HPLC Analysis
The HPLC analysis of standard Nitidine and extracts was carried using a method described by Aktin Chemicals, Inc (China) with some modifications. The HPLC was performed on LC-10AT (Shimadzu Corporation, Kyoto, Japan) with SPD-M10A vp diode array detector set at wavelength of 296nm. The conditions of the analysis includes isocratic elution with acetonitrile: water: formic acid (27:73:0.1 v/v/v), with Chemsil ODS-2 C-18 column (250x4.6 mm). The flow rate of mobile phase was 1.0 ml/min.