Topical anti-inflammatory and analgesic activities of standardized pomegranate rind extract in comparison with its marker compound ellagic acid in vivo

Abstract

Ethnopharmacological relevanceIn Chinese traditional medicine, the peels of Punica granatum L. have been used to treat traumatic hemorrhage, burn, and ulcers. Aims of the studyThis study aimed to assess the topical anti-inflammatory and analgesic activities of a standardized pomegranate rind extract (SPRE) of which ellagic acid (EA) was the major antioxidant constituent and the marker compound. Material and methodsThe topical anti-inflammatory effects of SPRE were evaluated against acute models (croton oil-induced mouse ear edema and carrageenan-induced rat paw edema) and chronic model (complete Freund's adjuvant (CFA)-induced polyarthritis). The topical analgesic activities of SPRE were investigated in the rat punctuate mechanical hyperalgesia test and in the mouse formalin test. All studies of SPRE were carried out in parallel with its marker compound EA. ResultsSPRE (5%, 2.5%, and 1%, w/w) and the equivalent EA (0.65%, 0.325%, and 0.13%, w/w) dose-dependently reduced the croton oil-induced mouse ear edema with a maximal inhibition of 86.30% and 80.82%, respectively. SPRE dose-dependently attenuated the inflammatory responses in the carrageenan-induced rat paw edema and in the CFA-induced polyarthritis but the equivalent EA were effective only at the doses of 0.65% and 0.325%. Both SPRE (5%) and EA (0.65%) showed significant topical analgesic activities in the rat punctuate mechanical hyperalgesia test and in the mouse formalin test. ConclusionsSPRE was more active as an anti-inflammatory agent than EA. The anti-inflammatory and analgesic effects of SPRE were achieved through inhibiting the leukocyte infiltration and modulating the pro-inflammatory cytokines IL-β and TNF-α. These results clearly demonstrated that SPRE is a promising phytomedicine that could find use in the treatment of inflammatory diseases.