[HPLC analysis of the active ingredients of Forsythia suspensa]

Forsythia suspensa is a widely used traditional Chinese herb. Because of the need to evaluate its quality, a HPLC method was developed to analyze the active ingredients in its fruits and leaves. One g of powdered plant material was cold macerated over-night with 10 ml of methanol added then supersonic extracted for 20 min. Four ml of the extract were mixed with 1 ml of water, centrifuged (400 x g, 15 min), and then analyzed by HPLC with a Nucleosil C--18 column. The mobile phase for gradient elusion consisted of MeOH(containing 1% tetrahydrofuran) and H2O (containing 0.01 mol/L KH2PO4,pH 3.2) and monitored by UV absorption at 280 nm. The identity and purity of the peaks were checked by photodiode array detector and in comparison with standards. By this procedure, the active constituents caffeic acid, rutin, forsythoside A, forsythin, and forsythigenin were separated successfully, and the quantity of each compound was determined by peak area. Some fruit samples obtained from various sources and the leaf sample made as tea were analyzed by this method.