Antifungal trichothecene sesquiterpenes obtained from the culture broth of marine-derived Trichoderma cf. brevicompactum and their structure-activity relationship

Two new trichothecene sesquiterpenes, trichobreols D (1) and E (2), were isolated from the culture broth of marine-derived Trichoderma cf. brevicompactum together with trichobreol A (3). The structures of 1 and 2 were assigned on the basis of their spectroscopic data. Compound 1 inhibited the growth of two yeast-like fungi, Candida albicans and Cryptococcus neoformans, with equivalent MIC values (6.3 mu g/mL), while 2 gave MIC values of 12.5 and 25 mu g/mL, respectively. The antifungal activities of five semisynthetic derivatives (4-8) prepared from 3 were evaluated and compared to investigate the preliminary structure-activity relationship.