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A series of novel dibenzo[b,d]thiophene tethered imidazo[1,2-a]pyridine carboxamides 7a-s were designed and synthesized. The required building block, 2-dibenzo[b,d]thiophenyl imidazo[1,2-a]pyridine carboxylic acid (5) was synthesized from commercial dibenzo[b,d]thiophene in good yields following five-step reaction sequence. The desired carboxamides 7a-s was prepared through coupling of acid 5 with various benzyl amines. All the new analogues 7a-s was characterized by their NMR and mass spectral analysis. Among nineteen new compounds 7a-s screened for in vitro antimycobacterial activity against Mycobacterium tuberculosis H37Rv, three compounds 7k (MIC: 0.78μg/mL); 7e and 7n (MIC: 1.56μg/mL) were identified as potent analogues with low cytotoxicity. The results reported here will help global efforts for identification of potential lead antimycobacterial agents., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

2-Styrylquinazolones are reported as a novel class of potent anti-mycobacterial agents. Forty-six target compounds have been synthesized using one pot reaction involving isatoic anhydride, amine, and triethyl orthoacetate followed by aldehyde to construct the 2-styrylquinazolone scaffold. The anti-mycobacterial potency of the compounds was determined against H37Rv strain. Twenty-six compounds exhibited anti-Mtb activity in the range of 0.40-6.25μg/mL. Three compounds 8c, 8d and 8ab showed MIC of 0.78μg/mL and were found to be non-toxic (<50% inhibition at 50μg/mL) to HEK 293T cell lines with the therapeutic index >64. The most potent compound 8ar showed MIC of 0.40μg/mL with the therapeutic index >125. An early structure activity relationship for this class of compounds has been established. The computational studies indicate the possibility of these compounds binding to the penicillin binding proteins (PBPs)., (Copyright © 2016. Published by Elsevier Ltd.)

Natural alkaloid, tryptanthrin (indolo[2,1-b]quinazoline-6,12-dione) and its analogues are found to exhibit potent anti-tubercular activity against MDR-TB. A novel class of indolo[2,1-b]quinazolinones have been synthesized to evaluate their anti-mycobacterial activity. Enoyl-acyl carrier protein reductase (InhA) of Mycobacterium tuberculosis is one of the key enzymes and has been validated as an effective anti-microbial target. In silico molecular docking study demonstrates that the synthesized compounds exhibit high affinity for the M. tuberculosis drug target InhA. Phaitanthrin is a natural product, which belongs to a family of tryptanthrin and exhibits structural similarity except at position 6. Phaitanthrin derivatives are prepared by modifying the keto functionality of tryptanthrin. These phaitanthrin congeners are found to display promising anti-tubercular activity., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Focus in this Letter is made to design and synthesize a series of nineteen new 6-(4-((substituted-1H-1,2,3-triazol-4-yl)methyl)piperazin-1-yl)phenanthridine analogues employing click chemistry and evaluated for their anti-tubercular activity against Mycobacterium tuberculosis H37Rv. Among the tested compounds, 7f and 7 j exhibited good activity (MIC = 3.125 μg/mL), while 8a displayed excellent activity (MIC = 1.56 μg/mL) against the growth of M. tuberculosis H37Rv. In addition, 7f, 7 j and 8a compounds were subjected to cytotoxic studies against mouse macrophage (RAW264.7) cell lines and the selectivity index values are >15 indicating suitability of compounds for further drug development., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

A series of novel natural product like 2-substiuted-3H-benzofurobenzofurans designed by molecular hybridization were synthesized in very good yields. The key reactions involved in the synthesis are iodination of 2-dibenzofuranol using iodine monochloride followed by palladium-copper catalyzed Sonagashira-coupling of 1-iododibenzofuran-2-ol with various alkyl and aryl acetylenes. Among the all 10 new compounds screened for in vitro anti-mycobacterial activity against Mycobacterium tuberculosis H37Rv, 2-(4-methoxy-2-methyl phenyl)-3H-benzofuro[3,2-e]benzofuran (7c) was found to be most active with MIC 3.12 μg/mL and has shown lower cytotoxicity with good therapeutic index., (Copyright © 2013 Elsevier Ltd. All rights reserved.)