Research on effect of Celastrus orbiculatus extract on inhibiting invasion and metastasis of human gastric cancer SGC-7901 cells by mediating matrix metalloproteinases group and their inhibitors Protoplast Culture and Plant Regeneration of Celastrus orbiculatus Thunb. Chemical constituents in stem of Celastrus orbiculatus Determination of kaempferitrin in Celastri Orbiculati Fructus by HPLC