Solvent effects on phenolic contents and biological activities of the halophyte Limoniastrum monopetalum leaves

Limoniastrum monopetalum is a traditional medicinal species which leaf infusion exhibits antidysenteric properties against infectious diseases. In this study, ten kinds of leaf extracts were used to examine the effect of extraction solvent system with varying polarities on polyphenol contents and DPPH scavenging activity. Then the superoxide scavenging activity and the reducing power of the most promising solvent extracts were evaluated too. Moreover, the efficiency of the best leaf extract has been investigated against pathogenic bacteria and yeast. Eventually leaf extract was hydrolyzed by acid and the phenolics identified by RP-HPLC. Results showed that phenolic contents and antioxidant activities varied considerably as function of solvent polarity. Leaf extract using pure methanol showed the highest polyphenol content (15.85 mg GAE/g DW). Moreover, antiradical capacities against DPPH and superoxide, and reducing power were maxima in acetone/water (8:2) of leaf extract. However, the latter showed a slight antimicrobial activity against human pathogen strains such as Staphylococcus aureus, Micrococcus luteus and Candida holmii. The HPLC analysis revealed several phenolic compounds in L. monopetalum leaf including vanillic and gallic acids as major phenolics. Our findings identified the appropriate solvent for extracting halophyte phenolics which might provide a rich and novel source of natural antioxidants as food additives replacing synthetic ones in food industry.     

Polyphenol composition and antioxidant activity of cumin (Cuminum cyminum L.) seed extract under drought

This research evaluated the effect of drought on total and individual polyphenol contents as well as the antioxidant activities of cumin (Cuminum cyminum L.) seeds of 2 geographic origins, Tunisia (TCS) and India (ICS). Plants were treated with different levels of water deficit: control. Our results indicated that, in both varieties, moderate water deficit (MWD) improved the number of umbels per plant as well as the number of umbellets per umbel and the seed yield, in comparison to the control, but it decreased under severe water deficit (SWD). Besides, total phenolic contents were higher in the treated seeds and drought increased the level of total and individual polyphenols. This increase was appreciably more important in TCS than in ICS. Moreover, antioxidant activities of the extracts were determined by 4 different test systems, namely 2,2-diphenyl-1-picrylhydrazyl, β-carotene/linoleic acid chelating, and reducing power assays, and showed that treated seeds exhibited the highest activity, for both TCS and ICS.     

Antioxidant activities of buckwheat extracts

The antioxidant activities of buckwheat (Fagopyrum esculentum Möench) extracts were evaluated and compared with butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT) and tertiary butylhydroquinone (TBHQ) using a β-carotene bleaching assay, a 2,2-diphenyl-β-picrylhydrazyl (DPPH) assay and the Rancimat method. Buckwheat was extracted with solvents of different polarities. The methanol extract showed the highest antioxidant activity coefficient (AAC) of 627 ± 40.0 at 200 mg/l by the β-carotene bleaching method and longest induction time of 7.0 ± 0.2 h by the Rancimat method. The acetone extract showed the highest total phenolics of 3.4 ± 0.1 g catechin equivalents/100 g and the highest scavenging activity of 78.6 ± 6.2% at 0.1 mg/ml by the DPPH method. The properties of the extracting solvents significantly affected the yield, total phenolics and antioxidant activity of buckwheat extract.     

Antioxidant activity and phenolic content of phenolic rich fractions obtained from black cumin (Nigella sativa) seedcake

The antioxidant activities of crude methanolic extract (CME) and its fractions using ethyl acetate (EAF), hexane (HF) and water (WF) of black cumin seedcake were investigated. DPPH radical scavenging activity, β-carotene–linoleate bleaching, and inhibition of corn oil oxidation were used to evaluate the antioxidant capacity. The total phenolics were found to be 78.8, 27.8, 32.1 and 12.1 mg gallic acid equivalents (GAE)/g in EAF, CME, WF and HF, respectively. The CME and EAF exhibited the highest DPPH followed by WF and HF. The extract/fractions showed high effect on reducing the oxidation of β-carotene. The effect of extract/fractions on the oxidative stability of corn oil at 70 °C was tested in the dark and compared with butylated hydroxyanisole (BHA). The oil peroxide and anisidine values were generally lower with addition of PRFs in comparison to a control. The predominant phenolic compounds identified by HPLC–DAD in CME and WF of black cumin seedcake were hydroxybenzoic, syringic and p-cumaric acids.     

Selection of the Solvent and Extraction Conditions for Maximum Recovery of Antioxidant Phenolic Compounds from Coffee Silverskin

The extraction of antioxidant phenolic compounds from coffee silverskin (CS) was studied. Firstly, the effect of different solvents (methanol, ethanol, acetone, and distilled water) on the production of antioxidant extracts was evaluated. All the extracts showed antioxidant activity (FRAP and DPPH assays), but those obtained with methanol and ethanol had significantly higher (p?<?0.05) DPPH inhibition than the remaining ones. Due to the lower toxicity, ethanol was selected as extraction solvent, and further experiments were performed in order to define the solvent concentration, solvent/solid ratio, and time to maximize the extraction results. The best condition to produce an extract with high content of phenolic compounds (13 mg gallic acid equivalents/g CS) and antioxidant activity [DPPH?=?18.24 μmol Trolox equivalents/g CS and FRAP?=?0.83 mmol Fe(II)/g CS] was achieved when using 60 % ethanol in a ratio of 35 ml/g CS, during 30 min at 60–65 °C.     

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.     

青钱柳叶活性成分的抗氧化活性及UPLC-QTOF-MS/MS分析

利用96孔板法测定青钱柳叶不同溶剂(水、70%乙醇、乙酸乙酯和正己烷)提取物中总酚、总黄酮含量及抗氧化活性(DPPH自由基清除能力、还原能力、总抗氧化能力),考察酚类物质含量与抗氧化活性的相关性,并采用超高效液相色谱-四极杆飞行时间串联质谱(ultra performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spetrometry,UPLC-QTOF-MS/MS)分析提取物中主要活性成分。结果表明:不同提取物中总酚、总黄酮含量及抗氧化活性存在显著性差异且70%乙醇溶液提取物表现出最高的总酚(219.01 mg GAE/g)、总黄酮含量(7.23 mg CE/g)及最强的DPPH自由基清除能力(35.46 mg TE/g)和还原能力(1.89 mmol Fe SO_4/g);总酚、总黄酮含量与DPPH自由基清除能力、还原能力之间呈正相关,与总抗氧化能力呈显著负相关,表明多酚类物质是青钱柳中主要的抗氧化剂。UPLC-QTOF-MS/MS分析70%乙醇溶液提取物并初步鉴定出22种化合物,包括2种有机酸、4种酚酸、5种黄酮、8种三萜皂苷类和3种酯类,其中酚酸和黄酮类化合物是主要的抗氧化活性成分,有机酸、三萜皂苷及酯类化合物可能是潜在的抗氧化活性成分。     

Antioxidant activity of lettuce tree (Pisonia morindifolia R.Br.) and tamarind tree (Tamarindus indica L.) and their efficacy in peanut oil stability

Different solvent extracts of lettuce tree (Pisonia morindifolia R. Br.) and tamarind tree (Tamarindus indica L.) were tested for antioxidant activities. The extracts exhibited effective reducing power and higher radical scavenging efficacy against DPPH and hydroxyl radicals. They also showed metal chelating ability and inhibited peroxidation in the β-carotene/linoleic acid emulsion system. The extracts contained considerable levels of vitamin C, vitamin E, total phenolics, tannins, and total flavonoids estimated through standard spectrophotometric methods. As the acetone and methanol extracts of lettuce and tamarind tree recorded pronounced activities, their protective effects in stabilizing peanut oil were tested in terms of their peroxide value, free fatty acid contents, and p-anisidine values in comparison with the synthetic antioxidants butylated hydroxyanisole and butylated hydroxytoluene. Additionally, the antioxidant activity of the extract-treated oil samples and their phenolic contents were monitored to obtain a complete perspective of the influence of the phenolic compounds in oil stability. Results indicated that the selected leafy vegetables, besides acting as good sources of antioxidants, may serve as substitute for synthetic antioxidants in the stabilization of peanut oil.     

Effects of Various Heat Treatments on Phenolic Profiles and Antioxidant Activities of Pleurotus eryngii Extracts

Free (FP) and bound phenolics (BP) were extracted from freeze dried (FD), oven dried (OD), as well as boiling treated (BT) Pleurotus eryngii samples. Free, bound, total phenolics were quantified using Folin–Ciocalteau assay. Qualitative and quantitative analysis of phenolic compounds were carried out using high‐performance liquid chromatography (HPLC) coupled with diode array detector (DAD), and a total of 8 phenolic compounds were detected. Free phenolic contents followed the order: Freeze‐dried free phenolics (FDFP) > Oven‐dried free phenolics (ODFP) > Boiling‐treated free phenolics (BTFP), and ranged from 95.42 (BTFP) to 442.50 (ODPF) μg gallic acid equivalents (GAE)/g dry weight (DW). Bound and total phenolic contents followed the order: FD > OD > BT, and ranged from 218.33 (BTBP) to 774.17 (FDBP) and 313.75 (BT total phenolics) to 1090.42 (FD total phenolics) μg GAE/g DW. Bound phenolics contributed 49.76% (OD), 69.59% (BT), and 71% (FD) of the total phenolic contents. All free and bound phenolic extracts were investigated for their antioxidant activities by 3 different assays, 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) radical scavenging activity, reducing power, and superoxide anion radical scavenging activity. FDFP showed strongest DPPH radical scavenging activity (IC₅₀ at 32.61 μg/mL), ODFP showed strongest reducing power (IC₅₀ at 26.31 μg/mL), and BTBP showed strongest superoxide anion radical scavenging activity (IC₅₀ at 14.07 μg/mL).     

Antioxidant activity and contents of essential oil and phenolic compounds in flowers and seeds of Alpinia zerumbet (Pers.) B.L. Burtt. & R.M. Sm

Alpinia zerumbet leaves and rhizomes have been extensively studied for their chemical compositions and biological activities. However, less attention has been given to its flowers and seeds. In our study, essential oil, total phenolics and antioxidant capacities assayed by 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging and β-carotene bleaching methods were evaluated in flowers and seeds of A. zerumbet. In addition, their phenolic composition was determined by GC–MS and HPLC. 1,8-Cineol, camphor, methyl cinnamate and borneol were the major constituents in flower oils, whereas the main components in seeds oil were α-cadinol, T-muurolol, α-terpineol, δ-cadinene and terpinene-4-ol. The results showed that the hexane extract of flowers contained a significantly higher quantity of dihydro-5,6-dehydrokawain (DDK) than that of seeds. Total phenolic contents of flower and seed extracts were measured as 56.7 and 13.7 mg gallic acid equivalent per gram extract, respectively. The ethyl acetate extract of flowers and seeds possessed a high antiradical activity and prevented the bleaching of β-carotene. The HPLC analysis indicated that p-hydroxybenzoic acid, ferulic acid and syringic acid were the predominant phenolics in the ethyl acetate extract of flowers, whilst p-hydroxybenzoic acid, syringic acid and vanillin were the major phenolics in seeds.     

Antioxidant activity of the differentially processed seeds of Jack bean (<Emphasis Type="Italic">Canavalia ensiformis</Emphasis> L. DC)

Antioxidant activity of 70% acetone extracts of raw and processed seeds of Jack bean (Canavalia ensiformis L. DC) was evaluated by various in vitro antioxidant assays, including total antioxidant, free radical scavenging, reducing power, metal ion chelating, β-carotene/linoleic acid bleaching, and antihemolytic activities. The total phenolics and tannin contents were higher in the extract of seeds processed by autoclaving with 1% ash solution (3.2 and 1.6 g/100 g extract, respectively). In general, all the extracts of processed seeds exhibited higher activity in various antioxidant systems, when compared to raw seeds but significant differences were noticed between processing methods. The extract of seeds autoclaved with 1% sugar solution showed higher DPPH radical scavenging activity (IC₅₀ 10.6 mg/mL). Interestingly, the extract of dry heated seeds registered higher inhibition of hemolysis (76.1%) compared to standards butylated hydroxyanisole (BHA) (66.2%) and α-tocopherol (59.3%) at the concentration of 500 μg/mL.     

Reutilization of mango byproducts: study of the effect of extraction solvent and temperature on their antioxidant properties

Mango biowastes, obtained after processing, contain large amounts of compounds with antioxidant activity that can be reused to reduce their environmental impact. The present study evaluates the effect of solvent (methanol, ethanol, acetone, water, methanol:water [1:1], ethanol:water [1:1], and acetone:water [1:1]), and temperature (25, 50, and 75 °C) on the efficiency of the extraction of antioxidants from mango peel and seed. Among the factors optimized, extraction solvent was the most important. The solvents that best obtained extracts with high antioxidant capacity were methanol, methanol:water, ethanol:water, and acetone:water (β-carotene test, antioxidant activity coefficient 173 to 926; thiobarbituric acid reactive substances test, inhibition ratio 15% to 89%; 2,2'-azino-bis-(3-ethylbenzothiazoline)-6-sulfonic acid ABTS(·+); and 2,2-diphenyl-1-picrylhydrazyl DPPH· scavenging, 7 to 22 and 8 to 28 g trolox equivalent antioxidant capacity [TE] per 100 g mango biowaste on a dry matter basis [DW]). Similarly, the flavonoid (0.21 to 1.4 g (+)-catechin equivalents per 100 g DW), tannin (3.8 to 14 g tannic acid equivalents per 100 g DW), and proanthocyanidin (0.23 to 7.8 g leucoanthocyanidin equivalents per 100 g DW) content was highest in the peel extracts obtained with methanol, ethanol:water, or acetone:water and in the seed extracts obtained with methanol or acetone:water. From the perspective of food security, it is advisable to choose ethanol (which also has a notable antioxidant content), ethanol:water, or acetone:water, as they are all solvents that can be used in compliance with good manufacturing practice. In general, increasing temperature improves the capacity of the extracts obtained from mango peel and seed to inhibit lipid peroxidation; however, its effect on the extraction of phytochemical compounds or on the capacity of the extracts to scavenge free radicals was negligible in comparison to that of the solvent. PRACTICAL APPLICATION: There are many antioxidant compounds in mango peel and seed, and they could be used as a natural and very inexpensive alternative to synthetic food additives. However, the conditions in which the antioxidants are extracted must be optimized. This work proves that conditions such as extraction solvent or temperature have a crucial impact on obtaining extracts rich in antioxidants from mango biowastes.     

Evaluation of antioxidant activities of various solvent extracts of Carissa opaca fruits

The chloroform and aqueous fractions of Carissa opaca fruit, a traditional medicinal fruit in Pakistan possessed a high amount of total phenolic and flavonoid contents as compare to other solvent fractions with potent antioxidant activities in scavenging DPPH, superoxides, hydroxyl, hydrogen peroxide, ABTS radicals, and had strong iron chelating activity. On the other hand, the ethyl acetate fraction showed the highest inhibition of β-carotene linoleic acid peroxidation and phosphomolybdate assay. A high correlation coefficient existed between EC₅₀ values of DPPH, superoxides, hydroxyl, hydrogen peroxide, ABTS radicals, total phenolics and flavonoids, but a non significant correlation was found in the case of iron chelaters, β-carotene and phosphomolybdate assay. This study verified that the chloroform and aqueous fractions have strong antioxidant activities which were correlated with its high level of phenolics and flavonoids. These fractions can be used as a source of potential antioxidant or functional food material.     

Antioxidant activity of stem and root extracts of Rhubarb (Rheum ribes): An edible medicinal plant

The antioxidant activity of chloroform and methanol extract of roots and stems of Rhubarb (Rheum ribes L.), which are used for medicinal purposes and also its fresh stems and petioles are consumed as vegetable, was studied. The antioxidant potential of both extracts of roots and stems were evaluated using different antioxidant tests, namely total antioxidant (lipid peroxidation inhibition activity), DPPH (1,1-diphenyl-2-picrylhydrazyl) radical scavenging, superoxide anion radical scavenging, ferric reducing power, and cupric reducing power (CUPRAC), and metal chelating activities. Total antioxidant activity was also measured according to the β-carotene bleaching method, and all four extracts exhibited stronger activity than known standards, namely butylated hydroxytoluene (BHT) and α-tocopherol. Particularly, higher activity was exhibited by roots with 93.1% and 84.1% inhibitions of chloroform and methanol extracts, while 82.2% and 82.0% inhibitions by stem extracts, respectively. However, both methanol extracts exhibited higher DPPH radical scavenging activity than the corresponding chloroform extracts, moreover, methanol extract of the stems showed better activity than BHT. In addition, both root extracts showed more potent superoxide anion radical scavenging activity than BHT, and comparable with well known radical scavenger l-ascorbic acid. Except chloroform extract of the roots, the other three extracts exhibited better metal chelating activity than quercetin. Also, total phenolic and flavonoid contents in both extracts of the roots and stems of R. ribes were determined as pyrocatechol and quercetin equivalents, respectively.     

Antioxidant potency of cumin varieties—cumin, black cumin and bitter cumin—on antioxidant systems

Cumin is one of the commonly used spices in food preparations. It is also used in traditional medicine as a stimulant, a carminative and an astringent. In this study, we characterized the antioxidant activity of three commercially available cumin varieties, viz., cumin (Cuminum cyminum), black cumin (Nigella sativa) and bitter cumin (C. nigrum). The antioxidant capacity of cumin varieties was tested on Fe²⁺ ascorbate induced rat liver microsomal lipid peroxidation, soybean lipoxygenase dependent lipid peroxidation and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging methods. The total phenolic content of methanolic extracts of cumin varieties ranged from 4.1 to 53.6 mg g^–1 dry weight. Methanolic extracts of all the three varieties of cumin showed higher antioxidant activity compared with that of the aqueous extract. Among the cumin varieties, bitter cumin showed the highest antioxidant activity followed by cumin and black cumin in different antioxidant systems. IC₅₀ values of the methanolic extract of bitter cumin were found to be 0.32, 0.1 and 0.07 mg dry weight of cumin seeds on the lipoxygenase dependent lipid peroxidation system, the DPPH radical scavenging system and the rat liver microsomal lipid peroxidation system, respectively. The data also show that cumin is a potent antioxidant capable of scavenging hydroxy, peroxy and DPPH free radicals and thus inhibits radical-mediated lipid peroxidation. The high antioxidant activity of bitter cumin can be correlated to the high phenolic content among the three cumin varieties. Thus, bitter cumin with a high phenolic content and good antioxidant activity can be supplemented for both nutritional purposes and preservation of foods.     

Comparative evaluation of antioxidant and anti food-borne bacterial activities of essential oils from some spices commonly consumed in Iran

The antioxidant potency, anti food borne bacterial activity, and total phenolic contents of essential oils (EOs) from avishane shirazi (Zataria multiflora), clove (Syzgium aromaticum), cinnamon (Cinnamomum zeylanicum), cumin (Cuminum cyminum), black cumin (Bunium persicum), spearmint (Mentha spicata), horsemint (Mentha longifolia), coriander (Coriandrum sativum), sage (Salvia officinalis), and ginger (Zingiber officinale) were evaluated. In 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, free radical scavenging activities of clove and avishane shirazi EOs were 90.69% and 88.63%, respectively. In reducing power assay, the EO of clove showed the highest reducing capacity. The highest concentrations of total phenolics (66.01 mg and 44.81 mg GAE/gram sample) were also detected for the EOs of clove and avishane shirazi, respectively. The results of disc diffusion assay showed that the EOs of avishane shirazi, cinnamon, and clove strongly inhibited growth of the tested bacteria. The EO of cinnamon had the lowest minimal inhibitory concentration (MIC) (0.312 mg/mL).     

溶剂提取对青稞中不同形态多酚组成及抗氧化活性的影响

为研究不同极性溶剂对青稞全谷物中不同形态酚类化合物含量、组成及抗氧化性的影响,建立适宜于青稞全谷物中多酚提取的方法。以4?个不同品种青稞为原料,比较4?种不同溶剂及酸法、碱法分别对青稞中游离酚和结合酚含量、组成与抗氧化活性的影响。结果表明,所有提取试剂中80%丙酮溶液提取的游离态总酚含量（139.79～235.96?mg/100?g）及总黄酮含量（9.88～15.52?mg/100?g）最高,酸法提取的青稞结合态总酚含量是碱法的1.9～3.1?倍,结合态黄酮含量是碱法的1.3～2.9?倍;80%丙酮溶液提取物中检测到8～18?种青稞游离酚类化合物,且酚类化合物含量显著高于其他溶剂,绿原酸、苯甲酸、儿茶素、槲皮素、芦丁是其主要的游离酚类化合物。与碱法相比,酸法能释放出更多的结合酚类化合物类型及含量,没食子酸、p-香豆酸、丁香酸、苯甲酸、藜芦酸、橙皮苷是其主要的结合酚类化合物;参试青稞80%丙酮溶液提取物显示出最高的1,1-二苯基-2-三硝基苯肼（1,1-diphenyl-2-picrylhydrazyl,DPPH）自由基清除能力（852.56～1?484.18?μmol/100?g）,2,2’-联氮-双-（3-乙基苯并噻唑啉-6-磺酸）二铵盐（2,2’-azinobis-(3-ethylbenzthiazoline-6-sulphonate),ABTS）自由基清除能力（358.93～518.09?μmol/100?g）及铁离子还原能力（ferric ion reducing antioxidant power,FRAP）（1?250.55～2?041.16?μmol/100?g）。酸法水解参试青稞结合酚DPPH自由基清除能力、FRAP、ABTS＋?清除能力分别是碱法水解的7.6～10.3、1.2～1.8?倍和1.1～1.3?倍。因此,80%丙酮溶剂和酸法分别是青稞中游离酚与结合酚的适宜提取溶剂,且本研究表明青稞全谷物中富含丰富的酚类物质,是一种潜在的天然抗氧化剂来源。     

A comprehensive study of polyphenols contents and antioxidant potential of 39 widely used spices and food condiments

Spices and condiments are rich sources of potent antioxidants. In the present investigation, total equivalent antioxidant capacities (TEAC) of 39 spices were studied using 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging, 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) scavenging, and cupric reducing antioxidant capacity (CUPRAC) assays. Their total phenolic contents (TPC) and total flavonoid contents (TFC) were also determined. TEAC, TPC, and TFC varied significantly (P?<?0.05) among these spices. ABTS, DPPH, and CUPRAC assay values of studied spices ranged from 1.42 to 112.94 mg ascorbic acid equivalents (AAE)/g, 1.14 to 91.09 mg Trolox equivalents (TE)/g, and 0.52 to 54.47 mg TE/g, respectively (dry weight basis; DW). Based on Folin–Ciocalteu assay, TPC ranged from 2.93 to 160.55 mg of gallic acid equivalents (GAE)/g DW. Strong correlations between TPC and TEAC values (R?=?0.966, 0.825, and 0.954 for ABTS, DPPH, and CUPRAC, respectively) were found. This indicates that phenolic compounds are potent antioxidants in these spices. Principal component analysis (PCA) indicated that cloves (flower buds of Syzygium aromaticum) had the most distinct and potent antioxidant capacity, followed by allspice (fruits of Pimenta dioica) and cinnamon (bark of Cinnamomum verum). Results of the present study provide adequate evidence that polyphenols are responsible for their compelling antioxidant capacities of studied spices. Thus, consumption of antioxidant-rich spices such as cloves, allspice, and cinnamon can significantly prevent oxidative stress in the human body.     

Antioxidant activities and phenolic compounds of pigmented rice bran extracts

This study was carried out to investigate the antioxidant activities and phenolic compounds of pigmented rice (black, red, and green rice) and brown rice brans. Antioxidant activity was determined by using 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical assay, 2,2-azino-bis-(3-ethylenebenzothiozoline-6-sulfonic acid) (ABTS) radical cation assay, reducing power, and chelating ability. Phenolic compounds were measured by using HPLC. Pigmented rice brans were extracted by using aqueous mixtures of acetone, ethanol, and methanol to determine the most effective extraction solvent. Of all solvents examined, extract from 40:60 acetone-water mixtures (v/v) provided the highest DPPH radical assay as well as the highest total phenolic and flavonoid content. We finally selected 40% acetone as an extraction solvent for antioxidant study of pigmented rice bran. Antioxidant activities of 40% acetone extracts of pigmented rice bran, measured in the range of 0 to 1500 μg/mL. At 500 μg/mL concentration, red rice bran, which had the highest total phenolic (259.5 μg/mg) and total flavonoid (187.4 μg/mg) contents, showed the highest antioxidant activity: 83.6%, 71.5%, 1.2%, and 16.4% for DPPH radical assay, ABTS radical cation assay, reducing power, and chelating ability, respectively. Red rice bran showed a lower EC(50) value (112.6 μg/mL) than that of butylated hydroxytoluene (144.5 μg/mL) from the DPPH radical assay. The major phenolic acids of red rice bran were ferulic, vanillic and p-coumaric acids. The results indicated pigmented rice bran might be used as a natural antioxidant. PRACTICAL APPLICATION: The present study revealed black and red rice bran shows high antioxidant activities and they contain high amount of phenolic compounds. Indeed, black and red rice bran could be better raw materials for manufacturing the food with high antioxidant activity.     

牡丹花水提物对肾素和ACE的双重抑制作用

研究了牡丹花水提物对肾素-血管紧张素系统中两种关键酶肾素和血管紧张素转化酶(ACE)的抑制作用,选取典型的牡丹花色品种,并与芍药进行比较,考察了样品水提物的肾素和ACE抑制活性及抗氧化能力,并分析酚类及黄酮类物质的含量与其功能活性的相关性。结果表明,红色系的牡丹和芍药花水提物具有优良的肾素和ACE抑制活性,而白色系的牡丹花水提物抑制肾素和ACE活性的能力则很弱。其中活性最高的样品水提物抑制肾素的IC50值为0.08 mg/mL,抑制ACE的IC50值为0.23 mg/mL;此外,红色系的牡丹和芍药花水提物的ABTS自由基清除能力为115.89~121.75mgTE/gDW,DPPH自由基清除能力为192.67~200.46mg TE/g DW,铁离子还原能力为119.86~208.94 mg TE/g DW,总酚含量为99.29~122.45 mg GAE/g DW,白色牡丹花水提物的抗氧化能力及总酚含量均远低于红色系样品水提物。相关性分析表明,不同样品水提物的肾素和ACE抑制活性及DPPH、ABTS自由基清除能力和铁离子还原能力与总酚含量显著正相关(p<0.01),相关系数分别为0.99、0.91、0.99、0.99和0.98。本研究指出深色系的牡丹花水提物倾向于表现出更强的肾素和ACE抑制活性,其中酚类化合物是潜在的重要活性物质,这可为探讨新型血压调控因子及实现不同品系牡丹花的高值化利用提供更丰富的基础理论支撑。