A major fungitoxin from Pachira aquatica and its accumulation in outer bark

A major fungitoxin in the root of Pachira aquatica (Bombacaceae) was isolat ed and identified as isohemigossypolone. Quantitative analysis of isohemigo ssypolone in different parts of P. aquatica revealed that the outer bark of the swollen trunk accumulated a large amount of the fungitoxin. The concen tration of the substance was more than 1 mg/g fresh weight in the outer bar k tissues. Pure isohemigossypolone showed clear antifungal activity against Pythium ultimum at a minimum dose of 10 mu g/disk, and it may function as a defensive chemical to protect storage tissues of P. aquatica.