Analgesic, anti-inflammatory and anti-platelet activities of the methanolic extract of Acacia modesta leaves

The current study was aimed to evaluate Acacia modesta for analgesic, anti-inflammatory, and anti-platelet activities. The analgesic and anti-inflammatory effects were assessed in rodents using acetic acid and formalin-induced nociception, hot plate and carrageenan-induced rat paw oedema tests. The intraperitoneal (i.p.) administration of the methanolic extract (50 and 100 mg/kg) produced significant inhibition (P < 0.01) of the acetic acid-induced writhing in mice and suppressed formalin-induced licking response of animals in both phases of the test. In the hot plate assay the plant extract (100 mg/kg) increased pain threshold of mice. Naloxone (5 mg/kg i.p.) partially reversed the analgesic effect of the extract in formalin and hot plate tests. A. modesta (100 and 200 mg/kg i.p.) exhibited sedative effect in barbiturate-induced hypnosis test similar to that produced by diazepam (10 mg/kg i.p.). The plant extract (50-200 mg/kg i.p.) produced marked anti-inflammatory effect in carrageenan-induced rat paw oedema assay comparable to diclofenac and produced a dose-dependent (0.5-2.5 mg/mL) inhibitory effect against arachidonic acid induced platelet aggregation. These data suggest that A. modesta possesses peripheral analgesic and anti-inflammatory properties, with analgesic effects partially associated with the opioid system.