Antiproliferative activity of flavonoids on several cancer cell lines

Twenty-seven Citrus flavonoids were examined for their antiproliferative ac tivities against several tumor and normal human cell lines. As a result, 7 flavonoids were judged to be active against the tumor cell lines, while the y had weak antiproliferative activity against the normal human cell lines. The rank order of potency was luteolin, natsudaidain, quercetin, tangeretin , eriodictyol, nobiletin, and 3,3',4',5,6,7,8-heptamethoxyflavone. The stru cture-activity relationship established from comparison among these flavone s and flavanones showed that the ortho-catechol moiety in ring B and a C2-C 3 double bond were important for the antiproliferative activity. As to poly methoxylated flavones. C-3 hydroxyl and C-8 methoxyl groups were essential for high activity.