Biochemical characteristics and antioxidant activity of crude and purified sulfated polysaccharides from Gracilaria fisheri

Sulfated polysaccharides (SPs) from Gracilaria fisheri of Thailand, which were extracted in low-temperature (25 °C) water showed the highest content of phenolic compounds compared with those extracted at high temperature (55 °C). Crude SP antioxidant activity was evaluated by measuring the DPPH free radical scavenging effect which is directly related to the level of phenolic compounds. The sulfate content, total sugar, and SPs yield were also directly related to the extraction temperature. All extracts contained galactose as a major monosaccharide. High antioxidant activity of crude SP, positively correlated with the phenolic compound contents (R² = 0.996) contributed by the existence of sulfate groups and phenolic compounds. In purified SP, F1 fraction exhibited strong radical scavenging ability, but it was not significantly different compared to crude SP extracted at 25 °C. This indicated that the appropriate density and distribution of sulfate groups in the SP extract showed the best antioxidant activity.     

不同成熟度老鹰茶中酚类化合物含量及抗氧化活性研究

为了探究两种不同成熟度老鹰茶中酚类化合物含量及抗氧化活性的差异,以对其进行辨识及质量评价,该研究利用液相色谱-串联质谱(LC-MS/MS)法测定老鹰茶中15种酚类化合物,采用DPPH自由基清除率、ABTS⁺自由基清除率、Fe³⁺还原能力评价两种茶叶抗氧化能力,再通过数据统计分析探讨两种老鹰茶酚类化合物含量及抗氧化活性的差异,并进一步探索老鹰茶中不同酚类化合物对于抗氧化的贡献。结果表明:(1)嫩叶茶中儿茶素、对香豆酸、异槲皮苷、金丝桃苷、烟花苷、紫云英苷、山奈酚、槲皮素、阿福豆苷含量显著高于老叶茶,其中儿茶素、异槲皮苷、紫云英苷平均含量比老叶茶分别高1 039.43、169.12、257.35 mg·100 g^-1。聚类分析(HCA)、主成分分析(PCA)、正交偏最小二乘判别分析(OPLS-DA)均可将二者区分。(2)方差分析(ANOVA)结果显示在抗氧化能力上,二者在DPPH自由基清除率、ABTS⁺自由基清除率、Fe³⁺还原能力之间具有显著性差异,嫩叶茶优于老叶茶。(3)偏最小二乘回归分析(PLSR)法提示老鹰茶中的异槲皮苷、儿茶素、紫云英苷、绿原酸、金丝桃苷、对香豆酸、山奈酚是其发挥抗氧化效能的主要酚类化合物。该研究结果可为老鹰茶的质量控制及应用推广提供一定的参考。     

Phenolic composition and antioxidant activities of two Phlomis species: A correlation study

Two traditional Chinese medicines (Phlomis umbrosa Turcz. and Phlomis megalantha Diels), as well as five pure phenolic compounds (protocatechic, chlorogenic, benzoic, rosmarinic acid, and rutin) have been studied for antioxidant activities in acetone and methanol extracts from leaves. An HPLC method was developed to quantify the amounts of 14 phenolic compounds in the leaf extracts. The antioxidant capacities of the studied species are high. Almost all samples were capable of directly scavenging DPPH and superoxide free radicals, inhibiting linoleic acid oxidation, acting as reducing agents, and reducing plasmid DNA damage induced by hydroxyl radicals. Among different extracts, the acetone extract of P. megalantha exhibited the highest antioxidant activity. The major phenolic compounds identified were protocatechic, chlorogenic, caffeic, rosmarinic acid, and (−)-epicatechin. Antioxidant activities of pure compounds and correlation analysis indicated that protocatechic and rosmarinic acids were the major contributors to the observed antioxidant activities of the investigated Phlomis extracts. To cite this article: Y. Zhang, Z.-z. Wang, C. R. Biologies 332 (2009).     

Host-hemiparasite transfer of the C-glucosyl xanthone mangiferin between Mangifera indica and Dendrophthoe falcata

Abstract

To test the hypothesis that higher antioxidant potential of hemiparasitic plants is due to sequestration of phenolic compounds from the host plants, samples of Dendrophthoe falcata, a hemiparasite collected from different hosts, were investigated for total phenolics, total flavonoids and 1,1-diphenyl-2-picryl-hydrazyl (DPPH) radical scavenging activity. The hosts significantly influenced the phenolic content of the hemiparasite. However, similar influence was not detected on radical scavenging activity and no correlation was found in the phenolics and free radical scavenging activities. Further investigation on transfer of constituents revealed that D. falcata sample obtained from a host, Mangifera indica, contained mangiferin, a C-glucosyl xanthone, and some unidentified flavonoids as confirmed by HPTLC flavonoid patterns. The data indicated that the hosts significantly affected total phenolics and total flavonoids in a hemiparasite. This is the first report of transfer of mangiferin from M. indica to a hemiparasite. The present report points towards the need of further investigations on the possible role of transferred phenolics either as mediators of host defense, host defense compounds utilized as cues of identification of the host by the hemiparasite or compounds taken up by the parasites to support their defense against rejection by the hosts.     

Effect of different conditioning treatments on total phenolic content and antioxidant activities in two Sargassacean species: Comparison of the frondose Sargassum muticum (Yendo) Fensholt and the cylindrical Bifurcaria bifurcata R. Ross

The effects of different conditioning treatments (fresh, freezing, freeze‐drying, oven‐drying and greenhouse‐drying) on the total phenolic content (TPC) and antioxidant activities of two brown algae, Sargassum muticum and Bifurcaria bifurcata, were investigated and compared. Phenolic compounds were extracted in a methanol/water (50:50) solution, and TPC was measured by the colorimetric Folin‐Ciocalteu assay. Antioxidant activity was assessed by the DPPH (2, 2‐diphenyl‐1‐picrylhydrazyl) radical scavenging assay and the β‐carotene bleaching method. The dried seaweeds showed lower phenolic contents and lower antioxidant capacities than the fresh and frozen ones, which suggests that the phenolic content and antioxidant activities are decreased by the drying treatments, especially, oven‐ and greenhouse‐drying. Relationships between TPC, antioxidant properties and conditioning treatments are discussed.     

Variation in Phenolic Content,Profile, and Antioxidant Activity of Seeds among Different Paeonia ostii Cultivated Populations in China

The purpose of this study was to analyze the phenolic profiles of seeds from fifteen Paeonia ostii cultivated populations in China and identify their relationship with antioxidant activities and associated environmental factors. Thirteen individual phenolic compounds were quantitatively determined by HPLC, and (+)‐catechin was the most abundant phenolic compound in the seeds. Correlation analysis showed that phenolics were the most effective antioxidant compound class by evaluating DPPH, ABTS, and hydroxyl radical scavenging activities as well as ferric reducing antioxidant power. Latitude and annual rainfall had significant effects on the contents of many phenolic compounds, and elevation was only significantly correlated with gallic acid content. Within fifteen P. ostii cultivated populations, the seeds of Tongling population exhibited the highest phenolic contents and strongest antioxidant activities. These results suggest that Tongling population has a relatively high utilization value and a potential for sources of natural antioxidants.     

Bio-Guided Investigation of Sideritis cypria Methanol Extract Driven by in Vitro Antioxidant and Cytotoxic Assays

Sideritis cypria Post is an endemic and endangered species of Northern Cyprus. The overall aim of the present study was to evaluate the total phenolic content, the antioxidant, the cytotoxic and the antimicrobial activity of the methanol extract obtained from the aerial parts of cultivated S. cypria. A bio-guided approach led to the isolation of 27 chemical compounds by using various analytical techniques. Their structures were elucidated on the basis of 1D and 2D NMR spectroscopy. The crude extract exerted strong antioxidant activity (DPPH and FRAP assays) which was attributed to its high total phenolic content. Furthermore, groups rich in phenolic content showed highest antioxidant property, whereas groups with phytosterols, diterpenoids and apigenin derivatives exerted cytotoxic effects in MDA-MB231 cancer cell line by the MTT method. Moreover, the cytotoxic activity of four isolated apigenin derivatives was evaluated in the same cancer cells. The antimicrobial activity of the extract and groups were measured, demonstrating lack of activity. To the best of our knowledge, this survey is the first report on the biological activities of the methanol extract of S. cypria.     

Quercus ilex L.: How season,Plant Organ and Extraction Procedure Can Influence Chemistry and Bioactivities

Quercus species have a plethora of applications, either in wine and wood industries, in human and animal nutrition or in human health. In order to improve the knowledge on this genus, the aim of the present study was to correlate, for the first time, the phenolic composition of different Quercus ilex L. plant tissues (leaves in two maturation stages, acorns, teguments and cotyledons) and different extraction procedures with scavenging and anticholinesterase activities. The hydromethanolic and aqueous extracts obtained showed strong radical scavenging activity against DPPH, superoxide anion radical and nitric oxide radical, leaves exhibiting higher total phenolic content and revealing the best antioxidant properties, followed by tegument and acorns. Concerning the phenolic profile, fifteen compounds were identified and quantified by HPLC‐DAD, ranging from 1568.43 to 45,803.16 mg/kg dried extract. The results indicate that Q. ilex can be a source of strong antioxidant phenolic compounds with possible interest for food and pharmaceutical industries.     

Antioxidant properties and phenolic profiling by UPLC-QTOF-MS of Ajwah,Safawy and Sukkari cultivars of date palm

Date palm (P. dactylifera) plays a vital role in ethnomedicinal practices in several parts of the world. There are over 2000 cultivars of date palm that differ in chemical composition and extent of bioactivity. The present study was undertaken to comparatively evaluate the antioxidant potential of three cultivars of date palm (Ajwah, Safawy and Sukkari) from Saudi Arabia and analyze their phenolic constituents in order to draw a rationale for their activity. Antioxidant activities of the date cultivars were evaluated by different quantitative methods including 2,2-diphenyl-1-picrylhydrazyl (DPPH) and hydroxyl radical scavenging assay, total antioxidant capacity, reducing power, total phenolic (TPC), flavonoid (TFC) and tannin content (TTC), while qualitative phenolic composition was determined using ultra performance liquid chromatography coupled to quadropole time of flight mass spectrometry (UPLC-QTOF-MS). All the three date extracts showed good DPPH radical scavenging (IC₅₀ 103–177 μg/mL) and hydroxyl radical scavenging (IC₅₀ 1.1–1.55 mg/mL) activity and total antioxidant capacity (IC₅₀ 87–192 μg/mL). The reducing power was also comparable to that of ascorbic acid, used as standard in above experiments. All the three samples contain significant amount of major antioxidant components (phenolic, flavonoid and tannin) that successfully correlates with the results of radical scavenging assays. UPLC-QTOF-MS revealed a total of 22 compounds in these date cultivars classified into common phenolics, flavonoids, sterols and phytoestrogens. Significant variation in the degree of antioxidant activity of these three date cultivars can be attributed to the difference in the content and composition of phenolic compounds.     

Antioxidant constituents from rhubarb: structural requirements of stilbenes for the activity and structures of two new anthraquinone glucosides

The methanolic extracts from five kinds of rhubarb were found to show scavenging activity for DPPH radical and .O2-. Two new anthraquinone glucosides were isolated from the rhizome of Rheum undulatum L. together with two anthraquinone glucosides, a naphthalene glucoside, and 10 stilbenes. In the screening test for radical scavenging activity of rhubarb constituents, stilbenes and a naphthalene glucoside showed activity, but anthraquinones and sennosides did not. In addition, most stilbenes inhibited lipid peroxidation of erythrocyte membrane by tert-butyl hydroperoxide. Detailed examination of the scavenging effect on various related compounds suggested the following structural requirements; 1) phenolic hydroxyl groups are essential to show the activity; 2) galloyl moiety enhances the activity; 3) glucoside moiety reduces the activity; 4) dihydrostilbene derivatives maintain the scavenging activity for the DPPH radical, but they show weak activity for .O2-. In addition, several stilbenes with both the 3-hydroxyl and 4'-methoxyl groups inhibited xanthine oxidase.     

Phenolic metabolites from Pyruscalleryana and evaluation of its free radical scavenging activity

Investigation of the aqueous alcoholic extract of Pyruscalleryana Decne. leaves led to the isolation of two new phenolic acids glycosides, namely protocatechuoylcalleryanin-3-O-β-glucopyranoside (1) and 3′-hydroxybenzyl-4-hydroxybenzoate-4′-O-β-glucopyranoside (2), together with nine known compounds among them lanceoloside A and methylgallate, which have been isolated for the first time from the genus Pyrus. Structures of the isolated compounds were established by spectroscopic analysis, including UV, IR, HRESI-MS, and 1D/2D NMR. The total extract and some isolated compounds were determined against DPPH (2,2-diphenyl-1-(2,4,6-trinitrophenyl) hydrazinyl radical, for their free radical scavenging activity, the total alcoholic extract showed strong antioxidant activity while the two new compounds showed weak antioxidant activity.     

3种百合鳞茎中多酚类物质的抗氧化活性分析

以野生百合渥丹、山丹和传统食用的兰州百合为研究对象,对其鳞茎中多酚类物质、11种单体酚的含量及抗氧化活性(ABTS自由基、超氧阴离子、羟自由基的清除能力,铜离子还原能力以及抑制脂质过氧化活性)进行了分析。结果表明:两种野生百合鳞茎中的多酚类物质含量及抗氧化活性均显著高于兰州百合。3种百合鳞茎中单体酚的种类也有所不同,但均含有没食子酸、矢车菊素-3-芸香糖苷、儿茶素、表儿茶素、杨梅酮、芦丁、对香豆酸、山奈酚。相关性分析显示,除对羟自由基的清除力外,各酚类物质总量与不同抗氧化指标之间呈显著正相关关系。试验结果认为,野生百合鳞茎可作为天然抗氧化资源应用于食品和医药业,具有一定的开发应用前景。     

Antioxidant activity and phenolic content of the Indian wheat varieties

In this study, Indian wheat varieties grown under different agro-climatic zones were evaluated for their antioxidant potential. Different grain fractions (bran, flour, shorts) and the whole meal were tested using two free radicals (ABTS and DPPH) for their radical scavenging activities. More variation was observed in the antioxidant activities from different zones using DPPH assay. Irrespective of the method used, the whole meal and the bran of central zone varieties showed the highest and the north western plains zone varieties showed the lowest antioxidant activities. Within each growing zone, both the effect of genotype and environment was observed on the antioxidant activity. Both free and bound phenolic compounds were extracted from the bran of varieties representing different zones. Total phenolic content (TPC) varied from 2,900 to 5,650 μg Gallic acid equivalents/g of bran. Bound phenolic content was found to be more strongly correlated to the TPC than the free phenolic content. Highly significant genotypic differences were observed in the total phenolic content. This study therefore indicates that Indian wheat varieties have good antioxidant activity and high content of phenolic compounds and can be used further in breeding programmes to increase the content of phytochemicals responsible for antioxidant activity.     

Antioxidant and antimicrobial studies on fused-ring pyrazolones and isoxazolones

A series of 3-nitrochalcones have been synthesized enroute towards fused ring pyrazolones and isoxazolones. Base catalyzed condensation of the chalcones with ethylacetoacetate yielded cyclohexenones in good yields (74–76%). The treatment of cyclohexenones with hydrazine hydrate or hydroxylamine chloride in the presence of a base afforded the corresponding fused-ring pyrazolinones (70–78% yield) and isoxazolinones (58–66% yield). The newly synthesized compounds were characterized by IR, 1D and 2D NMR and HRMS spectral analysis. The compounds were screened for their antioxidant and antimicrobial activities. Pyrazolinones showed good DPPH radical scavenging and iron metal chelating properties. The para-hydroxy group was important for a compound to have enhanced antioxidant activity. Pyrazolinones and isoxazolinone exhibited a wider range of antimicrobial activities compared to cyclohexenones. Pyrazolinones and isoxazolinone bearing a thiophene ring were the most potent type of compounds against Bacillus subtilis and Candida albicans with MIC values of 0.313–1.25 μg/mL. Some of the synthesized compounds were found to have promising antioxidant, metal chelation and antimicrobial activities.     

Synthesis and antioxidant activities of some new triheterocyclic compounds containing benzimidazole,thiophene, and 1,2,4-triazole rings

Abstract

Various triheterocyclic compounds containing benzimidazole, thiophene, and 1,2,4-triazole rings (3–6) were synthesized and screened for their antioxidant activities. The structures of the synthesized compounds (2–6) were judged by ¹H NMR, ¹³C NMR, elemental analysis, and LC-MS spectral data. Antioxidant activities of the synthesized compounds (2–6) were determined with CUPric Reducing Antioxidant Capacity (CUPRAC), ABTS (2,2-azinobis(3-ethylbenzothiazoline-6-sulfonic acid)/persulfate, and DPPH (1,1-diphenyl-2-picrylhydrazyl) assays. Most of the compounds showed a significant antioxidant activity and especially, compound 5c showed very good SC₅₀ value for DPPH method and compound 5h exhibited very high scavenging activity to ABTS method.     

In vitro antioxidant activity and phenolic contents in methanol extracts from medicinal plants

Antioxidant activities and phenolic contents of 26 species extracts from 20 botanical families grown in north-western Himalaya were investigated. Antioxidant activities were determined using DPPH (1,1-diphenyl-2-picrylhydrazyl) radical scavenging and ferric reducing antioxidant power (FRAP) assays. Total phenolic content (TPC) was determined using a Folin-Ciocalteu assay. Quantitative and qualitative analysis of phenolic compounds was also carried out by reverse phase high performance liquid chromatography (RP-HPLC) using diode array detector (DAD). Major phenolics determined using RP-HPLC in analyzed species were gallic acid, chlorogenic acid, p-hydroxy benzoic acid, caffeic acid, vanillic acid, syringic acid, p-coumaric acid and ferulic acid. Antiradical efficiency (1/EC₅₀) determined using DPPH radical scavenging assay ranged from 0.13 to 5.46. FRAP values ranged from 8.66 to 380.9 μmol Fe(II)/g dw. Similarly, the total phenolic content in the analyzed species varied from 3.01 to 69.96 mg of gallic acid equivalents (GAE)/g dry weight. Gallic acid was found in the majority of the samples, being most abundant compound in Syzygium cumini bark (92.64 mg/100 g dw). Vanillic acid was the predominant phenolic compound in Picrorhiza kurroa root stolen (161.2 mg/100 g dry weight). The medicinal plants with highest antioxidant activities were Taxus baccata and Syzygium cumini. A significant positive correlation, R ²?=?0.9461 and R ²?=?0.9112 was observed between TPC determined using Folin-Ciocalteu method and antiradical efficiency and FRAP values respectively, indicating that phenolic compounds are the major contributor of antioxidant activity of these medicinal plants.     

New insights into the antioxidant activity of hydroxycinnamic and hydroxybenzoic systems: Spectroscopic,electrochemistry, and cellular studies

Abstract

A series hydroxycinnamic and gallic acids and their derivatives were studied with the aim of evaluating their in vitro antioxidant properties both in homogeneous and in cellular systems. It was concluded from the oxygen radical absorbance capacity-fluorescein (ORAC-FL), 1,1-diphenyl-2-picrylhydrazyl (DPPH), and cyclic voltammetry data that some compounds exhibit remarkable antioxidant properties. In general, in homogeneous media (DPPH assay), galloyl-based cinnamic and benzoic systems (compounds 7–11) were the most active, exhibiting the lowest oxidation potentials in both dimethyl sulfoxide (DMSO) and phosphate buffer. Yet, p-coumaric acid and its derivatives (compounds 1–3) disclosed the highest scavenging activity toward peroxyl radicals (ORAC-FL assay). Interesting structure–property– activity relationships between ORAC-FL, or DPPH radical, and redox potentials have been attained, showing that the latter parameter can be a valuable antioxidant measure. It was evidenced that redox potentials are related to the structural features of cinnamic and benzoic systems and that their activities are also dependent on the radical generated in the assay. Electron spin resonance data of the phenoxyl radicals generated both in DMSO and phosphate buffer support the assumption that radical stability is related to the type of phenolic system. Galloyl-based cinnamic and benzoic ester-type systems (compounds 9 and 11) were the most active and effective compounds in cell-based assays (51.13 ± 1.27% and 54.90 ± 3.65%, respectively). In cellular systems, hydroxycinnamic and hydroxybenzoic systems operate based on their intrinsic antioxidant outline and lipophilic properties, so the balance between these two properties is considered of the utmost importance to ensure their performance in the prevention or minimization of the effects due to free radical overproduction.     

Comparative Studies of Phytochemical Screening,HPLC‐PDA‐ESI‐MS/MS‐LC/HR‐ESI‐MS Analysis,Antioxidant Capacity and in Vitro Fermentation of Officinal Sage (Salvia officinalis L.) Cultivated in Different Biotopes of Northwestern Tunisia

We aimed in the present study to investigate the chemical composition, the antioxidant capacities as well as the in vitro fermentation properties of Salvia officinalis leaves aqueous extract (SOLAE) grown in four regions of northwestern Tunisia. Our data firstly indicated a spatial variation (P<0.05) in condensed tannins, total lipids, polyphenols and flavonoids contents. The HPLC‐PDA‐ESI‐MS/MS‐LC/HR‐ESI‐MS technique allowed to the identification of 13 phenolic compounds and showed that protocatechuic acid is the major constituent of the plant leaves grown in Tabarka, Ain Draham and Testour. The SOLAE of the plant grown in Tabarka presents the most potent scavenging activity against DPPH radical and had the highest percentage of inhibition. More importantly, we found in the present study that the digestibility of dry matter and in vitro fermentation showed a significant variation between the regions and the animal species. Also, we showed a very positive correlation between antioxidant properties and phenolic compounds contents. In conclusion, we suggest that SOLAE had potential beneficial effects owing in part to its antioxidant and ROS scavenging activities. Therefore, S. officinalis can be proposed as an additive food for animals’ nutrition and health.     

Synthesis and Characterization of Novel Thiazolo[3,2‐a]pyrimidine Derivatives and Evaluation of Antioxidant and Cytotoxic Activities

A series of novel thiazolo[3,2‐a]pyrimidines were synthesized and characterized by FT‐IR, ¹H, ¹³C‐NMR and mass techniques. Their antioxidant activities were investigated by 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) radical scavenging assay and the results showed that all the synthesized compounds exhibit good antioxidant activity. In addition, it was found that any substituent on the aromatic ring of the products plays an important role in their antioxidant activity. In vitro cytotoxicity of compounds 4a – 4j was investigated using MTT cell viability assay. Among these compounds, 6‐ethyl 2,3‐dimethyl 5‐(4‐chlorophenyl)‐7‐methyl‐2,3‐dihydro‐5H‐[1,3]thiazolo[3,2‐a]pyrimidine‐2,3,6‐tricarboxylate ( 4e ) bearing a chlorine substituent displayed the highest cytotoxic effect (IC₅₀=6.26±0.6 μm ) in comparison with doxorubicin (IC₅₀=0.68±0.1 μm ) as a standard after 72 h. Therefore, it is assumed that these compounds could be used as effective antioxidant and cytotoxic agents.     

Antioxidant activities in tropical marine macroalgae from the Yucatan Peninsula,Mexico

Extracts from 48 marine macroalgae species (17 Chlorophyta, 8 Phaeophyta and 23 Rhodophyta) from the coasts of Yucatan and Quintana Roo (Mexico) were evaluated for antioxidant activity. The antioxidant activity was measured with the DPPH (2,2-diphenyl-1-picrylhydrasyl) method, and the phenolic content of each extract were also evaluated. All species exhibited a DPPH radical scavenging activity, and three species (Avrainvillea longicaulis, Chondria baileyana and Lobophora variegata) demonstrated great antioxidant potential with very low oxidation index EC₅₀ (1.44 ± 0.01, 2.84 ± 0.07 and 0.32 ± 0.01 mg mL⁻¹, respectively), significantly equivalent to EC₅₀ of some commercial antioxidants such as α-tocopherol, ascorbic acid, BHA and BHT. Moreover, extracts of the most active species exhibited reducing activities, superoxide anion radical scavenging and inhibition of lipid peroxidation. These results suggest that some macroalgae from the Yucatan peninsula have a great antioxidant potential which could be considered for future applications in medicine, food production or cosmetic industry.