Novel phytoalexins (oryzalexins A, B and C) isolated from rice blast leaves infected with Pyricularia oryzae. Part I: Isolation, characterization and biological activities of oryzalexins.

Oryzalexins A, B and C were isolated as a group of novel phytoalexins from rice (Oryza saliva) blast leaves infected with Pyricularia oryzae. The basis of the structures of Oryzalexins A, B and C was laid by spectroscopic methods and their inhibitory activities against spore germination and germ tube growth of P. oryzae were assayed.