Jpn. J. Pharmacol. 86 (2), 223-229 (2001)

Structure-Activity Relationships of Triterpenoid Derivatives Extracted From Gymnema inodorum Leaves on Glucose Absorption

Kazumasa Shimizu1,*, Mie Ozeki1, Akira Iino1, Shinjiro Nakajyo1, Norimoto Urakawa1 and Mikito Atsuchi2

1Division of Veterinary Pharmacology, Nippon Veterinary and Animal Science University, Musashino-shi, Tokyo 180-8602, Japan
2Technical Research Laboratory, Kowa Chemical Industries Co., Ltd., Ohta-ku, Tokyo 144-0032, Japan

*Corresponding author. FAX: +81-422-31-4457

Abstract: The leaves of Gymnema inodorum (GI) have been known to be effective for some diseases including diabetes mellitus, rheumatic arthritis and gout. The crude saponin mixtures extracted from GI leaves inhibited glucose absorption in the isolated intestinal tract and suppressed the increased blood glucose in rats. In this study, we examined the relationship between chemical structure and pharmacological activity of the four components from GI leave extracts (GiA-1, GiA-2, GiA-5 and GiA-7). These components were the derivatives of (3b,4a,16b)-16,23,28-trihydroxyolean-12-en-3-yl-b-D-glucopyranosiduroic acid. GiA-2, GiA-5 and GiA-7 that have suppressive effects on the high K+-induced contraction, an increase in DPD and the increased blood glucose level in the glucose tolerance test have −H at the 21st position and −CH2OH at 4b of aglycon. On the other hand, GiA-1 that does not have any effects on the three parameters mentioned above has −H at the 21st position and −CH3 at 4b of aglycon. In conclusion, it is suggested that the inhibitory effect of triterpenoids in Gymnema leaves on glucose absorption from the intestinal tract relies on −CH2OH at 4b.

Keywords: Gymnema inodorum, Triterpenoid, Structure, Glucose absorption, Blood glucose
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