ABSTRACT
Bioassay guided fractionation of the hydro-alcoholic extract of the fruits of Capparis moonii, led to the isolation of two new chebulinic acid derivatives. The compounds 1 and 2 displayed significant glucose uptake effect of 223% and 219% over the control at the 10ng/ml and 100ng/ml concentration, respectively. The increased glucose uptake effects of the compounds were associated with significant IR and IRS-1 phosphorylation, GLUT4 and PI3-kinase mRNA expression in the L6 cells.
Subject(s)
Capparis/chemistry , Glucose/metabolism , Hydrolyzable Tannins/isolation & purification , Hydrolyzable Tannins/pharmacology , Animals , Cell Line , Glucose Transporter Type 4/genetics , Insulin Receptor Substrate Proteins/metabolism , Molecular Mimicry , Phosphatidylinositol 3-Kinases/genetics , Phosphorylation/drug effects , Phytotherapy , RNA, Messenger/analysis , RNA, Messenger/drug effects , Rats , Receptor, Insulin/metabolismABSTRACT
BACKGROUND: Cinnamomum cassia (Family: Lauraceae) is an Ayurvedic medicinal plant used traditionally for the treatment of a number of diseases, including diabetes. The hypoglycemic effect of this plant has been established in vivo. However, the effects of cinnamic acid, isolated from C. cassia, on the insulin signaling cascade in an in vitro model have not been elucidated. Hence, the aim of the present study was to evaluate the anti-diabetic effect of cinnamic acid on glucose transport by L6 myotubes. METHODS: The mechanism of action of cinnamic acid was determined using specific targets in the insulin signaling pathway, including protein tyrosine phosphatase (PTP) 1B, phosphatidylinositol 3-kinase (PI3-K) and the glucose transporter GLUT4. After differentiation of myoblast to myotubes, the cells were serum deprived for 5 h and then treated with 1 ng/mL cinnamic acid and 50 µmol/L rosiglitazone for 18 h and 100 nmol/L insulin for 20 min for gene expression studies. RESULTS: Expression of GLUT4 mRNA was increased following treatment of L6 myotubes with 1 ng/mL cinnamic acid. Furthermore, cinnamic acid inhibited PTP1B activity (by 96.5%), but had no significant effect on PI3-K activity. CONCLUSION: On the basis of the results of the present study, we postulate that cinnamic acid isolated from the hydro-alcoholic extract of Cinnamomum cassia activates glucose transport by a PI3-K-independent pathway. However, the detailed mechanism of action requires further analysis.
