Antifungal Activities of Dimeric Sesquiterpenes, Shizukaols C and F, Isolated from Chloranthus japonicus Sieb.

Two dimeric sesquiterpenes were separated from Chloranthus japonicus Sieb. and identified as shizukaols C and F. They exhibited potent antifungal activities (MICs = 4-16 μg/ml) in vitro against various plant pathogenic fungi (Pythium ultimum, Phytophthora infestans, Botrytis cinerea, Colletotrichum lagenarium, Alternaria kikuchiana, and Magnaporthe grisea). Shizukaol C showed 88% and 91% protective activities in the greenhouse against Puccinia recondita (wheat leaf rust) and Phytophthora infestans (tomato late blight), respectively, at 100 μg/ml; shizukaol F exhibited 93% antifungal activity against Puccinia recondita at the same concentration. Therefore, these compounds might serve as interesting candidates for effective antifungal agents.