New N-arylamino biquinoline derivatives: synthesis, antimicrobial, antituberculosis, and antimalarial evaluation.

A new series of N-arylamino biquinoline derivatives 5a-x were synthesized by reaction of 2-chloro-3-formyl quinolines 2a-d with malononitrile and various enhydrazinoketones 4a-f in absolute ethanol. The newly synthesized compounds were evaluated for their in vitro antimicrobial activity against a representative panel of pathogenic strains and antituberculosis activity against Mycobacterium tuberculosis H37Rv. Compounds 5h and 5s exhibited excellent antibacterial activity and some of the compounds demonstrated moderate antituberculosis activities compared with the first line drugs. The compounds were evaluated in vitro for their activity against the growth of Plasmodium falciparum, the malaria causing parasite. Some of them showed antimalarial activity with IC(50) values as low as 0.005-0.009 µg/mL.

Synthesis and antimicrobial evaluation of new pyrano[4,3-b]pyran and Pyrano[3,2-c]chromene derivatives bearing a 2-thiophenoxyquinoline nucleus.

A new series of pyrano[4,3-b]pyran 4a-i and pyrano[3,2-c]chromene 6a-r derivatives bearing a 2-thiophenoxyquinoline nucleus were synthesized by reaction of 2-(4-(un)-substituted thiophenoxy)quinoline-3-carbaldehydes 2a-i with 6-methyl-4-hydroxypyran-2-one 3 and 4-hydroxy-6-(un)-substituted-2H-chromen-2-one 5a-b respectively and malononitrile at room temperature in the presence of KOH as a basic catalyst. All the compounds were screened against three Gram-positive bacteria (Streptococcus pneumoniae, Bacillus subtilis, Clostridium tetani), three Gram-negative bacteria (Salmonella typhi, Escherichia coli, Vibrio cholerae) and two fungi (Candida albicans, Aspergillus fumigatus) using the broth microdilution MIC (minimum inhibitory concentration) method. Upon antimicrobial screening, it was observed that the majority of the compounds were found to be active against Bacillus subtilis, Clostridium tetani and Candida albicans as compared to standard drugs.

Microwave assisted synthesis and antimicrobial evaluation of new fused pyran derivatives bearing 2-morpholinoquinoline nucleus.

A new series of fused pyran derivatives 5a-x bearing 2-morpholinoquinoline nucleus has been synthesized under microwave irradiation by a reaction of 2-morpholinoquinoline-3-carbaldehyde 2a-c, malononitrile 3 and compounds 4a-h in presence of NaOH as basic catalyst. All the compounds were screened against three Gram positive bacteria (Streptococcus pneumoniae, Clostridium tetani, Bacillus subtilis), three Gram negative bacteria (Salmonella typhi, Vibrio cholerae, Escherichia coli) and two fungi (Aspergillus fumigatus, Candida albicans) using broth microdilution MIC (Minimum Inhibitory Concentration) method. Of the compounds studied, compounds 5b, 5f, 5k, 5m, 5q, 5s and 5v have found to be most efficient members of the series.

Synthesis and identification of ß-aryloxyquinolines and their pyrano[3,2-c]chromene derivatives as a new class of antimicrobial and antituberculosis agents.

A new class of ß-aryloxyquinolines 3a-i and their pyrano[3,2-c]chromene derivatives 6a-r incorporating a validated molecular target has been synthesized via a nucleophilic displacement and a one-pot multicomponent reaction respectively. In vitro antimicrobial activity of the synthesized compounds were investigated against a representative panel of pathogenic strains specifically Bacillus subtilis, Clostridium tetani, Streptococcus pneumoniae, Escherichia coli, Salmonella typhi, Vibrio cholera, Aspergillus fumigatus and Candida albicans. Compounds 3c, 3e, 3g, 6f, 6l and 6q exhibited excellent antibacterial activity while compound 6p exhibited more potent antifungal activity than that of first line standard drugs. In vitro antituberculosis activity was evaluated against Mycobacterium tuberculosis H37Rv and compound 6f is emerged as the promising antimicrobial member with better antitubercular activity. Majority of the compounds appears to be better antimicrobials but poor antituberculars.