Effect of pressure cooking on the antioxidant activity of extracts from three common bean (Phaseolus vulgaris L.) cultivars

Common bean is a traditional legume that is becoming more attractive because of its dietary and associated health benefits. Flor de Mayo M38, Pinto Villa and Bayo Victoria, three common bean cultivars developed in Mexico, were tested for phenol content and free radical scavenging activity before and after autoclaving. Independent analysis of seed coat and cotyledon was performed for each cultivar. Longer cooking times enhanced diffusion of phenols from seed coats to cooking water and from there to cotyledons. Cooking waters showed a remarkable activity similar to crude seed coats extracts although their phenol content was 80% lower.     

Radiation-induced enhancement of antioxidant activity in extracts of rosemary (Rosmarinus officinalis L.)

Dry rosemary leaf powder was subjected to 30 kGy of gamma ray irradiation, followed by solvent extraction with methanol, ethanol or water. The antioxidant activity of the extracts was assessed using the DPPH radical-scavenging method and the reducing power test. EC₅₀ values, using the radical-scavenging method, indicate a 22% increase in the antioxidant activity of ethanol and water extracts as a result of irradiation treatment. EC₅₀ values in the reducing power test show an increase of 45% and 28% for the ethanol and water extracts, respectively. The antioxidant activity of methanol extracts of irradiated rosemary remained the same as in the controls in both types of test. A high correlation was found between the EC₅₀ values obtained in the DPPH radical test and those from the reducing power test. Total phenolic content (Folin–Denis test) increased by 35% in the water extracts as a result of irradiation but remained the same in the methanol and ethanol extracts. The methanol extract showed the highest antioxidant activity and the highest amount of total phenolic compounds. Radiation reduced the good correlation between antioxidant activity and total phenolic content.     

Optimisation,characterisation and quantification of phenolic compounds in olive cake

The phenolic compounds in extracts from pressed olive cake were investigated. Free phenolic compounds were extracted from olive cake using methanol. To liberate bound phenolic compounds, the olive cake was subjected to basic and acidic hydrolysis followed by methanol extraction. The individual phenolic compounds and antioxidant activity of the extracts were determined. The highest total phenolic content and antioxidant activity were obtained using methanol extraction for 12 h at 70 °C. The RP-HPLC profiles for full-fat and defatted olive cake showed that protocatechuic acid, hydroxybenzoic acid, sinapic acid, p-coumaric acid, rutin and hesperidin were the predominant free phenolic compounds. Meanwhile, syringic acid, sinapic acid, caffeic acid and protocatechuic acid were the predominant bound phenolic acids. A positive correlation was observed between total phenolic content and antioxidant activity. The results indicated that most of the phenolic compounds in olive products were present in their free forms (75–90% of total phenolic content), while bound phenolic compounds were only a small proportion (10–25%) of total phenolic content.     

Effect of processing on the antioxidant properties of extracts from Mexican barley (Hordeum vulgare) cultivar

The effect of traditional cooking, roasting and germination on the antioxidant capacity of a Mexican barley cultivar is presented. Barley dried grains were processed and phenolic extracts obtained by successive extractions with hexane, aqueous acetone (70%), aqueous methanol (50%) and water. Total phenolic content was evaluated by the Folin–Ciocalteu method and the radical scavenging capacity by the DPPH method. The inhibition of LDL oxidation was also determined. Results showed that cooking and roasting barley extracts increase, the total phenolic content in comparison with control (unprocessed) barley extracts, but the germination reduces it. Germinated seeds subjected to roasting, cooking and unprocessed barley grains showed a higher antioxidant activity (IC₅₀). Traditionally cooked barley grains showed the highest inhibition of LDL oxidation. These results indicate that processing affects significantly the antioxidant capacity of barley phenolic extracts.     

RP-HPLC–DAD analysis of phenolic compounds in pomace extracts from five grape cultivars: Evaluation of their antioxidant,antiradical and antifungal activities in orange and apple juices

Phenolic compounds, related to antioxidative and antifungal properties of ethanolic extracts from five commercial grape cultivars (three red and two white) grown in Turkey were determined. A reversed-phase high performance liquid chromatography (RP-HPLC) procedure was developed, and a total 18 different phenolic compounds were identified. Total phenolic contents of the extracts were determined using Folin–Ciocalteau method. Antioxidant activities of the extracts were evaluated by using DPPH radical scavenging and phosphomolybdenum methods. All extracts exhibited strong antioxidant and antiradical activity. Phenolic compounds and antioxidant activities of the extracts were variety dependent. Antifungal activities of the pomaces and extracts were screened by both in vitro agar-well diffusion assay and antifungal activity in apple and orange juices in situ using Zygosaccharomyces rouxii and Z. bailii. Antifungal activities revealed that the pomaces and extracts of Gamay and Kalecik karasi could be more effective antifungal agents than those of Emir, Narince and Okuzgozu grape cultivars.     

Phenolics and antioxidative activities in common beans (Phaseolus vulgaris L)

Six bean cultivars grown in southern Manitoba for 2 years were evaluated for variability in yield of millstreams and phenolic constituents. The ethanolic extract of bean cultivars and millstreams was screened for antioxidant activity using the β‐carotene‐linoleate and the 1, 1‐diphenyl‐2‐picrylhydrazyl (DPPH) in vitro model systems. Cultivar was the main source of variation for yield of millstreams, content of phenolic compounds and antioxidant activities. Phenolic compounds in cultivars varied from 3.3 to 16.6 mg catechin equivalent and from 0.15 to 0.32 mg cyanidin‐3‐glucoside equivalent g^?1 bean for total phenolic and anthocyanin contents, respectively. The bean cultivars exhibited antioxidant activity (AA) of 10–46% inhibition of lipid peroxidation in the linoleate and 0.4–1.3 trolox equivalent antioxidant capacities (TEAC) in the DPPH model systems. The hull millstream with maximum concentration of phenolic compounds exhibited the strongest antioxidant activity of 383 µM trolox equivalent g^?1 hull. Total phenolic content, alone or in combination with other phenolic constituents, is a potential candidate as a selection criterion for antioxidant activity in beans. Copyright © 2005 Society of Chemical Industry     

Antioxidant capacity of pummelo and navel oranges: Extraction efficiency of solvents in sequence

Extraction efficiency of five different solvents on the antioxidant capacities of pummelo and navel oranges was measured by five widely used antioxidant methods. Freeze-dried edible parts of pummelo and navel oranges were extracted with five different solvents such as hexane, ethyl acetate, acetone, methanol and methanol:water (8:2). The total phenolic content of the extracts was determined by Folin-Ciocalteu method and expressed as catechin equivalents. The highest phenolic content was obtained from ethyl acetate and the minimum phenolic content was found in methanol extract. The dried extracts were screened for their radical scavenging activity using three different methods such as α,α-diphenyl-β-picrylhydrazyl (DPPH), 2,2′-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) radical assay and ORAC methods. Ethyl acetate extract from navel orange and pummelo was found to be most active radical scavenging activity, whereas hexane extract from pummelo and methanol extract from navel orange was found to be lowest activity. Moreover, all the extracts from pummelo and navel orange were studied for their antioxidant capacity by the formation of phosphomolybdenum complex and reducing power by potassium ferricyanide reduction method at various concentrations. The order of antioxidant capacity of pummelo and navel orange was found to be ethyl acetate>acetone>MeOH:water>methanol> hexane and ethyl acetate>MeOH:water>acetone>methanol>hexane, respectively. Acetone and methanol extracts from pummelo and navel oranges showed highest reducing power than other extracts at 1000 μg/ml. Significant differences in antioxidant capacity were found between the values obtained by the same method in different solvents and as well as each extract antioxidant capacity obtained by the different method. Results of the present study may be due to the extent of antioxidant capacity of each extract is in accordance with the amount of carotenoids, phenolics and vitamin C present in the extracts.     

The antioxidant, angiotensin converting enzyme inhibition activity, and phenolic compounds of bamboo shoot extracts

This study was undertaken to evaluate the functional properties of two of the most popular species of edible bamboo shoots in Korea (Phyllostachys pubescens and Phyllostachys nigra). Powdered bamboo shoots were extracted with methanol and an aqueous suspension of the obtained methanol extract was partitioned successively with chloroform, ethyl acetate, and butanol, leaving a residual water extract. All obtained extracts were evaluated for their antioxidant capacity and antimicrobial activity, angiotensin converting enzyme (ACE) inhibition activity, and ascorbic acid and phenolic compound content. Methanol and water fractions showed a particularly high ascorbic acid contents. The ethyl acetate fraction contained a high concentration of phenolic compounds. Among all extracts, the ethyl acetate and butanol fractions showed particularly high antioxidant activity. Methanol extract had a significantly higher ACE inhibitory activity than other extracts. None of the extracts inhibited the tested bacteria.     

Studies on the dual antioxidant and antibacterial properties of parsley (Petroselinum crispum) and cilantro (Coriandrum sativum) extracts

Antioxidant and antibacterial activities of freeze-dried and irradiated parsley (Petroselinum crispum) and cilantro (Coriandrum sativum) leaves and stems were determined on methanol and water extracts. The total phenolic content was quantified with the Folin–Ciocalteau reagent. Several mechanisms of potential antioxidant activity of all extracts, including determining relative free radical-scavenging and ferrous ion-chelating activities, as well as reducing power, were examined. Assessment of the total antioxidant activity of all extracts was done using an iron-induced linoleic acid oxidation model system. Antimicrobial activity towards Bacillus subtilis and Escherichia coli by different extracts was assessed by determining cell damage. Total phenolic content varied between parsley and cilantro, leaf and stem, as well as methanol and water extracts. Methanol-derived leaf extracts exhibited significantly (p < 0.05) greater radical-scavenging activity towards both lipid- and water-soluble radicals, which was attributed to the total phenolic content. Ferrous ion-chelating activity was significantly (p < 0.05) greater in the stem methanol extracts, and corresponded to antioxidant activity. Prooxidant activity was a feature of all aqueous extracts and corresponded to the reducing activity of both leaf and stem parts of parsley and cilantro. Bacterial cell damage, resulting in significant (p < 0.05) greater growth inhibition of B. subtilis and E. coli, corresponded to ferrous sequestering activity of methanol-derived stem extracts.     

Phenolic content,antioxidant potential and DNA damage protection of pearl millet (<Emphasis Type="Italic">Pennisetum glaucum</Emphasis>) cultivars of North Indian region

Total phenolic contents, condensed tannin content, antioxidant activity and DNA damage protection of twelve pearl millet cultivars from North Indian region were assayed. All pearl millet cultivars showed considerable amount of bioactive compounds with antioxidant potential. PUSA-415 showed the presence of maximum amount of extractable total phenolic content (7.32 mg GAE/g DWB), whereas HHB-223 cultivar depicted the highest amount of condensed tannin contents (138.45 mg CE/100 g DWB). Antioxidant activity was measured using different methods viz., DPPH, ABTS, FRAP, TAC and HFRSA. A clear correlation was observed between total phenolic content and antioxidant activity of different pearl millet cultivars. The extracts of all cultivars prevented the oxidative damage to plasmid DNA (pBR322) against DNA damaging Fenton’s reagent. However, cultivars PC-383, PUSA-415, PUSA-605, PC-612 and 841-B showed prominent DNA damage protection activity. The results of this study provide a scientific basis of the traditional use of pearl millet as a natural antioxidant mitigating DNA damage.     

In vitro synergism of antimutagenic and antioxidant activities of Phoenix dactylifera fruit

The availability of total phenolics of date flesh (Pheonix dactylifera) in aqueous and acidified methanol and in vitro synergism of their antimutagenic and antioxidant activities were investigated. The antimutagenic activities of date flesh extracts tested against Salmonella strains TA-98 and TA-100 using Ames bacterial testing were in the range of 36.47 to 79.74% against the standard mutagens potassium dichromate and sodium azide. The antioxidant activities assessed as maximal inhibitory concentrations (IC₅₀) for DPPH radicals and linoleic acid peroxidation inhibition were 812.90 to 2,076.10 μg/mL and 54.43 to 80.89%, respectively. The total phenolic contents of date flesh extracts (35.76 to 114.09mg/g of gallic acid equivalents) were found to be correlated with the biological activities. Use of 0.5 N acidified methanol was efficient for extraction of phenolic compounds with retained antioxidant and antimutagen activities. Dates are a good candidate as a source for development of chemotherapeutic drugs, nutracueticals, and functional food ingredients.     

Biological activity and composition of extract from aerial root of Ficus microcarpa L. fil.

Total phenolic content, antioxidant and antibacterial activities of Ficus microcarpa aerial roots were determined on methanol extract and its sub-fractions (hexane, ethyl acetate, n -butanol and water). The ethyl acetate fraction possessed the highest amount of phenolic compounds evaluated by Folin-Ciocalteu reagent method. It also showed the highest antioxidant activity when tested the following methods: DPPH, ABTS⁺ radical-scavenging, superoxide radical scavenging, reducing power and β -carotene linoleic acid bleaching. On the other hand, high phenolics content extracts (ethyl acetate, methanol and n -butanol) showed significantly higher inhibitory activity than low phenolics content extracts (water and hexane) against five tested Gram positive and Gram negative bacteria. Protocatechuic acid, catechol, p -vinylguaiacol, syringol, p -propylphenol, vanillin, p -propylguaiacol, isovanillic acid, 4- n -Propylresorcinol, syringaldehyde and oleanolic acid contained in ethyl acetate fraction were identified by GC-MS and HPLC based on their cochromatography with standard compounds. Protocatechuic acid, catechol and syringol exhibited nearly same antioxidant activity as did by positive control Trolox using the mentioned assays. Results here showed that the ethyl acetate fraction has strong antioxidant and antibacterial activities, which are correlated with its high level of phenolic compounds.     

Evaluation of the antioxidant and antiproliferative activities of extracted saponins and flavonols from germinated black beans (Phaseolus vulgaris L.)

Flavonoids and saponins from common beans have been widely studied due to their bioactivity. This research evaluated the effect of germination of black beans (Phaseolus vulgaris L.) on the antioxidant capacity and antiproliferative activity against cancer cell lines of saponins and flavonoids extracted from seed coats, cotyledons and sprouts. Principal component analysis was performed to achieve punctual associations between the black bean saponins and flavonoids concentrations to the antioxidant capacity and the antiproliferative activities. Total phenolic content and antioxidant capacity of extracts were higher when obtained from seed coats, mainly from the 3rd germination day. The extracts obtained from seed coats after 3 and 5 germination days inhibited all cancer cell lines proliferation with no cytotoxicity against control cells. Genistein was related with the activity against mammary cancer cells but flavonols and group B saponins were more related with hepatic and colon cancers. Non-glycosilated flavonols were related with antioxidant capacity.     

Radical scavenging and reducing properties of extracts of cashew shoots (Anacardium occidentale)

The total phenolic content and antioxidant activities of methanol, hexane and ethyl acetate extracts of the shoots of Anacardium occidentale were measured. Total phenolic content was assessed by the Folin–Ciocalteau assay whereas antioxidant activities were assessed by measuring the ability of the extracts to scavenge the ABTS^·+ and DPPH^· radicals, superoxide anion radicals and nitric oxide radicals as well as their ability to reduce ferric ions. Results indicated that the methanol extract of A. occidentale was the most potent reducing agent and radical-scavengers compared to the other two extracts. The ethyl acetate extract exhibited some antioxidant activities whereas the hexane extract is the least reactive. The order of the antioxidant potency of the plant extract is methanol > ethyl acetate > hexane. The methanol extract contained more than 7 fold of total phenolic content compared to the hexane and ethyl acetate extracts indicating the likely possibility that the observed antioxidant activities were partly contributed by the phenolics. The results suggest that the shoots of A. occidentale are a source of natural antioxidants.     

Analysis of flavonoids and phenolic acids in Greek aromatic plants: Investigation of their antioxidant capacity and antimicrobial activity

The phenolic fraction of plant extracts has been linked to their antioxidant capacity and antimicrobial activity. In the present paper, RP-HPLC with UV detection was employed to distinguish phenolic compounds from the other constituents of the plants examined. The phenolic substances were identified and quantified after comparison with reference standards. A GC–MS method is also presented for characterization of different phenolics as trimethylsilyl derivatives. The antioxidant capacity was determined, in dried plants and in their methanol extracts, with the Rancimat test using sunflower oil as substrate. Both pulverized plants and extracts showed antioxidant capacity. Total phenolic content in the extracts was determined spectrometrically applying the Folin-Ciocalteu assay. It ranged from 2.9 to 28.2 mg gallic acid/100 g dry sample. Antimicrobial activity of the extracts against selected microorganisms was also investigated.     

A systematic survey of antioxidant activity of 30 Chinese medicinal plants using the ferric reducing antioxidant power assay

The antioxidant activities and total phenolic contents of 30 Chinese medicinal plants were evaluated using the ferric reducing antioxidant power assay and the Folin–Ciocalteu method, respectively. The Chinese medicinal plants were extracted by the traditional method, boiling in water and also in 80% methanol. A significant and linear correlation coefficient between the antioxidant activity and the total phenolic content was found in both aqueous (R² = 0.7917) and methanol (R² = 0.7584) extracts. Phenolic compounds are thus a major contributor of antioxidant activity. Comparing the extraction efficiency of the two methods, the boiling water method extracted phenolic compounds more efficiently, and antioxidant activity of the extract was higher. It was found that the Chinese medicinal plants Rhodiola sacra Fu, the stem of Polygonum multiflorum Thunb. and the root of P. multiflorum Thunb. possessed the highest antioxidant activities and thus could be potential rich sources of natural antioxidants.     

Mung beans processed by solid-state bioconversion improves phenolic content and functionality relevant for diabetes and ulcer management

Mung bean substrate was enriched with phenolic antioxidants and levo-dihydroxy phenylalanine (l-DOPA) through solid-state bioconversion (SSB) by Rhizopus oligosporus, with the goal to enhance health-linked functionality. The alpha-amylase inhibition linked to diabetes management and Helicobacter pylori inhibition linked to peptic ulcer management were investigated in bioprocessed extracts. The protein content and β-glucosidase activity of the substrate which are indicators of effective fungal colonization, increased with growth. The phenolic content increase with growth was linked to fungal β-glucosidase activity, indicating phenolic mobilization. The antioxidant activity as measured by DPPH (1,1-diphenyl-2-picrylhydrazyl) inhibition method were high (65%) initially and increased to 90% on day 12, than maintained higher levels during the rest of growth. The antioxidant activity measured by β-carotene assay was high between days 4–8 when phenolic levels increased. Fungal-linked superoxide dismutase (SOD) activity was high in late stages indicating quenching of reactive oxygen species. The l-DOPA content was low during early growth stage (0.6–0.7 mg/g DW) and gradually doubled to 1.2 mg/g DW in late stages. The α-amylase inhibition potential was moderately high during early stages (days 0–2) followed by higher inhibition during days 4–10 which correlate to higher phenolic content. The change in the antimicrobial activities of the extracts against H. pylori was high on day 4 and was associated with high antioxidant activity but not high phenolic content. Elevated inhibition on day 8 directly correlated with high total phenolics content suggesting the role of phenolic mobilization. The major implication from this research is that SSB is a good strategy to improve the phenolic content of mung beans for enhanced functionality with improved antioxidant activity that contributes to α-amylase inhibition relevant to potential diabetes management and H. pylori inhibition linked to peptic ulcer management.Industrial relevanceSolid State Bioconversion (SSB) of mung bean by R. oligosporus is a good strategy to enhance ingredient functionality due to mobilization of phenolic antioxidants. Such enhanced phenolic antioxidant activity potentially contributes to health-relevant functionality such as amylase inhibition for diabetes management and H. pylori inhibition for peptic ulcer management. Optimization of such SSB systems at industrial scale can help large-scale low cost production of such health-relevant ingredients.     

Antioxidant activity of lactic-fermented Chinese cabbage

Lactic-fermented cabbage, similar to Kimchi in Korea, is a very popular fermented vegetable product in Taiwan and China. In this study, fermented cabbage prepared by a dry-salt method was first extracted with water and methanol. Antioxidant activity such as DPPH radical scavenging effects, reducing power and Fe²⁺-chelating ability of the solvent extracts of fermented cabbage was determined and the effect of fermentation on the change of antioxidant activity, total phenolic and total flavonoid content was also investigated. Results revealed that antioxidant activity observed on the Chinese cabbage mixture may vary with extraction solvents and fermentation. Generally, the methanol extract of the cabbage mixture showed a higher DPPH radical scavenging activity and reducing activity than the water extract. Although, fermentation did not alter the Fe²⁺-chelating ability and reducing activity of the methanol extract of the cabbage mixture, it reduced these same antioxidant activities in the water extract. Amongst the various extracts examined, the methanol extract of fermented cabbage showed the highest DPPH radical scavenging effect. On the other hand, the highest Fe²⁺-ion chelating and reducing activities were exerted by the methanol extracts of both the cabbage mixture and the fermented cabbage, which showed no significant difference (p < 0.05). Additionally, the type of solvent and fermentation were also found to affect the total phenolic and flavonoid content of the extracts. Fermentation increased the total phenolic content of the methanol extract, whilst reducing the total flavonoid content of the water extract. Furthermore, changes in the antioxidant activity observed on the extracts of the cabbage mixture and fermented cabbage did not coincide exactly with the total phenolic and total flavonoid content.     

Antioxidant activity and rosmarinic acid changes in salicylic acid-treated Thymus membranaceus shoots

In order to characterise the antioxidant activity of Thymus membranaceus Boiss. subsp. membranaceus, an endemic species in Southeast Spain, five different analytical methods were used. Water, methanol and hexane extracts obtained from 60-day-old in vitro-grown shoots were assayed for their antioxidative properties using DPPH (1,1-diphenyl-2-picrylhydrazyl radical), ABTS (2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonate), FRAP (ferric reducing antioxidant power), reducing power and conjugated diene assays. Total soluble phenol content, as well as rosmarinic acid, in the different extracts were also determined. Methanolic extracts exhibited the best antioxidant activity and the highest amounts of total soluble phenolics. A single application of salicylic acid (10 μM) on culture media resulted in an increase in rosmarinic acid and phenolic levels, which in turn improved the extracts’ antioxidant properties. These current findings open new opportunities for obtaining valuable natural antioxidants for commercial exploitation by using tissue culture systems.     

Antioxidant activity and total phenolics of edible mushroom extracts

Methanol and water crude extracts from Shiitake mushroom (Lentinus edodes) and straw mushroom (Volvariella volvacea) were investigated for their antioxidant capacity in three different assays, namely, the β-carotene and linoleic acid system, 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity, and inhibition of hemolysis of rat erythrocyte induced by peroxyl radicals. Among the four mushroom extracts, the water extract from L. edodes showed the most potent radical scavenging activity in each assay, showing 75.9% (at 20 mg/ml) in the β-carotene bleaching method, 55.4% in the DPPH radical scavenging method (at 6 mg/ml) and 94.9% of inhibition of erythrocyte hemolysis (at 5 mg/ml). Total phenolics in the water extracts were higher than that of the methanol ones. Positive correlations were found between total phenolic content in the mushroom extracts and their antioxidant activities. Edible mushrooms may have potential as natural antioxidants.