Antifungal properties of surangin B, a coumarin from Mammea longifolia

The natural product electron transport inhibitor surangin B was examined for its ability to inhibit in vitro mycelial growth and spore germination in several species of fungi. As an inhibitor of mycelial growth, surangin B showed strongest activity against Rhizoctonia solani (IC50 = 3.8 microM) and Botrytis cinerea (IC50 = 11.2 microM). Inhibitory effects were less pronounced in Alternaria dauci, Fusarium oxysporum and Penicillium sp. (IC50 values > 30 microM) and absent in Trichoderma harzianum. Surangin B reduced the level of spore germination in Fusarium oxysporum (IC50 = 2.3 microM) and Botrytis cinerea (IC50 = 1.4 microM), although Alternaria dauci was considerably more tolerant of this coumarin (IC50 = 500 microM). Our results indicate that surangin B may have potential as an antifungal agent.