Effects of Soybean and Tempeh Water Extracts on Regulation of Intestinal Flora and Prevention of Colon Precancerous Lesions in Rats

Soybean bioactivity is significantly enhanced during tempeh fermentation. This study aimed to evaluate the efficacy of tempeh on colorectal cancer cells in vitro and colon precancerous lesions (aberrant crypt foci, ACF) in vivo. In the in vitro assay, tempeh water extract (WET) could inhibit the proliferation of Caco-2 cells. In the animal assay using 1,2-dimethylhydrazine (DMH)-induced Sprague-Dawley (SD) rats, 12-weeks daily feeding of tempeh could decrease the level of Clostridium perfringens in cecum contents and reduce the number of large (>= 4 foci) ACF in the colon of treated rats, compared to the DMH control. By the results of TOF-MS and Edman degradation, the isolated antioxidant dipeptide, tripeptides, and tetrapeptides from WET might contain methionine, proline, and lysine. The bioactive peptides in tempeh might inhibit colon cancer by suppressing the growth of C. perfringens in the intestinal tract.