Effects of extraction solvent mixtures on antioxidant activity evaluation and their extraction capacity and selectivity for free phenolic compounds in barley (Hordeum vulgare L.)

Four kinds of solvent extracts from three Chinese barley varieties (Ken-3, KA4B, and Gan-3) were used to examine the effects of extraction solvent mixtures on antioxidant activity evaluation and their extraction capacity and selectivity for free phenolic compounds in barley through free radical scavenging activity, reducing power and metal chelating activity, and individual and total phenolic contents. Results showed that extraction solvent mixtures had significant impacts on antioxidant activity estimation, as well as different extraction capacity and selectivity for free phenolic compounds in barley. The highest DPPH* and ABTS*+ scavenging activities and reducing power were found in 80% acetone extracts, whereas the strongest *OH scavenging activity, O2*- scavenging activity, and metal chelating activity were found in 80% ethanol, 80% methanol, and water extracts, respectively. Additionally, 80% acetone showed the highest extraction capacity for (+)-catechin and ferulic, caffeic, vanillic, and p-coumaric acids, 80% methanol for (-)-epicatechin and syringic acid, and water for protocatechuic and gallic acids. Furthermore, correlations analysis revealed that TPC, reducing power, DPPH* and ABTS*+ scavenging activities were well positively correlated with each other (p < 0.01). Thus, for routine screening of barley varieties with higher antioxidant activity, 80% acetone was recommended to extract free phenolic compounds from barley. DPPH* scavenging activity and ABTS*+ scavenging activity or reducing power could be used to assess barley antioxidant activity.     

Lettuce and chicory byproducts as a source of antioxidant phenolic extracts

A process to obtain enriched antioxidant phenolic extracts from lettuce (baby, romaine, and iceberg cultivars) and chichory byproducts as a way to valorize these byproducts was developed. Two extraction protocols using water and methanol as solvent were used. Amberlite XAD-2 nonionic polymeric resin was used to purify the extracts. The extraction yield, phenolic content, and phenolic yield were evaluated as well as the antioxidant capacity of the extracts (DPPH, ABTS, and FRAP assays). Baby and romaine lettuce byproducts showed the highest water extract yields [27 and 26 g of freeze-dried extracts/kg of byproduct fresh weight (fw), respectively], whereas baby and iceberg lettuce showed highest methanol extract yields (31 and 23 g of freeze-dried extracts/kg of byproduct fw, respectively). Methanol extraction yielded a raw extract with a high phenolic content, the baby and chicory extracts being the richest with approximately 50 mg of phenolics/g of freeze-dried extract. Regarding the purified extracts, water extraction yielded a higher phenolic content, baby and chicory being also the highest with mean values of approximately 190 and 300 mg of phenolics/g of freeze-dried extract, respectively. Both raw and purified extracts from baby and chicory showed the higher antioxidant contents (DPPH, ABTS, and FRAP assays). The antioxidant capacity was linearly correlated with the phenolic content. The results obtained indicate that lettuce byproducts could be, from the industrial point of view, an interesting and cheap source of antioxidant phenolic extracts to funcionalize foodstuffs.     

Phenolic, flavonoid, and lutein ester content and antioxidant activity of 11 cultivars of chinese marigold

This study analyzed 11 Chinese cultivars of marigold to determine their major phytochemical contents and antioxidant activities. Dried marigold flowers were extracted with ethanol, ethyl acetate, and n-hexane and the extracts were analyzed by high-performance liquid chromatography-mass spectrometry and chemical methods to determine their lutein esters, phenolic and flavonoid contents, and antioxidant activity, respectively. The different cultivars of marigold showed considerable variations in their lutein ester contents, ranging from 161.0 to 611.0 mg/100 g of flower (dry basis). The lutein esters in marigolds consisted predominantly of six all trans-diesters, but small amounts of cis isomers of the respective diesters were also present. The different cultivars of marigold also showed marked variations in total phenols and flavonoids, as well as antioxidant and radical-scavenging activities. Ethanol was confirmed to be the best solvent for extracting both phenols and flavonoids from marigold flowers, while n-hexane was the worst. The ethanolic extracts also exhibited the highest antioxidant and radical-scavenging activities. The cultivar Xinhong had the highest phenolic and flavonoid contents and radical-scavenging activity, as well as one of the highest lutein contents and antioxidant activities.     

Antioxidant and antiradical activities in extracts of hazelnut kernel (Corylus avellana L.) and hazelnut green leafy cover

Phenolic compounds in the aqueous systems were extracted, from hazelnut kernel (HK) and hazelnut green leafy cover (HGLC), with 80% (v/v) ethanol (HKe and HGLCe) or 80% (v/v) acetone (HKa and HGLCa). The extracts were examined for their phenolic and condensed tannin contents and phenolic acid profiles (free and esterified fractions) as well as antioxidant and antiradical activities by total antioxidant activity (TAA), antioxidant activity in a beta-carotene-linoleate model system, scavenging of DPPH (2,2-diphenyl-1-picrylhydrazyl) radical, and reducing power. Significant differences (p < 0.05) in the contents of total phenolics, condensed tannins, and TAA existed among the extracts that were examined. HGLCa extract had the highest content of total phenolics (201 mg of catechin equivalents/g of extract), condensed tannins (542 mg of catechin equivalents/g of extract), and TAA (1.29 mmol of Trolox equivalents/g of extract) followed by HGLCe, HKa, and HKe extracts, respectively. Five phenolic acids (gallic acid, caffeic acid, p-coumaric acid, ferulic acid, and sinapic acid) were tentatively identified and quantified, among which gallic acid was the most abundant in both free and esterified forms. The order of antioxidant activity in a beta-carotene-linoleate model system, the scavenging effect on DPPH radical, and the reducing power in all extracts were in the following order: HGLCa > HGLCe > HKa > HKe. These results suggest that both 80% ethanol and acetone are capable of extracting phenolics, but 80% acetone was a more effective solvent for the extraction process. HGLC exhibited stronger antioxidant and antiradical activities than HK itself in both extracts and could potentially be considered as an inexpensive source of natural antioxidants.     

Effects of extraction methods on phenolic contents and antioxidant activity in aerial parts of Potentilla atrosanguinea Lodd. and quantification of its phenolic constituents by RP-HPLC

The effects of different solvent systems (methanol, ethanol, acetone, and their 50% aqueous concentrations) and extraction procedures (microwave, ultrasound, Soxhlet and maceration) on the antioxidant activity of aerial parts of Potentilla atrosanguinea were investigated by three different bioassays: 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS), 2,2'-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assays and ferric reducing antioxidant potential (FRAP). The 50% aqueous ethanol extracts exhibited strong antioxidant activity measured in terms of Trolox equivalent antioxidant capacity (TEAC) [(54.34 to 122.96, 29.82 to 101.22 and 13.64 to 41.43) mg of Trolox/g] with ABTS (*+), DPPH (*) and FRAP assays, respectively. In general, TEAC of Soxhlet extracts was found to be 1.8 and 3 times higher than ultrasound and maceration but slightly (1.2 times) higher than microwave. A positive correlation (r(2) = 0.931 to 0.982) was observed between total polyphenol (TPC) and total flavonoid (TFC) contents which ranged between 26.7 to 30.7 mg/g gallic acid equivalent and 16.8 to 20.8 mg/g quercetin equivalent respectively, with antioxidant activity. In addition, some of its bioactive phenolic constituents which contribute largely toward antioxidant potential such as chlorogenic acid, catechin, caffeic acid, p-coumaric acid and quercetin were also quantified in different extracts by RP-HPLC.     

Optimization of simultaneous flavanol, phenolic acid, and anthocyanin extraction from grapes using an experimental design: application to the characterization of champagne grape varieties

Optimization of polyphenol extraction from grape skin, seed, and pulp was performed on Vitis vinifera L. cv. Pinot Noir, by response surface methodology using a Doehlert design. An acidified mixture of acetone/water/methanol was the best solvent for simultaneous extraction of major polyphenol groups from all berry parts, while optimum extraction times and solid-to-liquid ratios varied according to the part. The determined composition from the model agreed with independent experimental results. Analysis of the three Champagne grape varieties showed that proanthocyanidins were the major phenolic compounds in each part (60-93%). The total berry proanthocyanidin content was highest in Pinot Meunier (11 g kg(-1)) and lowest in Chardonnay (5 g kg(-1)), but Pinot Meunier pulp contained lower amounts of proanthocyanidins and phenolic acids (210 and 127 mg kg(-1) berry, respectively) than that of the other two varieties. The berry anthocyanin content was equivalent in both Pinot Noir and Pinot Meunier (632 and 602 mg kg(-1), respectively).     

Antioxidant activity of extracts obtained from residues of different oilseeds

Residues of the oil-extracting process of oilseeds contain bioactive substances such as phenolic compounds, which could be used as natural antioxidants for the protection of fats and oils against oxidative deterioration. Thus, the extraction of such constituents from residual material can be considered to contribute to the added value of these residues, which could justify their isolation. In the present work the fat-free residues of eight different oilseeds whose oils are usable for nutritional applications, and also as renewable resources, were extracted with 70% methanol, 70% acetone, water, and ethyl acetate/water, respectively. The resulting extracts were investigated regarding their content of total phenolic compounds by the Folin-Ciocalteau assay, sinapine, flavanoids, and the UV-absorption spectra. Further, the antioxidant activity of the extracts was characterized by the DPPH method, the beta-carotene-linoleic acid assay, and ESR investigations. The fat-free residues of the different oilseeds contained considerable amounts of extractable substances. The yields decreased with decreasing polarity of the solvent in the order water, 70% methanol, 70% acetone, and ethyl acetate. The ratio of total phenolic compounds to the extractable compounds ranged from 3 to 19%. There was no significant correlation between the amount of total extractable compounds and the total phenolic compounds (p < 0.001). All extracts showed remarkable antioxidant activities determined with the different methods. The effects depended strongly on the solvent used for the extraction as well as on the extracted residue. A correlation between the methods used for the characterization of the antioxidant activity and the composition of the residues could not be shown.     

Total Phenolic Content and Antioxidant Capacity of Germinated,Popped, and Cooked Huauzontle (Chenopodium berlandieri spp. nuttalliae) Seeds

Raw, germinated, popped, and cooked huauzontle (Chenopodium berlandieri spp. nuttalliae) seeds were analyzed for the contents of phenolics extracted with water (WE), methanol, 1:1 (v/v) methanol/water (MWE), and 1.2M HCl in 1:1 (v/v) methanol/water (HMWE); radical scavenging capacity measured by the 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) and 2,2′‐azino‐bis(3‐ethylbenzothiazoline‐6‐sulphonic acid) (ABTS) methods was studied. The effect of the system solvents used for the accurate quantification of antioxidant content and capacity showed that for raw, germinated, and cooked extracts, water gave the highest yield of total phenolic content, and MWE could recover the highest yield in popped extracts. Thermal treatments increased the flavonoid content more in all extracts than did the germinating process, with values ranging from 10 to 620 μg/g db of quercetin equivalents. However, all treatments significantly decreased (P < 0.05) the total phenolics (from 3,010 μg of gallic acid equivalents/g db in raw seeds WE to 710 μg/g db in germinated seeds MWE). HMWE in all treatments showed the highest values (up to 95.41%) by the DPPH method. With the ABTS method, germinated and popped MWE showed the highest values (up to 2,740mM Trolox/kg db). Based on these results, huauzontle seeds represent a useful potential ingredient for consumer health, because it has been shown to be a good source of total phenolic content having high antioxidant activity; moreover, for further studies, water appears to be effective as an extraction solvent of phenolic compounds.     

Water-deficit impact on fatty acid and essential oil composition and antioxidant activities of cumin (Cuminum cyminum L.) aerial parts

This study is designed to examine the effect of water deficit on growth, fatty acid and essential oil composition, and antioxidant activities of Cuminum cyminum aerial part extracts. Plants were treated with different levels of water deficit: control (C), moderate water deficit (MWD), and severe water deficit (SWD). Plant growth (height, fresh and dry matter weights) as well as yield components were significantly increased under moderate water deficit and conversely reduced at severe level. Total fatty acid content decreased significantly with severity of constraint. Drought reduced considerably the proportions of major fatty acids and the unsaturated to saturated fatty acid ratio. The essential oil yield was 0.14% (based on the dry weight); it increased by 2.21-fold at MWD but decreased by 42.8% under SWD in comparison to the control. Drought results in the modification of the essential oil chemotype from 1-phenyl-1-butanol to 1-phenyl-1,2-ethanediol. Antioxidant activities of the acetone extracts were determined by two complementary test systems, namely, DPPH and β-carotene/linoleic acid. The highest activity was exhibited by moderately stressed plants and was reduced significantly under SWD. In control plants, the total phenolic amount was 10.23 mg GAE/g DW, which increased by 1.5-fold under MWD and decreased by 42% under SWD.     

Evaluation of Saskatoon berry (Amelanchier alnifolia Nutt.) cultivars for their polyphenol content, antioxidant properties, and storage stability

The polyphenol contents and antioxidant activities were assessed for 17 Saskatoon berry cultivars grown in Canada in fresh and stored fruits at -20 degrees C for 9 months. The Nelson cultivar was the richest in total polyphenol, anthocyanin, and procyanidin contents (801, 382, and 278 mg/100 g fresh weight, respectively). This cultivar was characterized also by the highest antioxidant potential measured with DPPH and ABTS radicals (2.8 and 5.0 mM/100 g FW, respectively). Cultivar-dependent changes in polyphenol content after freezer storage were observed. In the Lee 2 cultivar, significant increases in anthocyanin and flavonol contents occurred, while in the Lee 3 and Martin cultivars considerable decreases were observed. During the freezer storage, the antioxidant activity remained unchanged except for the Smokey which showed to be the most sensitive cultivar during storage. The Nelson and Lee 2 were the most stable cultivars during storage. The high polyphenol content and antioxidant activity of the Nelson cultivar and its good storage stability would make this cultivar the optimal material for fruit growers and food producers.     

Capabilities of Oat Extracts in Inhibiting Cholesterol and Long Chain Fatty Acid Oxidation During Heating

The antioxidant activities of oat groat extracts using different solvents were investigated. For acetone, hexane, and methanol extracts, the total phenolic compound contents were 12.83, 8.56, and 26.17 μg of catechin equivalent/g, respectively. Their corresponding free radical scavenging activities measured using the DPPH (2,2'‐diphenyl‐1‐picrylhydrazyl) method were 0.68, 0.35, and 0.79 μmol of Trolox equivalent/g, respectively. All oat extracts presented significantly greater capability in preventing cholesterol oxidation than the control (no extract added) during heating at the three levels of addition (1, 5, and 10 mg). The capability of the hexane or acetone extract in preventing cholesterol oxidation was not as effective as the methanol extract. In the docosahexaenoic acid (DHA, C22:6) oxidation test, all oat extracts at the level of 5 and 10 mg had greater inhibition capability on DHA oxidation than the control (DHA only). No significant inhibition was found for the hexane and acetone extract at the level of 1 mg, except for the methanol extract. The capabilities of oat extracts to inhibit oxidation of cholesterol and DHA from high to low was methanol, acetone, and hexane extract, which agreed with their free radical scavenging activities and total phenolic compound contents.     

Extraction of Antioxidants from Wheat Bran Using Conventional Solvent and Microwave-Assisted Methods

Total phenolic and tocopherol contents and free radical scavenging capability of wheat bran extracted using conventional and microwave-assisted solvent extraction methods were studied. Three different solvents (methanol, acetone, and hexane) were used in the conventional solvent extraction. Methanol was the most effective solvent, producing higher extraction yield (4.86%), total phenolic compound content (241.3 μg of catechin equivalent/g of wheat bran), and free radical scavenging capability (0.042 μmol of trolox equivalent/g of wheat bran) than either acetone or hexane. However, there was no significant difference in the total tocopherol contents (13.6–14.8 μg/g of wheat bran) among the three different solvent extraction methods. Microwave-assisted solvent extraction using methanol significantly increased the total phenolic compound content to 467.5 and 489.5 μg of catechin equivalent; total tocopherol content to 18.7 and 19.5 μg; and free radical scavenging capability to 0.064 and 0.072 μmol of trolox equivalent/g of wheat bran at extraction temperatures of 100 and 120°C, respectively. However, extraction yields of conventional methanol solvent and microwave-assisted methanol extractions at different temperatures were not significantly different.     

茶花粉酶法破壁工艺提高提取物抗氧化活性及多酚含量

为了建立蜂花粉抗氧化活性物质的提取工艺并探索其抗氧化活性与多酚含量的关系,该文研究了破壁用酶、提取溶剂、超声波处理对茶花粉提取液多酚含量及其抗氧化活性的影响。结果表明,茶花粉经纤维素酶破壁后其上清液具有较高的还原力和DPPH自由基清除能力;与温水和酸处理相比,纤维素酶破壁沉淀物经乙醇提取后,溶液多酚含量较高、抗氧化活性较强;茶花粉不同提取方式多酚含量与2种抗氧化活性指标具有一定的相关性（r=0.8685及r=0.7600）（p＞0.05）;与乙醇提取和水提取相比,纤维素酶破壁处理结合乙醇提取将茶花粉的多酚含量、还原力及DPPH自由基清除能力分别提高1.82倍、2.17倍、1.4倍和1.56倍、1.38倍、11倍,且二者对混合物还原力、DPPH自由基清除能力及多酚含量的贡献比例分别为1.6：1、3：1、1.08：1。该研究结果可为花粉资源的开发利用提供参考。     

Characterization of the constituents and antioxidant activity of Brazilian green tea (Camellia sinensis var. assamica IAC-259 cultivar) extracts

Freeze-dried extracts from Camellia sinensis var. assamica IAC-259 cultivar named Brazilian green tea were prepared by hot water and ultrasound-assisted extractions using leaves harvested in spring and summer. Their caffeine and catechin contents were measured by high performance liquid chromatography-diode array detector. The antioxidant activity of the major green tea compounds and Brazilian green tea extracts was evaluated using a 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. The levels of caffeine were higher in the summer samples (p < 0.05); otherwise, there were no significant variations related to the catechin contents between spring and summer samples. The sonication method using water/acetone as solvent had a high efficiency to extract not only epigallocatechin gallate but also epicatechin gallate (p < 0.05). Antioxidant activities of the Brazilian green tea extracts were not significantly different among seasons and extraction systems. The antioxidant data (IC50) of the Brazilian green tea extracts showed a significant correlation with their epigallocatechin gallate and epicatechin gallate contents (p < 0.05).     

Antioxidant activities of phenolic,proanthocyanidin, and flavonoid components in extracts of Cassia fistula

Cassia fistula L., a semi-wild Indian Labernum, is widely cultivated in Mauritius as an ornamental tree for its beautiful bunches of yellow flowers and also used in traditional medicine for several indications. The total phenolic, proanthocyanidin, and flavonoid contents, and the antioxidant activities, of fresh vegetative and reproductive organs of Cassia fistula harvested at different stages of growth were determined using the Trolox equivalent antioxidant capacity (TEAC) and ferric-reducing antioxidant power (FRAP) assays. The antioxidant activities were strongly correlated with total phenols (TEAC r = 0.989; FRAP r = 0.951) in all organs studied, and with proanthocyanidins (TEAC r = 0.980; FRAP r = 0.899) in reproductive organs including fruits. The antioxidant activities of reproductive parts were higher than those of the vegetative organs, with the pods having highest total phenolic, proanthocyanidin, and flavonoid contents and antioxidant potentials (TEAC = 992 +/- 0.4 micromol/g dry weight; FRAP = 811 +/- 23 micromol/g dry weight).     

Determination of antioxidant and antimicrobial activities of Rumex crispus L. extracts

The antioxidant activities, reducing powers, 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activities, amount of total phenolic compounds, and antimicrobial activities of ether, ethanol, and hot water extracts of the leaves and seeds of Rumex crispus L. were studied. The antioxidant activities of extracts increase with increasing amount of extracts (50-150 microg). However, the water extracts of both the leaves and seeds have shown the highest antioxidant activities. Thus, addition of 75 microg of each of the above extracts to the linoleic acid emulsion caused the inhibition of peroxide formation by 96 and 94%, respectively. Although the antioxidant activity of the ethanol extract of seed was lower than the water extract, the difference between these was not statistically significant, P > 0.05. Unlike the other extracts, 75 microg of the ether extract of seeds was unable to show statistically significant antioxidant activity, P > 0.05 (between this extract and control in that there is no extract in the test sample). Among all of the extracts, the highest amount of total phenolic compound was found in the ethanol extract of seeds, whereas the lowest amount was found in the ether extract of seeds. Like phenolic compounds, the highest reducing power and the highest DPPH scavenging activity were found in the ethanol extract of seeds. However, the reducing activity of the ethanol extract of seeds was approximately 40% that of ascorbic acid, whereas in the presence of 400 microg of water and ethanol extracts of seeds scavenging activities were about 85 and 90%, respectively. There were statistically significant correlations between amount of phenolic compounds and reducing power and between amount of phenolic compounds and percent DPPH scavenging activities (r = 0.99, P < 0.01, and r = 0.864, P < 0.05, respectively) and also between reducing powers and percent DPPH scavenging activities (r = 0.892, P < 0.05). The ether extracts of both the leaves and seeds and ethanol extract of leaves had shown antimicrobial activities on Staphylococcus aureus and Bacillus subtilis. However, none of the water extracts showed antimicrobial activity on the studied microorganisms.     

Determination of total phenolic content and antioxidant activity of garlic (Allium sativum) and elephant garlic (Allium ampeloprasum) by attenuated total reflectance-Fourier transformed infrared spectroscopy

The total phenolic contents and antioxidant activities of garlics from California, Oregon, Washington, and New York were determined by Fourier transform infrared (FT-IR) spectroscopy (400-4000 cm(-1)). The total phenolic content was quantified [Folin-Ciocalteu assay (FC)] and three antioxidant activity assays, 2,2-diphenyl-picrylhydrazyl (DPPH) assay, Trolox equivalent antioxidant capacity (TEAC) assay, and ferric reducing antioxidant power (FRAP), were employed for reference measurements. Four independent partial least-squares regression (PLSR) models were constructed with spectra from 25 extracts and their corresponding FC, DPPH, TEAC, and FRAP with values for 20 additional extracts predicted (R > 0.95). The standard errors of calibration and standard error of cross-validation were <1.45 (TEAC), 0.36 (FRAP), and 0.33 μmol Trolox/g FW (DPPH) and 0.55 mg gallic acid/g FW (FC). Cluster and dendrogram analyses could segregate garlic grown at different locations. Hydroxyl and phenolic functional groups most closely correlated with garlic antioxidant activity.     

Comparative analysis of polyphenolic profiles and antioxidant and antimicrobial activities of tunisian pome fruit pulp and peel aqueous acetone extracts

Pome trees, apple, pear, and quince, are classified into the subfamily Pomoideae, belonging to the Rosaceae family. Their autumnal fruits are consumed worldwide in different forms, that is, fresh or transformed into jams, jelly, juices, etc. Their well-established beneficial properties to human health were found mainly related to their phenolic content. Pulp and peel aqueous acetone extracts obtained from Tunisian fruits at commercial maturity were comparatively evaluated for their phenolic profiles and antioxidant and antimicrobial potentials. The phenolic compounds present in the extracts were identified and quantified using RP-HPLC-DAD and ESI-MS techniques. Significant differences in the chromatographic profiles among these fruits, as well as between pulp and peel extracts of each fruit, were observed. Quince, followed by 'Red Delicious', peel extracts showed the highest phenolic content (160.33 and 110.90 mg/100 g of fresh weight). The stronger inhibitory effect on DPPH radicals corresponded to those obtained from peel materials. A comparative analysis of the antimicrobial potential against a range of microorganism strains was also carried out. Staphylococcus aureus, Pseudomonas aeruginosa, and Bacillus cereus were the most sensitive to the active extracts. Among the examined phenolic extracts, 'Red Delicious' and quince peels showed the highest effects for inhibiting bacteria growth. Minimum inhibitory and bactericide concentrations ranged from 10(2) to 10(4) microg of polyphenol/mL. Red skin apple and quince peels could be of great interest as important antioxidant and antimicrobial polyphenol sources.     

Aorta and liver changes in rats fed cholesterol-containing and raw vegetable-supplemented diets: experiments in vitro and in vivo

The aim of this investigation was to compare the liver and aorta changes in rats fed cholesterol-containing diets and the possible improvement when diets would be supplemented with frequently used raw vegetables. The phenolic compounds of three vegetables in methanol-water (1:1) fraction were characterized using electrospray ionization mass spectra (ESI-MS). Results showed that the content of polyphenols, flavonoids, quercetin, flavanols, tannins, and ascorbic acid varied for garlic and white and red onions ranging from 6.68 to 18.08 mg GAE/g DW, 490.4-701.0 μg CE/g DW, 281.2-1100.0 μg, 32.40-41.30 μg CE/g DW, 2.88-3.12 mg CE/g DW, 1.87-2.33 mg AA/g DW, 1388.2-1442.3 μg CGE/g DW, respectively. The radical scavenging capacities (μM TE/g DW) for the same investigated vegetables for ABTS, FRAP, CUPRAC, and DPPH assays ranged from 48.78 to 92.42, 9.41-28.56, 3.06-10.41, and 6.49-23.42, respectively. Good correlations were observed between the phenolic contents and the radical scavenging capacities of the vegetables. The interaction between BSA and quercetin, BSA and garlic and onions extracts was measured by 3-dimensional fluorescence (3D-FL) and Fourier transform infrared (FT-IR) spectroscopy. The highest polyphenol content was found in methanol/water fraction of onions and garlic; therefore, for the investigation of in vitro interactions with BSA only polyphenols of this fraction were used. For in vivo studies, 30 male Wistar rats were divided into 5 groups each of 6 and named Control, Chol, Chol/Garlic, Chol/OnionRed, and Chol/OnionWhite. During 6 weeks, the rats of all 5 groups were fed a basal diet (BD). The rats of the Control group were fed the BD only. The BD of the Chol group was supplemented with 10 g/kg of nonoxidized cholesterol (NOC). Each of the other three groups was supplemented with 10 g/kg of NOC and 500 mg of raw fresh garlic, 500 mg of raw fresh red onion, and 500 mg of raw fresh white onion on 1 kg of body weight for Chol/Garlic, Chol/OnionRed, and Chol/OnionWhite diet groups, respectively. In order to detect the changes in the liver and aorta, a histological procedure was applied, and the liver enzymes were determined and compared. It was found that the main changes vs the Control group were in the liver of rats fed the cholesterol-containing diet without vegetable supplementation. Significantly less histological changes in the liver and lower level of liver enzymes vs those of the Chol group were detected in rats of the Chol/Garlic group (P < 0.05). The interaction between the polyphenol extract of garlic and BSA in vitro showed its strong ability comparable with that of quercetin to quench the intrinsic fluorescence of BSA. In conclusion, all studied vegetables showed protective effects, but raw garlic supplemented with cholesterol-containing diets significantly prevented the aorta and liver damages of rats.     

广东石豆兰不同溶剂提取物抗氧化及与总黄酮、总酚含量的关系

为明确广东石豆兰的抗氧化能力及抗氧化成分,以鳞茎为材料,以甲醇、乙醇、丙酮和乙酸乙酯为提取剂得到4种提取物,测定了4种提取物中总黄酮、总酚含量及其抗氧化活性,并分析了两者之间的关系。结果表明,石豆兰总酚含量高于总黄酮,乙醇为总酚和总黄酮2种物质的最佳提取溶剂;甲醇提取物对羟基自由基清除力和对Fe²⁺的螯合力最强,对DPPH自由基清除效果最差;丙酮提取物具有最强的总还原力和清除超氧阴离子的能力,而清除羟基自由基能力最弱;乙酸乙酯提取物清除DPPH自由基的能力最强,但总还原力、清除超氧阴离子的能力、Fe²⁺的螯合力最弱。此外,除了DPPH自由基外,其他4个抗氧化指标与总黄酮或总酚含量呈正相关(0.185<r<0.969),总还原力与总黄酮含量呈显著相关。本研究结果为广东石豆兰抗氧化物质的提取及进一步开发利用提供了参考依据。