Antioxidant, anti-inflammatory and antinociceptive activities of methanolic extract of <i>Justicia secunda</i> Vahl leaf

Abstract

Background of study: Plants used for traditional medicine contain a wide range of substances which can be used to treat various infectious diseases.

Aim: The study evaluated the in vitro antioxidant, antinociceptive, and anti-inflammatory activities of the methanolic extract of Justicia secunda Vahl leaf.

Methods: The acute toxicity was performed with up and down method and the highest dose used was 2 g/kg. The anti-inflammatory activity was evaluated using the carrageenan and formalin-induced paw edema models, and antinociceptive activity was evaluated using acetic acid-induced writhing reflex and tail flick test models while the antioxidant activity was evaluated using 2,2-diphenyl-2-picryl hydrazyl (DPPH) and ferric reducing antioxidant power (FRAP) photometric assay.

Results: The extract was well tolerated as no signs of toxicity or death were noticed during the period of observation. The extract produced a concentration dependent increase in antioxidant activities in both DPPH and FRAP models. The extract produced its optimum activity at 400 lg/ml in both DPPH (54.07%) assay and FRAP (1.58 lM) assay. The extract produced significant (P < 0.05) dose-dependent increase in both anti-inflammatory and antinociceptive activities. The antinociceptive and anti-inflammatory activities of the extract (0.4 g/kg) were comparable with the reference drugs (aspirin and pentazocine) used in the study.

Conclusion: This study suggests that J. secunda possesses anti-inflammatory, antinociceptive and antioxidant activities and also provide the pharmacological basis for its uses in traditional medicine for these purposes.

Keywords: Justicia secunda; Anti-inflammatory; Antinociceptive; Antioxidant; Paw edema; Acetic acid