Antioxidant activity of tocopherols, tocotrienols, and gamma-oryzanol components from rice bran against cholesterol oxidation accelerated by 2,2'-azobis(2-methylpropionamidine) dihydrochloride

Red and white wines inhibit cholesterol oxidation induced by free radicals

The capabilities of two red (RW) and two white wines (WW) in inhibiting cholesterol oxidation were evaluated using a cholesterol emulsion (CE) system. Each RW or WW was mixed with CE at different (v/v) ratios. Cholesterol oxidation was accelerated by a free radical generator, 2,2'-azobis(2-methylpropionamidine) dihydrochloride (AAPH), at 37 °C. The major oxidation product, 7-ketocholesterol, was monitored to determine cholesterol stability in the CE system. At a ratio of 1:250 (RW/CE), 7-ketocholesterol production was not detected during 72 h of oxidation. At a 1:1000 ratio, the inhibition rate of each RW was maintained at 100% at 24 h but decreased afterward. Both WWs had 100% inhibition rate within 48 h at a ratio of 1:10. Also, the capabilities of catechin and resveratrol solutions (1 mg/mL) in inhibiting cholesterol oxidation were studied. Each of the wine polyphenolics showed a 100% of 7-ketocholesterol inhibition rate in 24 h at a ratio of 1:500 (solution/CE). However, the inhibition rate of resveratrol was lower than that of catechin at 48 or 72 h. The results demonstrated that red wine possesses great anti-cholesterol-oxidation capability, which may contribute to health benefits in preventing cardiovascular diseases. Catechin may play a more important role than resveratrol in inhibiting cholesterol oxidation.

Oral administration of γ-aminobutyric acid and γ-oryzanol prevents stress-induced hypoadiponectinemia

Metabolic syndrome is a cluster of risk factors including insulin resistance and type 2 diabetes and is found to associate partly with chronic stress at work in human. Adiponectin circulates in mammal blood mainly as a low molecular weight (LMW) trimer, hexamer, and a high molecular weight (HMW) multimers. Low circulating levels of adiponectin are related to metabolic syndrome. We have then investigated the influence of immobilization stress on plasma adiponectin concentrations in mice. Relative LMW and HMW adiponectin levels were markedly reduced by immobilization stress (0.66±0.07 and 0.59±0.06 after 102 h, respectively), significantly different from the control values (p<0.01 and 0.05, respectively). γ-Aminobutyric acid (GABA) and γ-oryzanol abundantly contained in germinated brown rice have some physiological functions. We further investigated the effect of GABA, γ-oryzanol, GABA plus γ-oryzanol on adiponectin levels in mice subjected to immobilization stress. GABA and γ-oryzanol significantly increased the relative LMW and HMW adiponectin levels under immobilization stress (1.10±0.11 and 0.99±0.19 after 102 h, respectively, for GABA; 1.08±0.17 and 1.15±0.17 after 102 h, respectively, for γ-oryzanol). Additionally, the co-administration of GABA and γ-oryzanol also increased both relative LMW and HMW adiponectin levels (1.02±0.07 and 0.99±0.10 after 102 h, respectively) and was effective in an earlier phase from 30 to 54 h. The results indicate that the co-administration of GABA and γ-oryzanol might be effective in preventing stress-induced hypoadiponectinemia in mice and be also a promising tool for improving metabolic syndrome aggravated by chronic stress.

γ-Oryzanol recovers mouse hypoadiponectinemia induced by animal fat ingestion

Adiponectin is an insulin-sensitizing adipocyte-derived adipokine. The decrease in plasma adiponectin level (hypoadiponectinemia) is involved in the development of insulin resistance and the resulting type 2 diabetes. Our previous studies have demonstrated that γ-oryzanol (ORZ) from rice bran suppressed NF-κB activation and increased adiponectin secretion from adipocyte. In this study, we have evaluated effects of oral administration of animal fat (beef tallow) and palmitate on mouse serum adiponectin level. Oral administrations of beef tallow and palmitate significantly suppressed serum adiponectin levels into around half of the initial level from 48 to 96 h after administration compared with the case of corn oil (P<0.05). Coadministration of ORZ successfully remedied mouse hypoadiponectinemia induced by ingestion of beef tallow and the relative adiponectin levels attained to 1.66±0.23 at 96 h after administration (mean value±s.e., P<0.05). Diverse physiological functions of ORZ in crop bran might be promising us to prevent chronic inflammations in the pathogeneses of the metabolic or insulin resistance syndromes.

Laser-induced oxidation of cholesterol observed during MALDI-TOF mass spectrometry

Conditions for the detection of three odd-electron cholesterol oxidation peaks were determined and these peaks were shown to be artifacts of the matrix-assisted laser desorption time of flight (MALDI-TOF) process. Matrix choice, solvent, laser intensity and cholesterol concentration were systematically varied to characterize the conditions leading to the highest signals of the radical cation peaks, and it was found that initial cholesterol solution concentration and resultant density of solid cholesterol on the MALDI target were important parameters in determining signal intensities. It is proposed that hydroxyl radicals, generated as a result of laser irradiation of the employed 2,5-dihydroxybenzoic acid (DHB) matrix, initiate cholesterol oxidation on the MALDI target. An attempt to induce the odd-electron oxidation peaks by means of adding an oxidizing agent succeeded using an acetonitrile solution of DHB, cholesterol, and cumene hydroperoxide. Moreover, addition of free radical scavengers reduced the abundances of some oxidation products under certain conditions. These results are consistent with the mechanism of oxidation proposed herein involving laser-induced hydroxyl radical production followed by attack on neutral cholesterol. Hydroxyl radical production upon irradiation of dithranol matrix may also be responsible for generation of the same radical peaks observed from cholesterol in dithranol by an analogous mechanism.

Antioxidants and antioxidant activity of several pigmented rice brans

This study investigated the antioxidant content and activity of phenolic acids, anthocyanins, α-tocopherol and γ-oryzanol in pigmented rice (black and red rice) brans. After methanolic extraction, the DPPH free radical scavenging activity and antioxidant activity were measured. The pigmented rice bran extract had a greater reducing power than a normal rice bran extract from a long grain white rice. All bran extracts were highly effective in inhibiting linoleic acid peroxidation (60-85%). High-performance liquid chromatography (HPLC) analysis of antioxidants in rice bran found that γ-oryzanol (39-63%) and phenolic acids (33-43%) were the major antioxidants in all bran samples, and black rice bran also contained anthocyanins 18-26%. HPLC analysis of anthocyanins showed that pigmented bran was rich in cyanidin-3-glucoside (58-95%). Ferulic acid was the dominant phenolic acid in the rice bran samples. Black rice bran contained gallic, hydroxybenzoic, and protocatechuic acids in higher contents than red rice bran and normal rice bran. Furthermore, the addition of 5% black rice bran to wheat flour used for making bread produced a marked increase in the free radical scavenging and antioxidant activity compared to a control bread.

Effects of genotype and environment on steryl ferulates in wheat and rye in the HEALTHGRAIN diversity screen

The effects of genetic and environmental factors on the content and composition of steryl ferulates in wheat and rye were studied. The wheat and rye genotypes were grown at the same location in Hungary over three consecutive years (28 genotypes) or at four different locations across Europe during a single year (12 genotypes). The steryl ferulates were analyzed using HPLC. The genotype and growing location significantly affected the content and composition of wheat steryl ferulates, whereas the year of growth did not result in considerable variation. Less variation was observed in rye, due to fewer genotypes. Campestanyl and sitostanyl ferulates were the main species in both cereals. Knowledge of the natural variation in steryl ferulates and other bioactive compounds allows cultivators and plant breeders to select genotypes with high, stable levels of beneficial compounds. Thus, it is possible to enhance the intake of health-promoting compounds from natural sources.

Phenolic profiles and antioxidant activity of black rice bran of different commercially available varieties

Increased consumption of whole grains has been associated with reduced risk of developing major chronic diseases. These health benefits have been attributed in part to their unique phytochemicals. Previous studies on black rice mainly focused on anthocyanins. Little is known about the phytochemical profiles and antioxidant activities of different black rice varieties. The objective of this study was to determine the phytochemical profiles and antioxidant activity of rice bran samples from 12 diverse varieties of black rice. The free, bound, and total phenolic contents of black rice bran samples ranged from 2086 to 7043, from 221.2 to 382.7, and from 2365 to 7367 mg of gallic acid equiv/100 g of dry weight (DW), respectively. The percentage contribution of free phenolics to the total ranged from 88.2 to 95.6%. The average values of free, bound, and total phenolic contents of black rice bran were 8, 1.5, and 6 times higher than those of white rice bran, respectively (p < 0.05). The free, bound, and total flavonoid contents of black rice bran samples ranged from 3462 to 12061, from 126.7 to 386.9, and from 3596 to 12448 mg of catechin equiv/100 g of DW, respectively. The percentage contribution of free flavonoids to the total ranged from 96.3 to 97.6%. The average values of free, bound, and total flavonoid contents of black rice bran were 7.4, 1.9, and 6.7 times higher than those of white rice bran, respectively (p < 0.05). The free, bound, and total anthocyanin contents of black rice bran samples ranged from 1227 to 5096, from 4.89 to 8.23, and from 1231 to 5101 mg of cyanidin-3-glucoside equiv/100 g of DW, respectively. The percentage contribution of free anthocyanins to the total ranged from 99.5 to 99.9%. Cyanidin-3-glucoside, cyanidin-3-rutinoside, and peonidin-3-glucoside were detected in black rice bran samples and ranged from 736.6 to 2557, from 22.70 to 96.62, and from 100.7 to 534.2 mg/100 g of DW, respectively. The free, bound, and total antioxidant activities of black rice bran samples ranged from 476.9 to 180, from 47.91 to 79.48, and from 537.5 to 1876 mumol of Trolox equiv/g of DW, respectively. The percentage contribution of free antioxidant activity to the total ranged from 88.7 to 96.0%. The average values of free, bound, and total antioxidant activity of black rice bran were more than 8, 1.5, and 6 times higher than those of white rice bran, respectively (p < 0.05). The total antioxidant activity of black rice bran was correlated to the content of total phenolics, total flavonoids, and total anthocyanins and also was significantly correlated to the contents of cyanidin-3-glucoside, cyanidin-3-rutinoside, and peonidin-3-glucoside. These results indicate that there are significant differences in phytochemical content and antioxidant activity among the different black rice varieties. Black rice bran has higher content of phenolics, flavonoids, and anthocyanins and has higher antioxidant activity when compared to white rice bran. Interestingly, the phenolics, flavonoids, and anthocyanins of black rice bran are mainly present in free form. Knowing the phytochemical profile and antioxidant activity of black rice bran gives insights to its potential application to promote health.

Health benefits of whole grain phytochemicals

A whole grain consists of the intact, ground, cracked, or flaked caryopsis, whose principal anatomical components--the starchy endosperm, germ, and bran--are present in the same relative proportions as they exist in the intact caryopsis. Whole grain food products can be intact, consisting of the original composition of bran, germ, and endosperm, throughout the entire lifetime of the product, or reconstituted, in which one or more of the original components of a whole grain is recombined to the relative proportion naturally occurring in the grain kernel. Increased consumption of whole grains has been associated with reduced risk of major chronic diseases including cardiovascular disease, type II diabetes, and some cancers. Whole grain foods offer a wide range of phytochemicals with health benefits that are only recently becoming recognized. The unique phytochemicals in whole grains are proposed to be responsible for the health benefits of whole grain consumption. In this paper, whole grain phytochemicals and the health benefits associated with their consumption are reviewed.

Study on total phenolic contents and their antioxidant activities of Thai white, red and black rice bran extracts

In this study, different brans of Thai rice cultivars which were divided into 3 groups: white color (Hom mali 105, Supan, Saohai, Hom chaiya and Hom jun), red color (3256, GS 18003, 21606, 21699 and 5718) and black color (96041-20, 96051-37, 96004-49, 96023-35 and 96065-42) were investigated their Total Phenolic Content (TPC) and antioxidant activities. The rice brans were firstly extracted using methanol. The extracts were analyzed using Folin-Ciocalteau method for total phenolic content while thiocyanate method and 1,1-diphenyl-2-picrylhydrasyl (DPPH) free radical-scavenging assay were used for antioxidant activities determination. The results indicated that the total phenolic content of white, red and black rice bran extract were in the range of 0.8931-0.9884, 1.0103-1.0494 and 1.0810-1.2239 mg gallic acid equivalent (GAE mg(-1)), respectively. With thiocyanate method, percentage inhibition were in the range of 10.15-20.68, 30.64-38.80 and 25.52-26.28 for white, red and black rice bran extract, respectively. With DPPH radical-scavenging assay, methanolic extract of 5718 showed the highest (IC50=0.0057 mg mL(-1)) while Homchaiya showed the lowest (IC50=0.2582 mg mL(-1)) activities. All of extracts showed lower activity than BHA (IC50=0.0012 mg mL(-1)). However, the antioxidant activity of all rice bran extracts indicated high antioxidant efficiency in the following order: red>black>white color rice brans. It is a promising that Thai rice bran are potential antioxidant sources.

Physicochemical properties and antioxidant activity of gamma-oryzanol-loaded liposome formulations for topical use

The objective of this study is to prepare the gamma-oryzanol-loaded liposomes and investigate their physicochemical properties and antioxidant activity intended for cosmetic applications. Liposomes, Composing phosphatidylCholine (PC) and Cholesterol (Chol), CHAPS or sodium taurocholate (NaTC) were prepared by sonication method. Gamma-oryzanol-loaded liposomes were prepared by using 3, 5 and 10% gamma-oryzanol as an initial concentration. The formulation factors in a particular type and composition of lipid and initial drug loading on the physicochemical properties (i.e., particle size, zeta potential, entrapment efficiency, drug release) and antioxidant activity were studied. The particle sizes of bare liposomes were in nanometer range. The gamma-oryzanol-loaded liposomes in formulations of PC/CHAPS and PC/NaTC liposomes were smaller than PC/Chol liposomes. The incorporation efficiency of 10% gamma-oryzanol-loaded PC/Chol liposomes was less than gamma-oryzanol-loaded PC/CHAPS liposomes and PC/NaTC liposomes allowing higher in vitro release rate due to higher free gamma-oryzanol in buffer solution. The antioxidant activity of gamma-oryzanol-loaded liposomes was not different from pure gamma-oryzanol. Both gamma-oryzanol-loaded PC/CHAPS liposomes and PC/NaTC liposomes were showed to enhance the antioxidant activity in NHF cells. gamma-oryzanol-loaded PC/Chol liposomes demonstrated the lowest cytotoxicity in NHF cells. It was conceivably concluded that liposomes prepared in this study are suitable for gamma-oryzanol incorporation without loss of antioxidant activity.

The effects of hydroxycinnamic acid derivatives on adiponectin secretion

Adiponectin is positively correlated with insulin sensitivity. Hydroxycinnamic acid derivatives (HADs), observed ubiquitously in plants, have some physiological functions. In this study, we investigated the effect of HADs on serum adiponectin concentrations in mice and on adiponectin secretion of 3T3-L1 adipocytes. In mice, serum adiponectin concentrations were increased by gamma-oryzanol administration. CAPE, curcumin, and trans-ferulic acid markedly enhanced the adiponectin secretion of 3T3-L1 adipocytes, but not gamma-oryzanol. To clarify the effects of gamma-oryzanol in mice or the effects of HADs on the underlying mechanisms of adiponectin secretion, we further investigated the effect of HADs on adiponectin secretion in the NF-kappaB activation state. Although the adiponectin secretion was reduced in the presence of lipopolysaccharide plus TNF-alpha and IFN-gamma, only gamma-oryzanol supported the activity of adiponectin secretion under NF-kappaB activated condition. The results indicate that these HADs might regulate adiponectin secretion by the inhibition of NF-kappaB activation. HADs might be effective for ameliorating type 2 diabetes.

Lipophilic and hydrophilic antioxidants and their antioxidant activities in purple rice bran

Purple rice bran was separated and collected at two different milling periods, resulting in two bran (outer and inner layer) fractions. The distribution of lipophilic and hydrophilic antioxidants and their antioxidant activities in the two fractions were studied. The bran fractions were extracted with hexane followed by methanol to obtain lipophilic and hydrophilic extracts, respectively. The total phenolic content and free radical scavenging activity of the extracts were determined and compared. The lipophilic extract from the outer bran fraction (OBF) exhibited a lower level of total tocols and gamma-tocols, compared with the inner bran fraction (IBF), while the levels of gamma-oryzanol in both fractions were not different. However, the lipophilic phenolic content and free radial scavenging activity of the OBF were 6.0 microg catechin equivalent (CE)/g and 5.6 micromol trolox equivalent (TE)/g and higher than those of the IBF, respectively. For the hydrophilic extracts, the level of anthocyanins in the IBF (29.0 mg/g) was 8 times higher than that in the OBF. Also, the hydrophilic phenolic content and free radical scavenging activity of the IBF were 489.1 microg CE/g and 433.6 micromol TE/g, respectively, while they were 113.9 microg CE/g and 78.2 micromol TE/g in the OBF. Both hydrophilic extracts showed significantly higher phenolic content and free radical scavenging activity than any lipophilic extract. The results of this study indicated that the activity of purple rice bran hydrophilic antioxidants was much greater than that of its lipophilic antioxidants and anthocyanins and gamma-tocols largely located in the inner portion of purple rice bran.

The effect of trans-ferulic acid and gamma-oryzanol on ethanol-induced liver injury in C57BL mouse

The effects of the oral administration of trans-ferulic acid and gamma-oryzanol (mixture of steryl ferulates) with ethanol (5.0 g per kg) for 30 days to c57BL mice on ethanol-induced liver injury were investigated. Preventions of ethanol-induced liver injury by trans-ferulic acid and gamma-oryzanol were reflected by markedly decreased serum activities of plasma aspartate aminotransferase, alanine aminotransferase and significant decreases in hepatic lipid hydroperoxide and TBARS levels. Furthermore, the trans-ferulic acid- and gamma-oryzanol-treated mice recovered ethanol-induced decrease in hepatic glutathione level together with enhancing superoxide dismutase activity. These results demonstrate that both trans-ferulic acid and gamma-oryzanol exert a protective action on liver injury induced by chronic ethanol ingestion.