Antioxidant potential of flavonoid glycosides from Manniophyton fulvum Müll. (Euphorbiaceae): Identification and molecular modeling

Chemical investigation of the leaves of Manniophyton fulvum led to the isolation of seven flavonoid glycosides: myricetin-3-O-β- Dd -rhamnoside (1), kaempferol-3-O-β- d -rhamnoside (2), quercetin-3-O-β- d -glucoside (3), quercetin-3-O-β- d -rhamnoside (4), quercetin-3-O-β- d -galactoside (5), rutin (6) and quercetin (7). The structures of the compounds were established by spectroscopic analyses as well as by comparison with published data. Some of the compounds showed strong antioxidant activity which validates the traditional use of the plant. An attempted correlation between the computed HOMO-LUMO energies and the measured antioxidant activities was established. We have also estimated the cardiotoxicity of the compounds by calculating the predicted logarithm of the human Ether-`a-go-go Related Gene (loghERG) using the QikProp program. These purified flavonoids are new potential lead compounds for the development of antioxidant drugs.