Anhydroicaritin 3- O-rhamnosyl(1 → 2)rhamnoside from Epimedium koreanum and a reappraisal of other rhamnosyl(1 → 2, 1 → 3 and 1 → 4)rhamnoside structures

An anhydroicaritin 3- O-rhamnosylrhamnoside from Epimedium koreanum is defined as the 3-O-α- l-[α- l-rhamnopyranosyl(1 → 2)rhamnopyranoside ] on the basis of 2D NMR evidence. Complete assignments of the 1H and 13C NMR spectra of this compound are presented for the first time. The NMR distinction of 1 → 2, 1 → 3 and 1 → 4 linked rhamnopyranosylrhamnopyranosides are discussed and indicate that baohuosides III and V from E. davidii and baohuoside VI from E. davidii and E. pubescens, respectively, are (1 → 2) linked.