Fundamental studies on the inhibitory action of Acanthopanax senticosus Harms on glucose absorption.
OBJECTIVE
Acanthopanax senticosus Harms extract (ASE) is used as an ingredient of over-the-counter drugs and functional foods, such as health supplements, in Japan. ASE exhibits a hypoglycemic effect; however, the mechanism of the hypoglycemic effect is not clear. In the present study, we investigated whether ASE has a glucose absorption inhibitory action.


METHODS
We examined the effects of ASE on α-amylase and α-glucosidase activities, and on glucose uptake in Caco-2 cells. We also examined the effects of ASE oral administration on glucose tolerance in type 2 diabetes mellitus model db/db mice.


RESULTS
The addition of ASE inhibited α-glucosidase activity but not α-amylase activity. The α-glucosidase inhibitory activity of ASE was approximately 1/13 of that of acarbose. The addition of ASE inhibited 2'-deoxy-D-glucose (DG) uptake in human intestinal Caco-2 cells, and the inhibitory activity of ASE was approximately 1/40 of that of phloretin. Kinetic analysis of glucose uptake indicated that ASE has no effects on DG uptake through passive diffusion, but that ASE inhibits intracellular DG uptake chiefly by inhibiting transport via a glucose transporter. In the glucose tolerance study, db/db mice orally administered ASE for 3 days showed significantly lower plasma glucose level than the control group 30 min after sucrose loading, without affecting plasma insulin levels. In addition, ASE oral administration significantly inhibited α-glucosidase activity in the small intestine mucosa extirpated from the mice.


CONCLUSIONS
These findings indicate that ASE may be useful as an ingredient of functional foods to improve postprandial hyperglycemia and prevent type II diabetes mellitus.
Watanabe
Kazuhiro
K
Hokkaido Pharmaceutical University School of Pharmacy, 7-1 Katsuraoka-cho, Otaru, Hokkaido 047-0264, Japan. watanabe@hokuyakudai.ac.jp
Kamata
Keiko
K
Sato
Juichi
J
Takahashi
Tunehisa
T
D000284:Administration, Oral; D000327:Adsorption; D000818:Animals; D001786:Blood Glucose / Q000032:analysis; D018938:Caco-2 Cells; D018929:Cell Culture Techniques; D003921:Diabetes Mellitus, Experimental / Q000097:blood / Q000188:drug therapy*; D003924:Diabetes Mellitus, Type 2 / Q000097:blood / Q000188:drug therapy*; D028001:Eleutherococcus / Q000737:chemistry*; D005947:Glucose / Q000378:metabolism*; D005951:Glucose Tolerance Test; D006801:Humans; D007004:Hypoglycemic Agents / Q000302:isolation & purification / Q000494:pharmacology* / Q000627:therapeutic use; D007328:Insulin / Q000097:blood; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D024301:Plant Bark / Q000737:chemistry; D010936:Plant Extracts / Q000302:isolation & purification / Q000494:pharmacology* / Q000627:therapeutic use; D000516:alpha-Amylases / Q000378:metabolism; D000520:alpha-Glucosidases / Q000378:metabolism
D001786:Blood Glucose; D007004:Hypoglycemic Agents; D007328:Insulin; D010936:Plant Extracts; D000516:alpha-Amylases; D000520:alpha-Glucosidases; D005947:Glucose