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Antioxidant potential of rice bran oil prepared from red and white rice
Bopitiya, D., &Madhujith, T. (2014) has carried out a study to determine the total phenolic content (TPC) and antioxidant potential of Rice Bran Oil (RBO). The bran of two rice varieties, BG 400 (white) and LD 365 (red) was obtained and stabilized and subsequently RBO was extracted into hexanes. The phenolic fraction of the oil was extracted into methanol by passing the oil through a glass column packed with silica (60 Å, pore diameter). The antioxidant potential of the oil extracts was evaluated using DPPH and ABTS radical scavenging assays and β-carotene/linoleate modelsystem. The total phenolic content (TPC) of the crude RBO extracts was determined colorimetrically using Folin–Ciocalteu’s reagent method. TPC was determined and expressed as mg gallic acid equivalents (GAE) per gram extract. Antioxidant capacity of RBO extracts was assessed using 2,2-diphenyl-1- picrylhydrazylhydrate (DPPH) free radical.
The total antioxidant capacity of the extracts was determined using ABTS radical. The ABTS+ was generated by reacting 2,2'-azobis (2-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) with 2,2'-azobis (2-methylpropanimidamide) dihydrochloride (AAPH), which acts as the radical generator. Five different concentrations ranging between 0.1 and 1.0 mg/mL of each extract (40 μL) was mixed with 1.96 mL of ABTS radical solution and absorbance was measured at 765 nm using a UV visible spectrophotometer (UV 1601, Shimadzu, Japan).
Also they determinated the antioxidant efficacy using β-carotene/linoleate model system.The ability of pomegranate extracts to inhibit β-carotene bleaching was estimated according to the method explained by Shahzadet al. (2006) with minor modifications. β- Carotene/linoleate emulsion was prepared by mixing 10 mg of β-carotene, 40 mg of linoleic acid, 600 mg of Tween 20 emulsifier and 100 mL of oxygenated deionised water. The prepared emulsion (2 mL) was mixed with 200 μL of extracts and incubated at 50℃. The oxidative loss of emulsion was monitored using a UV visible spectrophotometer.
DPPH and ABTS radical scavenging capacities were expressed as IC50 values and inhibition of linoleic acid induced oxidation of β-carotene was expressed as percent inhibition. The TPC of the two extracts was not significantly different (p>0.05). However, the extract obtained from red rice variety exhibited significantly high (p<0.05) DPPH radical scavenging activity and inhibition of linoleic induced β-carotene oxidation. It was also revealed that the radical scavenging activity was dose dependent. The RBO extracts did not exhibit any prooxidant activity at the highest level tested (0.1 g/mL
Results revealed that both white and red RBO extracts possessed strong antioxidant activity compared to the reference antioxidant, α-tocopherol. Thus they concluded that, RBO can be categorized as an edible oil with high antioxidant potential. Antioxidantactivity as measured by ABTS and DPPH radical assays and using β-carotene/linoleatemodel system well correlated with TPC (0.972≤ r ≤ 0.999). The results indicated thatantioxidant activities of RBO extracts were largely attributable to the phenolic compoundspresent.
2. Antioxidant properties of some SriLankan traditional red rice (Oryza sativa l.)
Abeysekera, Wet al. (2013) evaluated the antioxidant properties of some Sri Lankan traditional red rice varieties, Masuran (M), Dik Wee (DW), GodaHeeneti (GH) and SuduHeeneti (SH). Freeze-dried 70% ethanolic extracts of brans of 4 traditional red that were used in this study. Antioxidant properties of bran extracts of selected RV were evaluated using total polyphenolic content (TPC) (n=6), 1,1-diphenyl-2-picryl-hydrazyl (DPPH) radical scavenging (n=4), 2-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid [ABTS] radical scavenging (n=4) and ferric reducing antioxidant power (FRAP) (n=6) in vitro antioxidant assays.
The total polyphenolic content (TPC) of rice bran extracts was determined by the Folin-Ciocalteu method using 96-well micro-plates. The 2-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid (ABTS+) radical scavenging assay was performed according to the method described by Re et al. and 1,1-diphenyl-2-picryl-hydrazyl (DPPH.) radical scavenging assay by Biolis [4] using 96-well micro-plates. Ferric reducing antioxidant power (FRAP) of rice bran was performed according to modified method of Benzie and Strain‘s protocol using 96-well micro-plates.
Significant differences were observed among bran extracts of selected RV for investigated antioxidant properties (P<0.05). Mean TPC, DPPH, ABTS and FRAP antioxidant properties were in the range of 11.74 – 29.75 mg gallic acid equivalents/g, 5.14 ± 0.17 – 6.77 ± 0.06 mmolTrolox equivalents (TE)/100g, 8.67 ± 0.14 – 14.25 ± 0.46 mmol TE/100g, 8.30 ± 0.15 – 11.02 ± 0.25 mmol FeSO4/100 g rice bran respectively. The order of mean TPC was SH > M > GH > DW. Bran extracts of all the RV exhibited dose dependent radical scavenging activity against both DPPH• and ABTS radicals. Bran extracts of GH demonstrated maximum radical scavenging activity for both radicals. However, the order of scavenging was observed to be different among bran extracts of different RV for DPPH• and ABTS radicals. The order of scavenging for DPPH• was GH > SH > DW > M and for ABTS it was observed as GH > SH > M > DW. Highest mean FRAP was observed for bran extract of GH variety while lowest for bran extract for SH variety. The antioxidant power of the bran extracts was in the order of GodaHeeneti>Masuran>Dik Wee >SuduHeeneti.
3. Antioxidants in rice bran oil from Sangyod breeding rice and application in cream-gel
In this research, Rattanapiboon N. et al. (2012) extractedthe oil in the Sangyod rice bran and the antioxidants in Sangyod rice bran oil were determined. The body cream-gel lotion incorporated with the obtained Sangyod rice bran oil as moisturizer was investigated. The oil was extracted from Sangyod rice bran by solvent extraction and cold pressing method. The quantity of antioxidants, such as γ-oryzanol, α-tocopherol, β-carotene and anthocyanin in the obtained oil and the rice bran were measured by HPLC. Selected extracts and volume of Sangyod rice bran oil (5, 8, 10% by wt.) appropriate to use as an ingredient in skin care product (cream-gel). After that, it was tested by 30 volunteers who were observed the results after daily using for 5 days. Finally, the stability of cream-gel incorporated with the Sangyod rice bran oil was studied by freeze- thaw cycle method and also investigated the antioxidant activity, viscosity, pH, moisture, color and odor of the cream-gel.
Mixed 0, 5, 8, 10% (by wt.) of Sungyod rice bran oil into the cream gel base which consisted of (1% (by wt.) carbopol polymer No.940, 95% ethanol, tween 20 and distilled water. The antioxidant activity (DPPHo )(4).in the mixed cream gels were studied. The optimized content of oil in the cream gel and the cream gel mixed jojoba oil (8% by wt.) that used as control were evaluated by 30 volunteers(15 females and 15 males). The Sangyod rice bran oil cream gel (5 g.) was applied on the dorsum of the hand skin 2 times/day for 1 week. The dorsum of hand skin before and after applied the Sangyod rice bran oil cream gel were evaluated by the digital camera which resolution 12 million pixel.
The content of antioxidants in SRBOs: The contents of the γ-oryzanol, the α-tocopherol, the β-carotene, and the anthocyanin in SRBO-SE and SRBO-CP were presented on Table 1.
From the study on the effect of the cream gel mixed SRBO-CP on the dorsum of hand skin (before and after) was discovered that the 97% of the volunteers applied the cream gel mixed. All the results indicated that the oil from Sangyod rice bran extracted by cold pressing provide the potential as a natural moisturizer.
5. Antioxidant stability in palm and rice bran oil using simple parameters
Valantina. S.R. et al. (2010) investigated the antioxidant stability in palm oil and rice bran oil at different times of heating using the parameters like density, viscosity, adiabatic compressibility and acoustic impedance of the oils at different times of heating. The antioxidant stability is resolute at every time of heating. The study of thermal degradation and antioxidant stability in the oil is carried out by heating the oil to the frying temperature up to 250°C for 0.5, 1, 1.5, 2hrs. After heating to desired time, the viscosity of ricebran and palm oil is measured at 30°C.
The antioxidant in the oils breaks oxidation by adding hydrogen atom to free radicals. The antioxidant activity of palm oil is found to be lost during heating. The percentage of lose in antioxidant activity of palm oil during heating is due to volatile nature of carotene. The parameter ρ, Z, β and η of rice bran oil shows that the composition of oil does not get saturated due strong stability of antioxidants on heating.
Hence, they recommended that rice bran oil can be used for frying without adverse effect preventing the incidence of malignancy and coronary heart diseases.
6. Biological activities of the rice bran extract and physical characteristics of its entrapment in niosomes by supercritical carbon dioxide fluid
Manosroi.,A et al. (2010) compared the biological activities of the rice bran (Oryza sativa Linn.) extracts prepared by supercritical carbon dioxide fluid (scCO2) and ethanolic maceration, and the physical properties of niosomes entrapped with the extracts prepared by scCO2 and chloroform film method. Total phenolic contents (TPC) in the form of gallicacid in the extracts were determined using the Folin–Ciocalteu reagent. Free radical scavenging activities of the extracts, standard antioxidants (vitamin C and E) and standard unsaturated fatty acids were determined by a modified DPPH assay.
TPC in the form of gallic acid in the extracts from the scCO2 method and ethanolic maceration were 0.65±0.05 and 0.51±0.07 mg/g, respectively.
7. Antioxidant properties of rice bran oil from different varieties extracted by solvent extraction methods
Daud N.S.M. et al () investigated antioxidant properties of rice bran oil from different rice bran varieties; Rice Bran-Bario (RB-Bario), Rice bran-Lowland (RB-Low) and Rice Bran- Upland rice (RB-Up).
Measurement of antioxidant properties was evaluated by TPC (total phenolic content) and DPPH scavenging activities. The total polyphenolic content (TPC) of rice bran extracts was determined by the Folin-Ciocalteu method . The concentration of phenolic compound in the extracts was determined using spectrophotometric methods. The radical scavenging assay was performed by 1,1-diphenyl-2-picryl-hydrazyl (DPPH.)
As shown in Table 1, the phenolic content was different with three various solvent, the higher phenolic content was determined in RB-Low with Ethanol as solvent of extraction (±509.0 ppm), while RB-Bario type give the higher measurement with hexane as solvent for ex-traction (±447.3 ppm). The phenolic compound may contribute directly to antioxidant activity.
8. Examination of antioxidant activity and development of rice bran oil and gamma-oryzanolmicroemulsion
Vorarat S. et al (2010) examine the antioxidant activity and formulate rice bran oil and gamma-oryzanol product. Two methods of antioxidant activity examination were DPPH radical scavenging assay and Ferric Reducing Antioxidant Potential (FRAP) assay. According to their study, the outcome of free radical scavenging properties of gamma-oryzanol was demonstrated in term of Trolox equivalent antioxidant capacity (TEAC). For DPPH assay, TEAC values were of 0.0015-0.0206 mmol/g when the concentrations were 0.0625-1.0000 mg/ml. For FRAP assay, TEAC values were of 0.0054-0.0272 mmol/g when the concentrations were 0.0680-1.0910 mg/ml. While the linear correlation between TEAC and log concentration was determined as R2 = 0.9929 and 0.9975 respectively. The outcomes of free radical scavenging properties of rice bran oil, for DPPH assay, TEAC values were of 0.0059-0.0214 mmol/g when the concentrations were 8-40 mg/ml. While FRAP assay, could not examine the antioxidant activity because of the immiscibility between reagent and rice brain oil. Then microemulsion was formulated using rice brain oil and gamma-oryzanol as an active antioxidant, Cremophor and Span 80 as a surfactant and absolute ethanol as a cosurfactant. They concluded that the developed formulation had high antioxidant activity with no skin irritation.
9. Value added products from by-products of rice bran oil processing
Kaewboonnum W. et al. (2008)studied the production of value-added product derived from rice bran oil processing by-products. The investigation was divided into two parts, Part I: subcritical water (SW) hydrolysis of deoiled rice bran and Part II: separation of from rice bran oil soapstock.ABTS (2,2’-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) radical cation scavenging assay was carried out following a modified method. For comparing the antioxidant activity of the extracts obtained at various conditions, concentration of sample producing 50% reduction of the radical absorbance (IC50) was used as an index.
10. Evaluation of antibacterial, antioxidant, anti-inflammatory activity and trace element analysis of Njavara (Oryza sativa Linn)
Paul N.M. & Moolan R.J. (2014) evaluatedIn Vitro Antioxidant Activities of njavara (Oryza sativa Linn).The antioxidant activity of the extract was compared with the standard ascorbic acid. For this various concentrations of extract (50, 100, 150µg/ml) as well as Ascorbic acid in 1 ml of 5% DMSO were mixed with 2.5 ml phosphate buffer (0.2M, pH 6.6) and 1 % potassium ferricyanide (2.5m).The free radical scavenging activity of different extracts of sample, L-ascorbic acid (vitamin c) was measured in terms of hydrogen donating or radical scavenging ability using the stable radical DPPH.
The reducing capabilities of the methanolic and Ethanolic extracts of Njavara grain, bran and mixture compared to vitamin C. In both Ethanolic and methanolic extract antioxidant and reducing power were increased with increasing amount of extract. In both case bran showed highest activity, Ethanolic extract of bran showed more activity than methanolic extract (table 5). The reducing capacity of compounds serves as an indicator of its potential antioxidant activity. As with the free radical scavenging assays, the reducing potential of extracts increased in a dose dependent manner with significant reusing potential for Njavara Black glumed.
The result indicated that the extract at higher concentration showed significant anti oxidant potential. However the anti-oxidantactivity of the methanolic extract of bran were considerably low compared to its Ethanolic extract. In conclusion,thet say it is conceivable that the Njavara variety could be exploited as one of the potential sources for plant based pharmaceutical products.
11. The study of anti-inflammatory and antioxidant activity in cold press rice bran oil from rice in Thailand
Settharaksa S. et al (2014) investigated the rice bran oil from four rice varieties in term of anti-inflammatory and antioxidant activities. Two methods for antioxidant activities, DPPH radical scavenging assay (DPPH assay) and Ferric Reducing Antioxidant Power (FRAP) assay were used and compared with gallic acid standard and ferric sulfate (FeSO4 Results: For the Oryza Sativa L. Khaw-khaw exhibited the highest activity against the NO production with an IC ), respectively.
The rice bran samples were used from different Thai rice varieties, namely Oryza Sativa L. CV. Hom-Pathum; O. Sativa L. CV. Hom-Mali; O. Sativa L. CV. Hom-Mali Gorkho and O. Sativa L. CV. Khaw-Khaw. The samples were passed through sieve number 20 and immediately extracted under cold press conditions. The bran is extracted with screw press machine.
DPPH radical-scavenging activity of rice bran extracts were determined according to the method reported by Brand and Williams.The FRAP assay is the method used for measuring the ability of reductants (antioxidants) to reduce Fe3+– Fe2+. They have stated that the reducing power evaluation may be taken as an important parameter for the assessment of antioxidant activity.
The scavenging effects of all extracts on DPPH radicals increased with increasing of concentration (Table 2) and DPPH. radical scavenging at IC50 values of rice bran extract is shown in Table 2. With consider to IC50 values of DPPH- scavenging activity, the highest DPPH. However, DPPH free radical-scavenging of all the rice bran cultivars was weaker than gallic acid, a synthetic antioxidant. As rice bran extracts have a high ability to donate hydrogen atoms, the results of DPPH free radicalscavenging might be due to hydrogen donation ability. Radical scavenging of rice bran extracts was found in Hom Mali Gorkho (0.08 mg/ml) and lowest activity was in Khaw-Khaw (0.88 mg/ml).