CAULERCHLORIN, A NOVEL CHLORINATED BISINDOLE ALKALOID WITH ANTIFUNGAL ACTIVITY FROM THE CHINESE GREEN ALGA CAULERPA RACEMOSA

Caulerchlorin (2), a novel chlorinated bisindole alkaloid with an eight-membered cyclic ring between two indole rings incorporated directly with a chlorine atom, together with three known related metabolites, caulerpin (3), monomethyl caulerpinate (4), and caulersin (5), has been isolated from the Chinese green alga Caulerpa racemosa (Forssk.) J. Agardh. The structure of 2 was determined on the basis of extensive spectroscopic analysis. Compounds 2-5 were evaluated for their antifungal activity against Candida albicans (SC5314), Candida albicans (Y0109), Candida parapsilosis (ATCC 22019), Candida glabrata (537), Microsporum gypseum (Cmccfmza), Trichophyton rubrum (Cmccftla), Aspergillus fumigatus (07544), and Cryptococcus neoformans (32609), and the result showed that only compounds 2 and 4 had a moderate/weak antifungal activity against Cryptococcus neoformans (32609) with MIC80 values of 16 and 64 mu g mL(-1), respectively.