Verbascoside and luteolin-5-O-β-D-glcoside isolated from Halleria lucida L. exhibit antagonistic anti-oxidant properties in vitro

The purpose of this investigation was to determine and characterise the anti-oxidant activity of the methanol extract of the leaves of Halleria lucida utilizing the DPPH (2,2-diphenyl-1-picrylhydrazyl) assay. The methanol extract of the leaves of H. lucida displayed promising anti-oxidant activity with an IC50 value of 8.49 +/- 0.12 mu g/ml and was subsequently subjected to activity-guided fractionation resulting in the isolation of a flavone-type flavonoid and phenylpropanoid glycoside, namely luteolin-5-O-beta-D-glucoside and verbascoside (acteoside), respectively. Both compounds displayed promising anti-oxidant activities with IC50 values of 6.12 +/- 0.40 and 7.18 +/- 0.08 mu g/ml for luteolin-5-O-beta-D-glucoside and verbascoside, respectively. Furthermore, isobologram construction was undertaken to determine pharmacological interactions between the isolated molecules resulting in a concentration-dependent additive and antagonistic interaction being recognised. (c) 2007 SAAB. Published by Elsevier B.V. All rights reserved.