Antidiabetic, antihyperlipidemic and anti-inflammatory effects of tilianin in streptozotocin-nicotinamide diabetic rats

Flavonoids from medicinal plants have been used in traditional medicine to treat a variety of prevalent diseases. Flavones activate the signaling pathways promoting fuel metabolism and insulin sensitizing in hepatocytes and adipocytes, which suggests that flavones may have the potential to exert in vivo antidiabetic and antihyperlipidemic effects. Thus, the aim of the current study was to determine the antidiabetic, antihyperlipidemic and anti-inflammatory effects of tilianin in diabetic rats. Also, to understand the mechanism involved using in vitro 3T3-L1 cells and tissues from experimental animals treated with test samples through molecular profile studies. Non insulin-dependent diabetic mellitus (NIDDM) rats were treated over a short period (for 10 days) with 60mg/Kg/day of tilianin. After treatment, a biochemical blood profile was determined. Also, adipose and thoracic aortic tissues were used to determine pro-inflammatory profile, adiponectin and adhesion molecules by real-time PCR. In 3T3-L1 cells pretreated with tilianin (10μM), PPARα, PPARγ, GLUT4, FATP-1 and ACSL-1 mRNA expression were measured. In order to explain the potential PPARα interaction with tilianin, a docking study with PPARα was carried out. Thus, intragastric administration of tilianin and metformin induced a decrease in plasma glucose (GLU) in diabetic rats on day 6, and remained significantly lower until the end of the treatment; also blood triacylglycerides (TAG) and cholesterol (CHOL) (p<0.05) were diminished. Moreover, IL-1β and IL-18 expression was significantly decreased in adipose tissue (p<0.05); meanwhile adiponectin was significantly overexpressed (p<0.05). Besides, ICAM-1 expression was significantly reduced in aortic tissue (p<0.05). In 3T3-L1 cells it was found that tilianin increased PPARα and ACSL1 mRNA levels (p<0.05). Finally, tilianin docking studies with PPARα showed polar interactions with Glu269, Tyr314, His 440 and Tyr464 residues. In conclusion, short-term tilianin treatment might exert its antidiabetic and antihyperlipidemic effect by modulating a pro-inflammatory profile, and increasing adiponectin expression. In addition, our results suggest the possible interaction of tilianin with PPARα.