Comparative hypoglycemic and nephroprotective effects of tocotrienol rich fraction (TRF) from palm oil and rice bran oil against hyperglycemia induced nephropathy in type 1 diabetic rats

Diabetic nephropathy (DN) is a serious complication confronted by patients with diabetes. Available data indicate that the development of DN is linked to hyperglycemia. Tocotrienol rich fraction (TRF) from palm oil (PO) and rice bran oil (RBO) has been shown to lower the blood glucose level in patients and preclinical animal models. This study was designed to investigate if TRF from PO and RBO could improve the renal function in DN by the virtue of their hypoglycemic and antioxidant activities. Male Wistar rats having an average body weight (bw) 250 g were divided into four groups of six each .The first group served as diabetic control [injected with 55 mg/kg bw of streptozotocin (STZ), intraperitoneally], while the second and third group received PO-TRF and RBO-TRF, respectively, by gavage at a dose of 200 mg/kg bw/day, over a period of 8 weeks post-induction of diabetes. The fourth group comprised of age-matched male Wistar rats that received single intraperitoneal injection of normal saline only and served as control. After 8 weeks of STZ injection and TRF treatment, 24 h urine was collected and animals were sacrificed. Fasting blood glucose, glycosylated hemoglobin, biochemical markers of renal function and oxidative stress were evaluated in serum, urine and kidney tissue. The results show that treatment with PO-TRF as well as RBO-TRF significantly improved the glycemic status and renal function in type 1 diabetic rats but PO-TRF afforded greater efficiency at similar dose as compared to RBO-TRF. In conclusion, PO-TRF was found to be more effective hypoglycemic and nephroprotective agent in DN than RBO-TRF.     

Purification and characterization of a lectin from rice bran

A rice bran lectin was purified to homogeneity by precipitation with ammonium sulfate and chromatography on ovomucoid-Sepharose and CM-cellulose. The molecular weight of the dimer lectin was estimated to be around 37,000 by ultracentrifugation studies. The sedimentation coefficient was 3.8S. On Sepharose 6B gel filtration in the presence of 6 M guanidine-HCl, the lectin showed a molecular weight of 19,000. On reduction and carboxymethylation, the lectin further dissociated into two nonidentical subunits, with molecular weights of about 11,000 and 8,000. These subunits did not show hemagglutinating activity. Equilibrium dialysis experiments using N-acetyl-[1-14C]glucosamine indicated that about 1.8 mol of the sugar was bound to 19,000 g of the lectin. The lectin was mitogenic against mouse splenic lymphocytes and human peripheral lymphocytes. The lectin enhanced the rate of glucose oxidation and inhibited epinephrine-stimulated lipolysis in mouse adipocytes. Some characteristics of the lectin are compared with those of wheat germ agglutinin.     

Covalently attached ferulic acid in a proteoglycan from rice bran

A water-soluble proteoglycan, precipitated with ammonium sulfate from the hot-water extract of rice bran, contained ferulic acid, which was liberated by alkaline treatment. Evidence for the linkage between the carboxyl group of ferulic acid and the proteoglycan was obtained by the characterization of ferulic acid hydroxamate after treatment of the proteoglycan with hydroxylamine.     

Structural features of rice bran hemicellulose

Rice bran hemicellulose was fractionated by ammonium sulphate precipitation, ion-exchange chromatography and enzymatic techniques. Methylation analysis of each fraction revealed that the bran hemicellulose consisted mainly of highly branched arabinoxylan and xyloglucan. The acidic arabinoxylan main component appeared to have more doubly-branched xylose residues in the main chain and also more complicated side chains than the endosperm arabinoxylan. Xyloglucan was also isolated from the crude hemicellulose but the amount of β-(1 → 3), (1 → 4)-glucan was very small compared to the endosperm hemicellulose.     

Effect of long term feeding of rice bran oil upon lipids and lipoproteins in rats

The effects of feeding two levels of rice bran oil (RBO) on the growth, lipid parameters, and fatty acid composition of the plasma and liver of rats (Wistar strain) were compared with those produced on animals which had been fed the same levels of peanut oil (PNO). The control animals were fed synthetic diets containing 5 and 20% peanut oil (PNO) and the experimental groups were fed similar diets, containing the same level of rice bran oil (RBO). There was no significant difference with respect to the organ weights between the control and the experimental groups. In general, groups fed 20% oil gained more weight than groups fed 5% oil. The animals which received rice bran oil in their diet had, in general, comparatively lower levels of cholesterol, triglycerides and phospholipids. On the other hand, animals receiving 20% rice bran oil in their diet, showed an increase of 20% in high density lipoproteins (HDL-C), within 18 weeks (p<0.05), when compared to the animals fed with peanut oil. Similarly, low density lipoprotein cholesterol (LDL-C) and very low density lipoprotein cholesterol (VLDL-C) were lower in RBO-fed groups, than in the PNO-fed groups. There was, however, no significant differences in the cholesterol/phospholipid (C/P) ratio of the two groups. Analysis of plasma and of liver fatty acids indicated, in a general way, the type of fat consumed. There were no significant difference in the P/S ratio, nor any in the oleic/linoleic, oleic/stearic, palmitoleic/palmitic, oleic/palmitic, and oleic/palmitoleic ratios. Furthermore, levels of saturated (SAFA), monounsaturated (MUFA), and polyunsaturated (PUFA) fatty acids were identical in both the groups. Thus, our results suggest that feeding a high level of rice bran oil (RBO) has no deleterious effect on the growth and blood lipid profile of rats.Abbreviations PNO peanut oil - RBO rice bran oil - HDL-C high density lipoprotein cholesterol - LDL-C low density lipoprotein cholesterol - VLDL-C very low density lipoprotein cholesterol - SAFA saturated fatty acids - MUFA mono-unsaturated fatty acids     

Trypsin inhibitor,mineral availability,and performance of broiler chickens fed on diets based on rice bran

Trypsin inhibitor in rice bran was inactivated by moist heat, but not by dry heating or treatments with 0.1% H₂SO₄, 0.1% NaOH or 0.1% NaCl. Heating rice bran could not improve its growth promotion value in the diet of broilers, which was related to the feed intake. Groundnut meal was the major protein supplement in the diets. Rice bran diets did not affect weight of pancreas (1.45–1.50 g/kg body weight). Use of ⁴⁵Ca revealed that availability of calcium on a rice bran diet was lower than on a maize-based diet. A similar effect on ⁵⁹Fe-availability was noted, although this result needs confirmation. Lack of differences in weight of thyroid glands and uptake of ¹³¹I by thyroids of birds on maize- and rice bran-based diets indicated the absence of any goitrogenic substance in the rice bran.     

Antioxidant capacity responsible for a hypocholesterolemia is independent of dietary cholesterol in adult rats fed rice protein

Dietary cholesterol and aging are major risk factors to accelerate oxidation process for developing hypercholesterolemia. The major aim of this study is to elucidate the effects of rice protein on cholesterol level and oxidative stress in adult rats fed with and without cholesterol. After 2 weeks of feeding, hepatic and plasma contents of cholesterol, reduced glutathione (GSH), oxidized glutathione (GSSG), malondialdehyde (MDA) and protein carbonyl (PCO) were measured. In liver, total antioxidative capacity (T-AOC), activities of antioxidant enzymes (total superoxide dismutase, T-SOD; catalase, CAT), glutathione metabolizing enzyme activities and gene expression levels (γ-glutamylcysteine synthetase, γ-GCS; glutathione reductase, GR; glutathione peroxidase, GPx) were determined. Under cholesterol-free/enriched dietary condition, T-AOC, activities of T-SOD and CAT, glutathione metabolism related enzymes' activities and mRNA levels (γ-GCS, GR and GPx) were effectively stimulated by rice proteins as compared to caseins. Compared with caseins, rice proteins significantly increased hepatic and plasma GSH contents, whereas hepatic and plasma accumulations of MDA, PCO and GSSG were significantly reduced by rice protein-feedings. As a result, the marked reductions of cholesterol in the plasma and in the liver were observed in adult rats fed rice proteins with and without cholesterol. The present study demonstrates that the hypocholesterolemic effect of rice protein is attributable to inducing antioxidative response and depressing oxidative damage in adult rats fed cholesterol-free/enriched diets. Results suggest that the antioxidant capability involved in the hypocholesterolemic action exerted by rice protein is independent of dietary cholesterol during adult period.     

Relationship between trace metal concentration and antioxidative activity of ancient rice bran (red and black rice) and a present-day rice bran (Koshihikari).

Antioxidative activity and polyphenol and trace metal content in bran from ancient rice varieties (red and black rice) and a present-day variety of rice (Koshihikari) were measured. The antioxidative properties of rice bran in terms of scavenging and quenching activity for reactive oxygen species (ROS), including superoxide anion radicals (*O(2)(-)), hydroxyl radicals (*OH), singlet oxygen ((1)O(2)) and lipid peroxide (LOO*), correlated well with polyphenol and trace metal content. In particular, the possibly that Mn content greatly contributes to the antioxidative properties of rice bran was revealed.     

Biodiesel production from rice bran by a two-step in-situ process

The production of fatty acid methyl esters (FAMEs) by a two-step in-situ transesterification from two kinds of rice bran was investigated in this study. The method included an in-situ acid-catalyzed esterification followed by an in-situ base-catalyzed transesterification. Free fatty acids (FFAs) level was reduced to less than 1% for both rice bran A (initial FFAs content = 3%) and rice bran B (initial FFAs content = 30%) in the first step under the following conditions: 10 g rice bran, methanol to rice bran ratio 15 mL/g, H₂SO₄ to rice bran mass ratio 0.18, 60 °C reaction temperature, 600 rpm stirring rate, 15 min reaction time. The organic phase of the first step product was collected and subjected to a second step reaction by adding 8 mL of 5 N NaOH solution and allowing to react for 60 and 30 min for rice bran A and rice bran B, respectively. FAMEs yields of 96.8% and 97.4% were obtained for rice bran A and rice bran B, respectively, after this two-step in-situ reaction.     

Hydrolysis of rice bran oil using immobilized lipase in a stirred batch reactor

Candida cylindracea lipase was immobilized by adsorption on acid washed glass beads. It was observed that protein loading of the support depends on the size of the particle, with smaller particle containing higher amount of protein per unit weight. Initial reaction rate linearly varied up to enzyme concentration of 17.25 U/mL. Amount of free fatty acids produced was linearly proportional up to the enzyme loading of 1650 μg/g of bead. Achievement of chemical equilibrium took longer time in the case of less protein loading. Degree of hydrolysis was found to decrease in second and third consecutive batch operations on repeated use of immobilized lipase.     

Fractionation of the rice bran layer and quantification of vitamin E, oryzanol, protein, and rice bran saccharide

Value-added processing with respect to rice milling has traditionally treated the rice bran layer as a homogenous material that contains significant concentrations of high-value components of interest for pharmaceutical and nutraceutical applications. Investigators have shown that high-value components in the rice bran layer vary from differences in kernel-thickness, bran fraction, rice variety, and environmental conditions during the growing season. The objectives of this study were to quantify the amount of rice bran removed at pre-selected milling times and to correlate the amount of rice bran removed at each milling time with the concentration of vitamin E, gamma-oryzanol, rice bran saccharide, and protein obtained. The ultimate goal of this research is to show that rice bran fractionation is a useful method to obtain targeted, nutrient-rich bran samples for value-added processing. Two long grain rice cultivars, Cheniere and Cypress, were milled at discrete times between 3 and 40 seconds using a McGill mill to obtain bran samples for analysis. Results showed that the highest oryzanol and protein concentrations were found in the outer portion of the rice bran layer, while the highest rice bran saccharide concentration was found in the inner portion of the bran layer. Vitamin E concentration showed no significant difference across the bran layer within a variety, though the highest magnitude of concentration occurs within the first 10 seconds of milling for both varieties. To extract the higher concentration of oryzanol and protein only the outer portion of the bran layer requires processing, while to extract the higher concentration of rice bran saccharide, only the inner portion of the bran layer requires processing. Rice bran fractionation allows for the selective use of portions of the bran layer and is advantageous for two reasons: (1) bran fractions contain higher concentrations of components of interest with respect to the overall bran layer average, and (2) less bran needs to be processed to obtain components of interest.     

Isolation of oryzanol from crude rice bran oil

The isolation of oryzanol from crude rice bran oil (RBO) was achieved by a two-step crystallization process. In the first crystallization, oryzanol was concentrated in the liquid phase along with free fatty acid (FFA), monoacylglycerol (MG), squalene, tocols, and phytosterols, whereas the solid phase contained mainly triacylglycerol (TG) and steryl esters. Oryzanol-rich product obtained from the first crystallization was subjected to the second crystallization where the oryzanol-rich product was kept at room temperature (20.5+/-1.5 degrees C) for 24h. Hexane was added as anti-solvent to the oryzanol-rich product and kept at 5+/-1 degrees C for another 48h. Parameters that affect the isolation of oryzanol from crude RBO were systematically investigated. Under optimal operation conditions, oryzanol with purity and recovery of 93-95% and 59%, respectively, was obtained from RBO with an initial FFA content of ca. 5%.     

Neuronal-glial interactions in rats fed a ketogenic diet

Glucose is the preferred energy substrate for the adult brain. However, during periods of fasting and consumption of a high fat, low carbohydrate (ketogenic) diet, ketone bodies become major brain fuels. The present study was conducted to investigate how the ketogenic diet influences neuronal-glial interactions in amino acid neurotransmitter metabolism. Rats were kept on a standard or ketogenic diet. After 21 days all animals received an injection of [1-(13)C]glucose plus [1,2-(13)C]acetate, the preferential substrates of neurons and astrocytes, respectively. Extracts from cerebral cortex and plasma were analyzed by (13)C and (1)H nuclear magnetic resonance spectroscopy and HPLC. Increased amounts of valine, leucine and isoleucine and a decreased amount of glutamate were found in the brains of rats receiving the ketogenic diet. Glycolysis was decreased in ketotic rats compared with controls, evidenced by the reduced amounts of [3-(13)C]alanine and [3-(13)C]lactate. Additionally, neuronal oxidative metabolism of [1-(13)C]glucose was decreased in ketotic rats compared with controls, since amounts of [4-(13)C]glutamate and [4-(13)C]glutamine were lower than those of controls. Although the amount of glutamate from [1-(13)C]glucose was decreased, this was not the case for GABA, indicating that relatively more [4-(13)C]glutamate is converted to GABA. Astrocytic metabolism was increased in response to ketosis, shown by increased amounts of [4,5-(13)C]glutamine, [4,5-(13)C]glutamate, [1,2-(13)C]GABA and [3,4-(13)C]-/[1,2-(13)C]aspartate derived from [1,2-(13)C]acetate. The pyruvate carboxylation over dehydrogenation ratio for glutamine was increased in the ketotic animals compared to controls, giving further indication of increased astrocytic metabolism. Interestingly, pyruvate recycling was higher in glutamine than in glutamate in both groups of animals. An increase in this pathway was detected in glutamate in response to ketosis. The decreased glycolysis and oxidative metabolism of glucose as well as the increased astrocytic metabolism, may reflect adaptation of the brain to ketone bodies as major source of fuel.     

Natural occurrence of toxigenic fungi and mycotoxins in rice bran

Thirty four samples of rice bran, of which 9 were from raw (untreated) rice (RR) and 25 from parboiled rice (PbR) were collected from commercial rice mills in and around Madras and analysed for storage mycoflora and mycotoxins. Fungi of the Aspergillus flavus group were present in 29 of the 34 samples (8 from RR and 21 from PbR) in quantities ranging from <1–432 thousand propagules/g, though not always as the dominant mycoflora. Fungal numbers were usually higher in RR than in PbR samples.Five of the 9 RR samples and 6 of the 25 PbR samples were positive for aflatoxins. Among 29 isolates of A. flavus obtained from the bran samples, 16 isolates –6 from RR bran and 10 from PbR bran — were found to be toxigenic in vitro. Some isolates of A. candidus also seemed to produce aflatoxin and other fluorescent substances.     

Tocotrienol levels in various tissues of Sprague-Dawley rats after intragastric administration of tocotrienols

A tocotrienol (T3) mixture was intragastricaly administered to Sprague-Dawley rats, and the T3 levels in various tissues were measured 0, 4, 8 and 24 hr after the administration. In blood clots, brain, thymus, testes, vice-testes and muscles, T3 homologues were not detected at all. In epididymal adipose, renal adipose, subcutaneous adipose and brown adipose tissues and in the heart, the T3 levels were maintained or increased for 24 hr after the administration. In the serum, liver, mesenteric lymph node, spleen and lungs, the T3 levels were highest 8 hr after the T3 administration. These results suggest that the distribution and metabolism of T3 in the rat vary considerably among different tissues.     

Preparation and characterization of activated carbon from rice bran

A study on the preparation of rice bran-based activated carbon was conducted, with and without an acid treatment step prior the activation process. The influence of the activation time on the structure of the activated carbons was evaluated. The acid treatment had a significant positive influence on sorption properties. The rice bran-activated carbon presented a BET surface area of 652m(2)g(-1) and a pore volume of 0.137cm(3)g(-1), with mesopores predominance (ca. 55%). These experimental results indicated the potential use of rice bran as a precursor in the activated carbon preparation process, thus representing an economically promising material.     

Isolation and partial characterization of proteoglycans from rice bran

Extraction of rice bran with hot water, followed by removal of protein and starch, yielded a proteoglycan. Successive fractionation of this proteoglycan by salting out with ammonium sulfate and by DEAE-Sephadex column chromatography yielded several fractions shown to be homogeneous by disc electrophoresis. Treatment of the fractions with alkali and a proteolytic enzyme has shown that the polysaccharide and protein of the proteoglycan are most probably linked through an O-glycosyl linkage through hydroxyproline.     

Anti-stress and anti-fatigue effects of fermented rice bran.

The anti-stress and anti-fatigue effects on rats and mice of a hot water extract of rice bran fermented with Saccharomyces cerevisae IFO 2346 were investigated. Oral administration (1 g/kg/day) of the hot water extract of fermented rice bran (FRB) inhibited major changes in the weight of the adrenal, thymus, spleen and thyroid, showing an anti-stress effect. The hot water extract of FRB also inhibited increases in the GPT and LDH activity, cholesterol and glucose in the serum. The administration (1 g/kg/day) for 2 weeks significantly prolonged the swimming time, resulting in an increase in the anti-fatigue effect. It is considered from these results that FRB had anti-stress and anti-fatigue effects.     

Extraction of defatted rice bran with subcritical aqueous acetone

Defatted rice bran extracts were obtained by subcritical treatment using aqueous acetone as extractant. Treatment with 40% (v/v) acetone at 230 °C for 5 min yielded an extract with the highest 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity (0.274 mmol of ascorbic acid/g of bran), total carbohydrate (0.188 g/g of bran), protein (0.512 g/g of bran), and total phenolic contents (88.2 mg of gallic acid/g of bran). The effect of treatment temperature (70-230 °C) was investigated using 40% (v/v) acetone, and the extract under 230 °C treatment showed the highest levels of all the determinations described above. The extracts obtained with various concentrations of aqueous acetone were subjected to UV absorption spectra and HPLC analysis, and the results showed changes in composition and polarity. Antioxidative activity evaluated against oxidation of bulk linoleic acid of the extract obtained with 80% (v/v) acetone was higher than that not only of the extract from subcritical water treatment but also of that obtained 40% (v/v) acetone treatment.     

Extraction of defatted rice bran by subcritical water treatment

Defatted rice bran was treated with subcritical water in the temperature range of 180–280 °C for 5 min using 117 mL and 9 mL vessels to produce the extracts. The total sugar and protein contents and radical scavenging activity of the extracts were then estimated for both vessels. The total sugar concentration of ca. 0.3 g/L-extract was the highest for the extracts at 200 °C, and it significantly decreased at the higher temperatures. The protein concentration and radical scavenging activity were higher at the higher temperatures. Extraction was also done at 200 °C and 260 °C for various times using the small vessel. The total sugar concentration decreased with the increasing extraction time, while the protein concentration and radical scavenging activity only slightly depended on the extraction time. The extracts at 200 °C or lower temperatures using the large vessel possessed the emulsifying and emulsion-stabilizing activities. The HPLC analysis of the extract at 260 °C for 5 min using the small vessel indicated that it contained both hydrophilic and hydrophobic substances. The hydrophilic fraction of the extract mainly contained low-molecular-mass substances.