Comparative study of the anti-inflammatory and antinociceptive effects of two varieties of Punica granatum

Abstract

Context: Studies have shown that pomegranate, Punica granatum Linn. (Lythraceae), has remarkable biological and medicinal properties.

Objective: This work aimed to explore and compare the analgesic and anti-inflammatory activities of the methanol extract (MoE) obtained from fruit peels of two varieties of pomegranate: Amrouz (MoEA) and Sefri (MoES).

Materials and methods: Antinociceptive activity of MoEA and MoES was examined using four models of pain. The extracts were administered by the intraperitoneal route (i.p.) in writhing (50, 100 and 150 mg/kg) and formalin tests (25, 50 and 100 mg/kg) and by intra-cerebroventricular injection (i.c.v.) in hotplate and tail-immersion tests (10, 25 and 50 µg/3 µl/rat). anti-inflammatory activity was studied using the hind paw egg albumin test (50, 100 and 150 mg/kg, i.p.).

Results: In the writhing test, the index of pain inhibition (IPI) was 52% for MoEA (150 mg/kg, i.p.) and 29% for MoES (150 mg/kg, i.p.). In the formalin test, the IPI of early and late phase were, respectively, 75% and 82% for MoEA (100 mg/kg, i.p.) and 8% and 63% for MoES (100 mg/kg, i.p.). In the hotplate and tail-immersion test, MoEA and MoES increased in a dosedependent manner the reaction latency to the thermal stimuli. MoEA seems to be more potent than MoES. Only the analgesic effect of MoEA was partially inhibited by pretreatment with naloxone. Both extracts exerted a significant anti-inflammatory effect.

Discussion and conclusions: The results demonstrated that P. granatum contains active constituents, which possess antinociceptive and anti-inflammatory activity, justifying its popular uses.

Keywords::

• Pomegranate fruit peel
• methanol extract
• intracerebroventricular injection
• formalin test
• opioid system
• egg albumin induced edema

Acknowledgments

We are very thankful to Pr. A. Ouhamou for helping with the plant specimen’s identification and to Mr. A. Regragui for his technical assistance.

Declaration of interest

The authors report no declarations of interest.