Study of constituents of Veronicastrum villosulum.

We investigated the constituents of Veronicastrum villosulum (Miquel) Yamazaki (Scrophulariaceae), an endangered species belonging to the IA group. From the aerial parts of this plant cultivated at the botanical garden of Sojo University, we isolated two new cucurbitacine-type glycosides, 3-O-alpha-L-rhamnopyranosyl-(1 --> 2)-[beta-D-glucopyranosyl-(1 --> 3)]-beta-D-glucopyranosides of 3beta,25-dihydroxycucurbit-5,23(E)-diene-7-one-25-methyl ether and 3beta,23-dihydroxycucurbit-5,24-diene-7-one-23-methyl ether.