Objective: Moringa oleifera (family Moringaceae) has been widely used in African folk medicine, and researchers have recently revealed its anti-inflammatory effects in human. This study aimed to evaluate the analgesic properties of methanolic extracts of M. oleifera in complete Freund's adjuvant (CFA)-induced arthritis in rats.
Methods: Adult male Wistar rats, weighing 200 to 220 g, were used in this study. Adjuvant arthritis was induced on day 0 by a single subcutaneous injection of CFA. The prepared extracts from both the root and leaf (200, 300 and 400 mg/kg) of M. oleifera were administered intraperitonealy to rats in the treatment groups 0, 3 and 6 d after CFA injection and indomethacin (5 mg/kg) was used as a positive control drug. Thermal hyperalgesia and mechanical allodynia were evaluated for the analgesic effect 0, 3 and 6 d after CFA injection. Combined methanolic root and leaf extracts of M. oleifera (200 mg/kg) were also tested for the analgesic effect.
Results: The potency of the root or leaf extracts of M. oleifera (300 and 400 mg/kg) was similar to that of indomethacin, resulted in significant reductions in both thermal hyperalgesia and mechanical allodynia in rats with CFA-induced arthritis compared with the control group after 3 and 6 d, respectively (P<0.01 or P<0.05). Combined root and leaf extracts (200 mg/kg) of M. oleifera resulted in a significant reduction in thermal hyperalgesia compared with the control group after 3 and 6 d, respectively (P<0.01). Prophylactic injections of combined root and leaf extracts of M. oleifera (200 mg/kg) resulted in a significant reduction in thermal hyperalgesia compared with the control group, the root extracts group, and the leaf extracts group after 3 and 6 d, respectively (P<0.01).
Conclusion: The methanolic extracts of the root or leaf of M. oleifera are effective in the reduction of pain induced by CFA in rats. A comparison of single and combination therapies of root and leaf extracts also showed a synergistic effect on pain reduction.