A New Lactone from Chaetomium globosum Strain M65 that Inhibits the Motility of Zoospores.

In a search for endophytes from medicinal plants of Bangladesh, we isolated the M65 fungal strain from the fruit of Azadirachta indica. Following chemical screening, chromatographic purification of the culture extract of strain M65 led to the isolation of the previously reported lasiodiplodin (2), the known derivative 1, and the new derivative 3a, along with two further known compounds (4 and 5). The new (3R,5R)-5-hydroxylasiodiplodin (3a), the enantiomer of the known (3S,5S)-5-hydroxylasiodiplodin (3b), inhibited the motility of zoospores of a devastating late blight phytopathogen Phytophthora capsici by 100% at a concentration of 10 µg/mL. The respective activities of the other metabolites were negligible.