Supplementation with rice bran hydrolysates reduces oxidative stress and improves lipid profiles in adult dogs.

Oxidative stress is defined as an imbalance between reactive oxygen species (ROS) production and antioxidant defense mechanisms of the body. An overproduction of ROS leads to lipid and protein oxidation, injuring the cells both in normal and pathological conditions. Rice bran protein hydrolysates (RBH) has potent antioxidant, anti-inflammatory, anti-angiotensin converting enzyme (ACE) and hypolipidemic effects. Little is known, however, about the effects of RBH in dogs. The present study evaluated the antioxidative, anti-ACE and metabolic effects of RBH in adult dogs. Eighteen adult dogs were divided into 2 groups: control (n=7) and RBH supplemented groups (n=11), received a diet with the same nutritional compositions. The RBH supplemented group was fed with RBH 500 mg/kg body weight (BW) mixed with food for 30 days. BW, blood glucose, lipid profiles, liver enzymes, electrocardiography (ECG), plasma ACE activity, oxidative stress and antioxidant biomarkers were determined on day 0 and day 30 of supplementation periods. Results showed that RBH decreased oxidative stress and increased antioxidant biomarkers by significantly reducing plasma malondialdehyde (MDA) and protein carbonyl, enhanced blood glutathione (GSH) and improved the GSH redox ratio. Moreover, decreased LDL-C and increased HDL-C levels were found after RBH supplementation whereas BW, blood glucose, liver enzymes, plasma ACE activity, plasma catalase (CAT) and superoxide dismutase (SOD) activity and cardiac function were not significantly changed. These results suggest that RBH may help to lower the risk of oxidative stress and dyslipidemia in adult dogs.

Nil-Surin Rice Bran Hydrolysates Improve Lipid Metabolism and Hepatic Steatosis by Regulating Secretion of Adipokines and Expression of Lipid-Metabolism Genes.

Overconsumption of a high caloric diet is associated with metabolic disorders and a heightened risk of diabetes mellitus (DM), hepatic steatosis, and cardiovascular complications. The use of functional food has received much attention as a strategy in the prevention and treatment of metabolic disorders. This present study investigated whether Nil-Surin rice bran hydrolysates (NRH) could prevent or ameliorate the progression of metabolic disorders in rats in which insulin resistance (IR) was induced by a high fat-high fructose diet (HFFD). After 10 weeks of the HFFD, the rats showed elevated fasting blood glucose (FBG), impaired glucose tolerance, dysregulation of adipokine secretion, distorted lipid metabolism such as dyslipidemia, and increased intrahepatic fat accumulation. The IR was significantly attenuated by a daily dose of NRH (100 or 300 mg/kg/day). Doses of NRH rectified adipokine dysregulation by increasing serum adiponectin and improving hyperleptinemia. Interestingly, NRH decreased intrahepatic fat accumulation and improved dyslipidemia as shown by decreased levels of hepatic triglyceride (TG) and serum TG, total cholesterol and low-density lipoprotein cholesterol, and increased high-density lipoprotein cholesterol. In addition, a modulation of expression of lipid metabolism genes was observed: NRH prevented upregulation of the lipogenesis genes Srebf1 and Fasn. In addition, NRH enhanced the expression of fatty-acid oxidation genes, as evidenced by an increase of Ppara and Cpt1a when compared with the HFFD control group. The activities of NRH in the modulation of lipid metabolism and rectifying the dysregulation of adipokines may result in a decreased risk of DM and hepatic steatosis. Therefore, NRH may be beneficial in ameliorating metabolic disorders in the HFFD model.

Protective effects of rice bran hydrolysates on heart rate variability, cardiac oxidative stress, and cardiac remodeling in high fat and high fructose diet-fed rats

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 1000 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.

Rice bran hydrolysates induce immunomodulatory effects by suppression of chemotaxis, and modulation of cytokine release and cell-mediated cytotoxicity

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.

The production of hydrolysates from industrially defatted rice bran and its surface image changes during extraction.

BACKGROUND: This research employed a mild subcritical alkaline water (mild-SAW) extraction technique to overcome the difficulty of active compound extractability from industrially defatted rice bran (IDRB). Mild-SAW (pH 9.5, 130 °C, 120 min) treatment followed by enzymatic hydrolysis (Protease G6) was applied to produce rice bran hydrolysate (RBH). Response surface methodology was used to identify proteolysis conditions for maximizing protein content and ABTS radical scavenging activity (ABTS-RSA). Microstructural changes occurring in IDRB during extraction were monitored. The selected RBH was characterized for protein recovery, yield, antioxidant activities, phenolic profile and hydroxymethylfufural (HMF) content. RESULTS: Optimal proteolysis conditions were 20 mL kg-1 IDRB (enzyme/substrate ratio) for 6 h. Under these conditions, the yield, ABTS-RSA, ferric reducing antioxidant power and total phenolic content of the RBH were 46.1%, 294.22 µmol trolox g-1 , 57.72 µmol FeSO4 g-1 and 22.73 mg gallic acid g-1 respectively, with relatively low HMF level (0.21 mg g-1 ). The protein recovery was 4.8 times greater than that by conventional alkaline extraction. Its major phenolic compounds were p-coumaric and ferulic acids. The microstructural changes of IDRB confirmed that the mild-SAW/Protease G6 process enhanced the release of active compounds. CONCLUSION: The process of mild-SAW extraction followed by proteolysis promotes the release of active compounds from IDRB. © 2017 Society of Chemical Industry.

Rice bran protein hydrolysates attenuate diabetic nephropathy in diabetic animal model.

INTRODUCTION: Diabetic nephropathy (DN) is an important microvascular complication of uncontrolled diabetes. The features of DN include albuminuria, extracellular matrix alterations, and progressive renal insufficiency. Rice bran protein hydrolysates (RBPs) have been reported to have antihyperglycemic, lipid-lowering, and anti-inflammatory effects in diabetic rats. Our study was to investigate the renoprotective effects of RBP in diabetic animals and mesangial cultured cells. METHODS: Eight-week-old male db/m and db/db mice were orally treated with tap water or RBP (100 or 500 mg/kg/day) for 8 weeks. At the end of the experiment, diabetic nephropathy in kidney tissues was investigated for histological, ultrastructural, and clinical chemistry changes, and biomarkers of angiogenesis, fibrosis, inflammation, and antioxidant in kidney were analyzed by Western blotting. Protection against proangiogenic proteins and induction of cytoprotection by RBP in cultured mesangial cells was evaluated. RESULTS: RBP treatment improved insulin sensitivity, decreased elevated fasting serum glucose levels, and improved serum lipid levels and urinary albumin/creatinine ratios in diabetic mice. RBP ameliorated the decreases in podocyte slit pore numbers, thickening of glomerular basement membranes, and mesangial matrix expansion and suppressed elevation of MCP-1, ICAM-1, HIF-1α, VEGF, TGF-ß, p-Smad2/3, and type IV collagen expression. Moreover, RBP restored suppressed antioxidant Nrf2 and HO-1 expression. In cultured mesangial cells, RBP inhibited high glucose-induced angiogenic protein expression and induced the expression of Nrf2 and HO-1. CONCLUSION: RBP attenuates the progression of diabetic nephropathy and restored renal function by suppressing the expression of proangiogenic and profibrotic proteins, inhibiting proinflammatory mediators, and restoring the antioxidant and cytoprotective system.

Rice bran protein hydrolysates reduce arterial stiffening, vascular remodeling and oxidative stress in rats fed a high-carbohydrate and high-fat diet.

PURPOSE: Rice bran protein hydrolysates (RBPH) contain highly nutritional proteins and antioxidant compounds which show benefits against metabolic syndrome (MetS). Increased arterial stiffness and the components of MetS have been shown to be associated with an increased risk of cardiovascular disease. This study aimed to investigate whether RBPH could alleviate the metabolic disorders, arterial stiffening, vascular remodeling, and oxidative stress in rats fed a high-carbohydrate and high-fat (HCHF) diet. METHODS: Male Sprague-Dawley rats were fed either a standard chow and tap water or a HCHF diet and 15 % fructose solution for 16 weeks. HCHF rats were treated orally with RBPH (250 or 500 mg/kg/day) for the final 6 weeks of the experimental period. RESULTS: Rats fed with HCHF diet had hyperglycemia, insulin resistance, dyslipidemia, hypertension, increased aortic pulse wave velocity, aortic wall hypertrophy and vascular remodeling with increased MMP-2 and MMP-9 expression. RBPH supplementation significantly alleviated these alterations (P < 0.05). Moreover, RBPH reduced the levels of angiotensin-converting enzyme (ACE) and tumor necrosis factor-alpha in plasma. Oxidative stress was also alleviated after RBPH treatment by decreasing plasma malondialdehyde, reducing superoxide production and suppressing p47phox NADPH oxidase expression in the vascular tissues of HCHF rats. RBPH increased plasma nitrate/nitrite level and up-regulated eNOS expression in the aortas of HCHF-diet-fed rats, indicating that RBPH increased NO production. CONCLUSION: RBPH mitigate the deleterious effects of HCHF through potential mechanisms involving enhanced NO bioavailability, anti-ACE, anti-inflammatory and antioxidant properties. RBPH could be used as dietary supplements to minimize oxidative stress and vascular alterations triggered by MetS.

Rice Bran Protein Hydrolysates Improve Insulin Resistance and Decrease Pro-inflammatory Cytokine Gene Expression in Rats Fed a High Carbohydrate-High Fat Diet.

A high carbohydrate-high fat (HCHF) diet causes insulin resistance (IR) and metabolic syndrome (MS). Rice bran has been demonstrated to have anti-dyslipidemic and anti-atherogenic properties in an obese mouse model. In the present study, we investigated the beneficial effects of rice bran protein hydrolysates (RBP) in HCHF-induced MS rats. After 12 weeks on this diet, the HCHF-fed group was divided into four subgroups, which were orally administered RBP 100 or 500 mg/kg, pioglitazone 10 mg/kg, or tap water for a further 6 weeks. Compared with normal diet control group, the MS rats had elevated levels of blood glucose, lipid, insulin, and HOMA-IR. Treatment with RBP significantly alleviated all those changes and restored insulin sensitivity. Additionally, RBP treatment increased adiponectin and suppressed leptin levels. Expression of Ppar-γ mRNA in adipose tissues was significantly increased whereas expression of lipogenic genes Srebf1 and Fasn was significantly decreased. Levels of mRNA of proinflammatory cytokines, Il-6, Tnf-α, Nos-2 and Mcp-1 were significantly decreased. In conclusion, the present findings support the consumption of RBP as a functional food to improve insulin resistance and to prevent the development of metabolic syndrome.

Peptides-Derived from Thai Rice Bran Improves Endothelial Function in 2K-1C Renovascular Hypertensive Rats.

In recent years, a number of studies have investigated complementary medical approaches to the treatment of hypertension using dietary supplements. Rice bran protein hydrolysates extracted from rice is a rich source of bioactive peptides. The present study aimed to investigate the vasorelaxation and antihypertensive effects of peptides-derived from rice bran protein hydrolysates (RBP) in a rat model of two kidney-one clip (2K-1C) renovascular hypertension. 2K-1C hypertension was induced in male Sprague-Dawley rats by placing a silver clip around the left renal artery, whereas sham-operated rats were served as controls. 2K-1C and sham-operated rats were intragastrically administered with RBP (50 mg kg(-1) or 100 mg kg(-1)) or distilled water continuously for six weeks. We observed that RBP augmented endothelium-dependent vasorelaxation in all animals. Administration of RBP to 2K-1C rats significantly reduced blood pressure and decreased peripheral vascular resistance compared to the sham operated controls (p < 0.05). Restoration of normal endothelial function and blood pressure was associated with reduced plasma angiotensin converting enzyme (ACE), decreased superoxide formation, reduced plasma malondialdehyde and increased plasma nitrate/nitrite (p < 0.05). Up-regulation of eNOS protein and down-regulation of p47phox protein were found in 2K-1C hypertensive rats-treated with RBP. Our results suggest that RBP possesses antihypertensive properties which are mainly due to the inhibition of ACE, and its vasodilatory and antioxidant activity.

Rice bran protein hydrolysates prevented interleukin-6- and high glucose-induced insulin resistance in HepG2 cells.

Rice bran, which is a byproduct of rice milling process, contains various nutrients and biologically active compounds. Rice bran protein hydrolysates have various pharmacological activities such as antidiabetic and antidyslipidemic effects. However, there are limited studies about the mechanisms of rice bran protein hydrolysates (RBP) on insulin resistance and lipid metabolism. RBP used in this study were prepared from Thai Jasmine rice. When HepG2 cells were treated with IL-6, the IRS-1 expression and Akt phosphorylation were suppressed. This effect of IL-6 was prevented by RBP in association with inhibition of STAT3 phosphorylation and SOCS3 expression. RBP could increase the phospho-AMPK levels and inhibit IL-6- or high glucose-induced suppression of AMPK and Akt activation. High glucose-induced dysregulation of the expression of lipogenic genes, including SREBP-1c, FASN and CPT-1, was normalized by RBP treatment. Moreover, impaired glucose utilization in insulin resistant HepG2 cells was significantly alleviated by concurrent treatment with RBP. Our results suggested that RBP suppresses inflammatory cytokine signaling and activates AMPK, and thereby these effects may underlie the insulin sensitizing effect.

Raman spectroscopy determines structural changes associated with gelation properties of fish proteins recovered at alkaline pH.

Structural changes of alkali-treated rockfish protein isolate (AKPI) during frozen storage were elucidated using a Raman spectrometer and scanning electron microscope (SEM). The results were compared to conventional surimi (CS). No significant textural difference was noted between AKPI stored at pH 5.5 and 7.0. The strongest texture was found for AKPI frozen with cryoprotectants and CS, while the weakest texture was observed in AKPI frozen without cryoprotectants. SEM revealed the most discontinuity in gels of AKPI with no cryoprotectants and a more aggregated microstructure after storage at pH 5.5 than at neutral pH. Raman spectral analysis demonstrated refolding of AKPI by pH readjustment to 7.0, although the refolded structure was not identical to that before the pH shift. CS showed higher alpha-helix content (approximately 50%) than AKPI (approximately 20-30%). Frozen storage induced a decrease and an increase in the alpha-helix content of CS and AKPI samples, respectively. AKPIs were slightly less stable than CS during frozen storage.