Chem. Pharm. Bull., 48(11),1720-1725, November 2000

Regular Articles

Bioactive Saponins and Glycosides. XVII.¹⁾ Inhibitory Effect on Gastric Emptying and Accelerating Effect on Gastrointestinal Transit of Tea Saponins: Structures of Assamsaponins F, G, H, I, and J from the Seeds and Leaves of the Tea Plant

Toshiyuki MURAKAMI, Junko NAKAMURA, Tadashi KAGEURA, Hisashi MATSUDA, and Masayuki YOSHIKAWA^*

Kyoto Pharmaceutical University, Misasagi, Yamashina-ku, Kyoto 607-8414, Japan.

Following the investigation of assamsaponins A, B, C, D, and E, four new saponins termed assamsaponins F, G, H, and I were isolated from the seeds of the tea plant (Camellia sinensis L. var. assamica PIERRE), while assamsaponin J was isolated from its leaves. The structures of assamsaponins F-J were elucidated on the basis of chemical and physicochemical evidence and found to be 16,22-O-diacetyl-21-O-angeloyltheasapogenol E 3-O-[b-D-galactopyranosyl(12)][b-D-glucopyranosyl(12)-a-L-arabinopyranosyl(13)]-b-D-glucopyranosiduronic acid, 21-O-angeloyl-22-O-acetyltheasapogenol E 3-O-[b-D-galactopyranosyl(12)][b-D-glucopyranosyl(12)-a-L-arabinopyranosyl(13)]-b-D-glucopyranosiduronic acid, 21-O-angeloyl-28-O-acetyltheasapogenol E 3-O-[b-D-galactopyranosyl(12)][b-D-glucopyranosyl(12)-a-L-arabinopyranosyl(13)]-b-D-glucopyranosiduronic acid, 21-O-tigloyl-28-O-acetyltheasapogenol E 3-O-[b-D-galactopyranosyl(12)][b-D-glucopyranosyl(12)-a-L-ara-binopyranosyl(13)]-b-D-glucopyranosiduronic acid, and 16,21-O-diacetyl-22-O-cinnamoyltheasapogenol B 3-O-[b-D-galactopyranosyl(12)][b-D-rhamnopyranosyl(12)-a-L-arabinopyranosyl(13)]-b-D-glucopyra-nosiduronic acid, respectively.
The saponin mixture from the seeds of the tea plant was found to exhibit an inhibitory effect on gastric emptying and an accelerating effect on gastrointestinal transit in mice. Theasaponin E₁, the principle saponin of the tea plant, showed potent activity, while theasaponin E₂ showed none, so that the position of the acyl groups in the sapogenin moiety is important from a pharmacological point of view.

Key words assamsaponin; Camellia sinensis var. assamica; tea plant; oleanene-type triterpene oligoglycoside; gastric emptying inhibitor; gastrointestinal transit accelerator