The anti-cancer activity and potential clinical application of rice bran extracts and fermentation products

Abstract

Rice bran is the main by-product of rice processing and contains approximately 64% of the nutrients in rice. Its various nutrient elements include rice bran proteins, oil, oryzanol, vitamins, polysaccharides, etc. The use of fermented technology can increase the content of bioactive peptides, promote the absorption efficiency, and further improve the functionality and added value of rice bran. In recent years, the nutritional value and function of the extracts and fermented products of rice bran have been emphatically studied. Rice bran extracts and fermentation products serve a critical role in the anti-inflammatory reaction, reducing the plasma lipid effect and increasing anti-cancer activity. Moreover, few review studies have been reported on the anti-cancer activity and potential mechanism of action of rice bran extract and its fermentation products. In this review, we focused on the anti-cancer function, mechanisms, and potential clinical usage of rice bran extracts and fermentation products in the adjuvant therapy of cancer patients.

Fig. 1. The role of rice bran extracts and FRB in reducing inflammation. Supplementation of RBP hydrolysate and RBO inhibited the production of proinflammatory factors. Gamma-oryzanol inactivated the NF-κB signaling pathway and reduced inflammatory reactions. FRB effectively mitigated dextran sodium sulfate-induced colitis by suppressing the infiltration of inflammatory cells and the secretion of inflammatory factors.

Fig. 2. Rice bran extracts arrest the cancer cell cycle. Gamma-tocotrienol, gamma-oryzanol, and phytic acid (IP6) arrested the cell cycle at the G0/G1 phase of gastric adenocarcinoma SGC-7901 cells; prostate cells DU145, colon cancer cells HT-29, and breast cancer cells MCF-7. Momilactone B treatment resulted in human leukemia cell U937 arrest at the G1 phase. Tricin and gamma-oryzanol could also arrest the breast cancer cells MDA-MB-468 and prostate cell lines (PC3 and LNCaP) at the G2/M phase.

Fig. 3. Rice bran extracts and FRB promote cancer cell apoptosis. Rice bran extracts (phytic acid, cycloartenyl ferulate, gamma/delta-tocotrienol, and MGN-3/Biobran) and FRB administration dramatically induced cancer cell apoptosis via promoting the expression of proapoptosis proteins (Bax, Bcl-xl, Bak, P21, P27, P53, and caspase 3/8/9), activating apoptosis-related receptors (DR4/5, CD95, and Fas) or inhibiting the expression of the anti-apoptotic protein Bcl-2.

Fig. 4. Rice bran extracts and FRB have chemopreventive effects. Tocotrienol treatment reduced DEN/AFF-induced liver carcinogenesis. A diet of FRB effectively inhibited BOP-induced pancreatic cancer, OH-BBN-induced bladder cancer, MNNG-induced gastric cancer, and NNK-induced lung cancer. MGN-3/Biobran supplementation enhanced the susceptibility of breast cancer cells to paclitaxel and daunorubicin.

Fig. 5. The potential mechanism of treatment with rice bran extracts and fermented products for cancer prevention and therapy. Rice bran is a by-product during rice processing, and the bioactive components of rice bran extracts and fermented products exert important roles in cancer prevention and therapy. Administration of these bioactive components contributes to reducing inflammatory reactions, arresting the cell cycle, promoting cell apoptosis, and preventing cancer occurrence.