Effects of myricetin on glycemia and glycogen metabolism in diabetic rats.
In our previous study, we found that myricetin, a naturally occurring bioflavonoid, was able to stimulate glucose transport in rat adipocytes and enhance insulin-stimulated lipogenesis. We report here that after 2 days of treatment with myricetin (3 mg/12 h), hyperglycemia in diabetic rats was reduced by 50% and the hypertriglyceridemia that is often associated with diabetes was normalised. Treatment with myricetin increased hepatic glycogen and glucose-6-phosphate content. It increased hepatic glycogen synthase I activity without having any effect on total glycogen synthase nor phosphorylase a activity. It lowered phosphorylase a activity in the muscle. Thus, the hypoglycemic effect of myricetin is likely to be due to its effect on glycogen metabolism. There was no indication of serious hepatotoxicity with myricetin treatment and therefore, myricetin could be of therapeutic potential in diabetes.
Ong
K C
KC
Department of Biochemistry, Faculty of Medicine, National University of Singapore, Republic of Singapore.
Khoo
H E
HE
D000818:Animals; D001786:Blood Glucose / Q000187:drug effects; D001835:Body Weight / Q000187:drug effects; D003921:Diabetes Mellitus, Experimental / Q000097:blood / Q000188:drug therapy / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004435:Eating / Q000187:drug effects; D005419:Flavonoids / Q000494:pharmacology*; D019298:Glucose-6-Phosphate / Q000378:metabolism; D006003:Glycogen / Q000378:metabolism*; D006006:Glycogen Synthase / Q000378:metabolism; D006614:Hindlimb; D006943:Hyperglycemia / Q000188:drug therapy*; D015228:Hypertriglyceridemia / Q000188:drug therapy; D007004:Hypoglycemic Agents / Q000494:pharmacology*; D008099:Liver / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D008112:Liver Glycogen / Q000378:metabolism; D008297:Male; D018482:Muscle, Skeletal / Q000201:enzymology / Q000378:metabolism; D010762:Phosphorylase a / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar
D001786:Blood Glucose; D005419:Flavonoids; D007004:Hypoglycemic Agents; D008112:Liver Glycogen; D019298:Glucose-6-Phosphate; C040015:myricetin; D006003:Glycogen; D010762:Phosphorylase a; D006006:Glycogen Synthase