TANNINS AND RELATED POLYPHENOLS OF EUPHORBIACEOUS PLANTS .14. EUPHORBIN-I, A NEW DIMERIC HYDROLYZABLE TANNIN FROM EUPHORBIA-WATANABEI

A new dimeric dehydroellagitannin, euphorbin I (3), was isolated toget her with twenty-eight known polyphenols including dimeric ellagitannin s, euphorbins A (1) and B (2), from the fresh leaves of Euphorbia wata nabei. The structure of 3 which has a macaranoyl group as a linking un it between the monomers was established based on spectroscopic methods and chemical correlation with 1. The structure of euphorbin B (2c), p reviously assigned as a dimer hating the valoneoyl group as the linkin g unit, was revised to 2 having a tergalloyl group.