HepG2 human liver cancer cell proliferation (14, 24). The cell cultures were exposed to various concentrations of the extracts during a 96-h growth period. Cell proliferation was measured by the ability of viable cells to reduce 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphe- nyl)-2-(4-sulfenyl)-2H-tetrazolium (MTS) to formazan. This product absorbs light at 490 nm and was measured spectrophotometrically. One extract for each component of each variety was analyzed in triplicate, and the absorbance was measured using a MRX II DYNEX spectro- photometer. The effective median dose (EC50) was determined and expressed as milligrams of apple component per milliliter ( SD.
Statistical Analysis. All data were reported as mean ( standard deviation of three replicates. The results were compared by analysis of variance (ANOVA) using Minitab software (Minitab, Inc., State College, PA). Pairwise multiple comparisons were done by Tukey’s significant difference test with the family error rate held at 0.05.