Antioxidant capacity of herbal infusions and tea extracts: A comparison of ORAC-fluorescein and ORAC-pyrogallol red methodologies

Oxygen radical absorbance capacity (ORAC) values have been obtained for a series of teas and herbal infusions employing 2,2′-azo-bis(2-amidinopropane) as free radical source, and fluorescein and pyrogallol red as target molecules. The amounts of phenols in the extracts were evaluated by Folin’s methodology. ORAC values are extremely dependent upon the employed target molecule. Even more, relative ORAC values measured for different infusions depend upon the employed methodology. For example, ORAC-fluorescein value of Aloysia citriodora is larger than that of green tea, while if pyrogallol red is employed as target molecule green tea appears as nearly nine times more efficient. Similarly, for extracts with comparable amounts of phenols, herbal infusions are more efficient than teas by ORAC-fluorescein, while opposite conclusions are obtained if ORAC-pyrogallol red values are considered. Extreme care must then be taken for conclusions obtained from ORAC values estimated by employing a single target molecule.     

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

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

Beneficial role of sulfated polysaccharides from edible seaweed Fucus vesiculosus in experimental hyperoxaluria

Sulfated polysaccharides from marine algae are known to possess numerous properties of pharmacological importance. The present study is an attempt to evaluate the efficacy of the sulfated polysaccharides from edible seaweed, Fucus vesiculosus in ameliorating the abnormal biochemical changes in experimental hyperoxaluria. Two groups of male albino rats of Wistar strain (140 ± 20 g) received 0.75% ethylene glycol for 28 days to induce hyperoxaluria, and one of them received sulfated polysaccharides (fucoidan from F. vesiculosus, 5 mg/kg b.wt., s.c.) treatment, commencing from the 8th day of the experimental period. One group was maintained as a control group and another group served as a drug control, which received only sulfated polysaccharides. Incongruity in the renal tissue enzymes (ALP, β-Glu and γ-GT) were observed during hyperoxaluria along with an increased activity of oxalate metabolizing enzymes like LDH, GAO and XO. These changes were reverted to near normalcy with sulfated polysaccharide administration. Alterations were observed in the activities/levels of tissue enzymic (superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, glutathione S-transferase and glucose-6-phosphate dehydrogenase) and non-enzymic (reduced glutathione, ascorbate and -tocopherol) antioxidants, along with high malondialdehyde levels in the hyperoxaluric group. However, normalized lipid peroxidation status and antioxidant defences were noticed with sulfated polysaccharide administration. Biochemical discrepancies observed in hyperoxaluria disrupt membrane integrity, favouring a milieu for crystal retention. Advocation of sulfated polysaccharides enhanced the antioxidant status, thereby preventing membrane injury and alleviating the microenvironment favourable for stone formation.     

不同取代度的硫酸化肠浒苔多糖抗氧化活性研究

采用氨基磺酸-N,N-二甲基甲酰胺法进行多糖的硫酸化修饰,获得不同取代度的硫酸化肠浒苔多糖,通过测定硫酸化肠浒苔多糖对DPPH自由基,羟基自由基,超氧阴离子的清除能力和还原能力,考察了肠浒苔多糖取代度与抗氧化活性的关系。结果表明,取代度的大小受到硫酸化温度、硫酸化时间、DMF用量、氨基磺酸用量等的影响,其中氨基磺酸用量的影响最显著。随着取代度增大,肠浒苔多糖的抗氧化性先增强后减小,取代度在0.8¹.2范围内,肠浒苔多糖的抗氧化性较强,表明适度进行硫酸化修饰是提高肠浒苔多糖抗氧化活性的有效方式。      

Antioxidant capacity and related parameters of different fruit formulations

Fruits and vegetables are known as good sources of phytochemicals, essential to prevent degenerative diseases like cancer and cardiovascular diseases (CVD). They contain a variety of antioxidants, which are useful to scavenge radical oxygen species (ROS). Besides smoothies, fruit purees, concentrates and juices - used by the food industry for these new beverages - were analysed. Total phenolics by Folin-Ciocalteu method, vitamin C content and antioxidant capacity (AOC) by FRAP, TEAC and ORAC assay were analysed by using high-throughput methods on a microplate reader. Vitamin C content ranged from 31 ± 3 mg/100 g in drinkable pomegranate concentrate to 1373 ± 125 mg/100 g in acerola puree; total phenolics content was quantified between 51 ± 1 mg gallic acid equivalents (GAE)/100 g in the mango-peach smoothie and 1152 ± 62 mg/100 g in the ascorbic acid rich acerola puree. The AOC differed depending on kind of fruit and antioxidant assay used. In most fruit products the major portion of AOC was generated by polyphenolic compounds, except acerola puree and orange juice. Very good correlations between total phenolics content and antioxidant capacity were found in the single fruit products, however not in the fruit and vegetable smoothies. Most of the analysed smoothies were able to supply with one package nearly the recommended dietary intake (RDI) of vitamin C for adults of 100 mg per day.     

米糠多糖及硫酸酯化米糠多糖的体外免疫应答和抗肿瘤活性研究

以小鼠黑色素瘤细胞(B16)为抗肿瘤模型,通过MTT比色法评价米糠多糖及硫酸酯化米糠多糖对B16增殖抑制能力。以小鼠巨噬细胞Raw264.7细胞系为免疫模型,通过MTT比色法评价Raw264.7增殖能力,中性红吞噬试验评价巨噬细胞活性,Griess方法检测一氧化氮(NO)释放量,以及酶联免疫(ELISA)检测肿瘤坏死因子(TNF-α)分泌量,考察米糠多糖及硫酸酯化米糠多糖的免疫活性。研究发现:米糠粗多糖(RBP)和米糠多糖纯化组分(RBP2a)主要通过增强机体的免疫功能而间接抑制肿瘤细胞。质量浓度为250μg/m L时,RBP和RBP2a样品组的NO释放量分别为对照组的4.67、6.36倍,TNF-α分泌量为对照组的441.1、465.5倍;RBP直接组和间接组的B16抑制率分别为8.16%、45.55%,间接组的B16抑制率比直接组增长458%。硫酸酯化米糠多糖(SRBP-B,SRBP-D,SRBP2a-B)一方面可以直接抑制B16增殖,质量浓度为1 000μg/m L时,对B16抑制率达73.65%、65.53%、78.43%,另一方面也可通过免疫途径提高NO和TNF-α等细胞因子释放,进一步提高抗肿瘤活性。但高浓度SRBP-B,SRBP-D,SRBP2a-B能抑制Raw264.7增殖,在500μg/m L时,Raw264.7存活率仅为83.26%、81.8%、79.78%。     

Antioxidant capacity of caseinophosphopeptides prepared from sodium caseinate using Alcalase

The antioxidant capacity of caseinophosphopeptide prepared at different pH from casein hydrolysate with Alcalase was evaluated using oxygen radical absorbance capacity (ORAC), reduction capacity and metal chelating activity. The yield of CPP production was dependent on the pH of supernatant from pH 4.6 clarified Alcalase hydrolysate of sodium caseinate. CPP of pH 3 had higher content of cysteine, aspartic acid, glycine, histidine, proline, tyrosine, and leucine, and less content of glutamic acid, serine, and isoleucine than those of other pH. The phosphate contents of all CPP were relatively similar, 5.0–5.4% (w/w) except at pH 3. The ORAC against peroxyl radical (ORACROO${\text{ORAC}}_{{\text{ROO}}^{\text{<glyph name="rad"></glyph>}}}$) of CPP decreased with increasing pH (3–8) in concentrations tested and was positively correlated with its reduction capacity. The ORAC against hydroxyl radical (ORACOH${\text{ORAC}}_{{\text{OH}}^{\text{<glyph name="rad"></glyph>}}}$) of CPP at 50 μg/ml increased with increasing pH to 7 and then decreased, and its metal chelating activity on ferrous ion increased linearly with increasing pH from 3 to 5, then slowly increased until pH 8, indicating that the ORACOH${\text{ORAC}}_{{\text{OH}}^{\text{<glyph name="rad"></glyph>}}}$ activity of CPP might be attributed to the scavenging activity on hydroxyl radical itself as well as the chelating activity of transition metals.     

Rheological characterisation of polysaccharides extracted from brown seaweeds

Hydrocolloids from seaweeds have interesting functional properties, such as thickening or gelling ability. Structural characteristics of polysaccharides extracted from Québec seaweeds have not yet been established. Thus, the determination of the relationship between their structure and rheological behaviour is limited. Alginate and fucoidan were extracted using selective solvents from three species: Saccharina longicruris, Ascophyllum nodosum and Fucus vesiculosus. Structural analysis (total sugars, uronic acids, sulfates and molecular weight) and rheological characterisation were performed at different polysaccharide concentrations with and without the addition of NaCl. The results showed important variation between species. Fucoidan and alginate exhibited Newtonian behaviour. Fucoidan extracted from F. vesiculosus had the highest viscosity level, which might be explained by the degree of branching of the molecules. For alginate, the one extracted from S. longicruris showed a higher apparent viscosity. This result can partially be explained by the block proportion of alginate. The gelation profile of alginate was also determined for each species. The final storage modulus, G′, was variable for each species. Differences between species were observed for both polysaccharides as a result of structural variation. Copyright © 2007 Society of Chemical Industry     

Antioxidant activity and protective effects of green and dark coffee components against human low density lipoprotein oxidation

The in vitro antioxidant activity and the protective effect against human low density lipoprotein oxidation of coffees prepared using different degrees of roasting was evaluated. Coffees with the highest amount of brown pigments (dark coffee) showed the highest peroxyl radical scavenging activity. These coffees also protected human low-density lipoprotein (LDL) against oxidation, although green coffee extracts showed more protection. In a different experiment, coffee extracts were incubated with human plasma prior to isolation of LDL particles. This showed, for the first time, that incubation of plasma with dark, but not green coffee extracts protected the LDL against oxidation by copper or by the thermolabile azo compound AAPH. Antioxidants in the dark coffee extracts must therefore have become associated with the LDL particles. Brown compounds, especially those derived from the Maillard reaction, are the compounds most likely to be responsible for this activity.     

Antioxidant activities,phenolic and β-carotene contents of sweet potato genotypes with varying flesh colours

Antioxidant activities (μmol Trolox equivalent (TE)/g fresh weight) of 19 sweet potato genotypes with distinctive flesh colour (white, cream, yellow, orange and purple) were measured by oxygen radical absorbance capacity (ORAC), 2,2-diphenyl-1-picrylhydrazyl (DPPH), and 2,2′-azinobis(3-ethyl-benzothiazoline-6-sulfonic acid) (ABTS). Total phenolics were measured using the Folin–Ciocalteau method, total anthocyanins by the pH-differential method, and β-carotene by HPLC. The total antioxidant activity (hydrophilic + lipophilic ORAC) was highest (27.2 μmol TE/g fresh weight (fw)) for NC415 (purple-fleshed) and lowest (2.72 μmol TE/g fw) for Xushu 18 (white-fleshed). The hydrophilic-ORAC values were significantly correlated with the DPPH (R² = 0.859) and ABTS (R² = 0.761) values. However, the lipophilic-ORAC values were poorly correlated with the β-carotene contents (R² = 0.480). The total phenolic contents (0.011–0.949 mg chlorogenic acid equivalent/g fw) were highly correlated with the hydrophilic-ORAC (R² = 0.937) and DPPH (R² = 0.820) values. Therefore, the total phenolic content can serve as a useful indicator for the antioxidant activities of sweet potatoes.     

Chemical characterization and antioxidant activity of sulfated polysaccharide from the red seaweed Gracilaria birdiae

Hydrocolloids from seaweeds have interesting functional properties, such as antioxidant activity and gelling ability. A polysaccharide was isolated by aqueous extraction at 90 °C from the red seaweed Gracilaria birdiae (Gb), with a yield of 27.2% of the seaweed dry weight. The sulfate content of the polysaccharide was 8.4% and the main sugars present were galactose (65.4 mol%), 3,6-anhydrogalactose (25.1 mol%) and 6-O-methylgalactose (9.2 mol%). Gel permeation chromatography showed that Gb polysaccharide is a heterogeneous system, with molar mass at the main peak of 3.7 × 10⁵ g mol⁻¹ and a shoulder of 2.6 × 10⁶ g mol⁻¹. The sulfated polysaccharide of Gb characterized by FTIR exhibits the characteristic bands of agarocolloids (at 1375 and 770 cm⁻¹).     

Antioxidant capacities of individual and combined phenolics in a model system

In order to understand how interaction of individual phenolics contributes to the total antioxidant capacity, we quantitatively measured antioxidant capacity of various phenolics in different combinations, using ABTS radical-scavenging ability in a model system. Selected phenolics included in this study were those often found in fruits and vegetables, such as catechin, chlorogenic acid, cyanidin, cyanidin 3-glucoside, cyanidin 3-rutinoside, epicatechin, peonidin, peonidin 3-glucoside, quercetin, quercetin 3-glucoside, quercetin 3-galactoside and quercetin 3-rutinoside. Individual phenolics showed their characteristic antioxidant capacities, while the mixtures, with two or three phenolics combined revealed that the summation of antioxidant capacities of individual phenolics led to total antioxidant capacity. Therefore, it can be concluded that there was no synergistic effect among the phenolics studied. Only an additive effect of antioxidant capacity was observed.     

Evaluation of the antioxidant activity of a series of 4-methylcoumarins using different testing methods

Continuing our research on oxidation reactions of 4-methylcoumarins (4-methyl-2H-1-benzopyran-2-ones), this study presents evaluation of the antioxidant activity of 23 4-methylcoumarin derivatives, using different spectrophotometric and spectrofluorimetric radical testing methods. All studied compounds showed activity comparable to Trolox, an already known antioxidant, which is used as a standard in most testing methods. Observations from the study were made with regard to structural features that regulated the behaviour of the compounds. This paper extends our knowledge of the range of valuable biological activities and possible roles in medicinal therapy associated with this group of compounds.     

海藻多糖的提取、分离纯化与应用研究进展

海藻多糖是海藻中的重要活性物质,含量较高。大量研究表明,海藻多糖具有良好的凝胶性、稳定性、成膜性,同时具有抗病毒、抗凝血、抗肿瘤、免疫调节、抗氧化等多种生物活性,被广泛应用于食品、保健医药及化妆品等方面。本文综述了海藻多糖的提取、分离纯化以及应用的研究新进展,比较分析了不同的提取及分离纯化方法的优缺点,列举了海藻多糖在食品、保健医疗及化妆品等方面的应用,指出了海藻多糖发展中存在的一些问题,并对海藻多糖未来的发展及应用进行了展望,以期能更好的开发利用海藻多糖,促进海藻多糖行业的持续健康发展。     

Chemical structure of sulfated polysaccharides from brown seaweed (Turbinaria turbinata)

The chemical structure of three sulfated polysaccharides fractions (TtF1, TtF2, and TtF3) obtained from anion-exchange separation of aqueous extracts of brown seaweed (Turbinaria turbinate) were studied. The infrared spectra patterns showed that the fractions possess functional groups similar to that of sulfated polysaccharides. The sulfated polysaccharides fractions exhibited molecular weights of 223.5, 495.5, and 326.05 kDa, respectively, for TtF1, TtF2, and TtF3. ¹H NMR spectra of TtF2 and TtF3 contain α-anomeric protons (5–5.6 ppm), ring protons (3.4–4.4), and methyl protons (1–1.3 ppm) while that of TtF1 only exhibited ring protons and methyl protons. Rheological data were fitted to power law which revealed that the fractions were Newtonian and/or presented weak pseudoplastic behavior. Consistency values increased with concentration in all fractions. Consistency values of TtF2 were the highest, followed by TtF1 and then TtF3. Thermal degradation patterns of TtF1 and TtF2 were similar but different from that of TtF3. This study confirmed that chemical and physical characteristics of sulfated polysaccharides fractions are interrelated and provided in-depth understanding of sulfated polysaccharides of brown algae.     

Phenolic Profiles and Total Antioxidant Capacity of Marketed Beers in Serbia

The aim of this research was to determine the total phenolic and flavonoid contents as well as to measure antioxidant activity of 24 different commercial beers consumed in Serbia. The major phenolic acids (gallic acid, protocatechuic acid, 4-hydroxybenzoic acid, 2,5-dihydroxybenzoic acid, vanillic acid, caffeic acid, syringic acid, p-coumaric acid, ferulic acid, sinapic acid, salicylic), (+)-catechin, and (-)-epicatechin were also determined by high pressure liquid chromatography method using a photodiode array detector. Gallic acid, ferulic acid, and protocatechuic acid are the most abundant phenolic acids in all samples, followed by (+)-catechin. The total phenolic content was determined using the Folin-Ciocalteu assay. The total flavonoids were measured using spectrophotometrics as the aluminum chloride assay. The results showed that the highest total phenolic and flavonoid contents were established in dark and light beer samples. 2,2-Diphenyl-1-picrylhidrazyl radical scavenging activity, 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) radical cation scavenging activity, and ferric reducing/antioxidant power were used to assess the antioxidant potential of beers. These assays, based on different chemical mechanisms, were selected to take into account the wide variety and range of action of antioxidant compounds present in selected beer samples. All beers showed antioxidant power, but a wide range of antioxidant capacities was observed. Statistical differences between ferric reducing-antioxidant power and the other two antioxidant capacity assays were confirmed. This study will be useful for the appraisal of phenolic profile and antioxidant activities of various beers, and it will also be of interest for people who like drinking this beverage.