Two major saponins from seeds of Barringtonia asiatica: putative antifeedants toward Epilachna sp. larvae.

Two major saponins have been isolated from a methanol extract of the seeds of Barringtonia asiatica, and their structures elucidated (mainly by two-dimensional NMR spectroscopy) as 3-O-[[beta-D-galactopyranosyl(1-->3)-beta-D-glucopyranosyl(1-->2)]-beta-D-glucuronopyranosyloxy]-22-O-(2-methylbutyroyloxy)-15,16,28-trihydroxy-(3beta,15alpha,16alpha,22alpha)-olean-12-ene (3) and 3-O-[[beta-D-galactopyranosyl(1-->3)-beta-D-glucopyranosyl(1-->2)]-beta-D-glucuronopyranosyloxy]-22-O-[2(E)-methyl-2-butenyloyloxy]-15,16,28-trihydroxy-(3beta,15alpha,16alpha,22alpha)-olean-12-ene (4). The antifeedant properties of 3 and 4 toward Epilachna larvae are discussed.