Effect of Yuanhua on Isolated Uterine Strips in Unpregnant Rats HPLC Analysis of Mimic Vinegar-processed Yuanbuacine Preparation of Yuanhuacine by Low Pressure Column Chromatography Determination of Yuanhuacine in Daphne genkwa Sieh. et Zucc. by HPLC Daphnane diterpene esters from flower buds of Daphne genkwa and their cytotoxic effects on cancer cells