Three Escin‐Like Triterpene Saponins: Assamicins VI, VII, and VIII from the Seeds of Aesculus assamica Griff

Three new escin‐like triterpene saponins, assamicins VI ( 1 ), VII ( 2 ), and VIII ( 3 ), were isolated from the seeds of A. assamica , together with a known saponin, isoescin Ib ( 4 ). Their structures were established as 28‐ O ‐acetyl‐21‐ O ‐(3,4‐di‐ O ‐angeloyl‐6‐deoxy‐ β ‐glucopyranosyl)‐3‐ O ‐{ O ‐ β ‐glucopyranosyl‐(1→2)‐O‐[ β ‐glucopyranosyl‐(1→4)]‐ β ‐glucopyranuronosyl}protoaescigenin ( 1 ), 21‐ O ‐angeloyl‐3‐ O ‐{ O ‐ α ‐rhamnopyranosyl‐(1→2)‐ O ‐[ β ‐glucopyranosyl‐(1→3)]‐ β ‐glucopyranuronosyl}protoaescigenin ( 2 ), and 21‐ O ‐angeloyl‐3‐ O ‐{ O ‐[ β ‐glucopyranosyl‐(1→3)]‐ β ‐glucopyranuronosyl}protoaescigenin ( 3 ) on the basis of spectroscopic analysis (protoaescigenin=(3 β ,4 β ,16 α ,21 β ,22 α )‐olean‐12‐ene‐3,16,21,22,23,28‐hexol; angelic acid=(2 Z )‐2‐methylbut‐2‐enoic acid).