Triterpenoid saponins from Vigna angularis

Three new 2,3-dihydro-2,5-dihydroxy-6-methyl-4H-pyran-4-one conjugated sapo nins, named AzII, AzIII and AzIV, were isolated from hypocotyls of adzuki b eans (Vigna angularis). On the basis of chemical and spectral evidence, the structures of AzII, AzII and AzIV were established as 3-O-[beta-D-glucopyr anosyl(1 --> 2)-beta-D-glucuronopyranosyl(1 --> 2)-beta-D-glucuronopyranosy l(1 -->)]-22-O-[2,3-dihydro-2,5-dihydroxy-6-methyl-4H-pyran-4-one(2' -->)]- 3-beta,22 beta,24-trihydroxyolean-12-ene, 3-O-[alpha-L-rhamnopyranosyl(1 -- > 2)-beta-D-glucuronopyranosyl(1 --> 2)-beta-D-glucuronopyranosyl(1 -->)]-2 2-O-[2,3-dihydro-2,5-dihydroxy- 6-methyl-4H-pyran-4-one(2' -->)]-3 beta,22 beta,24-trihydroxyolean-12-ene, and 3-O-[beta-D-glucopyranosyl(1 --> 2)-bet a-D-glucopyranosyl(1 --> 2)-beta-D-glucuronopyranosyl(1 -->)]-22-O-[2,3-dih ydro-2,5-dihydroxy-6-methyl-4H-pyran-4-one(2' -->)]-3 beta,22 beta,24-trihy droxyolean-12- ene, respectively. (C) 1999 Elsevier Science Ltd. All rights reserved.