Enzyme-enhanced extraction of antioxidant ingredients from red algae Palmaria palmata

The effect of various protease and carbohydrase treatments on the extraction of polyphenols and other antioxidant ingredients from the red algae Palmaria palmata (dulse) was investigated. In addition, the relative contribution of different fractions to the overall antioxidant capacity of the hydrolysate was evaluated. Considerable differences were observed both in total phenolic content (TPC) and antioxidant activities of the hydrolysates evaluated using 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, oxygen radical absorbance capacity (ORAC) and ferrous ion-chelating ability assays. All the proteases tested had significant enhancing effect on the extraction of polyphenols and other active components compared to carbohydrases and cold water extraction (control). The Umamizyme extract had the highest TPC and consequently exhibited the strongest scavenging capacity against DPPH and peroxyl radicals. Further fractionation of the Umamizyme extract revealed that the crude polyphenol fraction possessed the highest peroxyl radical scavenging activity, whereas the crude polysaccharide fraction was more effective for chelating ferrous ions. The data from this study suggest the potential of protease treatment to improve value-added utilization of dulse extracts as antioxidants in functional foods and nutraceuticals.     

Total phenolic content and DPPH radical scavenging activity of lettuce (Lactuca sativa L.) grown in Colorado

Total phenolic content (TPC) and antioxidant capacity of lettuce were evaluated using the Folin-Ciocalteu method and DPPH assay, respectively, on 25 cultivars of lettuce, including leaf, romaine, crisphead, and butterhead types, cultivated over two harvest periods. Leaf lettuce possessed the highest TPC and highest DPPH scavenging ability, followed by romaine, butterhead and Batavia (crisphead subtype). Within a lettuce type, red pigmented lettuce cultivars had higher TPC and antioxidant capacity than did green cultivars grown under the same conditions. In addition, lettuce harvested in July possessed higher TPC and antioxidant capacity than did lettuce harvested in September, suggesting that environmental conditions could influence the phenolic content and antioxidant activity of lettuce. These results suggest that Colorado grown lettuce may serve as potential dietary sources of natural phenolic antioxidants.     

Antioxidant activities and total phenolic contents of various extracts from defatted wheat germ

Defatted wheat germ (DWG) is the main by-product of the wheat germ oil extraction process. Its nutritional value has well been accepted. In this study, the antioxidant properties of 30% ethanol, 50% ethanol, 70% ethanol, 100% ethanol, and aqueous extracts of DWG were measured using various in vitro assays. Among the DWGEs (DWG extracts) tested, the 70% ethanol extract showed the best DPPH radical scavenging power while the 100% ethanol extract showed the highest ABTS radical scavenging activity and reducing power. In addition, both the 70% ethanol extract and the 50% ethanol extract exhibited relatively higher antioxidant activity in linoleic acid system. The extracts in question exhibited total phenolic contents ranging from 13.98 to 16.75 mg GAE/g. DWG, as a source of natural antioxidants, can be used to formulate nutraceuticals with potential applications to reducing the level of oxidative stress. The antioxidant potency of the DWG extracts could be the basis for its health promoting potential.     

Total phenolic contents,radical scavenging and cyclic voltammetry of seaweeds from Brittany

The role of polyphenols as antioxidants in our daily nutrition has been extensively investigated, but information on composition of tannins from marine sources on nutrient utilisation is limited. This study will be focused on the determination of the polyphenol quantities in brown seaweeds from Brittany coast in France; the extracts were delivered from algae centre for valorisation (CEVA), and the fidelity of the method was examined intraday and interlaboratories. The seaweed’s extracts are divided into three categories: Fucus Vesiculosus, Ascophyllum nodosum and Fucus Serratus. Consequently, the total polyphenol contents (TPC) of these extracts will be measured using Folin–Glombitza spectrophotometric method. Thereafter, the antioxidant properties of these polyphenols were determined using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging. All polyphenols extracted were tested using cyclic voltammetry (CV) in aprotic media. The CV is realised to compare the results from spectroscopic method and to electrochemically characterise the seaweed’s polyphenols.     

Total phenolic content and antioxidant properties of eclipse black beans (Phaseolus vulgaris L.) as affected by processing methods

ABSTRACT:  The effects of soaking, boiling, and steaming processes on the phenolic components and antioxidant activity of black beans were investigated. All processed beans exhibited significantly ( P < 0.05) lower antioxidant activities than raw beans in total phenolic content (TPC), DPPH free radical scavenging activity (DPPH), and oxygen radical absorbing capacity (ORAC). Steaming processes resulted in a greater retention of TPC and ORAC values than the boiling processes. Pressure boiling shortened processing time compared to regular boiling, resulted in insignificant differences in TPC, but significantly increased in ORAC as compared to the regular boiling method. Pressure steaming resulted in significant decreases in TPC, DPPH, while significantly increased in ORAC compared to regular steaming. Greater TPC, DPPH, and ORAC values were detected in boiling water than in the soaking and steaming water. Mass balance analysis showed that boiling caused more dry solid loss than steaming. All of these results indicated that processing methods significantly changed contents and activities of antioxidant components of black beans. Steam processing exhibited several advantages in appearance and texture of the cooked product, shortening processing time, and in greater retention of TPC and antioxidant activities. Steam processing may be used to develop high-quality health-promoting black bean products.     

Total phenolic content and antioxidant capacity of extracts obtained from six important fruit residues

The extracts from kinnow peel, kinnow seeds, litchi pericarp, litchi seeds, grape seeds, and banana peel were screened for total phenolic content (TPC), trolox equivalent antioxidant capacity (TEAC), 1,1 diphenyl-2-picryl hydrazyl (DPPH) radical scavenging activity, as well as reducing power. Kinnow peel extract exhibited the highest reducing power, TEAC, and DPPH free radical scavenging activity, whereas, the phenolic content of 37.4 mg GAE/g-dw was highest for grape seed extract. Banana peel extract with a low TPC showed the lowest reducing power, TEAC as well as DPPH free radical scavenging activity among the fruit residue extracts examined in the present study. Correlation analysis between the reducing power and DPPH radical scavenging ability; reducing power and ABTS radical scavenging activity; and ABTS and DPPH radical scavenging abilities showed a high degree of correlation (r² = 0.85-0.91). However, r² of 0.36, 0.66, and 0.49 between TPC and DPPH radical scavenging activity; TPC and reducing power; and TPC and ABTS radical scavenging ability, respectively, indicated that some non-phenolic compounds also contributed to the total antioxidant activity in fruit residue extracts examined in this study. To the best of our knowledge, this is the first paper presenting comprehensive data on TPC, reducing power, and antioxidant activity for the six fruit residues. This study demonstrated that kinnow peel, litchi pericarp, litchi seeds, and grape seeds, can serve as potential sources of antioxidants for use in food and pharmaceutical industry.     

Antioxidant properties of commercial wild rice and analysis of soluble and insoluble phenolic acids

To investigate the antioxidant properties of commercial wild rice, identify and quantify soluble and insoluble phenolic acids in wild rice whole grain, the alkaline hydrolysates from crude methanol extracts (soluble fraction) and residues (insoluble fraction) were separately analysed by high performance liquid chromatography (HPLC) coupled with photodiode array detection (PAD) and quadrupole-time of flight (Q-TOF) mass spectrometry (LC–MS). The antioxidant activity of wild rice methanol extract was found to be up to 10 times greater than that of white rice (control sample) according to their 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity and oxygen radical absorbance capacity (ORAC). Ferulic acid was found as the most abundant phenolic acid (up to 355 mg/kg) followed by sinapic acid in wild rice. They both occurred mainly in the insoluble form. Other monomeric phenolic acids present in wild rice consisted of p-coumaric, vanillic, syringic, and p-hydroxybenzoic acids, along with two phenolic acid aldehydes (p-OH-benzaldehyde and vanillin). They were present in both soluble and insoluble forms. Phenolic acid dehydrodimers are cell wall bound and only appeared in the insoluble fractions featured by diferulic acids (DiFA) and disinapic acids (DiSA). The chemical structures of DiFA included 8-8′, 5-5′, 8-O-4′, and 8-5′ (benzofuran form) coupled dimers, with 8-O-4′ as the predominant form (up to 34 mg/kg). DiSA only appeared as 8-8′-coupled products with the linear isomers in the most quantities (up to 19 mg/kg). The DPPH free radical scavenging activities of soluble and insoluble fractions suggest that the antioxidant activity of wild rice is partially attributed to its phenolic acid profile.     

Antioxidant and radical scavenging activities of the pyroligneous acid from a mangrove plant, Rhizophora apiculata

Total phenolics content, free radical scavenging activity, reducing power, and antioxidant activity of the pyroligenous acid from a mangrove plant, Rhizophora apiculata were evaluated. Dichloromethane extraction of the raw pyroligneous acid successfully yield 2 extracts, i.e. concentrated pyroligneous acid (CPA) and concentrated pyroligneous acid extract (CPAE). Phenolic contents in CPAE and CPA, expressed as (±)-catechin equivalents/g of the sample were 5465 ± 367 mg and 2502 ± 152 mg, and expressed as gallic acid equivalents/g of the sample were 2919 ± 209 mg and 1348 ± 90 mg, respectively. CPAE exhibited superior free radical scavenging activity with EC₅₀ value = 0.1235 mg/ml, or 80.96% of free radical scavenging capability. The ferric reducing power of CPAE was approximately 3.7, 5.1, 6.1, and 21.3 times higher than that of ascorbic acid, BHA, BHT and alpha-tocopherol. In phosphomolybdenum assay, CPAE showed the greatest antioxidant efficacy (A₆₉₅ = 1.278) compared to those of CPA and different standards. In addition, the free radical scavenging activity, ferric reducing power and total antioxidative activity of CPAE and CPA showed positive correlation with their total phenolic content with R² values ranging from 0.9624 to 0.9979.     

Evolution of major phenolic components and radical scavenging activity of grape juices through concentration process and storage

The total phenolic (TP) and radical scavenging activity (RSA) of concentrated grape juices during process and storage were characterized and quantified. TP were determined using the Folin–Ciocalteu method and RSA by the DPPH assay. The main phenolic components of juices were investigated by direct infusion electrospray ionization-mass spectrometry (ESI-MS) in the negative ion mode. Concord juice (CJ) demonstrated higher RSA and TP contents than Isabel juice (IJ) with some differences at each processing step. During storage, retention of TP and RSA were 90% and 77% in CJ and of 81% and 86% in IJ, respectively. During processing, peonidin and peonidin-3-O-glucoside gave place to malvidin and dimethoxy-flavylium as major significant components; piceatannol-O-glucoside became significant after concentration and malvidin decreased after 8 months of storage. Concentrated and refrigerated storage were effective in preserving total phenolics and antioxidative status of grape juices, although changes in compounds were observed.     

超声波处理对红葡萄酒总酚、总黄酮含量及自由基清除活性的影响

应用超声波处理红葡萄酒,探讨超声因素（超声频率,超声功率,超声处理温度,超声时间）对红葡萄酒中总酚、总黄酮含量及自由基清除活性的影响。结果表明超声处理会使红葡萄酒总酚含量、总黄酮含量与自由基清除活性显著降低（p<0.05）。超声处理红葡萄酒后,其抗氧化活性与其总酚含量呈高度正相关,回归方程为y=0.0270x+38.806（R2=0.9007,p<0.01）;其抗氧化活性与其总黄酮含量亦存在一定线性关系,回归方程为y=0.0592x+37.357（R²=0.4970,p<0.05）。在本文实验条件下根据实验结果可以推知,超声处理后红葡萄酒自由基清除活性的降低,部分是由于总酚含量和总黄酮含量降低所引起的。      

Free radical scavenging, inhibition of polyphenoloxidase activity and copper chelating properties of model Maillard systems

Antioxidant properties of Maillard reaction products (MRP) obtained from aqueous mixtures of glucose (0.8 mol/l) with proline, glycine, arginine, lysine, cysteine or glutathione (0.5 mol/l) heated at 103 °C for 1-92 h were investigated using different in vitro tests. Free radical scavenging activity was determined by measuring their reactivity towards DPPH° and lipidic radicals produced by AAPH. Contrary to glucose-proline and glucose-glycine MRP, glucose-lysine and glucose-arginine MRP displayed high scavenging activities. The activity of glucose-lysine MRP peaked after 14 h of heating while the activity of glucose-arginine constantly increased during the whole heat treatment. The high scavenging capacity observed towards DPPH° for glucose-cysteine mixtures could be attributed to the sulfhydryl group of cysteine.The inhibitory effect of MRP on activity of two copper-oxidoreductases, apple polyphenoloxidase and mushroom tyrosinase, assessed by polarography, showed that thiol-derived MRP were the most potent inhibitors, even at very low levels in the reaction medium. Conversely, the other MRP were only slightly efficient at high levels. Unheated mixtures containing thiol compounds exhibited a potent copper chelating ability, as efficient as EDTA, when determined by the tetramethylmurexide (TMM) test. After heating, these mixtures lost part of their chelating efficiency, but it remained higher than that of the other MRP, suggesting that the sulfhydryl group also played a role in the copper chelating properties.     

Chemical composition and biological activities of essential oil and extracts from Ocimum sanctum

The objective of the present research work was to evaluate the antioxidant, antimicrobial and antimalarial activities of essential oil and various extracts from O. sanctum. Gas chromatography-mass spectrometry analysis identified the following major compounds with their quantification as: eugenol (22.0%), β-elemene (19.2%), β-caryophyllene (19.1%), and Germacrene D (5.03%). HPLC analysis of O. sanctum extracts revealed that gallic acid, chlorogenic acid, p-hydroxy benzoic acid, caffeic acid, vanillic acid, p-coumeric acid, sinapic acid, and ferulic acid were the important phenolic acids. The methanol extract exhibited highest level of total phenolic (1.36 g/100 g dry plant material) and total flavonoid (0.67 g/100 g dry plant material) followed by ethanol and n-hexane extracts. The oil and extracts exhibited excellent free radical scavenging potential as measured by 2,2-diphenyl-1-picrylhydrazyl radical free radical-scavenging ability, and antioxidant activity as measured by inhibition of linoleic acid oxidation. Essential oil, n-hexane, methanol, and ethanol extracts exhibited moderate antimalarial potential in term of anti-haem biocrystallization activity. In the resazurin microtitre plate and disc diffusion assays, the essential oil of O. sanctum showed better antibacterial activity than various extracts. The results of the present investigation demonstrated significant (p < 0.05) variations in the antioxidant, antimicrobial, and antimalarial activities of essential oil and extracts from O. sanctum.     

Phenolic composition,antioxidant and antimicrobial activities of free and bound phenolic extracts of Moringa oleifera seed flour

Phenolic compounds, antioxidant and antibacterial activities of defatted Moringa oleifera seed flour (DMF) were investigated. The total phenolic and flavonoid contents were measured using colorimetric methods. Free phenolic acid and flavonoid profiles were analyzed by high performance liquid chromatography, while antioxidant capacities were evaluated using scavenging assays of 1,1-diphenyl-2-picrylhydrazyl radical (DPPH), ferric reducing antioxidant power and total antioxidant capacity. The results showed that extractability of phenolic compounds was significantly higher (p < 0.05) in bound phenolic extract (4173.00 ± 32.22 mg gallic acid equivalents (GAE)/100 g) than in free phenolic extract (780.00 ± 14.2 mg GAE/100 g) and it showed higher antioxidant and antimicrobial activities. The IC₅₀ value for DPPH radical scavenging activity was 0.9 ± 0.05 and 14.9 ± 0.07 mg/mL for bound phenolic and free phenolic extracts, respectively. Bound phenolic extract was more effective (minimum inhibitory concentration (MIC), 0.06–0.157%) than free phenolic extract (MIC, 0.117–0.191%) against tested bacteria. Ten phenolic compounds (gallic acid, p-coumaric acid, ferulic acid, caffeic acid, protocatechuic acid, cinnamic acid, catechin, epicatechin, vanillin and quercetin) were identified and quantified in both extracts. These natural plant phenolics from Moringa seeds could be a good source of antioxidants and antibacterials for food and pharmaceutical industries.     

Characterization of Brazilian lager and brown ale beers based on color, phenolic compounds, and antioxidant activity using chemometrics

BACKGROUND: Epidemiological studies have shown that beer has positive effects on inhibiting atherosclerosis, decreasing the content of serum low‐density lipoprotein cholesterol and triglycerides, by acting as in vivo free radical scavenger. In this research, the antioxidant activity of commercial Brazilian beers (n = 29) was determined by the oxygen radical absorbance capacity (ORAC) and 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH^·) assays and results were analyzed by chemometrics. RESULTS: The brown ale samples (n = 11) presented higher (P < 0.05) flavonoids (124.01 mg L^?1), total phenolics (362.22 mg L^?1), non‐flavonoid phenolics (238.21 mg L^?1), lightness (69.48), redness (35.75), yellowness (55.71), color intensity (66.86), hue angle (59.14), color saturation (0.9620), DPPH^· values (30.96% inhibition), and ORAC values (3, 659.36 µmol Trolox equivalents L^?1), compared to lager samples (n = 18). Brown ale beers presented higher antioxidant properties (P < 0.05) measured by ORAC (1.93 times higher) and DPPH (1.65 times higher) compared to lager beer. ORAC values correlated well with the content of flavonoids (r = 0.47; P = 0.01), total phenolic compounds (r = 0.44; P < 0.01) and DPPH (r = 0.67; P < 0.01). DPPH values also correlated well to the content of flavonoids (r = 0.69; P < 0.01), total phenolic compounds (r = 0.60; P < 0.01), and non‐flavonoid compounds (r = 0.46; P = 0.01). CONCLUSION The results suggest that brown ale beers, and less significantly lager beers, could be sources of bioactive compounds with suitable free radical scavenging properties. Copyright © 2010 Society of Chemical Industry     

Effect of fermentation on antioxidant properties of some cereals and pseudo cereals

The influence of fermentation by two types of microorganisms (lactic acid bacteria Lactobacillus rhamnosus, and yeast Saccharomyces cerevisiae) on antioxidant activities and total phenolics of 4 cereals, namely buckwheat, wheat germ, barley and rye, was determined and compared with those of their unfermented counterparts. The total phenolic content (TPC), determined by the Folin–Ciocalteu method, increased upon fermentation. Antioxidant activities (AOA) were assessed using 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging capacity, ferric ion-reducing antioxidant power (FRAP) and thiobarbituric acid (TBA) methods. The presence of those microorganisms was more or less important for enhanced levels of antioxidant activity. Thus fermentation offers a tool to further increase the bioactive potential of cereal products.     

Total Phenolic Compounds, Flavonoids, and Radical Scavenging Activity of 21 Selected Tropical Plants

ABSTRACT:  Free radical scavenging activity of 21 tropical plant extracts was evaluated using 1,1-diphenyl-2-picrylhydrazyl assay (DPPH). Total phenolic compounds and flavonoids were determined using Folin–Ciocalteu and HPLC, respectively. Results of the study revealed that all the plants tested exhibited excellent antioxidant activity with IC₅₀ in the range of 21.3 to 89.6 μg/mL. The most potent activity was demonstrated by  Cosmos caudatus  (21.3 μg/mL) and  Piper betle  (23.0 μg/mL) that are not significantly different than that of     -tocopherol or BHA.  L. inermis  extract was found to consist of the highest concentration of phenolics, catechin, epicatechin, and naringenin. High content of quercetin, myricetin, and kaempferol were identified in  Vitex negundo ,  Centella asiatica , and  Sesbania grandiflora  extracts, respectively. Luteolin and apigenin, on the other hand, were found in  Premna cordifolia  and  Kaempferia galanga  extracts. Strong correlation ( R  = 0.8613) between total phenolic compounds and total flavonoids ( R  = 0.8430) and that of antioxidant activity of the extracts were observed. The study revealed that phenolic, in particular flavonoids, may be the main contributors to the antioxidant activity exhibited by the plants.
Practical Application: Potent antioxidant from natural sources is of great interest to replace the use of synthetic antioxidants. In addition, some of the plants have great potential to be used in the development of functional ingredients/foods that are currently in demand for the health benefits associated with their use.     

The antioxidant activity and stability of the phenolic fraction of green olives and extra virgin olive oil

The antioxidant activity of phenolic extracts from olives and olive oil has been assessed by scavenging of 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) radicals and by studying the effects on the stability of stripped olive oil in the absence and presence of ferric chloride. The olive extracts contained a much higher concentration (1940–5800 mg kg^?1) of phenolic components than the olive oil extract (180 mg kg^?1). Some olive extracts were more effective than the olive oil extract in scavenging DPPH radicals, but the three varieties of olives examined showed relatively large differences in both polyphenol concentration and antioxidant activity of extracts. α‐Tocopherol and extracts from both olives and olive oil were effective antioxidants in stripped olive oil at 60 °C. Ferric chloride reduced the stability of stripped olive oil, but the olive extract studied was significantly more effective as an antioxidant in the presence of the metal salt than the olive oil extract or α‐tocopherol. Ferric ions catalysed the oxidation of caffeic acid, oleuropein and phenolic components of the olive and olive oil extracts in aqueous solution (pH 5.4). The olive extract oxidised more rapidly than the olive oil extract in aqueous solution. © 2001 Society of Chemical Industry     

Effect of ultrasonic treatment on the recovery and DPPH radical scavenging activity of polysaccharides from longan fruit pericarp

Ultrasonic technique was employed to extract polysaccharides from longan fruit pericarp (PLFP). The optimal conditions for ultrasonic extraction of PLFP were determined by response surface methodology. Box–Behnken design was applied to evaluate the effects of three independent variables (ultrasonic power, time and temperature) on the recovery and 1,1′-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity of PLFP. The correlation analysis of two mathematical-regression models indicated that quadratic polynomial model could be employed to optimize the ultrasonic extraction of PLFP. From response surface plots, ultrasonic power, time and temperature exhibited independent and interactive effects on the extraction of PLFP. The DPPH radical scavenging activity of PLFP could be improved by application of various ultrasonic power, time and temperature, which was possible due to the degradation of polysaccharides to different extent. The optimal conditions to obtain the highest recovery and the strongest DPPH radical scavenging activity of PLFP were 120 W, 22 min and 60 °C, as well as 241 W, 18 min and 51 °C, respectively. Under these optimal conditions, the experimental values agreed with the predicted ones by analysis of variance. It indicated high fitness of two models used and the success of response surface methodology for optimizing PLFP extraction.