P-14 New monomeric and dimeric ellagitannins of Tamarix nilotica

抄録

A phytochemical investigation of Tamarix nilotica (Ehrenb.) Bunge (collected in Egypt) led to the isolation of 15 new ellagitannins, along with 15 known ones. New tannins 9-14 were assigned as a series of monomeric tannins. Among these monomers, 14 includes a hellinoyl (m-GO-m-GOG) moiety. Structure 9 possesses both m-GOG and p-GOG moieties, and each of structures 10, 11, and 13 has a p-GOG unit. Structure 12 is the first methylated ellagitannin isolated from the family Tamaricaceae. The structures of the new dimers were grouped according to the type of linking unit and their connection mode: m-GOGand p-GOG linear dimers (15-19), m-GOG and p-GOG macrocyclic dimers (20 and 21), and m-GO-m-GOG dimers (23 and 24). Replacement of the HHDP group at O-4/O-6 with a galloyl group at the O-6 of glucose-2 in 23 is another structural feature. These findings reflect the ability of Tamarix plants to produce ellagitannins with various structures and provide valuable new information for elucidating the structure of higher oligomeric compounds.