Phytochemical and pharmacological investigations of Virola oleifera leaves

A methanolic extract and two fractions (n-hexane and ethyl acetate) from Vi rola oleifera leaves and some compounds (one lignan and two flavonoids) wer e investigated to verify the analgesic activity by using the writhing test in mice. The crude methanolic extract showed a moderate analgesic effect (a bout 40% of inhibition in this test at 10 mg/kg), whereas n-hexane and ethy l acetate fractions caused inhibition of 51.3 +/- 5.9% and 50.5 +/- 6.3%, r espectively. Oleiferin-C (1), a lignan isolated from the n-hexane fraction, showed an interesting analgesic potential in this model when compared to t wo standard drugs, paracetamol (4-acetamidophenol) and aspirin (acetylsalic ylic acid). The ID50 calculated for this compound was 17.25 mu mol/kg, with confidence interval between 13.7 and 21.3 mu mol/kg, being about 8 times m ore potent than the standard drugs. The mixture of two glycoside-flavonoids , identified as astilbin (2) and quercitrin (3), also exhibited good analge sic activity, causing 63% of reduction of abdominal constriction in mice. T hese results suggest beneficial effect of this plant to treat dolorous proc esses.