New insights into the in vitro, in situ and in vivo antihyperglycemic mechanisms of gallic acid and p-coumaric acid.

Objective: To explore the probable in vitro, in situ and in vivo mechanisms of gallic acid (GA) and p-coumaric acid (PCA) as anti-hyperglycemic agents.Animals and methods: Male albino rats were allocated into four groups, group1 was used as normal control. Group 2 was established as a diabetic control and group3 and 4 were treated with an oral dose of GA and PCA, respectively.Results: GA and PCA revealed a significant decrease in the activity of α-amylase, a noticeable rise in glucose induced-insulin secretion and glucose-uptake in peripheral glucose-uptake in vitro, increase also liver glycogen and serum insulin levels in vivo. Further, GA and PCA exhibited a significant reduction in intestinal glucose absorption in situ compared to blank.Conclusion: The antihyperglycemic activities of GA and PCA can be mediated through delaying intestinal glucose absorption, enhancing ß-cell activity and promoting glucose uptake by peripheral tissue via enhancing insulin sensitivity.

Modulation of hyperglycemia and dyslipidemia in experimental type 2 diabetes by gallic acid and p-coumaric acid: The role of adipocytokines and PPARγ.

There are many indications that confirm the vital role of adipocytokines and PPARγ in diabetics. Hence, the current investigation aimed to study the modulatory effects of gallic acid and p-coumaric acid on adipocytokines secretion and PPARγ mRNA expression in type 2 diabetic rats. After induction of type 2 diabetes, diabetic rats were orally treated with 20 mg/kg body mass gallic acid and 40 mg/kg body mass p-coumaric acid for six weeks. Among treatment diabetic rats, glucose and glycosylated hemoglobin levels significantly declined in diabetic rats, while insulin level and body weight significantly increased as compared to control group. Gallic acid and p-coumaric acid markedly decreased the level of TNF-α and increased the levels of PPARγ mRNA and adiponectin. In addition, the tested agents improved markedly lipid profile parameters, cardiovascular indices 1 and 2 and anti-atherogenic index. In conclusion, gallic acid and p-coumaric acid exhibited marked antidiabetic action that could be mediated via modulation of TNF-α and adipocytokines secretions as well as upregulation of PPARγ mRNA expression.