In vitro evaluation of antioxidant activities of aqueous extracts from natural and cultured mycelia of Cordyceps sinensis

Cordyceps sinensis, one of the best known traditional Chinese medicines and health foods, has been highly valued for the treatment of a wide range of diseases and reported to have antioxidant properties. In the present study, the antioxidant activities of hot-water extracts from natural and cultured mycelia of C. sinensis were investigated and evaluated using six in vitro assays, including inhibition of linoleic acid peroxidation; scavenging abilities on DPPH, hydroxyl and superoxide anion radicals; the reducing power and the chelating ability on ferrous ions. Among these assays, the extracts showed the best effect on the inhibition of linoleic peroxidation with the lowest IC50 values and with an inhibition rate over 90% at concentration of 0.8-1.6 mg/ml, more stable than that of α-tocopherol, a recognised natural antioxidant. The scavenging activities on superoxide anion and hydroxyl radicals of the two extracts were slightly lower than that of butylated hydroxytoluene. DPPH scavenging activities of both extracts reached over 80% inhibition at 4-8 mg/ml. Both extracts showed moderate reducing power and ferrous ion chelating activity. The IC50 value of the extract from cultured mycelia in all the tests, except for linoleic acid peroxidation, was significantly lower than that of natural mycelia. There was no evident correlation between the antioxidant activity and the content of protein, polysaccharides and mannitol of extracts from C. sinensis; the antioxidant activity may be due to a combined effect of these or some other compounds. These results suggested that both the extracts from cultured and natural mycelia have direct and potent antioxidant activities and that the cultured mycelia of the fungus could be used for the antioxidant activity to reduce the human demands on the natural resources of the fungus, an endangered species.     

A comparative study on the antioxidative and anti‐allergic activities of fresh and aged black garlic extracts

The antioxidative and anti‐allergic activities of fresh and aged black garlic extracts were investigated. The garlic samples were extracted with 70% ethanol (v/v) and the total phenolic content was measured. The antioxidant capacity of extracts was assessed by determining the scavenging activities on 1,1‐diphenyl‐2‐picrylhydrazyl and hydroxyl radicals, ferricyanide reducing power, ferrous ion‐chelating ability and inhibitory effect on linoleic acid peroxidation. The anti‐allergic activity of extracts was analysed by measuring their inhibitory effects against β‐hexosaminidase release. The aged black garlic exhibited significantly higher phenolic content and greater antioxidative activity than fresh garlic. Both garlic extracts showed strong antioxidant capacity in a dose‐dependent manner. On the other hand, a considerably higher suppression of β‐hexosaminidase release was found in fresh garlic extract at lower concentration compared with that of the black garlic. Results of this study illustrate that ageing of garlic could enhance its antioxidant capacity, but could decrease its anti‐allergic activity.     

In vitro antioxidative and antimutagenic activities of oak mushroom (Lentinus edodes) and king oyster mushroom (Pleurotus eryngii) byproducts

The in vitro antioxidative and antimutagenic activities of ethanolic extracts from oak mushroom (Lentinus edodes) and king oyster mushroom (Pleurotus eryngii) byproducts were investigated. The antioxidant capacity of the extracts was assessed by determining the ferricyanide reducing power, scavenging activity on nitrite, DPPH radical, superoxide anions and hydroxyl radicals, ferrous ion chelating ability, and inhibitory effect on linoleic acid peroxidation and xanthine oxidase. The antimutagenic activity, on the other hand, was based on the suppression of mitomycin C-induced mutagenesis in Escherichia coli cells. Both the mushroom extracts showed strong antioxidative and antimutagenic effects at higher concentrations. In general, extracts from the oak mushroom byproduct had greater antioxidative and antimutagenic abilities than that of the king oyster extract. Results of this study demonstrate that the mushroom byproducts possess strong antioxidant capacity in vitro and may be useful as a functional biomaterial in the preparation of health-promoting food products and animal feeds.     

Evaluation of antioxidant activities and phenolic subtype contents of ethanolic bran extracts of Thai pigmented rice varieties through chemical and cellular assays

This study revealed that the ethanolic bran extracts of 11 Thai pigmented (red and purple) and 2 nonpigmented rice varieties exerted scavenging activity against DPPH and ABTS radicals and ROS in HL‐60 cells in the following order: red > purple > nonpigmented rice. These rice extracts also showed the same order of phenolic and flavonoid contents, which were strongly correlated with their scavenging activity. Phenolic subtype analysis further indicated that proanthocyanidins as well as anthocyanins and protocatechuic acid contributed directly to antioxidant capacity in red and purple rice bran, respectively. In contrast, these pigmented rice bran extracts possessed moderate chelating activity partly attributed to their contents of phenolics and flavonoids, especially proanthocyanidins in red rice bran. Moreover, rice bran extracts significantly restored SOD and CAT activities in oxidative stress‐induced A549 cells. This study provides new insights on the intracellular potent antioxidant capacity of pigmented rice bran extracts in the cell‐based systems.     

火绒草提取物抗氧化活性的研究

测定火绒草水提物和醇提物中多酚及总黄酮含量,证实水提物和醇提物中含有以黄酮类为主要成分的多酚类物质。通过测定火绒草提取物的总还原力,超氧阴离子自由基(O2·)、羟自由基(·OH)清除能力、脂质过氧化抑制作用、清除亚硝酸盐自由基和亚硝胺阻断率,表明火绒草水提物和醇提物具有较强的还原性和清除·OH 和O2·的活性,且醇提物的作用比水提物更有效;对脂质过氧化的抑制率达到60% 以上。火绒草提取物具有较强的清除亚硝酸钠和阻断亚硝胺合成的能力,水提物对亚硝酸盐最大清除率为77.7%,醇提物对亚硝胺合成的阻断率98.0%。     

乳酸菌抗氧化活性的研究进展

介绍了乳酸菌的抗氧化活性、可能机制及其研究进展。在体外实验中，乳酸菌及其无细胞提取物能清除机体羟自由基(HO)、过氧化氢(H2O2)、二苯代苦味肼基自由基(DPPH)；可抑制脂质过氧化、螯合金属离子，具有总还原能力及SOD酶活性。并介绍了乳酸菌抗氧化活性的体内实验结果。     

Evaluation of antioxidative performance of tomato extracts obtained by different methods

BACKGROUND: Two extraction methods employing tetrahydrofuran and phosphate buffer (pH 7.4) respectively were used to process tomatoes. The antioxidant contents and antioxidative properties of extracts of four tomato cultivars were measured. To evaluate the overall antioxidative capacity of the tomato extracts, an antioxidative performance index (API) was used, defined as the average of four antioxidative assays, i.e. relative reducing power, ferrous ion‐chelating ability, 2,2‐diphenyl‐1‐picrylhydrazyl free radical‐scavenging activity and superoxide radical‐scavenging activity. RESULTS: A linear correlation between the total antioxidant content (TAC) and API of tomato extracts was found that was independent of the extraction method and tomato cultivar. CONCLUSION: The concept of representing multiple antioxidant activities by a single index is useful for evaluating the overall antioxidative capacity of antioxidants in tomatoes. Copyright © 2007 Society of Chemical Industry     

Determination of in vitro antioxidant activity of fennel (Foeniculum vulgare) seed extracts

In this study, the antioxidant activity of water and ethanol extracts of fennel (Foeniculum vulgare) seed (FS) was evaluated by various antioxidant assay, including total antioxidant, free radical scavenging, superoxide anion radical scavenging, hydrogen peroxide scavenging, metal chelating activities and reducing power. Those various antioxidant activities were compared to standard antioxidants such as butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), and α-tocopherol. The water and ethanol extracts of FS seeds showed strong antioxidant activity. 100 μg of water and ethanol extracts exhibited 99.1% and 77.5% inhibition of peroxidation in linoleic acid system, respectively, and greater than the same dose of α-tocopherol (36.1%). The both extracts of FS have effective reducing power, free radical scavenging, superoxide anion radical scavenging, hydrogen peroxide scavenging, and metal chelating activities. This antioxidant property depends on concentration and increasing with increased amount of sample. In addition, total phenolic compounds in the water and ethanol extracts of fennel seeds were determined as gallic acid equivalents. The results obtained in the present study indicated that the fennel (F. vulgare) seed is a potential source of natural antioxidant. Although, the tests presented here show the usefulness of FS extracts as in vitro antioxidants it still needs to be that this extracts show their activity in emulsions, biological systems, health implications or dry foods.     

Antioxidant and free radical scavenging potential of Achillea santolina extracts

The antioxidative activities of hydroalcoholic extract of Achillea santolina were investigated employing various established in vitro systems including total antioxidant activity in linoleic acid emulsion system, 1,1-diphenyl-2-picrylhydrazyl (DPPH), superoxide and hydroxyl radicals scavenging, reducing power, and inhibitory effect on protein oxidation as well as the inhibition of Fe²⁺/ascorbate induced lipid peroxidation in rat liver homogenate. Total phenolic and flavonoid content of A. santolina extract (ASE) was also determined by a colorimetric method. The results revealed that ASE has notable inhibitory activity on peroxides formation in linoleic acid emulsion system along with concentration-dependent quenching of DPPH and superoxide radicals. Furthermore, the extract showed both nonsite-specific (Fe²⁺ + H₂O₂ + EDTA) and site-specific (Fe²⁺ + H₂O₂) hydroxyl radical scavenging suggesting potent hydroxyl radical scavenging and chelating ability for iron ions in deoxyribose degradation model. A linear correlation between ASE and the reducing power was also observed (r² = 0.9981). ASE prevents thiobarbituric acid reactive substances formation in Fe²⁺/ascorbate induced lipid peroxidation in rat liver tissue in a dose-dependent manner. Moreover, free radical induced protein oxidation was suppressed significantly by the addition of ASE over a range of concentration. These results clearly demonstrated that A. santolina extract possess a marked antioxidant activity.     

超声波辅助乙醇提取莲子心总黄酮及其抗氧化活性的研究

通过超声波辅助乙醇提取莲子心总黄酮,用单因素及正交实验选择最佳提取工艺条件,研究了黄酮提取物对羟基自由基的清除效果及抗油脂氧化作用。结果表明,当用80%乙醇按料液比1:25(g:mL)在超声功率250W及超声温度50℃的水浴中提取30min后,莲子心黄酮的提取率为2.23%。该提取物具有清除羟基自由基及抗油脂氧化作用,对植物油的抗氧化能力强于对动物油的抗氧化能力,表明莲子心黄酮提取物可作为天然抗氧化剂使用。     

3种黑色粮油作物种皮提取物体外抗氧化活性研究

从总抗氧化力、还原能力、清除DPPH自由基能力和抗油脂氧化能力四个方面研究了黑米提取物、黑大豆提取物和黑玉米提取物的抗氧化活性。结果表明,在实验浓度范围内,3种黑色粮油作物种皮提取物均有一定程度的抗氧化活性,四个方面的抗氧化活性实验均显示抗氧化强弱顺序为黑大豆提取物>黑米提取物>黑玉米提取物,其中黑大豆提取物清除DPPH自由基能力及在花生油体系中的抗油脂氧化能力均高于Vc。     

4种龙眼核提取物的总黄酮含量、体外抗菌活性与抗氧化活性

以聚酰胺吸附-硝酸铝显色法测定龙眼核水提取物、95%乙醇提取物、丙酮提取物、乙酸乙酯提取物等4种不同极性提取物的总黄酮含量,同时采用管碟法、最小抑菌浓度(MIC)法测定比较4种提取物的抗菌活性,并测定评价在二苯代苦肼自由基(DPPH自由基)体系、羟自由基体系、超氧阴离子自由基体系及抗脂质体过氧化体系中各提取物的抗氧化活性。结果表明：95%乙醇提取物的总黄酮含量最高,为(3.90±0.12)%,其抗菌活性也强于其他3种提取物,在质量浓度100mg/mL时,对大肠杆菌、普通变形杆菌、枯草芽孢杆菌、藤黄八叠球菌、金黄色葡萄球菌、白菜软腐菌、甘蓝黑腐菌7种菌的抑菌圈直径均达15mm以上,对各菌的MIC均≤100mg/mL;在不同的自由基体系中,4种提取物均对超氧阴离子自由基的清除作用相对较弱,但对清除DPPH自由基、清除羟自由基、抗脂质体过氧化均表现出较强的效果;以清除率达50%时所对应的样液质量浓度IC50作为指标比较发现4种提取物对3种自由基的的抗氧化作用由强到弱依次是水提取物、95%乙醇提取物、丙酮提取物、乙酸乙酯提取物,其中水提取物对这3种自由基的IC50分别为0.20、0.15、2.69mg/mL。可见,龙眼核的95%乙醇提取物适宜作为植物源抗菌剂,水提取物则适宜作为植物源抗氧化剂以深度开发利用。     

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.     

Extractability of antioxidants from legume seed flour after cooking and in vitro gastrointestinal digestion in comparison with methanolic extraction of the unprocessed flour

Antioxidant activities were studied in methanolic and water extracts of nonprocessed, cooked and in vitro enzymatically digested seed flour, as well as in total protein hydrolysates and small peptide fractions (<3 and <10 kDa) of three pea and five grass pea cultivars. The antioxidative properties were determined by three spectrophotometric methods: 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) radical scavenging assay, Folin‐Ciocalteu (FC) reducing capacity assay and H₂O₂ scavenging. We also applied one luminometric assay for hydroxyl radical scavenging. The study showed that cooking and enzymatic digestion strongly enhanced the release of phenolic compounds in methanolic extracts of four analysed cultivars. Scavenging activity against DPPH radical, hydroxyl radical and hydrogen peroxide was increased in majority of analysed flour specimens subjected to processing. Our findings indicate that, besides the phenolic compounds, the small peptide fraction, especially the MW <3 kDa, in methanolic and aqueous extracts of cooked and digested seed flour significantly contribute to free radical and hydrogen peroxide scavenging activity in all investigated cultivars. Our data strongly suggest that simple cooking treatment and in vitro digestion of seed flour applied prior to extraction with methanol could improve antioxidative activity of obtained extracts.     

Studies on the antioxidative activity of Graptopetalum paraguayense E. Walther

This study was aimed to evaluate the antioxidative activities of water (GWE), 50% ethanolic (GE50), and 95% ethanolic (GE95) extracts of Graptopetalum paraguayense. The antioxidant activities, including the radical-scavenging effect, reducing power, and antioxidative effect on Fe/ascorbate-induced lipid peroxidation in a liposome model system, were studied in vitro. The results showed that GWE, GE50 and GE95 possessed antioxidant characteristics including radical scavenging, reducing power, and lipid peroxidation inhibition. It was found that the antioxidative activities of all the extracts increased with increasing concentrations, and the activities correlated with both the total phenol and anthocyanin contents. A comparison of the 50% inhibition concentration (IC₅₀) values of different antioxidative reactions revealed that GE50 was more effective in scavenging α,α-diphenyl-β-picrylhydrazyl (DPPH) radical and showed a higher reducing power than GWE and GE95. However, there were no significant differences (P > 0.05) in the lipid peroxidation-prevention effects among the extracts.     

春砂仁根和叶提取物抗氧化活性研究

以水为溶剂对春砂仁根、叶进行超声波浸提。通过测定还原能力及O2-.自由基清除率、.OH自由基清除率、DPPH.自由基清除率,比较春砂仁根、叶提取物与茶多酚的抗氧化活性。结果表明,春砂仁根、叶提取物都有一定的抗氧化性质;根、叶水提取物的还原能力最强;对O2-.自由基清除率大小顺序为:春砂仁叶提取物>茶多酚>春砂仁根提取物;对.OH自由基清除率大小顺序为:春砂仁根提取物>春砂仁叶提取物>茶多酚。     

辣椒籽提取物抗氧化活性研究

用不同溶剂提取辣椒籽中的抗氧化物质,从还原能力、抗脂质体氧化和对Fenton体系产生的羟自由基的清除效果等方面对辣椒籽提取物的抗氧化活性进行了试验研究和评价。结果表明:辣椒籽提取物具有较强的还原能力,对脂质体氧化、Fenton反应产生的羟自由基均具有抑制作用或消除作用,优于同浓度的Vc和VE的效果或基本相当,这表明辣椒籽提取物是一种优良的天然抗氧化剂和自由基消除剂,而且不同溶剂的辣椒籽提取物的抗氧化作用效果不同,其中脱脂甲醇提取物>甲醇提取物>脱脂水提取物>Vc>石油醚提取物>VE。     

不同提取方法的野马追提取物抗氧化作用的比较研究

以野马追干制品为原料,利用6种不同的提取方法得到粗提物,分别利用FRAP法、ABTS法、超氧阴离子自由基清除法、总还原力法、羟自由基清除法、抗脂质体过氧化法对抗氧化活性进行测定比较,其中以BHT和BHA为阳性对照。除抗脂质体过氧化活性以外,6种提取方法得到的粗提物均表现出较强的抗氧化活性,但不同方法粗提物的具体抗氧化活性指标差异显著。水煎物清除羟自由基的作用最明显,清除率为96.97%(P<0.05)。70%乙醇回流法提取物对超氧阴离子自由基的清除作用最明显,清除率高达87.70%(P<0.05)。渣提物的总还原能力最强(P<0.05)。六种提取物都具有高于BHT和BHA的ABTS+.清除能力,其中70%乙醇回流法和浸提法粗提物无显著性差异。     

杏花花粉中苦杏仁苷的抗氧化性研究

本实验主要从总抗氧化能力、还原力、清除DPPH自由基、清除羟自由基、抑制卵磷脂氧化等方面,对杏花花粉中的乙醇提取物、苦杏仁苷、苦杏仁苷结晶上清物进行了抗氧化性研究。结果表明:杏花花粉中苦杏仁苷的抗氧化能力,除清除羟自由基以外均低于杏花花粉醇提物和苦杏仁苷结晶上清物。故开发杏花花粉产品只需生产到乙醇提取物就可以达到抗氧化和抗癌的双重功效。     

五种抗氧化剂抗氧化活性的比较研究

本实验采用甲基紫比色法、MDA法和SDS-PAGE,检测了五种天然产物清除羟自由基的能力、对脂质过氧化及蛋白质氧化的保护作用.结果表明,五种化合物在不同的反应体系表现出不同的抗氧化活性.茜素红清除·OH的能力及对蛋白质氧化的保护作用最强,白藜芦醇对脂质过氧化的抑制作用最强.同时实验结果也反映出化合物的溶解性对其抗氧化作用有很大的影响.