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

BACKGROUND

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).

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.

CONCLUSIONS

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