Antioxidant and nitric oxide inhibition activities of selected Malay traditional vegetables

The antioxidant properties and the effect on nitric oxide (NO) production, in lipopolysaccharide-activated macrophages, of 12 traditional vegetables of the Malaysian Malays, including Pithecellobium confertum, Averrhoa bilimbi, Portulaca oleracea, Solanum torvum, Solanum nigrum, Persicaria tenella, Cosmos caudatus, Pandanus amaryllifolius, Curcuma mangga, Ocimum basilicum, Anacardium occidentale and Melicope ptelefolia, were investigated. Antioxidant activity of the methanolic extracts was evaluated by measuring the production of hydroperoxide and its degradation product (malonaldehyde) resulting from linoleic acid oxidation using ferric thiocyanate and thiobarbituric acid methods, respectively. Radical-scavenging potential was also evaluated using the 1,1-diphenyl-2-picrylhydrazyl radical. Griess assay was used to assess NO-inhibitory activity of the extracts. All species, except P. confertum, S. torvum and P. amaryllifolius, showed antioxidant activity. M. ptelefolia, P. oleracea and P. tenella showed in vitro activity on NO inhibition in murine peritoneal macrophages, whereas other plants showed no significant activity.     

Phenolic Content and Antioxidant Activity of Moscatel Dessert Wines from the Setúbal Region in Portugal

Moscatel wines from Setúbal were analyzed for their total phenolic (mean value 1,243 mg gallic acid equivalents/L), and total flavonoid (mean value 248 mg catechin/L) composition by spectrophotometric and chromatographic methods were used to quantify phenolic compounds as benzoic acids, cinnamic acids, stilbens, and some flavonoids. Antioxidant activity of the wines was evaluated by 1,1-diphenyl-2-picrylhydrazyl (DPPH; mean value 70.7% inhibition), ferric reducing antioxidant power (FRAP; mean value 3,098 mg of Trolox equivalents/L) and oxygen radical absorbance capacity (ORAC; mean value 10,724 μmol/L) assays. Results were analyzed using principal component analysis which allowed samples to be grouped in terms of both winemaking producer and vintage. By plotting correlation loadings, it was possible to understand which variables were responsible for sample distribution. The correlation between results obtained for variables show that, in general, total flavonoid content is a better estimation of antioxidant activity in Moscatel samples (r _{ORAC/flavonoids} = 0.832, r _{FRAP/flavonoids} = 0.677) than total phenolic content (r _{ORAC/phenolics} = 0.680, r _{FRAP/phenolics} = 0.372). No major correlations were detected for DPPH assay results (r _{DPPH/flavonoids} = 0.283, r _{DPPH/phenolics} = 0.271). Chromatographic profiles showed important differences among Moscatel wines. Gallic acid contents and results of antioxidant activity tests were strongly correlated (r values in the range 0.74–0.92). Correlations of the results obtained for antioxidant activity tests with contents of other phenolic compounds such as ethyl caffeate, ethyl gallate, caffeic acid, protocatechuic acid, and t-caftaric acid depend on sample and type of test employed. Presented at the “AOAC Europe section international workshop: Enforcement of European Legislation on Food and Water: Analytical and Toxicological Aspects”, in Lisbon, April 2008, and published in abstract form.     

艾叶提取物对黄嘌呤氧化酶的抑制作用及对高尿酸血症小鼠的降尿酸作用

以蒸馏水、无水乙醇为溶剂结合超声波辅助及传统煎煮方法对艾叶进行提取,测定各提取物总黄酮和总酚含量、自由基清除能力以及艾叶提取物对黄嘌呤氧化酶(Xanthine Oxidase,XOD)的抑制作用,并选取抑制效果较好的艾叶醇提物,利用动物实验,测定小鼠血清尿酸(UA),肌酐(Scr),尿素氮水平(BUN),肝脏XOD活性,研究艾叶提取物对高尿酸血症小鼠的降尿酸的作用。结果表明:总黄酮和总酚含量:醇提物传统法提取物水提物,清除自由基能力和抑制XOD作用:醇提物传统法提取物水提物,三种提取物对XOD的抑制作用均表现为不可逆抑制,其中传统法和醇提物对XOD的抑制类型为反竞争性抑制,水提物为混合性竞争性抑制;传统法和水提物与别嘌呤醇联合抑制作用表现为相加作用,醇提物表现为弱协同作用;艾叶醇提物对高尿酸血症小鼠的UA,Scr,BUN水平均具有降低效果,对肝脏XOD活性具有抑制作用。结论:艾叶各提取物具有较好的抑制黄嘌呤氧化酶和抗氧化作用,醇提物具有开发成为预防和治疗高尿酸血症药物的潜力。     

Antioxidant activity of ethanol and petroleum ether extracts from Brazilian propolis

Antioxidant activities of ethanol and petroleum ether extracts from Brazilian propolis were determined by α,α-diphenyl-β-picrylhydrazyl (DPPH) radical-scavenging and ferric thiocyanate (FTC) methods, using α-tocopherol and butylated hydroxytoluene (BHT) as references. The DPPH assay showed that ethanol extract possessed significantly higher activity compared with BHT and petroleum ether extract but lower than that of α-tocopherol. Results from the FTC assay indicated that the activity of ethanol extract was higher than that of α-tocopherol and petroleum ether extract but lower than BHT. Basically, this antioxidant activity was dose-dependent and ethanol extract exhibited higher activity than that of petroleum ether extract at the same concentration. Additionally, the chemical constituents of propolis were determined, and results showed that the propolis contained high content of antioxidant compositions, such as flavonoids (73.00 g kg⁻¹), total phenolic compounds (134.40 g kg⁻¹), and Vitamin E (0.16 g kg⁻¹), which contributed greatly to its strong antioxidant activity.     

槲皮素、芦丁、没食子酸抑制黄嘌呤氧化酶的活性及动力学特性

为了解槲皮素、芦丁、没食子酸及其与维生素C联用对黄嘌呤氧化酶(XOD)的抑制特性,本文通过建立黄嘌呤氧化酶体外抑制模型,以别嘌呤醇为阳性对照,测定这三种天然化合物在不同浓度下对XOD的抑制效果及抑制动力学。结果表明：三种物质对黄嘌呤氧化酶均有抑制作用,且具有浓度依赖性,其抑制效果与结构和本身性质有明显相关性,抑制作用强弱次序为槲皮素>芦丁>没食子酸,半抑制浓度IC50值分别为(5.51±0.41) μmol/L、(48.66±0.49) μmol/L、>200 μmol/L;单一没食子酸抑制效果较弱,而没食子酸在维生素C的协同下,对XOD的抑制率从20.17%提高至40.96%,起到提高抑制效果和体系稳定性的双重作用;以上三种物质对XOD的抑制类型属于不同模式的非经典型混合抑制剂。本文对研究此类物质的抑制机理和应用有重要意义。     

Evaluation of the antioxidant activity of Ruellia tuberosa

The antioxidant activity of Ruellia tuberosa L. (Acanthaceae) was investigated by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical-scavenging assay and the hydrogen peroxide-induced luminol chemiluminescence assay. The methanolic extract (ME) and its four fractions of water (WtF), ethyl acetate (EaF), chloroform (CfF), and n-hexane (HxF) were prepared and then subjected to antioxidant evaluation. The results of both methods revealed that R. tuberosa possesses potent antioxidant activity. The antioxidant activities of the different fractions tested decreased in the order of EaF > CfF > ME > WtF > HxF according to the hydrogen peroxide-induced luminol chemiluminescence assay, and results were the same with the exception of the rank order of HxF and WtF according to the DPPH free radical-scavenging assay. The results provide useful information on the pharmacological activities associated with free radicals of this traditional folk remedy.     

Antioxidant properties and chemical composition of technical Cashew Nut Shell Liquid (tCNSL)

The present study analysed the antioxidant activity of the technical Cashew Nut Shell Liquid (tCNSL) using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging assay and the xanthine oxidase assay, as well as in vivo evaluation by Saccharomycescerevisiae assay. Also, the chemical composition of tCNSL was determined by gas chromatography–mass spectrometry (GC–MS), revealing the presence of cardanols (40.26%), cardols (29.95%), phytosterol (10.68%), triacontanes (4.66%) and anacardic acid (1.79%). The DPPH-based assay results showed that tCNSL 1000 μg/ml reduced the radical level by 88.9%, and the scavenging of hydroxyl radicals in the xanthine oxidase assay indicated significant antioxidant activity (IC₅₀ = 702 μg/ml). In addition, tCNSL exerts an important protective effect against oxidative stress in yeast when used in 100–500 μg/ml concentration range, when exposed to paraquat or H₂O₂, indicating an in vivo antioxidant effect.     

Antioxidant activity of Japanese pepper (Zanthoxylum piperitum DC.) fruit

Antioxidants were extracted from Japanese pepper (Zanthoxylum piperitum DC.) fruit and characterized. The antioxidant activity of the methanol extract from Japanese pepper fruit was found to be equal to that of α-tocopherol and stable under heat treatment. The main compounds that gave a significant antioxidant activity from the methanol extract were identified to be hyperoside (quercetin-3-O-galactoside) and quercitrin (quercetin-3-O-rhamnoside) as determined by HPLC, mass spectrometry, UV/Vis spectroscopy, and TLC. Radical-scavenging activities of hyperoside and quercitrin from Japanese pepper fruit were evaluated using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) method. As a result, hyperoside and quercitrin scavenged DPPH radical strongly with IC₅₀ values of 16 and 18 μM, respectively. These observations show the presence of strong antioxidants, namely hyperoside and quercitrin in Japanese pepper fruit.     

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.     

Antioxidant activity of anacardic acids

Anacardic acids, 6-pentadec(en)ylsalicylic acids isolated from the cashew Anacardium occidentale L. (Anacardiaceae) nut and apple, were found to possess preventive antioxidant activity while salicylic acid did not show this activity. These anacardic acids prevent generation of superoxide radicals by inhibiting xanthine oxidase (EC 1.1.3.22, Grade IV) without radical-scavenging activity. Notably, the inhibition kinetics of anacardic acids do not follow hyperbolic dependence of enzyme inhibition on inhibitor contents (Michaelis–Menten equation) but follow the Hill equation instead. Anacardic acid (C_15:1) inhibited the soybean lipoxygenase-1 (EC 1.13.11.12, Type 1) catalyzed oxidation of linoleic acid with an IC₅₀ of 6.8 μM. The inhibition is a slow and reversible reaction without residual enzyme activity. The inhibition kinetics indicate that anacardic acid (C_15:1) is a competitive inhibitor and the inhibition constant, K_I, was 2.8 μM. Anacardic acids act as antioxidants in a variety ways, including inhibition of various prooxidant enzymes involved in the production of the reactive oxygen species and chelate divalent metal ions such as Fe²⁺ or Cu²⁺, but do not quench reactive oxygen species. The C₁₅-alkenyl side chain is largely associated with the activity.     

黄嘌呤氧化酶多酚抑制剂的筛选及其作用机制

黄嘌呤氧化酶(xanthine oxidase,XOD)是人体内次黄嘌呤和黄嘌呤代谢产生尿酸的关键酶,而多酚单体可抑制黄嘌呤氧化酶从而减少尿酸合成进而缓解痛风症状。为探究来源于天然产物的多酚单体对XOD的抑制作用机制,首先研究几种常见活性较好的多酚单体对黄嘌呤氧化酶的抑制率,及其对XOD的抑制动力学,并且通过荧光猝灭实验与分子对接模拟多酚单体与XOD之间的相互作用形式。在6种多酚单体中,白藜芦醇、表没食子儿茶素没食子酸酯(epigallocatechin gallate,EGCG)和橙皮苷对黄嘌呤氧化酶活性的抑制效果较好,室温下IC50分别为261.22、150.51、97.08μmol/L,是黄嘌呤氧化酶的竞争性抑制剂。荧光猝灭实验表明,单体与XOD结合使酶的内源荧光发生了猝灭现象,猝灭机制为静态猝灭。分子对接模拟表明,多酚单体能与XOD的氨基酸残基结合,结合位点位于钼蝶呤(molybdopterin,Mo-Pt)辅因子或黄素腺嘌呤二核苷酸(flavine-adenine dinucleotide,FAD)结构域的异恶嗪环附近。多酚单体是有效的XOD竞争性抑制剂,可以通过抑制黄嘌呤氧化酶的活性有效降低尿酸水平,在天然产物的开发和功能性食品的应用中具有很好的前景。     

Antioxidant activity of minor components of tree nut oils

The antioxidative components of tree nut oils were extracted using a solvent stripping process. Tree nut oil extracts contained phospholipids, sphingolipids, sterols and tocopherols. The chloroform/methanol extracted oils had higher amounts of phenolic compounds than their hexane extracted counterparts. The antioxidant activity of tree nut oil minor component extracts were assessed using the 2,2-azino-bis (3-ethylbenzthiazoline sulphonate) (ABTS) radical scavenging activity, 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging capacity, β-carotene bleaching test, oxygen radical absorbance capacity (ORAC) and photochemiluminescence inhibition assays. Results of these studies demonstrated that extracts of chloroform/methanol extracted oils possessed higher antioxidant activities than extracts of their hexane extracted counterparts. Meanwhile the extract of chloroform/methanol extracted pecan oil possessed the highest antioxidant activity.     

Xanthine Oxidase Inhibitory Activity and Hypouricemic Effect of Aspalathin from Unfermented Rooibos

Rooibos is rich in flavonoids such as aspalathin, which is a unique C‐glycosyl dihydrochalcone, that is used as a traditional herbal tea. This study was designed to evaluate the in vitro xanthine oxidase (XOD) inhibitory activity of the aspalathin‐rich fraction (ARF) and purified aspalathin from rooibos. The hypouricemic effects of the ARF and aspalathin on hyperuricemic mice were also assessed. The ARF was prepared from aqueous extract of unfermented rooibos leaves and stems, and it was collected by column chromatography; the aspalathin content in this fraction was 21.4%. The ARF and aspalathin inhibited XOD in a dose‐dependent manner. The concentrations of the ARF and aspalathin required to inhibit XOD at 50% (IC₅₀) were 20.4 μg/mL (4.4 μg/mL aspalathin equivalents) and 4.5 μg/mL, respectively. Lineweaver–Burk plot analysis indicated that aspalathin was a competitive inhibitor of XOD, and the inhibition constant (Ki) was 3.1 μM. In hyperuricemic mice induced by inosine‐5’‐monophosphate, treatment with the ARF and aspalathin significantly suppressed the increased plasma uric acid level in a dose‐dependent manner. The suppressed plasma uric acid level in mice could be attributed to the XOD inhibitory activity of the ARF and aspalathin. Further study is required to determine the effect of aspalathin or its metabolites on XOD activity in vivo.     

不同紫薯馒头黄嘌呤氧化酶抑制活性及感官品质比较

该研究采用8种紫薯粉,对比了其制备紫薯面团的pH值、可滴定酸度（Titratable Acidity,TTA）值与发酵能力,分析了8种紫薯馒头活性成分含量、黄嘌呤氧化酶抑制活性、抗氧化活性以及感官品质的差异,阐明了紫薯馒头活性成分与黄嘌呤氧化酶抑制活性和抗氧化活性之间的内在联系,并筛选出一种能制备具有潜在降尿酸功能紫薯馒头的紫薯粉。结果表明,济黑一号紫薯馒头总黄酮和总花色苷含量、黄嘌呤氧化酶抑制活性、超氧阴离子自由基清除活性与还原力分别为195.70 mg RE/100 g、2.16 mg C3G/100 g、11.93 μmol AE/100 g、29.07 mmol TE/100 g和2.69 mmol VE/100 g,均显著高于其它7种紫薯馒头（P<0.05）。相关性分析表明,总黄酮和总花色苷是造成不同紫薯馒头黄嘌呤氧化酶抑制活性与抗氧化活性存在差异的主要原因。济黑一号和济黑二号紫薯馒头感官评分相对较高,分别为86.56和88.22。因此,济黑一号紫薯馒头综合品质最优,济黑一号紫薯粉适用于降尿酸紫薯馒头的开发。该研究为紫薯馒头降尿酸活性的深入研究以及功能性紫薯馒头的开发与工业化生产提供理论依据。     

Effect of Polymerization on Antioxidant and Xanthine Oxidase Inhibitory Potential of Sea Buckthorn (H. rhamnoides) Proanthocyanidins

Abstract: Inhibitory potential of sea buckthorn (Hippophae rhamnoides L) seed proanthocyanidins against oxidative stress and xanthine oxidase activity was evaluated. Composition of antioxidant proanthocyanidins was profiled by analyzing the cleavage products obtained by the acid catalyzed hydrolysis in the presence of phloroglucinol. Catechin, epicatechin, gallocatechin, and epigallocatechin were found as the extension and terminal subunits of proanthocyanidins with an average degree of polymerization (ADP) of 14.7. Seed proanthocyanidins showed considerably high antioxidant and xanthine oxidase inhibitory potentials. Antioxidant and xanthine oxidase inhibitory capacity evaluation of proanthocyanidin fractions with varying ADP showed that proanthocyanidins with lower molecular size were more effective as superoxide anion (ADP ≤ 4.2) and hydroxyl radical (ADP ≤ 5.9) scavengers and xanthine oxidase (ADP ≤ 3.1) inhibitors. ADP of the studied proanthocyanidin fractions did not show significant influence on their DPPH and ABTS radical scavenging and ferric reduction capacities.     

15种中草药提取物抗氧化活性的研究

用石油醚、乙酸乙酯、甲醇和水对所选定的15种中草药进行浸泡提取,采用Folin-Ciocalteu方法测定各提取物中的总酚含量;用DPPH和FRAP分析法评估了同溶剂提取物的抗氧化活性,并与2种参照抗氧化剂(抗坏血酸和BHT)进行比较。结果表明:不同中草药显示出不同的抗氧化活性,在15种中草药中以大花紫薇叶(LagerstroemiaSpeciosa)的抗氧化活性最高,其甲醇提取物中酚类物质的含量最高;同一种中草药的不同溶剂提取物显示出不同的抗氧化活性,通常甲醇提取物比石油醚、乙酸乙酯和水提取物有更强的抗氧化活性和更高的总酚含量。与参照抗氧化剂比较,大花紫薇叶甲醇提取物对DPPH自由基的清除能力强于抗坏血酸。     

体外抗氧化试验筛选抗氧化肽的方法比较

为获得筛选抗氧化肽的快速、准确和重复性高的测定方法,利用具有抗氧化活性的谷胱甘肽对文献报道中常用的7种生物化学体外抗氧化实验进行筛选,对筛选后的方法在采用不同试验人员进行验证,而后对验证重复性比较好的方法再用合成的具有抗氧化活性的肽568 (Pro-Phe-Thr-Arg-Asn-Tyr-Tyr-Val-Arg-Ala-Val-Leu-HisLeu)、肽580(Trp-Asn-Trp-Ala-Asp)、肽567(Val-Tyr-Gln-Phe-Leu)和肽467(Pro-His-Cys-Lys-Arg-Met)进行确认,数据处理采用origin8.0和SPSS15.0进行。结果表明:常用的清除1,1-二苯基-2-三硝基苯肼(1,1-diphenyl-2-picrylhydrazyl,DPPH·)和超氧化物歧化酶(superoxide dismutase,SOD)这两种方法稳定性和重现性最佳,清除DPPH·和SOD可以作为抗氧化肽初步筛选的方法。     

海参酶解产物的分离及其体外抗氧化作用的研究

从海参酶解产物中分离制备海参肽.并研究其体外抗氧化作用。采用超滤、冷冻干燥方法分离不同分子质量范围的海参肽;采用二苯代苦味酰基自由基(DPPH),研究海参肽的抗氧化活性;经Sephadex G-25和反相高效液相色谱对抗氧化海参肽进行进一步分离。结果表明,分子质量在1000～3000u的海参肽表现出很强的抗氧化作用,对DPPH自由基的清除能力强于V_E,其再经Sephadex G-25分离得到海参肽Ⅰ的抗氧化活性最强,对DPPH自由基的清除率达56.3%(1mg/mL),海参肽Ⅰ经反相高效液相色谱将分离得到2个海参多肽组分.     

Isolation and Identification of Antioxidant Compounds from Gynura Bicolor Stems and Leaves

The antioxidant compounds in the stems and leaves of Gynura bicolor were studied. 1,1-diphenyl-2-picrylhydrazyl and 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) radical scavenging assays were employed to evaluate antioxidant capacity. By solvent extraction and Sephadex LH-20 column chromatography in sequence, ethanol extracts of Gynura bicolor stems and leaves were fractionated to obtain their active fractions, which were further separated to obtain 12 compounds: 1–8 from stems, and four, 8–12, from leaves. Their structures were elucidated on the basis of spectroscopic data (nuclear magnetic resonance and mass spectrometry). Among these substances, compounds 1, 2, 3, 4, and 8 with significant antioxidant activity were determined to be responsible active components for stems, and compounds 4, 8, and 12 for leaves.     

体外模拟消化对车前子来源毛蕊花苷抑制黄嘌呤氧化酶活性的影响

研究体外模拟消化各阶段的条件对车前子来源毛蕊花苷抑制黄嘌呤氧化酶活性的影响。结果发现毛蕊花苷含量在模拟消化作用4 h后降低,降低程度最高的是肠菌孵育样液,毛蕊花苷含量减少率为(71.26±0.96)%,其次是累加消化样液,达(28.46±0.50)%。模拟消化后各样液的黄嘌呤氧化酶抑制作用均有所增加,增加程度最大的为肠菌孵育样液(P0.05),其次为累加消化样液。经高效液相色谱-质谱联用分析发现,各消化样液中均能检出毛蕊花苷的代谢苷元咖啡酸和羟基酪醇,活性实验表明后两者对黄嘌呤氧化酶的体外抑制活性高于前体毛蕊花苷。毛蕊花苷降解成具有黄嘌呤氧化酶体外抑制活性的产物可能是其在体内表现生理活性的途径之一。