Ameliorative effect of p-coumaric acid, a common dietary phenol, on adjuvant-induced arthritis in rats.

p-Coumaric acid (3-(4-hydroxyphenyl)-2-propenoic acid), a common dietary polyphenol, is widely distributed in cereals, fruits and vegetables with antioxidant property. Numerous studies have enlightened the ability of dietary phenols to be considered as potential therapeutics against arthritis. In this study, we aimed to investigate the ameliorative effect of plant phenolic p-coumaric acid on adjuvant-induced arthritis in rats. The reference drug indomethacin was used for comparison purposes. Arthritis was induced in rats by a single intradermal injection of complete freund's adjuvant (0.1 mL) into the foot pad of right hind paw. p-Coumaric acid (100 mg/kg b wt) and indomethacin (3 mg/kg b wt) were administered intraperitoneally for 8 days from day 11 to 18 after adjuvant injection. An increase in the activities/levels of lysosomal enzymes, tissue marker enzymes, glycoproteins and paw thickness was observed in the arthritic rats, on the contrary, the body weight was found to be reduced in arthritic rats when compared to normal control rats. Administration of p-coumaric acid (100 mg/kg b wt) to the arthritic rats reverted back the altered physical and biochemical parameters to near normal levels comparable to indomethacin treatment. Histopathological evaluation of ankle joints in arthritic rats also revealed the anti-inflammatory effect of p-coumaric acid by the reduction in leukocytes infiltration. Thus, the present study clearly demonstrates the anti-inflammatory potential of the p-coumaric acid against adjuvant-induced arthritis in rats.