Phytotoxic constituents from Nimbya alternantherae

Depto de Química, Universidade Federal de Viçosa, Av. P.H. Rolfs s/n, Campus Universitario, 36571-000 Viçosa, MG, Brazil; Depto Fitopatologia, Universidade Federal de Viçosa, 36571-000 Viçosa, MG, Brazil; Depto de Bioquímica, Facultad de Química, Universidad Nacional Autónoma de México, Coyoacán, 04510 México, DF, Mexico
Biochemical Systematics and Ecology 01/2006; DOI: 10.1016/j.bse.2006.06.008

ABSTRACT A phytotoxic compound identified as 6-(3,3-dimethylallyloxy)-4-methoxy-5-methylphthalide (1), was isolated from the phytopathogenic fungus Nimbya alternantherae, cultivated on solid media. Catalytic hydrogenation of 1 resulted in the quantitative formation of second compound (2). Both compounds (1, 2) act by inhibiting the ATP synthesis in spinach thylakoids. A detailed investigation on the mechanism of action indicates that compound 1 acts as a Hill reaction inhibitor and uncoupler of photosynthesis.