ORIGINAL ARTICLE Cellular and Molecular Biology Effects of Naturally Occurring

Effects of polymethoxyflavonoids tangeretin and nobiletin and the related polyphenolic compounds baicalein, wogonin, quercetin, and epigallocatechin gallate on the cell growth, P-glycoprotein function, apoptosis, and cell cycle of human T lymphoblastoid leukemia MOLT-4 and its daunorubicin-resistant cells were investigated. The IC50 values of these compounds on the cell growth were 7.1–32.2 µmol/L, and the inhibitory effects were observed to be al-most equal to the parent MOLT-4 and the daunorubicin-resistant cells. Tangeretin and no-biletin showed the strongest effects with the IC50 values of 7.1–14.0 µmol/L. These poly-methoxyflavonoids inhibited the P-glycoprotein function and significantly influenced the cell cycle (p <.05), whereas they did not induce apoptosis