Bioactive Saponins and Glycosides. XXIII. Triterpene Saponins with Gastroprotective Effect from the Seeds of Camellia sinensis—Theasaponins E3, E4, E5, E6, and E7—

Masayuki Yoshikawa, Toshio Morikawa, Ning Li, Akifumi Nagatomo, Xian Li, Hisashi Matsuda
2005 Chemical and pharmaceutical bulletin  
The seeds of the tea plant [Camellia sinensis (L.) O. KUNTZE (Theaceae)] are known to contain saponin constituents with an insectifuge activity and its crude saponin fraction has been used as a surface-active agent. 2) Previously, we reported the structure elucidation and anti-sweet activity of two acylated polyhydroxyoleane-12-ene oligoglycosides, theasaponins E 1 (6) and E 2 (7), from the seeds of C. sinensis cultivated in Japan. 2) In addition, from the seeds and leaves of C. sinensis var.
more » ... samica PIERRE cultivated in Sri Lanka, we isolated assamsaponins A (8), B (9), C (10), D (11), E, F (12), G, H, and I (13) with gastric emptying activity and an accelerating effect on gastrointestinal transit. 3,4) Recently, we characterized floratheasaponins A (14), B, and C with antihyperlipidemic activity from the flowers of C. sinensis. 1) As a continuing study on the bioactivity of saponin constituents from the tea plant, we found that the saponin fraction of the methanolic extract from the seeds of C. sinensis showed protective effects on ethanol-and indomethacin-induced gastric December 2005 Chem. Pharm. Bull. 53(12) 1559-1564 (2005) 1559 The saponin fraction from the seeds of the tea plant [Camellia sinensis (L.) O. KUNTZE (Theaceae)] was found to exhibit potent protective effects on ethanol-and indomethacin-induced gastric mucosal lesions in rats. Five new triterpene saponins, theasaponins E 3 (1), E 4 (2), E 5 (3), E 6 (4), and E 7 (5), were isolated together with 11 known saponins from the saponin fraction. The chemical structures of 1-5 were elucidated on the basis of chemical and physicochemical evidence. Among the isolated saponins, theasaponins E 1 (6), E 2 (7), and E 5 (3) and assamsaponin C (10) showed an inhibitory effect on ethanol-induced gastric mucosal lesions at a dose of 5.0 mg/kg, p.o. and their activities were stronger than that of omeplazole. With regard to the structure-activity relationships of theasaponins, the following structural requirements for a protective effect on ethanol-induced gastric lesions were suggested; 1) the 21-and/or 22-acyl groups are essential for the activity, 2) acetylation of the 16-hydroxyl group reduce the activity.
doi:10.1248/cpb.53.1559 pmid:16327189 fatcat:dcmlo7qojzco7dytdtwmy4mbde