Objective: To evaluate the immunomodulatory effects of rice bran hydrolysates on cultured immune cells and their underlying mechanism. Methods: Rice bran hydrolysates were prepared from pigmented rice (Oryza sativa L.) by hydrothermolysis and protease digestion. Rice bran hydrolysates were assayed for phenolic content and antioxidant activity. Cell proliferation of Jurkat, THP-1 and peripheral blood mononuclear cells (PBMC) was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Chemotaxis was evaluated by transwell chamber methods. Immunoadherence of THP-1 was performed on cultured human umbilical vein endothelial cells (HUVEC). Cytokine released from PBMC was measured by ELISA assay kits. Lymphocyte-mediated cytotoxicity was carried out on KKU-452 cells. Proteins associated with immunomodulation were analyzed by Western immunoblotting assay. Results: Rice bran hydrolysates were rich in phenolic compounds, such as ferulic acid, catechin, quercetin, and quercetin glycosides. Rice bran hydrolysates suppressed phytohemagglutinin (PHA)- stimulated proliferation of PBMC and Jurkat cells, chemotaxis of Jurkat and THP-1 cells, and immunoadherence of THP-1 on HUVEC cultured cells. The cellular mechanism of rice bran hydrolysates involved the activation of AMPK as well as suppression of mTOR, NF-κB and VCAM-1. Rice bran hydrolysates potentiated PBMC on the PHA-stimulated release of IL-2, TNF-α, and IL-4, and enhanced PHA-induced non-MHC-restricted cytotoxicity on KKU-452 cancer cells. Conclusions: The immunomodulatory effect of phytochemicals derived from rice bran hydrolysates suggests its therapeutic potential for further investigation.

Objective: To investigate anti-tumor effect of rice bran hydrolysates (RBH) on proliferation, migration, invasion, and angiogenesis of cholangiocarcinoma (CCA) cells, and elucidate the underlying mechanisms. Methods: RBH was prepared from Tubtim Chumprae rice (Oryza sativa L.) by hydrothermolysis followed by protease digestion. Phenolic content in RBH was analyzed by high-performance liquid chromatography. Human CCA cells, KKU-156, KKU-452, and KKU-100, were used to study the effects of RBH on proliferation, migration, invasion, and adhesion by wound healing, Transwell chamber, and fibronectin cell adhesion assays. Angiogenesis was evaluated using human umbilical vein endothelial cells. Proteins associated with cancer progression were analyzed by immunobloting assays. Results: RBH contained carbohydrates, proteins, lipids, and various phenolic compounds and flavonoids. RBH did not inhibit CCA proliferation, but strongly suppressed migration, invasion, adhesion of CCA cells, and the formation of tube-like capillary structures of human umbilical vein endothelial cells. Moreover, RBH down-regulated phosphorylation of FAK, PI3K, and Akt, suppressed NF-κB nuclear translocation, decreased the expression of ICAM-1, vimentin and vascular endothelium growth factor (VEGF), and increased the expression of E-cadherin. Conclusions: RBH suppresses CCA cell migration and invasion and decreases expression of proteins involved in cancer metastasis. RBH is a potential food supplement for cancer prevention.

Objective: To examine the ameliorative effect of rice bran hydrolysates (RBH) on metabolic disorders, cardiac oxidative stress, heart rate variability (HRV), and cardiac structural changes in high fat and high fructose (HFHF)-fed rats. Methods: Male Sprague-Dawley rats were daily fed either standard chow diet with tap water or an HFHF diet with 10% fructose in drinking water over 16 weeks. RBH (500 and 1 000 mg/kg/day) was orally administered to the HFHF-diet-fed rats during the last 6 weeks of the study period. At the end of the treatment, metabolic parameters, oxidative stress, HRV, and cardiac structural changes were examined. Results: RBH administration significantly ameliorated metabolic disorders by improving lipid profiles, insulin sensitivity, and hemodynamic parameters. Moreover, RBH restored HRV, as evidenced by decreasing the ratio of low-frequency to high-frequency power of HRV, a marker of autonomic imbalance. Cardiac oxidative stress was also mitigated after RBH supplementation by decreasing cardiac malondialdehyde and protein carbonyl, upregulating eNOS expression, and increasing catalase activity in the heart. Furthermore, RBH mitigated cardiac structural changes by reducing cardiac hypertrophy and myocardial fibrosis in HFHF-diet-fed rats. Conclusions: The present findings suggest that consumption of RBH may exert cardioprotective effects against autonomic imbalances, cardiac oxidative stress, and structural changes in metabolic syndrome.