Antidepressant Effect of Methanol Fruit Extract of Capsicum annuum in Mice

Aims: To determine the antidepressant potential of methanol fruit extract of Capsicum annuum in Mice.

Methodology: Force Swim Test (FST), Tail Suspension Test (TST) and Open Field Test (OFT) were used. Immobility time in both FST and TST was determined by randomly dividing 30 mice into five (5) groups of six (6) mice each. Group 1 received saline, Group 2, Imipramine (15 mg/kg), Group 3, 4, and five were treated with 500 mg/kg, 1000 mg/kg, and 2000 mg/kg of methanol extract of fruits of Capsicum annuum respectively. In the OFT, 25 mice were divided into five(5) groups of five (5) mice each; Group 1 received normal saline, group 2, Diazepam (0.5 mg/kg), group 3,4 and 5 were treated with 500 mg/kg, 1000 mg/kg and 2000 mg/kg of methanol fruit extract of C. annuum respectively.

Results: Imipramine, and the doses of the methanol fruit extract significantly reduced the immobility time when compared with a normal saline group (p≤ 0.05) in the mice FST and TST. The effect of the extract was dose-dependent; 2000 mg/kg produced the highest reduction. In the Open field test (OFT), the number of square crossing showed no significant difference between Diazepam (0.5 mg/kg) and all the doses of the extract administered. This implied that the extract did not act as a stimulant.

Conclusion: The decrease behavioural despair in this study suggests that Capsicum annuum may be a promising candidate for the management of depression. The antidepressant like activity may be attributed to the presence of anti-inflammatory and antioxidant flavonoids and triterpene in the plants given the role of inflammation and oxidative stress in depression. Further work will be carried out to validate this result.