Analgesic and anti-inflammatory activity of ?-sitosterol isolated from leaves of Oxalis corniculata

Oxalis corniculata Linn. (Oxalidaceae) is one of the important medicinal plants used traditionally for the treatment of fever, pain and inflammation. To validate folk use of Oxalis corniculata as analgesic and anti-inflammatory remedy. The leaves of Oxalis corniculata was used for successive extraction with increasing polarity solvents. Petroleum ether extract was selected for activity guided fractionation to isolate ?-sitosterol due to its better efficacy than other extracts. Analgesic activity was done by hot plate test and acetic acid-induced writhings, while anti-inflammatory activity by carrageenan-induced paw edema method. All the extracts were screened at the dose of 100 mg/kg, i.p. and isolated ?-sitosterol was screened at the doses of 5, 10 and 20 mg/kg, i.p. Naloxone (1 mg/kg, s.c.) was used to understand the mechanism of nociception. In hot plate test, Petroleum ether extract was found most active with reaction time of 8.4 0.4 sec after 60 min while isolated ?-sitosterol at dose of 20 mg/kg showed 11.1 0.3 sec after 90 min. The number of writings in 30 min was compared with paracetamol. Petroleum ether extract and ?-sitosterol (20 mg/kg) showed 43.14 1.9 and 34.21 1.4 writhings respectively. Isolated ?-sitosterol (20 mg/kg) inhibited rat paw edema to 0.32 0.06 ml after 120 min. Naloxone reversed antinociceptive effects of extracts and isolated ?-sitosterol. It can be concluded that isolated ?-sitosterol is responsible for analgesic and anti-inflammatory activity of Oxalis corniculata leaves and it works through central mechanism.