Antiproliferative Activity of Soybean and Tempeh Extracts in Human Colorectal Cancer Cells

Tempeh, a traditional Indonesian food, is made through fermentation of soybean and increases the bioavailability of beneficial nutrients, including phytoestrogens and protein. Recent research indicates that fermenting soybeans to make tempeh could improve bio functional properties including anticancer activity. This study aims to explore whether defatted soybeans and tempeh (fermented soybeans) extracts possess anti-proliferative activity of human colorectal (CRC) cancer cells. The defatted soybean and tempeh samples were extracted at a concentration of 35 g/100 mL using 70% ethanol, evaporated and then lyophilized. HCT116 cells were treated with soybean extract (SE) and tempeh extract (TE) for 24 h and MTT (3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide) assay, flow cytometry, and Western blot analyses were performed. SE and TE exhibited inhibitory effects on cell viability, with TE showing a more significant dose-dependent inhibition compared to SE. Cell cycle analysis showed a significant increase in G1 arrest, along with a significant decrease in S and G2/M phases in both SE- and TE-treated cells. The induction of apoptosis was observed in cells treated with both SE and TE. Additionally, Western blot analysis showed increased Poly (ADP-ribose) polymerase cleavage for both treatments, indicating activation of apoptotic pathways in CRC cells treated with SE and TE. These findings indicate that soybeans and tempeh may be effective dietary options to help prevent colorectal cancer.