Antibacterial, Antiradical and Antiproliferative Potential of Green, Roasted, and Spent Coffee Extracts

The phytochemical compositions of green coffee beans (GB), roasted coffee (RC), and the solid residue known as spent coffee grounds (SCG) have been associated with beneficial physiological effects. The objective of this study was to analyze the total phenolic compounds, antiradical scavenging ability, antibacterial activity, and antiproliferative activity on cancer cells of aqueous and ethanolic extracts of GB, RC, and SCG samples. The total phenolic content was quantified by Folin-Ciocalteu assay, while the antiradical activity was evaluated by ABTS(?+) and DPPH radical assays, antibacterial activity was determined using the microtiter broth dilution method, and antiproliferative activity was evaluated by MTT assay in lung carcinoma cells (A549) and cervical cancer cells (C33A); furthermore, apoptosis and cell cycle arrest were evaluated by flow cytometry. Ethanolic extracts of RC and SCG showed the highest content of total phenols. The SCG ethanolic extract exhibited the lowest inhibitory capacity 50 (IC50) values for free radicals. The SCG extracts also had the lowest MIC values in bacteria. In antiproliferative assays, SCG extracts exhibited a significant decrease in viability in both cell lines, as well as increased apoptotic cells and promoted cell cycle arrest. The higher content of total phenols and antiradical activity of SCG ethanolic extracts was related to their antiproliferative activity in cancer cells, as well as their antibacterial activity against clinical isolates; therefore, the utilization of SCG adds value to an abundant and inexpensive residue.