The Effects of Dietary Cinnamic Acid and p‐coumaric Acid on Glucose and Lipid Metabolism in Normal Rats Fed a High‐Sucrose Diet

Abstract

Cinnamic acid (CIN) and p‐coumaric acid (COU) are widely distributed in edible plants and ingested by human in normal diet. CIN and COU are highly absorbed via the monocarboxylic acid transporter in gastrointestinal tract. The hypoglycemic effect of CIN on diabetic mice and rats has been observed while we reported the hypolipidemic effect of COU on normal rats fed a high‐fat, high‐cholesterol diet. In this study, we tested whether CIN and COU improved glucose and lipid metabolism in normal rats fed a high‐sucrose diet. Male SD rats were fed a high‐sucrose (50 %) diet containing 0.2% CIN or COU for 120 days. No significant differences were observed in total food intake, body, liver and visceral fat weight, serum glucose, lipid profile, aspartate transaminase (AST) and alanine transaminase (ALT) levels, hepatic triacylglycerol and cholesterol levels among all groups. Dietary CIN but not COU significantly decreased the hepatic mRNA expression of liver X receptor α (LXRα), ATP‐binding cassette, sub‐family A, member 1 (ABCA1), low density lipoprotein receptor (LDLr) and sterol regulatory element binding protein 2 (SREBP2) compared to control group. There were no significant differences among all groups concerning the other hepatic mRNA expression involved with lipid metabolism (ACC1, FAS, ME, G6PDH, SCD1, SREBP1c, ChREBP, CPT1a, PPARα, MTP, CYP7A1) and glucose metabolism (GK, G6Pase, F1,6BP, PEPCK1, PEPCK2). These results suggest CIN and COU did not improve glucose and lipid metabolism in normal rats fed a high‐sucrose diet although dietary CIN induced some variations in gene expression involved with lipid metabolism.