-formyl chromone, (sub)-2-amino pyridines, N1-(prop-2-ynyl)arylamides in the presence of indium triflate. The compounds were evaluated their preliminary in-vitro and in-vivo activity against Mycobacterium tuberculosis H37Rv (MTB) and multi-drug resistant M. tuberculosis (MDR-TB). Among them N-[(4aS)-2-(3-methyl-2-pyridinyl)-10-oxo-2,10-dihydro-4aH-chromeno[3,2-c]pyridin-3-yl]methyl-4-ethylbenzenecarboxamide 4d was found to be the most active compound in-vitro with MIC's of 0.22 and 0.07 microg/mL against MTB and MDR-TB respectively. In the in-vivo animal model 4d decreased the bacterial load in lung and spleen tissues with 1.11 and 2.94-log10 protections respectively at 25 mg/kg body weight dose.

Synthesis and in-vitro antimycobacterial evaluation of 1-(cyclopropyl/2,4-difluorophenyl/tert-butyl)-1,4-dihydro- 8-methyl-6-nitro-4-oxo-7-(substituted secondary amino)quinoline-3-carboxylic acids.

Fifty one newer 1-(cyclopropyl/2,4-difluorophenyl/tert-butyl)-1,4-dihydro-8-methyl-6-nitro-4-oxo-7-(substituted secondary amino)quinoline-3-carboxylic acids were synthesized from 1,3-dichloro-2-methylbenzene and evaluated for in-vitro antimycobacterial activities against Mycobacterium tuberculosis H37Rv (MTB), multi-drug resistant Mycobacterium tuberculosis (MDR-TB), and Mycobacterium smegmatis (MC(2)). Among the synthesized compounds, 1-cyclopropyl-1,4-dihydro-7-(3,4-dihydro-6,7-dimethoxyisoquinolin-2(1H)-yl)-8-methyl-6-nitro-4-oxoquinoline-3-carboxylic acid 9p was found to be the most active compound in vitro with a MIC value of 0.39 microM against MTB. Against MDR-TB, compound 7-(2-carboxy-5,6-dihydroimidazo[1,2-a]pyrazin-7(8H)-yl)-1-cyclopropyl-1,4-dihydro-8-methyl-6-nitro-4-oxoquinoline-3-carboxylic acid 9n was found to be the most active with a MIC value of 0.09 microM.

Antimycobacterial activities of novel fluoroquinolones.

Fifty-one novel 1-(cyclopropyl/2,4-difluorophenyl/t-butyl)-1,4-dihydro-6-fluoro-7-(sub secondary amino)-4-oxoquinoline-3-carboxylic acids were synthesized and evaluated for their antimycobacterial in vitro and in vivo against Mycobacterium tuberculosis H37Rv (MTB), multi-drug resistant Mycobacterium tuberculosis (MDR-TB) and Mycobacterium smegmatis (MC(2)) and also tested for the ability to inhibit the supercoiling activity of DNA gyrase from M. smegmatis. Among the synthesized compounds, 7-(3-(diethylcarbamoyl)piperidin-1-yl)-1-cyclopropyl-6-fluoro-1,4-dihydro-4-oxoquinoline-3-carboxylic acid (7l) was found to be the most active compound in vitro with MIC of 0.09 microM against MTB and MDR-TB respectively. In the in vivo animal model 7l decreased the mycobacterial load in lung and spleen tissues with 2.53- and 4.88-log10 protections respectively at a dose of 50mg/kg body weight.

Antitubercular activities of novel benzothiazolo naphthyridone carboxylic acid derivatives endowed with high activity toward multi-drug resistant tuberculosis.

Sixteen novel 3-nitro-2-(sub)-5,12-dihydro-5-oxobenzothiazolo[3,2-a]-1,8-naphthyridine-6-carboxylic acids were synthesized from 2,6-dimethoxynicotinic acid and 2-aminothiophenol and evaluated for their antitubercular activities in vitro and in vivo against Mycobacterium tuberculosis H(37) Rv (MTB) and multi-drug resistant M. tuberculosis (MDR-TB). Among the synthesized compounds, 2-(1,4-dioxa-8-azaspiro[4.5]dec-8-yl)-3-nitro-5,12-dihydro-5-oxobenzothiazolo[3,2-a]-1,8-naphthyridine-6-carboxylic acid (10n) was found to be the most active compound in vitro with MIC of 0.19 and 0.04 microM against MTB and MTR-TB, respectively. Compound 10n showed promising activity against MDR-TB and was 208 and 1137 times more potent than gatifloxacin and isoniazid, respectively. In the in vivo animal model 10n decreased the mycobacterial load in lung and spleen tissues with 2.81 and 4.94-log(10) protections, respectively, at a dose of 50 mg/kg body weight.

Synthesis and antimycobacterial activities of novel 6-nitroquinolone-3-carboxylic acids.

Various 1-(substituted)-1,4-dihydro-6-nitro-4-oxo-7-(sub-secondary amino)-quinoline-3-carboxylic acids were synthesized from 2,4-dichlorobenzoic acid by six step synthesis. The compounds were evaluated for antimycobacterial in vitro and in vivo against Mycobacterium tuberculosis H37Rv (MTB), multi-drug resistant Mycobacterium tuberculosis (MDR-TB) and Mycobacterium smegmatis (MC(2)) and also tested for the ability to inhibit the supercoiling activity of DNA gyrase from M. smegmatis. Among the 48 synthesized compounds, 7-(4-((benzo[d][1,3]dioxol-5-yl)methyl)piperazin-1-yl)-1-cyclopropyl-1,4-dihydro-6-nitro-4-oxoquinoline-3-carboxylic acid (8c) was found to be the most active compound in vitro with MIC of 0.08 and 0.16 microM against MTB and MDR-TB, respectively. In the in vivo animal model 8c decreased the bacterial load in lung and spleen tissues with 2.78 and 4.15-log10 protections, respectively, at the dose of 50 mg/kg body weight.

Synthesis, antimycobacterial activities and phototoxic evaluation of 5H-thiazolo[3,2-a]quinoline-4-carboxylic acid derivatives.

Thirty four novel 7-fluoro/nitro-1,2-dihydro-5-oxo-8-(sub)-5H-thiazolo[3,2-a]quinoline-4-carboxylic acids were synthesized from 2,4-dichlorobenzoic acid and 2,4-dichloro-5-fluoroacetophenone by multi step reaction, evaluated for in vitro and in vivo antimycobacterial activities against Mycobacterium tuberculosis H37Rv (MTB), multi-drug resistant Mycobacterium tuberculosis (MDR-TB) and Mycobacterium smegmatis (MC2) and also tested for the ability to inhibit the supercoiling activity of DNA gyrase from M. smegmatis. Among the synthesized compounds, 8-[6-[[(1,1-dimethylethoxy)carbonyl]amino]-3-azabicyclo[3.1.0]hex-3-yl]-1,2-dihydro-7-nitro-5-oxo-5H-thiazolo[3,2-a]quinoline-4-carboxylic acid (10q) was found to be the most active compound in vitro with MIC of 0.08 microM and <0.08 microM against MTB and MDR-TB respectively. Compound 10q was found to be 4.5 and >570 times more potent than isoniazid against MTB and MDR-TB respectively. In the in vivo animal model 10q decreased the bacterial load in lung and spleen tissues with 2.51 and 3.71-log10 protections respectively at the dose of 50 mg/kg body weight.

Antimycobacterial activities of novel 2-(sub)-3-fluoro/nitro-5,12-dihydro-5-oxobenzothiazolo[3,2-a]quinoline-6-carboxylic acid.

Various 2-(sub)-3-fluoro/nitro-5,12-dihydro-5-oxobenzothiazolo[3,2-a]quinoline-6-carboxylic acid derivatives were synthesized from 2-aminothiophenol by a five-step reaction, evaluated for in-vitro and in-vivo antimycobacterial activities against Mycobacterium tuberculosis H37Rv (MTB), multi-drug resistant Mycobacterium tuberculosis (MDR-TB), and Mycobacterium smegmatis (MC2), and also tested for the ability to inhibit the supercoiling activity of DNA gyrase from M. smegmatis. Among the thirty-four synthesized compounds, 2-(3-(diethylcarbamoyl)piperidin-1-yl)-)-3-fluoro-5,12-dihydro-5-oxobenzothiazolo[3,2-a]quinoline-6-carboxylic acid (7l) was found to be the most active compound in vitro with MIC of 0.18 and 0.08 microM against MTB and MTR-TB, respectively. Compound 7l was found to be 2 and 570 times more potent than isoniazid against MTB and MDR-TB, respectively. In the in-vivo animal model 7l decreased the bacterial load in lung and spleen tissues with 2.78 and 3.12-log10 protections, respectively, at the dose of 50 mg/kg body weight.

Novel ofloxacin derivatives: synthesis, antimycobacterial and toxicological evaluation.

Thirty novel 9-fluoro-2,3-dihydro-8,10-(mono/di-sub)-3-methyl-8-nitro-7-oxo-7H-[1,4]oxazino[2,3,4-ij]quinoline-6-carboxylic acids were synthesized from 2,3,4,5-tetrafluoro benzoic acid and evaluated for in vitro and in vivo antimycobacterial activities against Mycobacterium tuberculosis H37Rv (MTB), multi-drug resistant Mycobacterium tuberculosis (MDR-TB), and Mycobacterium smegmatis (MC(2)) and also tested for the ability to inhibit the supercoiling activity of DNA gyrase from mycobacteria. Among the synthesized compounds, 10-[2-carboxy-5,6-dihydroimidazo[1,2-a]pyrazin-7(8H)-yl]-9-fluoro-2,3-dihydro-3-methyl-8-nitro-7-oxo-7H-[1,4]oxazino[2,3,4-ij]quinoline-6-carboxylic acid was found to be the most active compound in vitro with MIC99 of 0.19 microM and 0.09 microM against MTB and MTR-TB, respectively. In the in vivo animal model also the same compound decreased the bacterial load in lung and spleen tissues with 1.91 and 2.91--log10 protections, respectively, at the dose of 50mg/kg body weight. Compound 10-[(4-((4-chlorophenyl)(phenyl)methyl)piperazin-1-yl)]-9-fluoro-2,3-dihydro-3-methyl-8-nitro-7-oxo-7H-[1,4]oxazino[2,3,4-ij]quinoline-6-carboxylic acid was found to be the most active in the inhibition of the supercoiling activity of DNA gyrase with an IC(50) of 10.0 microg/mL. The results demonstrate the potential and importance of developing new oxazino quinolone derivatives against mycobacterial infections.

Synthesis and antimycobacterial evaluation of newer 1-cyclopropyl-1,4-dihydro-6-fluoro-7-(substituted secondary amino)-8-methoxy-5-(sub)-4-oxoquinoline-3-carboxylic acids.

Thirty-four newer 1-cyclopropyl-1,4-dihydro-6-fluoro-7-(substituted secondary amino)-8-methoxy-5-(sub)-4-oxoquinoline-3-carboxylic acids were synthesized from 1,2,3,4-tetrafluoro benzene and evaluated for in vitro and in vivo antimycobacterial activities against Mycobacterium tuberculosis H37Rv (MTB), multi-drug resistant M. tuberculosis (MDR-TB) and Mycobacterium smegmatis (MC(2)) and also tested for the ability to inhibit the supercoiling activity of DNA gyrase. Among the synthesized compounds, 7-(1-(4-methoxybenzyl)-3,4,5,6,7,8-hexahydroisoquinolin-2(1H)-yl)-1-cyclopropyl-6-fluoro-1,4-dihydro-8-methoxy-5-nitro-4-oxoquinoline-3-carboxylic acid (13n) was found to be the most active compound in vitro with MIC of 0.16 and 0.33 microM against MTB and MDR-TB, respectively. In the in vivo animal model 13n decreased the bacterial load in lung and spleen tissues with 2.54 and 2.92-log10 protections, respectively, at the dose of 50mg/kg body weight. Compound 13n also inhibited the supercoiling activity of mycobacterial DNA gyrase with IC(50) of 30.0 microg/ml.

Synthesis, anti-HIV and antitubercular activities of nelfinavir diester derivatives.

Nelfinavir diesters were prepared by reacting nelfinavir with two molar amount of an appropriate substituted aromatic/aliphatic acid in the presence of dicylohexyl carbodiimide as the carboxyl group activator and 4-dimethylamino pyridine as catalyst. The synthesized compounds were evaluated for their inhibitory effects on the replication of HIV-1 (IIIB) in MT-4 cells by MTT assay method and antimycobacterial activity against Mycobacterium tuberculosis H37Rv by agar dilution method. Compound 3f emerged as the most potent anti-HIV agent with EC(50) of 0.043 microM and CC(50) more than >10 microM and was more potent than parent nelfinavir (EC(50) of 0.060 microM) and also showed antimycobacterial activity (MIC 8.49 microM).

Antimycobacterial activities of novel 1-(cyclopropyl/tert-butyl/4-fluorophenyl)-1,4-dihydro- 6-nitro-4-oxo-7-(substituted secondary amino)-1,8-naphthyridine-3-carboxylic acid.

Fifty-one 1-(cyclopropyl/tert-butyl/4-fluorophenyl)-1,4-dihydro-6-nitro-4-oxo-7-(substituted secondary amino)-1,8-naphthyridine-3-carboxylic acids were synthesized and evaluated for antimycobacterial in vitro and in vivo against Mycobacterium tuberculosis H37Rv (MTB), multi-drug-resistant Mycobacterium tuberculosis (MDR-TB) and Mycobacterium smegmatis (MC2) and also tested for the ability to inhibit the supercoiling activity of DNA gyrase from M. smegmatis. Among the synthesized compounds, 1-tert-butyl-1,4-dihydro-7-(4,4-dimethyloxazolidin-3-yl)-6-nitro-4-oxo-1,8-naphthyridine-3-carboxylic acid (10q) was found to be the most active compound in vitro with an MIC of 0.1 microM against MTB and MDR-TB and was 3 and 455 times more potent than isoniazid against MTB and MDR-TB, respectively. In the in vivo animal model 10q decreased the bacterial load in lung and spleen tissues with 2.39 and 3.89-log10protections respectively at the dose of 50 mg/kg body weight.

Antimycobacterial activity of novel 1-(5-cyclobutyl-1,3-oxazol-2-yl)-3-(sub)phenyl/pyridylthiourea compounds endowed with high activity toward multidrug-resistant Mycobacterium tuberculosis.

OBJECTIVES: The objective of this work was to synthesize 15 new 1-(5-cyclobutyl-1,3-oxazol-2-yl)-3-(sub)phenyl/pyridylthiourea compounds and evaluate their in vitro and in vivo antimycobacterial activities. METHODS: 5-Cyclobutyloxazol-2-amine was reacted with 1,1'-thiocarbonyldiimidazole, followed by various substituted anilines and 2-amino pyridines to yield the 15 compounds, which were subjected to in vitro and in vivo evaluation against Mycobacterium tuberculosis H37Rv (MTB) and a clinical isolate of multidrug-resistant M. tuberculosis (MDR-TB). RESULTS: Among the 15 compounds screened, 7 compounds inhibited both MTB and MDR-TB in vitro with MICs of < 1 microM. In the in vivo screening, compound 1-(5-cyclobutyl-1,3-oxazol-2-yl)-3-(2'-trifluoromethyl)phenylthiourea (compound 8) was equally active as isoniazid at the same dose level. CONCLUSIONS: Compound 8 was found to be the most active, with an in vitro MIC of 0.14 microM and was 2.5 and 80 times more active than isoniazid against MTB and MDR-TB, respectively. Compound 8 was non-toxic to Vero cells up to 183 microM, with a selectivity index of > 1307. In the in vivo animal model, compound 8 decreased the mycobacterium load in lung and spleen tissues with 2.8 and 3.94 log(10) reductions, respectively.

Synthesis, antiviral and cytotoxic activity of 6-bromo-2,3-disubstituted-4(3H)-quinazolinones.

In the present study, a series of 6-bromo-2,3-disubstitued-4(3H)-quinazolinones was synthesized by condensation of 6-bromo-2-substituted-benzoxazin-4-one with trimethoprim, pyrimethamine and lamotrigine. The chemical structures of the synthesized compounds were confirmed by means of IR, (1)H-NMR and mass spectral and elemental analysis. The antiviral activity and cytotoxicity of the compounds were tested in E(6)SM (Herpes simplex-1 KOS, Herpes simplex-1 TK-KOS ACV, Herpes simplex-2 G, Vaccinia virus, Vesicular stomatitis virus, Parainfluenza-3 virus, Reovirus-1, Sindbis virus, Coxsackie virus B4 and Punta Toro virus) and HeLa cell culture (Vesicular stomatitis virus, Coxsackie virus B4 and Respiratory syncyticla virus). Investigation of anti-HIV activity was done against replication of HIV-1 (HTLV-III B LAI) in MT-4 cells. 6-Bromo-2-phenyl-3-[(4-amino-5-(4-chlorophenyl)-6-ethylpyrimidin-2-yl]-4(3H)-quinazolinone (4) exhibited the most potent antiviral activity with a MIC of 1.92 microg/ml against vaccinia virus in E(6)SM cell culture. The other compounds did not exhibit antiviral activity nor afford significant cytoprotection to the E(6)SM and HeLa cell culture when challenged with the viruses. The study implies that 4 may possess activity against Pox viruses including variola. In the anti-HIV study, 6-bromo-2-methyl-3-[(4-amino-5-(4-chlorophenyl)-6-ethylpyrimidin-2-yl]-4(3H)-quinazolinone (3) and 6-bromo-2-phenyl-3-[(4-amino-5-(4-chlorophenyl)-6-ethylpyrimidin-2-yl]-4(3H)-quinazolinone (4) exhibited the least cytotoxic concentration (0.424, 0.461 microg/ml) which is an index of the infective viability of mock infected MT-4 cells with HIV-1. None of the compounds exhibited significant anti-HIV activity.