Effect of the roasting levels of Coffea arabica L. extracts on their potential antioxidant capacity and antiproliferative activity in human prostate cancer cells

Coffee, besides being one of the most consumed stimulating beverages in the world, has important bioactive activities, which have been attracting increasing attention from researchers. However, the standard process of roasting causes changes in its chemical composition. In the present study, extracts obtained from green and roasted beans (light, medium and dark) of Coffea arabica Linnaeus were submitted to high-power ultrasonic extraction and atomization by spray drying. Colorimetric analysis was used to classify the roasting levels of the dried extract samples. The effects of the roasting process on the bioactivity of the dried extracts were verified through the following assays: caffeine, chlorogenic acid and caffeic acid, by HPLC-PDA; total phenolics by Folin–Ciocalteu; antioxidant activity by DPPH, FRAP, ABTS and ORAC; antiproliferative activity, using the MTT assay; and cell cycle and apoptosis by flow cytometry in metastatic prostate cancer cell lines from bone (PC-3) and brain (DU-145). The results showed that the lowest levels of caffeine, chlorogenic and caffeic acids were observed in dark roasted coffee. In comparison to medium and dark extracts in PC-3 cells, the green and light coffee extracts had higher antioxidant activities and promoted cytotoxicity followed by cell cycle arrest in phase S and apoptosis induction. Thus, the roasting level of the coffee extracts may be related to the potential chemoprotective effects of Coffea arabica L. in prostate cancer cells.