LAUSR

We herein report Mannich aminomethylation of variously structural flavonoids and their biological evaluation against human breast cancer cell. Mannich reaction showed that substitution at C-6 position depends on amine basicity and C-ring feature of flavonoids. All five flavonoid substrates reacted with strong amine bases to afford the bis(6,8-aminomethyl) derivatives, while with weak amines, the different products were obtained dependently on structural characteristic of flavonoid. 3-OH and 3-O-substituted groups on the C-ring exhibited the deactivated aminomethylation at C-6 position, whereas substitution at this position was independent on bond feature at C-2 and C-3 on the C-ring. Screening anti-proliferative activity showed six flavonoids possessed activity against breast cancer cell, MDA-MB-231. Among them, the flavonoids, luteolin (2) and 3′,4′,5,7-tetrahydroxy-6,8-bis(pyrrolidin-1-ylmethyl)-3-rutinosylflavone (3a), displayed the highest anti-proliferative activity with the lowest IC50 values.