Inhibition of invasive breast cancer cell growth by selected peach and plum phenolic antioxidants

Abstract

Fruits and vegetables are known to play an important role in human health due to the range of phytochemicals they contain. Twenty-one peach genotypes and 45 plum genotypes with different flesh and skin color were analyzed for their antioxidant content and antioxidant activity. Anthocyanin content, phenolic content and antioxidant activity were higher in red-flesh than in light-colored flesh peaches. Carotenoid content was higher in yellow-flesh peaches. Among the peaches, the antioxidant activity was well correlated with phenolic content. The anthocyanin content among the plums increased with the red color intensity. Red-flesh plums generally had higher phenolic content than the other plums. Antioxidant activity was higher in red-flesh genotypes; however, it was strongly correlated only with the phenolic content in light-colored flesh plums. Extracts from selected genotypes of peaches and plums and their fractions were evaluated against two breast cancer cell lines (MDA-MB-435 and MCF-7) and one non-cancerous breast line (MCF-10A). The cells were cultured in the presence of peach and plum extracts and their fractions at various concentrations (0-500 µg/ml) and the cell viability and antiproliferation activity was evaluated by MTT assay and Coulter Counter. There was a dose-dependent reduction on cell viability of estrogen-negative MDA-MB-435 breast cancer cells. Only weak activity against MCF-7 was observed at high extract concentrations. There was no activity against MCF-10A after 24 h treatment. Fraction I, which consists of mainly phenolic acids such as chlorogenic acid and a caffeic acid derivative, reduces MDA-MB-435 breast cancer cell viability with the lowest IC50. The second most effective fraction was Fraction II which contained anthocyanins. Fraction III (flavonols) and Fraction IV (polymerized compounds) had no effect on the cell lines. Phenolic acids present in fraction I induced apoptosis in MDA-MB-435 estrogen receptor-negative cell line. Fraction I did not induced apoptosis in MCF-10A, a noncancerous cell line even at higher concentrations than the ones tested in MDA-MB- 435. Apoptosis induced by Fraction I was caspase 3 and PARP independent. After treatment with 50 µg of chlorogenic acid equivalent/ml there was an activation of p- ERK.