Verbascoside B — A minor iridoid ofVerbascum georgicum

Abstract

By preparative PC of the previously purified total iridoid material followed by chromatography on a column of silica, a new minor iridoid — verbascoside B (I) — has been isolated in the form of an amorphous substance with [α]_D −108 ± 4 (c 0.12; methanol). The structure of (I), corresponding to 6-α-L-rhamnopyranosyldecinnamoylglobularinin, has been shown on the basis of a passage from 6-α-L-rhamnopyranosylcatalpol and the spectral characteristics of (I) and of its nanoacetate (II). Characteristics of the IR and¹H and¹³C spectra of (I) and (II) and of the mass spectrum of (II) are given.