Characterization of antibacterial flavonoids and stilbenes of the root extract of Anogeissus leiocarpus by UHPLC-MS-QTOF

Anogeissus leiocarpus occurs in savannas in tropical and subtropical regions of Africa and is used among traditional medicinal practitioners for treatment of various diseases, among them bacterial infections [1]. Eight flavonoids [2], methyl ellagic acid, ellagic acid [4, 5] and the ellagitannins castalagin and flagallonic acid [6] have been reported from the leaves and bark of A. leiocarpus. There are just a few investigations on the phytochemistry of the roots [1], however. This study has aimed on in depth investigations on the phytochemistry of the root part. Ten microliters of 50 mg/ml methanol extract of the root of A. leiocarpus was applied on RP18 TLC reversed phase. Methanol, water and orthophosphoric acid were used as mobile phase. DPPH (2,2-diphenyl-1-picrylhydrazyl) reagent was used for detecting antioxidative compounds. In order to identify these compounds HPLC-DAD and UHPLC/MS/QTOF methods [3] were used. Aromadendrin, taxifolin, methyltaxifolin, ampelopsin and eriodictyol as well as pinosylvin and methylpinosylvin and 3,3´-Di-O-methyl ellagic acid glucoside were identified for the first time in the roots of A. leiocarpus. In addition pentagalloyglucose and digalloylglucose were found in the root. We have demonstrated that a methanolic root extract of A. leiocarpus gives promising antibacterial effects. These effects might be connected to antioxidative flavonoids and ellagic acid derivatives in this extract