Anti-inflammatory, analgesic and antioxidant activities of the aerial part extract of <i>Indigofera spicata</i> Forssk

Abstract

In Ethiopian traditional medicine the aerial parts of Indigofera spicata Forssk (Fabaceae) are used to treat pain, wound and swelling. The aim of this study is to evaluate the anti-inflammatory, analgesic and antioxidant effects of the plant. The aerial part of I. spicta was collected, dried and extracted by maceration using 80% methanol. The extract obtained was first subjected to in vivo acute oral toxicity test followed by in vivo anti-inflammatory and analgesic activity studies in mice. Anti-inflammatory effect of the extract was assessed using carageenan-induced mouse paw oedema assay, while acetic acid-induced writhing and hot plate test models were used to evaluate analgesic activity. DPPH assay was also employed to measure the in vitro free radical scavenging effect of the extract. Acute oral toxicity test revealed that the LD₅₀ of the crude extract   is greater than 2000 mg/kg. Four h after injection of carrageenan, the extract at doses of 125, 250 and 500 mg/kg resulted in maximum percentage anti-inflammatory effects of 33.7, 52.6 and 63.2%, respectively. The extract also exhibited significant central and peripheral analgesic activities at a dose of 125 mg/kg as well as moderate DPPH scavenging activity with an IC₅₀ value of 47.13 µg/ml. Thus, the results of the present study uphold the traditional use of the plant for the treatment of wounds and pain.

Keywords: Indigofera spicta, acute oral toxicity, anti-inflammatory, analgesic, antioxidant