Anti-HIV-1 constituents from Clausena excavata: Part II. Carbazoles and a pyranocoumarin.

Three carbazole derivatives, O-methylmukonal (1), 3-formyl-2,7-dimethoxycarbazole (2) and clauszoline J (3), and a pyranocoumarin, clausenidin (4), were isolated from the rhizomes and roots of Clausena excavata. Compound 1, isolated from this plant for the first time, has not been reported previously as having anti-HIV-1 activity. Compounds 1-4 displayed anti-HIV-1 activity in a syncytial assay with EC(50) values of 12, 29.1, 34.2 and 5.3 microm, respectively, and thus exhibited potential therapeutic index (PTI) values of 56.7, 8.0, 1.6 and 7.0, respectively. All isolated compounds demonstrated a lack of cytotoxicity against the KB and BC-1 cancer cell lines. Copyright (c) 2005 John Wiley & Sons, Ltd.