Analgesic and anti-inflammatory activities of the aqueous stem and leaf extract of Asystasia gangetica (Linn) T. Anderson.

Background: Asystasia gangetica (Linn) T. Anderson [family Acanthaceae] is used commonly in the sub-tropics and tropics for the management of inflammatory and algesic conditions.

Objective: The study was done to evaluate the analgesic and inflammatory activity of the aqueous stem and leaf extract of Asystasia gangetica.

Methods: The analgesic effect of the aqueous stem and leaf extract of Asystasia gangetica (25, 50, 100 and 200 mg/kg) was evaluated in rats and mice using the acetic acid induced writhing, cold water tail flick and hot plate models. Its anti-inflammatory effect was evaluated using carrageenan induced rat paw oedema and xylene induced mouse ear oedema models.

Results: The aqueous stem and leaf extract of Asystasia gangetica (25-200 mg/kg) significantly (p < 0.05) reduced the number of writhes in the acetic acid induced writhing test. At 100 mg/kg, it produced an increase in pain threshold comparable to that produced by morphine (10 mg/kg) in the tail flick test and peak analgesia at 200 mg/kg in the hot plate test. The extract (25-200 mg/kg) also produced significant (p < 0.05) inhibition of oedema comparable to indomethacin (10 mg/kg) in the carrageenan induced paw oedema model. The extract (200 mg/kg) produced a significant inhibitory effect (p < 0.05) comparable to that produced by 1 mg/kg dexamethasone in the xylene induced mouse ear oedema model. Preliminary phytochemical screening showed that the extract contains alkaloids, tannins, cardiac glycosides and flavonoids. It did not produce mortality or any visible sign of lethality 24 hours after single oral administration of 10 g/kg.

Conclusion: The results show that the aqueous stem and feaf extract of Asystasia gangetica possesses analgesic and antiinflammatory activities.