Semisynthesis of apigenin and acacetin-7-O-β-D-glycosides from naringin and their cytotoxic activities.

Apigenin-7-O-β-D-glycosides 1-8 and acacetin-7-O-β-D-glycosides 9-16 were semisynthesized from 4'-O-benzyl apigenin 17 and acacetin 18 by glycosidation and deprotection with the corresponding α-acetylglycosyl bromide, respectively. Compounds 17 and 18 were prepared by iodination followed by base-induced elimination, 4'-O-benzylation, or 4'-O-methylation and acid hydrolysis using naringin as starting material which is readily available and cheap. Their cytotoxic potential against five human cancer cell lines (HL-60, SMMC-7721, A-549, MCF-7, and SW480) was evaluated by standard MTT method. The results show that compounds 2, 9, and 19 exhibit moderate cytotoxicity against HL-60, SMMC-7721, A-549, MCF-7, and SW480, while compound 3 exhibits potent cytotoxicity against MCF-7 selectively. Among the synthesized target compounds, 3, 4, 7, 11, 12, 15, and 16 were new compounds, the natural product 8 was the first synthesized and the synthesis of natural products 5, 6, 13, and 14 was efficiently improved by the new synthetic routes.