Abstract
Two sesquiterpenoids, called components A1 and A2, were isolated from sweet potato root tissue either infected by Ceratocystis fimbriata or injured by HgCl2, and their chemical structures were determined. Both components inhibited germination and term-tube growth of Ceratocystis fimbriata-oak strain. The above results indicate that the components are among the phytoalexins of sweet potato. When 14C-component A2 was supplied to diseased tissue discs, the label was efficiently incorporated into dehydroipomeamarone, ipomeamarone, ipomeamaronol, and component B1, indicating it to be a close precursor of these components. In the case of 14C-component A1 administration, the label was mainly incorporated into the two unknown fractions.
