A new anti-inflammatory flavonol glycoside from Alchornea floribunda leaves

Abstract

Alchornea floribunda leaves are widely used in African ethnomedicine for the management of acute and chronic inflammatory disorders. In the present study, bioactivity-guided fractionation of the ethyl acetate fraction of the methanol leaf extract of the plant material led to the isolation of a new flavonol glycoside (AFF1). The anti-inflammatory activity of this novel compound was evaluated using egg albumen-induced rat paw oedema as a model of inflammation. AFF1 showed significant inhibition of the rat paw oedema in a dose-dependent manner. The activity of AFF1 (50 mg kg⁻¹) was higher than that of the standard anti-inflammatory drug, aspirin (100 mg kg⁻¹). The compound also significantly (p < 0.001) inhibited heat-induced haemolysis of human erythrocytes in vitro. The structure of AFF1 was elucidated as 3,5,7,3′-tetrahydroxyflavone-3-O-α-L-rhamnoside, using a combination of UV, IR, 1D and 2D (COSY) ¹H-NMR spectroscopy. This compound, in part, accounts for the anti-inflammatory effect of A. floribunda leaves.

Keywords:

• Alchornea floribunda
• Euphorbiaceae
• anti-inflammatory
• flavonol glycoside
• membrane stabilisation