Byakko-ka-ninjin-to (BN) has been used as a traditional Oriental medicine for diabetes. Suzuki et al. reported on the antidiabetic activity of orally administered BN in KK-CA y mice.1) We also found that BN decreased blood glucose levels in KK-Ay mice. Moreover, the 50 and 100% methanol layers of BN decreased blood glucose, while the water layer did not change. One of the constituents of BN is the rhizoma of Anemarrhena asphodeloides.The rhizoma of Anemarrhena asphodeloides has been used as a traditional Oriental medicine for diabetes (polyuria and polydipsia) and constipation, 2) and antidiabetic activity has been observed.2,3) However, because previous studies involved intraperitoneal administration, little is known its oral antidiabetic activity.4) The purpose of this study therefore is to examine the antidiabetic activity after oral administration and the active components from the water extract of the rhizoma of Anemarrhena asphodeloides (AA) using a type 2 diabetic animal model and bioassay-guided fractionation.
RESULTS
Effect of AA in Normal MiceNo change in mean blood glucose levels in normal mice was observed after oral administration of AA (90 mg/kg), as shown in Fig. 1. However, mice that received tolbutamide (50 mg/kg body weight), a known sulfonylurea hypoglycemic agent, had reduced blood glucose levels 7 h after administration of AA (pϽ0.01).
Effect of AA in KK-Ay Diabetic MiceThe mean blood glucose levels in KK-Ay mice after oral administration of various doses of AA and tolbutamide are shown in Fig. 2. The hypoglycemic effect of AA was dose-dependent in KKAy mice. AA 90 mg/kg lowered blood glucose from the basal level of 570Ϯ29 to 401Ϯ59 mg/dl (pϽ0.05), 7 h after administration. Mice that received tolbutamide 50 mg/kg-treated had lower blood glucose levels (pϽ0.05). The effects of AA on serum insulin level 7 h after administration are shown in Fig. 3. AA tended to decrease the serum insulin level in KKAy mice.Insulin Tolerance Test AA decreased blood glucose levels in KK-Ay mice 30 min after the administration of insulin when compared with baseline levels (pϽ0.01). A significant decrease in blood glucose was observed in AAtreated mice 30 and 60 min after insulin administration as compared with the corresponding controls (pϽ0.05) (Fig. 4). Kawahara-cho, Sakyo-ku, Kyoto 606-0123, Japan, Tsumura Central Research Laboratories, Tsumura and Co., c 3586 Yoshiwara, Amimachi, Inashiki-gun, Ibaraki 300-11, Japan, and Hi-tech Research Center, Suzuka University of Medical Science, d 1001-1 Kishioka, Suzuka, Mie, 510-0293, Japan. Received August 18, 2000; accepted May 26, 2001 The antidiabetic activity of the rhizoma of Anemarrhena asphodeloides was investigated in KK-Ay mice, an animal model of genetic type 2 diabetes. The water extract of the rhizoma (AA) (90 mg/kg) reduced blood glucose levels from 570؎29 to 401؎59 mg/dl 7 h after oral administration (pϽ0.05) and also tended to reduce serum insulin levels in KK-Ay mice. AA-treated KK-Ay mice had significantly reduced blood glucose levels in an insu...
