The total polyphenols and the antioxidant potentials of some selected cereals and pseudocereals

The objective of the present study was to investigate the effect of phenolic substances and proteins on the antioxidant potentials in some cereals and pseudocereals and to compare their bioability. The polyphenol dry matter extracts (PDME) from the investigated seeds of buckwheat, rice, soybean, amaranth and quinoa with 1.2 M HCl in 50% methanol/water (PDME50%Met/HCl) exhibited higher inhibition of lipid peroxidation than the ones extracted with 50% methanol/water (PDME50%Met) and were comparable to the antioxidant activity of butylated hydroxyanisole at concentration of 0.2 mg mL⁻¹. The antioxidant activities of these seed extracts determined by 2,2′-azinobis (3-ethylbenzothiazoline-6-sulfonate)-ABTS^●+/K₂S₂O₈, β-carotene bleaching (β-carotene), and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging methods showed high correlation coefficients (R ²) such as 0.9515, 0.9058 and 0.8723, respectively, with the presence of total polyphenols estimated by Folin-Ciocalteu assay. These results indicate that the major antioxidant components in these extracts mostly derived from the polyphenols, and proteins showed only minimal values of bioactivity. Based on high contents of polyphenols, anthocyanins, flavonoids and their antioxidant activities pseudocereals such as buckwheat, quinoa and amaranth can be a substitute for cereals for common and atherosclerotic diets and sometimes in the allergic cases.     

Comparison of antioxidant capacity and phenolic composition of peel and flesh of some apple varieties

BACKGROUND: Apples contain a large concentration of phenolic compounds, dependent on factors such as cultivar, harvest, storage conditions, and processing. This study aims to identify the essential phenolic compounds present in various apple varieties, to measure their total antioxidant capacity (TAC) with the CUPRAC (cupric ion reducing antioxidant capacity) and ABTS (2,2′‐azino‐bis(3‐ethylbenzothiazoline‐6‐sulfonate)) methods, and to correlate their TAC values with HPLC findings. RESULTS: The order of TAC (mmol Trolox g^?1 fresh weight) of apple peels determined with the CUPRAC method was: Granny Smith > Amasya > Sky Spur > Ervin Spur > King Luscious ≥ Arap Kizi ≥ Lutz Golden. The theoretically calculated TAC values of HPLC‐quantified compounds, with the aid of the combined HPLC‐CUPRAC method, accounted for 18.4–33.5% of the experimentally observed CUPRAC capacity of peel extracts and 19.5–56.3% of flesh extracts, depending on apple variety. CONCLUSION: In synthetic samples of apple antioxidants, the CUPRAC‐TAC values of constituents, identified and analyzed by HPLC, proved to be additive, enabling measurement of the cooperative action of antioxidants using the proposed methodology. Apple peel showed higher contents of phenolics and therefore higher TAC than apple flesh, confirming the health benefit of the consumption of apples together with peel. © 2012 Society of Chemical Industry     

Comparative study on the antioxidant activity of methanolic and aqueous extracts from the fruiting bodies of an edible mushroom <Emphasis Type="Italic">Pleurotus djamor</Emphasis>

In vitro antioxidant activities, total phenolic, and flavonoid contents of Pleurotus djamor extracts were analyzed based on radical scavenging activities of methanol and aqueous extracts using 1,1-diphenyl-2-picryl-hydrazyl (DPPH), N,N-dimethyl-p-phenylenediamine (DMPD), total Fe³⁺ reducing power, CUPRAC, phosphomolybdenum, metal chelating activity, and lipid peroxidation inhibition assays. Both extract types showed efficient radical scavenging activities against DPPH and DMPD radicals, ferric (Fe³⁺) and cupric (Cu²⁺) ion reducing powers, metal chelating activities, and lipid peroxidation inhibition. Total phenolic contents of methanol and aqueous extracts were 2.79 and 5.95 mg of GAE/g, respectively. Flavonoid contents of methanol and aqueous extracts were 6.35 and 5.75 mg of CAE/g, respectively. Consumption of the mushroom P. djamor can be beneficial due to antioxidant properties.     

Antioxidant activity and phenolic compounds of ginger (<Emphasis Type="Italic">Zingiber officinale</Emphasis> Rosc.) determined by HPLC-MS/MS

Oxidative stress related diseases often arise from over production of free radicals and reactive oxygen/nitrogen species. The prevention of these diseases could be possible with the use of natural antioxidant plants that could be promising as therapeutic candidates. Since antioxidant properties of a species could be stem from phenolic compounds, it is, therefore, important to evaluate antioxidant and total/individual phenolic and flavonoid content. For this purpose, we evaluated antioxidant properties of ginger (Zingiber officinale Rosc.) based on three parameters: the antioxidant capacity, total phenolic and flavonoid content as well as identification of phenolic acids of water extract (WEG) and ethanol extract (EEG) of ginger. For antioxidant capacity, we performed FRAP, CUPRAC assay, Fe²⁺ chelating ability, DPPH and DMPD radical scavenging activities. Also, total phenolic and flavonoid contents in both extracts were also measured via Folin Ciocalteu’s method. For identification of phenolic acids, HPLC-MS/MS method was performed. The results showed that EEG had generally better antioxidant activity than WEG in all assays. HPLC-MS/MS analysis showed that there are at least eight different phenolic acids found in ginger, among which pyrogallol p-hydroxybenzoic acid, ferulic acid and p-coumaric acid were more abundant in both extracts. This study clearly showed that ginger extracts demonstrated effective antioxidant properties and their consumption may reduce or delay the progression of diseases that oxidative stress take place due to lack of antioxidant supplementation.     

Antioxidant Capacity and Phenolic Content of the Aqueous Extract of Commonly Consumed Cucurbits

The antioxidant capacity of commonly consumed cucurbits vegetable was determined by the DPPH, FRAP, Fe³⁺ reducing power, and hydrogen peroxide scavenging assay. The aqueous extract of Luffa cylindrica showed the highest value of phenolic content and antioxidant capacity based on FRAP, Fe³⁺ reducing power, and hydrogen peroxide scavenging assay. However, Laginaria siceraria extract showed the highest flavonoid and DPPH scavenging activities among all three cucurbits used in this study. Phenolic content in aqueous extracts of Luffa cylindrica and Laginaria siceraria was almost equal. Cucurbita maxima exhibited the lowest phenolic, flavonoid content, and exhibited the lowest power of antioxidant scavenging. The antioxidant capacity of cucurbits was significantly correlated (P < 0.05) with the phenolic content of their extracts. The antioxidant capacity of Luffa cylindrica and Laginaria siceraria have also shown a significant correlation (P < 0.05).     

Phenolic composition,enzyme inhibitory,and antioxidant activity of <Emphasis Type="Italic">Bituminaria bituminosa</Emphasis>

This study aimed to evaluate the in vitro antioxidant and enzyme inhibitory activities of ethyl acetate, methanol, and water extracts of Bituminaria bituminosa. In phosphomolybdenum assay, the methanol extract showed the highest activity (166.78 μmol TEs/g dry plant). The water extract exhibited the highest scavenging activity on 1,1-diphenyl-2-picrylhydrazyl (DPPH^?) and 2,2-azino-bis (3-ethylbenzothiazloine-6-sulphonic acid) (ABTS^?+). In addition, it exhibited the highest activity in cupric ion reducing (CUPRAC) and ferric reducing antioxidant power (FRAP) assays (41.26 and 46.82 μmol TEs/g dry plant). The extracts did not show cholinesterase and tyrosinase inhibitory activity. However, α-glucosidase inhibition assay resulted in the superiority of water extract (1233.86 μmol ACEs/g dry plant). In the case of α-amylase inhibitory assay, the ethyl acetate extract showed the highest activity (53.65 μmol ACEs/g dry plant). The water extract exhibited the highest phenolic content (31.70 μmol GAEs/g dry plant). In contrast, the methanol extract was found rich in flavonoid compounds (5.29 μmol REs/g dry plant). The water extract contained considerable amounts of rosmarinic acid, luteolin, quercetin, and rutin. Therefore, it can be used as a source of new and alternative antioxidant and enzyme inhibitory agents.     

Phenolic profile,antioxidant, anticholinesterase,and anti-tyrosinase activities of the various extracts of Ferula elaeochytris and Sideritis stricta

In this study, the antioxidant, anticholinesterase, and anti-tyrosinase properties of (hexane, acetone, methanol, and water) extracts of Ferula elaeochytris and Sideritis stricta were determined with the total phenolic and flavonoid contents. The phenolic profile of the methanol and water extracts was analysed using HPLC-DAD. Protocatechuic acid was found as the major phenolic compound in the methanol (116.3 ± 3.1 µg/g) and water extracts (69.4 ± 1.3 µg/g) of F. elaeochytris. Coumarins (253.9 ± 4.1 µg/g) and catechin hydrate (175.2 ± 2.9 µg/g) were the most abundant phenolic compounds in the methanol and water extracts of S. stricta. β-carotene–linoleic acid, DPPH^?, ABTS^?+, CUPRAC, and metal-chelating assays were used to evaluate antioxidant properties of the extracts. The methanol and water extracts of F. elaeochytris and the acetone and methanol extracts of S. stricta containing the highest amount of total phenolic and flavonoid contents showed the highest antioxidant activities in β-carotene–linoleic acid, DPPH^?, ABTS^?+, and CUPRAC assays. The enzyme inhibitory potential of extracts was investigated against key enzymes involved in neurodegenerative (acetylcholinesterase (AChE) and butyrylcholinesterase (BChE)) and skin (tyrosinase) disorders. In the cholinesterase inhibitory assays, the hexane extracts of two species exhibited the best activity against AChE, while the hexane extract of F. elaeochytris and the methanol extract of S. stricta observed to be the most active against BChE. As for anti-tyrosinase activity results of extracts, the only acetone and methanol extracts showed mild inhibitory activity for both species.     

Antioxidant properties of durian fruit as influenced by ripening

The antioxidant properties of durian (Durio zibethinus Murr., cv. Mon Thong) at different stages of ripening were investigated using fluorometry, UV spectroscopy, and HPLC/DAD analyses. Total polyphenols, flavonoids, anthocyanins and flavanols in ripe durian were significantly higher (p < 0.05) than in mature and overripe fruits. Free polyphenols and flavonoids were at lower levels than hydrolyzed ones. Caffeic acid and quercetin were the dominant antioxidant substances in ripe durian. In these fruits, methanol extracts contained a relatively high capacity of 74.9 ± 7.1% inhibition using β-carotene-linoleic acid assay. Ferric-reducing/antioxidant power (FRAP) and cupric-reducing antioxidant capacity (CUPRAC) assays supported this finding. The correlation coefficients between polyphenols and antioxidant capacities of durian samples with all applied assays were about 0.98. In conclusion, the bioactivity of ripe durian was high and the total polyphenols were the main contributors to the overall antioxidant capacity.     

Influence of pressurised liquid extraction and solid–liquid extraction methods on the phenolic content and antioxidant activities of Irish macroalgae

The efficiencies of pressurised liquid extraction (PLE) and a traditional solid–liquid extraction (SLE) at extracting antioxidant polyphenols from Irish macroalgae Ascophyllum nodosum, Pelvetia canaliculata, Fucus spiralis and Ulva intestinalis were compared. PLE was more effective for extracting polyphenols with acetone/water (80:20); however, when food‐friendly solvents of ethanol/water (80:20) and water were employed, SLE resulted in higher phenolic content in brown macroalgal extracts. For example, the Fucus spiralis SLE water and ethanol/water extracts displayed total phenolic contents (TPCs) of 130.58 ± 2.78 and 142.81 ± 1.77 μg phloroglucinol equivalents (PGE) mg^?1 sample, respectively, compared with TPCs of 90.79 ± 1.16 and 124 ± 6.54 μg PGE mg^?1 sample for the corresponding PLE extracts. All SLE aqueous ethanolic macroalgal extracts possessed higher DPPH radical scavenging abilities (RSA) and ferric reducing antioxidant power (FRAP) than their PLE equivalents . This study indicates that the application of high extraction temperatures (50–200 °C) and pressures (500–3000 psi) used in PLE does not enhance the antioxidant activities of macroalgal extracts relative to SLE extraction. The ability to produce antioxidant food‐friendly macroalgal extracts using SLE could represent significant cost reductions on an industrial scale further enhancing the potential of macroalgal polyphenols to be used in functional food preparations.     

Comparative assessment of two extraction procedures for determination of bioactive compounds in some berries used for daily food consumption

Two extractions with methanol and water were used to determine the antioxidant and binding properties of some berries as a supplement to food. Fluorometry, FTIR spectra and radical scavenging assays were used for characterisation of bioactive compounds (polyphenols, flavonoids, flavanols and tannins) and the levels of their antioxidant activities (AAs). The contents of bioactive compounds and AAs in water and methanol polyphenol extracts in gooseberries, blueberries and cranberries differed, but not always significantly. Water extracts of gooseberries showed the lowest amounts of polyphenols (mg GAE g^?1), 6.24 ± 0.6, and flavonoids (mg CE g^?1), 0.29 ± 0.01, and AAs (μMTE g^?1) determined by DPPH, FRAP, ABTS and CUPRAC assays such as 6.05 ± 0.6, 8.07 ± 0.9, 18.70 ± 1.8 and 13.44 ± 1.2, respectively, in comparison with blueberries and cranberries. Polyphenol content highly correlated with antioxidant activity (R² from 0.94 to 0.81). The quenching properties of berries were studied by the interaction of water and methanol polyphenol extracts with HSA by 3D fluorescence. In conclusion, the bioactivity of gooseberries was lower than in blueberries and cranberries. Gooseberries can be used as a new source for food consumption and supplementation based on their antioxidant and binding properties. 3D fluorescence spectroscopy and FTIR spectroscopy can be applied as additional analytical tools for rapid estimation of the quality of different food products.     

Antioxidant activities of aqueous extracts of selected plants

The antioxidant properties of 25 edible tropical plants, expressed as Trolox equivalent antioxidant capacity (TEAC), were studied using DPPH (1,1-diphenyl-2-picrylhydrazyl free radical) scavenging and reducing ferric ion antioxidant potential (FRAP) assays. Their cupric ion chelating activities (CCA) and total polyphenol contents (TPC) were also determined. A strong correlation between TEAC values obtained for the DPPH assay (TEAC_DPPH) and those for the FRAP assay (TEAC_FRAP) implied that compounds in the extracts were capable of scavenging the DPPH free radical and reducing ferric ions. A satisfactory correlation of TPC with TEAC_DPPH and TEAC_FRAP suggested that polyphenols in the extracts were partly responsible for the antioxidant activities while its correlation with CCA was poor, indicating that polyphenols might not be the main cupric ion chelators. Principal component analysis (PCA) indicated that TEAC_DPPH, TEAC_FRAP and TPC contributed to the total variation in the antioxidant activities of the plants.     

Comparative content of some phytochemicals in Spanish apples,peaches and pears

Dietary fibre, total polyphenols and phenolic acids in Spanish apples, peaches and pears were analysed and compared with their total radical‐trapping antioxidative potential (TRAP). There were no significant differences in the content of dietary fibre among the studied fruits. The content of total polyphenols was 2.4 ± 0.4, 2.1 ± 0.3 and 6.9 ± 0.7 g kg^?1 in peeled fruits and 4.7 ± 0.4, 4.5 ± 0.4 and 11.1 ± 1.2 g kg^?1 in their peels for peaches, pears and apples respectively. The contents of dietary fibre, total polyphenols, caffeic, p‐coumaric and ferulic acids and the TRAP values were significantly (P < 0.05) higher in peels than in peeled fruits. The contents of all studied compounds and the TRAP values were significantly higher in peeled apples and their peel than in peaches and pears. We observed a strong correlation between the contents of total polyphenols and phenolic acids and the total radical‐trapping antioxidative potential in all three fruits. The relatively high content of dietary fibre, the highest contents of total polyphenols, caffeic, p‐coumaric and ferulic acids and the highest value of TRAP make apples preferable among the studied fruits for dietary prevention of atherosclerosis and other diseases. © 2002 Society of Chemical Industry     

Antioxidant Capacities,Phenolic Contents,and GC/MS Analysis of Rhodiola imbricata Edgew. Root Extracts from Trans‐Himalaya

Our aim was to assess the antioxidant capacities and phenolic constituents of methanol and aqueous extracts of Rhodiola imbricata Edgew. root from Trans‐Himalayan cold desert of Ladakh. The 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) and 2,2′‐azinobis‐(3‐ethylbenzothiazoline‐6‐sulfonic acid (ABTS) radical scavenging capacity of the root extracts increased in a dose‐dependent manner (up to 0.1 mg/mL) and root extract concentrations required for 50% inhibition of radical scavenging effect (IC₅₀) were recorded as 0.013 and 0.014 mg/mL (for DPPH) and 0.016 and 0.017 mg/mL (for ABTS) for methanol and aqueous extracts, respectively. The total antioxidant power of the extract was determined by ferric reducing antioxidant power (FRAP) assay. Total polyphenol and phenolic acid content of methanol and aqueous extracts were 112.24, 59.06, 39.02, and 16.95 mg gallic acid equivalent/g of extract, respectively. Total flavonoid and flavonol contents were estimated to be 30.2, 17.67, 20.68, and 7.38 mg quercetin equivalent/g of extract, respectively. In all antioxidant capacity assays, the methanol extract exhibited significantly higher antioxidant capacity than that of aqueous extract due to the presence of significantly higher amount of vital phytoconstitiuents, viz. polyphenol, phenolic acid, and flavonol. GC/MS analysis showed that phytosterols, alkyl halide, phenols, and fatty acid esters were major phytochemical clusters. On the other hand, monoterpenes, fatty acids, tocopherols, aliphatic hydrocarbons, and ethers were found to be present in comparatively less amount in the methanol extract. Hence, our study signifies that this high‐altitude medicinal herb could be used as the natural source of antioxidants and supports its use in traditional system of medicine to ameliorate oxidative stress and high‐altitude maladies.     

Release of phenolic acids from defatted rice bran by subcritical water treatment

BACKGROUND: Oil production from rice bran, an undervalued by‐product of rice milling, produces defatted rice bran (DRB) as a waste material. Although it is considered a less valuable product, DRB still contains useful substances such as phenolic compounds with antioxidant, UV‐B‐protecting and anti‐tumour activities. In this study the phenolic acids in DRB were extracted with subcritical water at temperatures of 125, 150, 175 and 200 °C. RESULTS: Analysis of total phenolics using Folin–Ciocalteu reagent showed about 2–20 g gallic acid equivalent kg^?1 bran in the extracts. High‐performance liquid chromatography analysis showed low contents of phenolic acids (about 0.4–2 g kg^?1 bran). Ferulic, p‐coumaric, gallic and caffeic acids were the major phenolic acids identified in the extracts. Thermal analysis of the phenolic acids was also done. The thermogravimetric curves showed that p‐coumaric, caffeic and ferulic acids started to decompose at about 170 °C, while gallic acid did not start to decompose until about 200 °C. CONCLUSION: Subcritical water can be used to hydrolyse rice bran and release phenolic compounds, but the high temperatures used in the extraction can also cause the decomposition of phenolic acids. Copyright © 2010 Society of Chemical Industry     

A simplified UV spectral scan method for the estimation of phenolic acids and antioxidant capacity in eggplant pulp extracts

The objective of this study was to determine if a simple UV spectral analysis method can be used as a screening tool to estimate the amount of phenolic acid and the antioxidant capacity of eggplant pulp extracts. Calibration curves for different concentrations of 5-O-caffeoylquinic acid standards were developed using UV spectral data, HPLC analysis, and ferric reducing antioxidant power (FRAP) assay. Seven different freeze-dried eggplant pulp samples belonging to different cultivars or grown under different environmental conditions along with single peel sample were selected as model substrates for this study. HPLC results, simple UV spectral scan data, and quantification of antioxidant capacity by FRAP assay in seven eggplant pulp extracts showed a strong correlation (R² > 0.9) between the three methods. These results suggest that the single absorption reading or a simple UV spectral scan can be used to estimate the concentration of phenolic acids and the antioxidant capacity in eggplant pulp extracts without peels. This screening tool can be potentially used to identify cultivars and growing conditions that influence phenolic acid content in eggplant samples.     

Chemical composition and antioxidant and radical‐scavenging activities of Periploca laevigata root bark extracts

BACKGROUND: The root powder of Periploca laevigata is used for preparing soft drinks and as an aromatic in Tunisia. The infusion or decoction of its root bark has widespread use in folk medicine. The plant is used to treat digestive disorders and hypertensive effects as well as other health problems. RESULTS: The antioxidant activities of extracts of P. laevigata root bark obtained with solvents of different polarity were investigated using assays of 1,1‐diphenyl‐2‐picrylhydrazyl radical‐scavenging activity, ferric‐reducing capacity, β‐carotene‐bleaching ability, hydroxyl radical‐scavenging activity and lipid peroxidation inhibition. The methanol extract, with the highest amount of total phenolics and flavonoids, showed the highest antioxidant activities in all assays, followed by the water extract. Gas chromatography/mass spectrometry was used to determine the composition of the water and methanol extracts. Thirty‐four compounds were identified in the methanol extract, with proflavine (516.2 g kg^?1 dry matter (DM)) and 4‐methoxysalicylaldehyde (198.3 g kg^?1 DM) being the most abundant. Sixteen compounds were identified in the water extract, of which 4‐hydroxy‐3‐methoxyphenethylene glycol (351.2 g kg^?1 DM) was the main component. CONCLUSION: As far as is known, this is the first report on the chemical composition and biological activities of phenolic extracts from P. laevigata. The results of the study indicate that the root bark of this plant might be a good candidate for further investigation in developing new antioxidants. Copyright © 2009 Society of Chemical Industry     

Antioxidant activity and phenolic content of pressurised liquid and solid–liquid extracts from four Irish origin macroalgae

The efficiency of solid–liquid extraction (SLE) and pressurised liquid extraction (PLE) for the recovery of antioxidant and polyphenols from the Irish macroalgae, Fucus serratus, Laminaria digitata, Gracilaria gracilis and Codium fragile, was assessed using the 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP) assays and the Folin–Ciocalteu total phenol content (TPC) assay. Fucus serratus had TPC and antioxidant activities thirty times higher than the other species. Solid–liquid extraction cold water (CW_SLE) had the highest TPC (81.17 μg GAE mg^?1 sample) derived from F. serratus, compared with the TPC of 61.12 μg GAE mg^?1 sample for the corresponding PLE extract. For both SLE and PLE extracts, low TPC levels were observed in L. digitata, G. gracilis and C. fragile. The majority of SLE extracts possessed higher FRAP and DPPH activities compared with their PLE counterparts. This study indicates that the high temperatures and pressures in PLE did not enhance the antioxidant activities relative to conventional SLE extraction.     

糙米体外消化过程中酚类物质含量及抗氧化活性

以糙米为对象,围绕其体外消化过程酚类物质及抗氧化活性变化开展研究。结果表明：粳型糙米中总酚含量显著高于籼型糙米（约1.5?倍）。胃和小肠消化显著促进粳型和籼型糙米中酚类物质释放（P＜0.05）,其释放量（以没食子酸当量计）最高值为460.9?mg/100?g和401.1?mg/100?g,粳型糙米中酚类物质释放量显著高于籼型糙米;两者酚类物质释放量随消化时间变化趋势均符合幂函数模型。铁离子还原/抗氧化能力（ferric-reducing antioxidant power,FRAP）和氧自由基清除能力（oxygen radical absorbance capacity,ORAC）实验表明糙米体外消化过程中释放的酚类物质具有良好抗氧化能力,粳型和籼型糙米消化液FRAP值（以Trolox当量计）最大为10.76、8.44?μmol/g,ORAC值（以Trolox当量计）最大为6.82?μmol/g和6.23?μmol/g。     

Anthocyanin content and antioxidant capacity in bran extracts of some Thai black rice varieties

This study investigated both the anthocyanin content and the antioxidant capacity of a set of genetically related glutinous and nonglutinous Thai black rice varieties. The ethanol/water extracts of the brans of these black rice varieties showed relatively potent antioxidant activities compared with those of tocopherol. These antioxidant activities were determined by thiocyanate, H₂O₂‐scavenging chemiluminescence (XYZ), Cu⁺⁺/bathocuproine colorimetry (PAO) and 1,1‐diphenyl‐2‐picrylhydrazyl radical‐scavenging assay. The structural identification and quantification of the black rice anthocyanins performed by high‐performance liquid chromatography coupled with electrospray ionisation and tandem mass spectrometry found cyanidin‐3‐O‐glucoside and peonidin‐3‐O‐glucoside as the major anthocyanins in the ranges of 16.01–34.40 and 2.43–7.36 μg mL^?1, respectively. The comparative study in terms of quantity of these phytochemicals and antioxidant capacity of the black rice bran extracts suggested the contribution of overall phenolic components rather than that of the particular anthocyanin pigments.     

A comparative study on the polyphenolic content,antibacterial activity and antioxidant capacity of different solvent extracts of Brassica oleracea vegetables

Brassica vegetables are rich in polyphenols, flavonoids and glucosinolates. Investigation was undertaken to optimise the best solvents among 60% ethanol, acetone and methanol for the extraction of polyphenols from Brassica vegetables. Furthermore, different properties such as antibacterial activity and antioxidant capacity were also investigated. Results showed that a 60% methanolic extract showed the highest total phenolic content which was 23.6, 20.4 and 18.7 mg gallic acid equivalents (GAE) g^?1 extract for broccoli, Brussels sprouts and white cabbage, respectively. The hydroxybenzoic acid content of various solvent extracts ranged from 5.86 to 8.91 GAE g^?1 extract for broccoli, 2.70 to 5.44 GAE g^?1 extract for Brussels sprouts and 3.69 to 4.86 GAE g^?1 extract for white cabbage, while the hydroxycinnamic acid content ranged from 0.78 to 1.26 chlorogenic acid equivalents (CAE) g^?1 extract for broccoli, 1.41 to 3.45 CAE g^?1 extract for Brussels sprouts and 0.49 to 1.14 CAE g^?1 extract for white cabbage. A concentration‐dependent antioxidative capacity was confirmed for different reactive oxygen species, and moderate antibacterial activity was observed against a number of Gram‐negative and Gram‐positive food spoilage and food pathogenic bacteria. Solvents significantly affected polyphenolic content and its different properties, and the methanol was found to be the best solvent for the extraction of polyphenols from studied Brassica vegetables.