Design, synthesis and biological evaluation of novel nitrogen and sulfur containing hetero-1,4-naphthoquinones as potent antifungal and antibacterial agents.

A series of 2-Arylamino-3-chloro-1,4-naphthoquinones (3), 2-Amino-3-arylsulfanyl-1,4-naphthoquinones (5), 2-Arylamino-3-arylsulfanyl-1,4-naphthoquinones (6), Dihydrobenzo[f]naphtho[2,3-b][1,4]thiazepine-6,11-diones (9) (via Pictet-Spengler cyclization), Isoindoline-1,3-dione derivatives of 1,4-naphthoquinone (13), 2,2'-(1,4-Dioxo-1,4-dihydronaphthalene-2,3-diyl)bis(methylene)dibenzonitrile (14), 13-Amino-12-substituted-6H-benzo[e]naphtho [2,3-b][1,4]diazepine-6,11(12H)-diones (15-16), 2-Chloro-3-arylsulfanyl-1,4-naphthoquinones (17-18) and 3-Methyl-6H-benzo[b]phenothiazine-6,11(12H)-dione (19) were synthesized and studied for their antifungal and antibacterial activities. The results indicate that compounds 3b, 5a and 5b have potent antifungal activity. Amongst the most promising antifungal compounds, 3b showed better antifungal activity than clinically prevalent antifungal drug Fluconazole (MIC(50)=2.0 microg/mL) against Sporothrix schenckii (MIC(50)=1.56 microg/mL), significant profile against Candida albicans (MIC(50)=1.56 microg/mL), Cryptococcus neoformans (MIC(50)=0.78 microg/mL) and Trichophyton mentagraphytes (MIC(50)=1.56 microg/mL) and same antifungal activity when compared with Amphotericin-B against C. neoformans (MIC(50)=0.78 microg/mL). Compounds 3b, 5a and 5b also showed promising antibacterial activity.