Evaluation of Analgesic and Anti-inflammatory Activities of the Root Extracts of <i>Indigofera spicata</i> F. in Mice

Abstract

Indigofera spicata F. (Fabaceae) has been used for the treatment of painful and inflammatory conditions in Ethiopia. The aim of the present study was to evaluate the analgesic and anti-inflammatory activities of the root extracts of I. spicata in mice. The analgesic activity of the aqueous and 80% methanolic root extracts of I. spicata at oral doses of 100, 200 and 400 mg/kg were evaluated using hot plate, acetic acid induced writhing and formalin tests, while the anti-inflammatory action was assessed on carrageenan-induced mouse paw oedema. Morphine, acetyl salicylic acid or indomethacin was used as a positive control, and 2% Tween 80 in water as a negative control. Results of the study revealed that both the aqueous and hydroalcoholic extracts significantly delayed reaction time of mice to thermally induced pain, reduced acetic-acid induced writhing, attenuated formalin-induced hind paw licking in both the early and late phases of formalin test. The extracts did also inhibit paw oedema. Whilst the highest doses of both extracts produced pronounced effect (p<0.001) comparable to the reference drugs, the aqueous extract displayed better activity in all the tests employed. The results clearly demonstrate the analgesic and anti-inflammatory effects of the aqueous and 80% methanolic root extracts of the plant, providing evidence in part for the folkloric use of the plant.

Keywords: Indigofera spicata, aqueous extract, 80% methanolic extract, antinociceptive, anti-inflammatory