Tuberculosis (TB) is still a major health concern worldwide. The increasing incidences of multi-drug-resistant tuberculosis (MDR-TB) necessitate the development of new anti-TB drugs acting via novel mode of action. The search of newer drugs for TB led to the identification of several quinoline-based antimycobacterial agents against both the drug-sensitive and MDR-TB. These agents have been designed by substituting quinoline scaffold with diverse chemical functionalities as well as by modifying quinoline/quinolone-based antibacterial drugs. Several of quinoline/quinolone derivatives displayed excellent antimycobacterial activity and were found free of cytotoxicity. This review highlights the critical aspects of design and structure-activity relationship of quinoline-and quinolone-based antimycobacterial agents.

Tubulin is the one of the most useful and strategic molecular targets for anticancer drugs. Agents that bind in Colchicine-binding site of tubulin include Phenstatin, Combretastatin A-4, Colchicine, Steganacin, Podophyllotoxin and certain other synthetic analogues of these compounds. Arylidene pyrollo and pyrido [2,1- b] quinazolones (isoindigatone and its synthetic analogues) have been earlier reported to be tubulin inhibitors evidenced by tubulin polymerization assay. The present study is an extension of the library of the isoindigatone and its synthetic analogues to generate the structure activity relationship. The study explores the role of the arylidene ring and also provides some intresting observations such as the placement of bicyclic ring such as naphylidene for potential activity. Some of the important interactions of KNH- 3 and KNH-11 with the amino acid residues of active site of Tubulin have also been observed by molecular modeling.