Synthesis and characterization of 9-O-alkyl substituted palmatine derivatives Structure modification of dammarane-type ginsenosides (aglycone) focusing on antitumor activities Advances in studies on pharmacological effect and structure-activity relationship of chrysin and its derivatives Process routing design on structure modifier of A-ring cleavage of ursolic acid Advances in studies on pharmacological effect and structure-activity relationship of chrysin and its derivatives