Phenylethylchromones with In Vitro Antitumor Promoting Activity from Aquilaria filaria

A new chromone, 2-(2-hydroxy-2-phenylethyl)chromone ( 1 ), was isolated together with ten known phenylethyl chromones from MeOH extracts of agarwood ( Aquilaria filaria ). The selected compounds were evaluated in an antiproliferative assay against five human tumor cell lines, including a multidrug-resistant cell line. They were also tested for antitumor promoting activity, as mediated by 12- O -tetradecanoylphorbol-13-acetate-induced activation of the Epstein-Barr virus early antigen in Raji cells. Among all compounds, 4′,7-dimethyoxy-6-hydroxychromone ( 2 ) displayed broad spectrum antiproliferative activity against all tumor cell lines tested with IC 50 values of 25–38 µM, while 8 was selectively inhibitory against multidrug-resistant cells. All tested compounds suppressed tumor promotion at noncytotoxic concentrations. 4′,6-Dihydroxyphenylethylchromone ( 7 ) exhibited the most potent effect with an IC 50 value of 319 mol ratio relative to 12- O -tetradecanoylphorbol-13-acetate. This study is the first to report the antitumor promoting activity of 2-(2-phenylethyl)chromone derivatives, as well as the selective antiproliferative activity of 8 against a multidrug-resistant tumor cell line.