Radical Cation Assay Research Articles

Encapsulation and Stabilization of α-Lipoic Acid in Cyclodextrin Inclusion Complex Electrospun Nanofibers: Antioxidant and Fast-Dissolving α-Lipoic Acid/Cyclodextrin Nanofibrous Webs.

In this study, electrospinning of nanofibers from alpha-lipoic acid/cyclodextrin inclusion complex systems was successfully performed without having any polymeric matrix. Alpha-lipoic acid (α-LA) is a natural antioxidant compound which is widely used as a food supplement. However, it has limited water solubility and poor thermal and oxidative stability. Nevertheless, it is possible to enhance its water solubility and thermal stability by inclusion complexation with cyclodextrins. Here, hydroxypropyl-beta-cyclodextrin (HP-β-CyD) and hydroxypropyl-gamma-cyclodextrin (HP-γ-CyD) were chosen as host molecules for forming inclusion complexation with α-LA. Accordingly, α-LA was inclusion complexed with HP-β-CyD and HP-γ-CyD by using very high concentrated aqueous solutions of CyD (200%, w/v) having 1/1 and 2/1 molar ratio of α-LA/CyD. Except α-LA/HP-β-CyD (1/1) solution, other α-LA/CyD solutions were turbid indicating the presence of some noncomplexed α-LA whereas α-LA/HP-β-CyD (1/1) solution was very homogeneous signifying that α-LA was fully complexed with HP-β-CyD. Even so, electrospinning was performed for all of the α-LA/HP-β-CyD (1/1 and 2/1) and α-LA/HP-γ-CyD (1/1 and 2/1) aqueous solutions, and defect-free bead-less and uniform nanofibers were successfully obtained for all of the α-LA/CyD solutions. However, the electrospinning process for α-LA/CyD (1/1) systems was much more efficient than the α-LA/CyD (2/1) systems, and we were able to produce self-standing and flexible nanofibrous webs from α-LA/CyD (1/1) systems. α-LA was efficiently preserved during the electrospinning process of α-LA/CyD (1/1) systems and the resulting electrospun α-LA/HP-β-CyD and α-LA/HP-γ-CyD nanofibers were produced with the molar ratios of ∼1/1 and ∼0.85/1 (α-LA/CyD), respectively. The better encapsulation efficiency of α-LA in α-LA/HP-β-CyD nanofibers was due to higher solubility increase and higher binding strength between α-LA and HP-β-CyD as revealed by the phase solubility test. α-LA was in the amorphous state in α-LA/CyD nanofibers and both α-LA/HP-β-CyD and α-LA/HP-γ-CyD nanofibers were dissolved very quickly in water and also when they wetted with artificial saliva. Additionally, the antioxidant activity of pure α-LA and α-LA/CyD nanofibers was comparatively evaluated using ABTS radical cation assay. α-LA/CyD nanofibers have shown significantly higher antioxidant performance compared to pure α-LA owing to improved water solubility by CyD inclusion complexation. The thermal stability enhancement of α-LA in α-LA/CyD nanofibers was achieved compared to pure α-LA under heat treatment (100 °C for 24 h). These promising results support that antioxidant α-LA/CyD nanofibers may have potential applications as orally fast-dissolving food supplements.

A paper-based device for simultaneous determination of antioxidant activity and total phenolic content in food samples

We report the first use of a paper-based device as a simple, low-cost and rapid detection platform for simultaneous determination of antioxidant activity and total phenolic content in food samples. Two antioxidant activity assays including 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulphonate) radical cation (ABTS) assay and cupric reducing antioxidant capacity (CUPRAC) assay and one total phenolic content assay, Folin Ciocaltue reagent (FC) assay were simultaneously employed as a proof-of-concept. The device composed of a central sample zone connected to four pretreatment zones and consecutive detection zones to accommodate all three assays and a sample blank measurement. The analysis was achieved by dropping the samples onto the sample zone to flow to the pretreatment and detection zones containing the stored reagents for each antioxidant assay making the color change that was measured using imageJ software. Assay optimization including key reagent concentrations, reaction time, and surface modification were carried out to obtain sensitive and wide linear rage analyses. Various antioxidant standards were then evaluated to determine the analytical features of the method. The paper-based assays were successfully applied to detect antioxidant activity and total phenolic content in 10 beverage samples with similar gallic acid equivalent (GAE) values to those obtained from traditional assays at a 95% confidence interval. Moreover, the GAE values of the samples obtained from three assay analyses were well correlated to each other with relatively high Pearson's correlation coefficients. These results indicated that the assays gave accurate results and are suitable for simultaneous analysis of antioxidant activity and total phenolic content in real samples.

Influence of extraction pre-treatments on some phytochemicals and biological activity of Transylvanian cranberries (Vaccinium vitis-idea L.)

Cranberries (Vaccinium spp.) are rich sources of phytochemicals, but their bioactivity depends on cultivar, harvesting time, processing, or extraction procedure. Thus, a wider variety of subspecies needs to be characterized, and the effects of treatments prior to consumption or extraction need to be determined. This study aims to phytochemically characterize pre-treated (fresh, frozen, and dried) Transylvanian cranberries (Vaccinium vitis-idea L.) and to evaluate their bioactivity. The profile and content of individual anthocyanins were analyzed by HPLC-PDA, total phenolics and flavonoids were determined spectrophotometrically, and antioxidant activity was evaluated by ABTS+ radical cation assay. Their antibacterial activity against Staphylococcus aureus, Escherichia coli, and Salmonella Typhimurium was assessed by disk diffusion. Total identified anthocyanins ranged from 11.14 to 123.02 mg cyanidin-3-O-galactoside/100 g fresh weight. Cranberries were rich in polyphenols and flavonoids, with the highest content in fresh berries; they inhibited E. coli and S. Typhimurium. Freezing enhanced their antibacterial activity. The significance of this study lies in the evaluation of how pre-treatments affect some novel natural food-grade antimicrobials from cranberries with the potential to replace synthetic food preservatives and to deliver phytochemicals with health benefits.

Chemical composition and antioxidant and antibacterial activity of Platymiscium gracile Benth.: A species threatened by extinction

Sawdust of Platymiscium gracile Benth. (Fabaceae) was extracted by percolation using n-hexane, dichloromethane, ethyl acetate, and methanol sequentially. Then, fractions were screened for their phenolic contents and antioxidant and antibacterial properties. The phenolic contents ranged from 13,667 ± 773 (ethyl acetate fraction) to 36,350 ± 3049 mg GAE/100 g extract (hexane fraction). In general, all fractions displayed a significant antioxidant activity with values ranging from 20,055 ± 1341 and 194,919 ± 7163 μmol TE/100 g extract, 1785 ± 225 and 32,264 ± 326 mg AAE/100 g extract, 30,081 ± 1618 and 901,706 ± 20,393 μmol TE/100 g extract for the DPPH, FRAP, and ABTS assays, respectively. Eleven compounds were isolated and identified, corresponding to homopterocarpin, scoparone, 8-hydroxyhomopterocarpin, calycosin, 3,4-dimethoxycinnamaldehyde, medicarpin, liquiritigenin, isoliquiritigenin, 3,4,5-trimethoxycinnamaldehyde, 8-methoxyhomopterocarpin, and oleanolic aldehyde acetate. Radical scavenging and antioxidant properties of isolated compounds showed that isoliquiritigenin exhibited the highest activity with values of 1173 ± 61 and 8104 ± 38 μmol TE/g for DPPH radical and ABTS radical cation assays, respectively, and presented 23.6 ± 0.7 mg AAE/g for reducing power assay. In addition, MIC values of isoliquiritigenin for S. aureus, B. cereus, and E. faecalis were 62.5 µg/mL (MIC value for Ampicillin® was 250 µg/mL against B. cereus). The results suggested that P. gracile might be an important source of metabolites with antibacterial and antioxidant activity; therefore, greater efforts should be made for the conservation of this species.

PHYTOCHEMICAL STUDY AND IN VITRO ANTIOXIDANT ACTIVITIES OF HAMMADA SCOPARIA EXTRACTS FROM SOUTHEASTERN ALGERIA

Objective: This study was carried out to determine the phytochemical constituents and to evaluate the antioxidant potential of the aerial part extracts of Hammada scoparia (Pomel) Iljin to validate the medicinal potential of this Algerian plant species.Methods: Crude extracts were prepared by cold maceration with absolute methanol and distilled water. Preliminary phytochemical screening is carried out to detect the presence of the major secondary metabolites using qualitative characterization methods. Quantitative estimation of total phenols, total flavonoids, flavanols, flavonols, and condensed tannins contents is performed using gallic acid, rutin, catechin, and quercetin as standards. In vitro antioxidant activity was evaluated by the free radical scavenging activity by 2,2-diphenyl-1-picrylhydrazyl (DPPH), trolox equivalent antioxidant capacity by scavenging of 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical cation assay, and the ferric reducing power assay (ferric reducing antioxidant power).Results: Phytochemical screening showed the presence of alkaloids, flavonoids, tannins, terpenes and sterols, saponins, and anthocyanins. Total phenols were present more in aqueous crude extract (ACE) with 336.756±0.855 mg gallic acid equivalent/g DM. Total flavonoids and flavonols were more abundant in methanolic crude extract (MCE) than ACE. However, condensed tannins and flavanols were present less in MCE with only 0.958±0.052 and 4.547±0.055 mg CE/g DM, respectively. The ACE of this plant species had greater antioxidant activity than the other extract by DPPH and ABTS assays (35.823±0.129 and 51.323±0.394 mg trolox equivalent/g DM). The better ferric reducing power (2060.535±2.566 mM Fe+2/g DM) was also recorded with the same extract.Conclusion: ACE of aerial part of H. scoparia (Pomel) Iljin showed a high amount of secondary metabolites. The obtained results confirmed that the extracting solvent influenced the antioxidant property estimations of this plant. Hence, the ACE can be further exploited further for in vitro and in vivo research work.

PC12 신경세포주에서 녹각영지버섯 주정 추출물의 산화 스트레스 개선 효과

This study was carried out to identify medicinal mushrooms with protective effects against oxidative stress in PC12 neuronal cell line, followed by evaluation of their antioxidant property. Extracts of medicinal mushrooms, including Ganoderma lucidum extract (GLE), antler-shaped Ganoderma lingzhi extract (AGLE), Hericium erinaceus extract (HEE), and Sanghuangporus baumii extract (SBE), were screened for cytotoxicity using MTT assay. None of the extracts up to 10 μg/ml concentration affected cell viability. These extracts were further checked for their protective effect against oxidative stress-induced reactive oxygen species (ROS) production. Exposure to 50 μM H2O2 induced ROS generation in PC12 cells, which was inhibited only by treatment with AGLE. In addition, inhibition of H2O2-induced ROS generation by AGLE was found to be in a dose-dependent manner (2.5, 5, and 10 μg/ml). Microscopic examination of DCF fluorescence for detection of ROS showed a similar pattern. Further, antioxidant activity of AGLE was determined by ABTS radical cation assay, and its IC50 was found to be 46.90±0.31 μg/ml. Taken together, these results suggest that AGLE may help to alleviate oxidative stress in PC12 neuronal cells.

Phenolic profile, antioxidant and enzyme inhibitory potential of methanolic extracts from different parts of Astragalus ponticus Pall.

This study was designed to document the phenolic profile, antioxidant activity and enzyme inhibitory potential of methanolic extracts of different parts of Astragalus ponticus. The leaves and roots possessed highest total phenolic (26.34 ± 0.50 mg GAEs/g extract) and total flavonoid (49.13 ± 0.51 mg REs/g extract) contents respectively. In vitro antioxidant assay, leaves extract showed highest activity in terms of DPPH radical scavenging (43.64 ± 0.94 mg TEs/g extract), phosphomolybdenum test (1.33 ± 0.14 mmol TEs/g extract); CUPRAC reducing power (64.28 ± 0.90 mg TEs/g extract) and FRAP reducing power (56.79 ± 4.34), while roots extract recorded maximum in ABTS radical cation (98.79 ± 1.95 mg TEs/g extract) assay. All the extracts showed weak enzyme inhibitory on AChE (1.77 ± 0.07–2.29 ± 0.04 mg GALAEs/g extract); BChE (stems and roots only possessed activity); α-amylase (0.56 ± 0.01–0.60 ± 0.01 mmol ACEs/g extract). On the other hand, the extract showed moderate to strong inhibition towards α-glucosidase (3.66 ± 0.02–22.81 ± 0.01 mmol ACEs/g extract) and tyrosinase (2.97 ± 0.84–15.63 ± 1.83 mg KAEs/g extract). The correlation analysis revealed a strong significant positive correlation between antioxidant activity and total phenolic content and luteolin concentration. Further the phytochemicals such as Hesperidin, p-coumaric acid and benzoic acid exert strong correlation with α-glucosidase inhibition. The findings indicate that the extracts from different parts of Astragalus ponticus might be considered as a novel source of antioxidant and enzyme inhibitory compounds in food and pharmaceutical industries.

THE IN VITRO ANTIOXIDANT PROPERTIES OF 2-ALKOXYPHENYLCARBAMIC ACID DERIVATIVES CONTAINING A 4´-(SUBSTITUTED PHENYL)PIPERAZIN-1´-YL MOIETY DETERMINED BY THE 2,2´-AZINOBIS(3-ETHYLBENZOTHIAZOLINE-6-SULFONIC ACID) DERIVED RADICAL CATION (ABTS•+) AND FERRIC RE

In an effort to comprehensively characterize an antioxidant profile of 2-alkoxyphenylcarbamic acid-based compounds containing a 4´-(substituted phenyl)piperazin-1´-yl fragment, they were in vitro screened in the 2,2´-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) derived radical cation (ABTS•+) and ferric reducing antioxidant power (FRAP) assay using the UV/VIS spectrophotometry. The ABTS•+ scavenging (reducing) potential of 1-[3-(2-methoxyphenylcarbamoyl)oxy-2-hydroxypropyl]-4-(4-fluorophenyl)piperazin-1-ium chloride was found to be the most promising and it was comparable to the efficiency of the carvedilol reference drug. Moreover, that 4´-fluoro group-containing compound was regarded as more active than the atenolol standard. When testing the molecules´ power to reduce the ferric 2,4,6-tris (2-pyridyl)-s-triazine complex [Fe(III)(TPTZ)2]3+, the most prospective was 1-[3-(2-ethoxyphenylcarbamoyl)oxy-2-hydroxypropyl]-4-(4-fluorophenyl)piperazin-1-ium chloride. On the other hand, its Fe3+ reducing power was lower compared to both standards carvedilol and atenolol. The study discussed structure–antioxidant properties relationships considering electronic, steric and lipophilic features.

포도주 부산물의 총 플라보노이드와 총 페놀 함량 및 항산화 효과

포도주 가공 중에 발생하는 포도주 부산물의 항산화 활성 검토를 위해 포도주 부산물을 유기용매로 추출 및 분획하여 총 플라보노이드 및 총 페놀 함량을 측정하고 포도주 부산물의 항산화 효과를 분석하였다. 포도주 부산물의 분획 및 추출물의 총 플라보노이드의 양을 측정한 결과 MeOH 추출물은 A+M 추출물보다 높은 함량의 총 플라보노이드를 함유하는 것으로 나타났고 분획물들 중에서는 85% aq. MeOH 분획물이 105.1±0.93 mg/g으로 가장 높았으며 총 페놀 함량은 MeOH 추출물과 n-BuOH 분획물에서 높은 함량을 나타내었다. DPPH를 통한 라디칼 소거활성능을 측정한 결과, 0.5 mg/ml 첨가농도에서 MeOH 추출물은 74%의 소거율을 나타내었으며 분획물들 중에서는 n-BuOH 분획물이 72%의 소거활성을 나타내었다. 또한 ABTS+를 통한 라디칼 소거활성능을 측정한 결과, 0.5 mg/ml 첨가농도에서 85% aq. MeOH 및 n-BuOH 분획물들은 각각 90% 및 92% 소거활성을 나타내어 동일한 BHT 농도에서 92%인 것과 비교해 보았을 경우 합성항산화제만큼 높은 항산화능을 나타내었다. 세포내 활성 산소종 소거 효과를 나타내는 ROS 실험을 통해 0.1 mg/ml 첨가농도에서 MeOH 추출물과 n-BuOH 분획물은 각각 64%와 60%의 소거 활성을 나타었다. 이상의 결과를 종합해 보면 포도 및 포도씨와 비교했을 때 포도주 부산물의 경우 총 플라보노이드 및 총 페놀 함유량은 다소 낮았지만 항산화 효과도 지속되는 것으로 여겨지므로 향후 포도주 부산물의 응용이 기대되어진다. We investigated the flavonoid and phenol contents and antioxidant effect of wine by-product extract. Antioxidant effects were measured with 1,1-diphenyl-2-picryhydrazyl (DPPH) and 2.2'-azino-bis(3-ethylbenothiazoline-6-sulfonic acid) diammonium salt radical cation (ABTS+) assays. Cellular reactive oxygen species (ROS) were measured with the dichlorofluorescein-diacetate (DCFH-DA) assay. The flavonoid and phenol contents of the methanol (MeOH) extract were greater than those of the acetone+methylene chloride (A+M) extract. Among fractions, the 85% aqueous methanol (85% aq. MeOH) fraction contained the highest flavonoid contents, while the n-BuOH fraction had more phenol contents. In the DPPH and ABTS assays, the MeOH extract showed a scavenging effect greater than that of the A+M extract (p<0.05). The n-BuOH fraction (0.5 mg/ml concentrations) showed scavenging effects of 72% and 92%, respectively, in the DPPH and ABTS assays (p<0.05). However, the 85% aq. MeOH fraction showed a 90% scavenging effect in the DPPH assay only. In 120 min ROS production assay, all tested fractions dose-dependently decreased cellular ROS production induced by H₂O₂ in comparison with that produced by exposure to the extract-free control. The MeOH extract showed a higher sinhibitory effect on cellular ROS producing than that of the A+M extract at all concentrations tested. Treatment with the n-BuOH fraction (0.1 mg/ml concentrations) inhibited cellular ROS production by 60%. These results indicate that the n-BuOH fraction of wine by-product extract inhibited cellular oxidation and may contain valuable bioactive compounds such as flavonoids and phenols.

Study of the Properties of Bearberry Leaf Extract as a Natural Antioxidant in Model Foods.

The common bearberry (Arctostaphylos uva-ursi L. Sprengel) is a ubiquitous procumbent evergreen shrub located throughout North America, Asia, and Europe. The fruits are almost tasteless but the plant contains a high concentration of active ingredients. The antioxidant activity of bearberry leaf extract in the 2,2′-azino-bis-3-ethylbenzothiazoline-6-sulphonic acid (ABTS) radical cation assay was 90.42 mmol Trolox equivalents/g dry weight (DW). The scavenging ability of the methanol extract of bearberry leaves against methoxy radicals generated in the Fenton reaction was measured via electron paramagnetic resonance. Lipid oxidation was retarded in an oil–water emulsion by adding 1 g/kg lyophilised bearberry leaf extract. Also, 1 g/kg of lyophilised bearberry leaf extract incorporated into a gelatin-based film displayed high antioxidant activity to retard the degradation of lipids in muscle foods. The present results indicate the potential of bearberry leaf extract for use as a natural food antioxidant.

In vitro antioxidant activity on roots of Limnophila heterophylla

Objective: The present study was investigating the antioxidant activity of methanol extract of roots of Limnophila heterophylla (Plantaginaceae). Methods: Roots of methanol extract of Limnophila heterophylla were tested for in vitro free radical scavenging assays, such as hydroxyl radical, antioxidant assay by thiocyanate method, inhibition of superoxide anion radical, 2, 2-diphenyl-1-picryl hydrazyl radical (DPPH), lipid peroxidation as- say, scavenging of 2, 2'- azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) diammonium salt radical cation assay (ABTS), total antioxidant activity (phosphomolybdic acid method) and reducing ability. Results: Limnophila heterophylla roots extract effectively scavenged free radicals at all different concentrations and showed its potent antioxidant activity. Further, these effects were in a dose dependent manner. Results were compared to standard antioxidants such as vitamin E, α-tocopherol, curcumin, querce- tin, rutin, butylated hydroxytoluene (BHT), and ascorbic acid. Conclusion: Limnophila heterophylla enclose strong antioxidant potential. Further the study validates the therapeutic benefits of the Indian system of medicine.

Study of the Antioxidant Property Variation of Cornelian Cherry Fruits during Storage Using HPTLC and Spectrophotometric Assays.

Cornus species fruits are well known as a rich source of antioxidant compounds responsible for their diverse health benefits. The present study aims to investigate the variation of the total antioxidant capacity of Cornelian cherry (Cornus mas L.) fruits during storage, using high-performance thin-layer chromatography (HPTLC) and two spectrophotometric assays based on different mechanisms: the 2,2-azinobis(3-ethylbenzothiazolyne-6-sulphonic acid) radical cation (ABTS+∙) assay and the ferric reducing antioxidant power (FRAP) assay. The fruit extract was stored at room temperature (22°C) for 19 days. No major differences in the total antioxidant capacity were observed during this period, indicating that storage does not have any deleterious effect on the antioxidant properties of the investigated fruits extract. The antioxidant capacity varied between 12.91 and 12.83 µmol Trolox/g fruit as determined by the HPTLC method and from 36.13 to 33.93 µmol Trolox/g fruit as determined by the ABTS assay.

Extraction of bilberry (Vaccinium myrtillus) antioxidants using supercritical/subcritical CO2 and ethanol as co-solvent

Anthocyanins and other phenolic compounds of bilberry (Vaccinium myrtillus) are known for their antioxidant properties. Supercritical (SC) and subcritical (SubC) CO2 extractions have been used to improve extraction and selectivity of plant bioactive compounds. Bilberry was extracted by SC CO2 followed by SubC CO2 with 10% v/v ethanol as co-solvent. Total phenolic compounds, anthocyanins and proanthocyanidins were quantified and chemically characterized by HPLC-DAD-ESI-MS/MS. Antioxidant activity was tested by reducing power assay, free radical scavenging activity (DPPH) and ABTS radical cation assay. SubC CO2 selectively extracted cyanidin-3-O-glucoside and cyanidin-3-O-arabinoside. Delphinidin-3-O-glucoside, ellagic acid pentoside, feruloyl hexoside and several quercetin glycosides were also extracted. SubC CO2 extracts showed a high antioxidant activity [DPPH IC50=102.66 (±2.64); ABTS IC50=8.49 (±0.41) and reducing power activity IC50=10.30 (±0.10)]. SubC-CO2 extraction of bilberry is an efficient method to recover selectively compounds with a high antioxidant activity and a high potential for pharmacological applications.

Mulberry Seed Oil: a Rich Source of δ‐Tocopherol

AbstractIn the present study, mulberry seed oil (MSO) samples obtained from seeds of different mulberry varieties as well as concentrated mulberry juice production waste (mulberry pomace) were investigated. Radical scavenging capacity, tocopherol and total phenolic content of MSO were determined. It was observed that MSO contain unique amounts of δ‐tocopherol varying between 1645–2587 mg kg−1 oil depending on the variety. The secondary tocopherol homologue was γ‐tocopherol within a concentration range of 299–854 mg kg−1 oil. MSO exhibited a very high antioxidant capacity varying in the range of 1013–1743 and 2574–4522 mg α‐tocopherol equivalents (α‐TE) per kg of oil for 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) and freeze‐dried 2,2′‐azino‐bis (3‐ethylbenzothiazoline‐6‐sulfonic acid) (FD‐ABTS) radical cation assays, respectively. Both antioxidant capacity and total phenolic content were higher for mulberry pomace oil compared with the seed oils. Fatty acid composition of MSO was also determined, and linoleic acid was found to be the primary fatty acid (66–80 %).

Isolation and identification of phenolic antioxidants in black rice bran.

Black rice bran contains phenolic compounds of a high antioxidant activity. In this study, the 40% acetone extract of black rice bran was sequentially fractionated to obtain 5 fractions. Out of the 5 fractions, ethyl acetate fraction was subfractionated using the Sephadex LH-20 chromatography. The antioxidant activity of phenolic compounds in the extracts was investigated by 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical assay, 2,2-azino-bis-(3-ethylenebenzothiozoline-6-sulfonic acid) (ABTS) radical cation assay, reducing power. The subfraction 2 from ethyl acetate fraction had the highest total phenolic contents (TPC) (816.0 μg/mg) and the lowest EC50 values (47.8 μg/mL for DPPH radical assay, 112.8 μg/mL for ABTS radical cation assay, and 49.2 μg/mL for reducing power). These results were 3.1, 1.3, and 2.6 times lower than those of butylated hydroxytoluene (BHT), respectively. At a concentration of 100 μg/mL, the antioxidant activity and TPC of various extracts was closely correlated, with correlation coefficients (R(2) ) higher than 0.86. The major phenolic acid in subfraction 2 was identified as ferulic acid (178.3 μg/mg) by HPLC and LC-ESI/MS/MS analyses. Our finding identified ferulic acid as a major phenolic compound in black rice bran, and supports the potential use of black rice bran as a natural source of antioxidant.

Radical Scavenging and Antioxidant Activities of Essential Oil Components – An Experimental and Computational Investigation

The antioxidant activities of eighteen different essential oil components have been determined using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging assay, the 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid (ABTS) radical cation assay, and the ferric reducing antioxidant power (FRAP) assay. The phenolic compounds, carvacrol, thymol, and eugenol, showed the best antioxidant activities, while camphor, menthol, and menthone were the least active. The structural and electronic properties of the essential oil components were assessed using density functional theory (DFT) at the B3LYP/6-311++G** level. Correlations between calculated electronic properties and antioxidant activities were generally poor, but bond-dissociation energies (BDEs) seem to correlate with DPPH radical-scavenging activities, and the ferric reducing antioxidant power (FRAP) assay correlated with vertical ionization potentials calculated at the Hartree-Fock/6-311++G** level.

Bioactive polysaccharides from marine algae

Abstract Laminaran, fucoidan and sulfated galactan were extracted from the seaweeds Desmarestia distans , Lessonia vadosa , and Gigartina skottsbergii , respectively. Modified polysaccharides were prepared by desulfation, depolymerization, and sulfation. Antioxidant, anticoagulant and immunostimulating activities of native and modified polysaccharides were assayed in vitro . The oversulfated derivatives showed high antioxidant capacity towards oxygen radical assay; however, no direct relation between sulfate content and antioxidant capacity was found. Oversulfated polysaccharides presented higher antioxidant capacity towards hydroxyl radicals than the native polysaccharide. Regarding the ABTS •+ radical cation assay moderate inhibition values (35.1–3.4%) were observed. The anticoagulant activity of native and modified polysaccharides was measured using the activated partial thromboplastin time assay; the native sulfated galactan from G. skottsbergii presented the highest value, close to that shown by heparin at similar concentrations. The immunostimulating activity of polysaccharides was measured through their effects on bone marrow-derived mice dendritic cell maturation. The native sulfated galactan from G. skottsbergii presented good dose-dependent activity inducing increased levels of MHC class II in dendritic cells.

Influence of conventional and ultrasonic-assisted extraction on phenolic contents, betacyanin contents, and antioxidant capacity of red dragon fruit (Hylocereus polyrhizus).

The aim of this study was to examine the effects of extraction methods on antioxidant capacities of red dragon fruit peel and flesh. Antioxidant capacities were measured using ethylenebenzothiozoline-6-sulfonic acid (ABTS) radical cation assay and ferric reducing antioxidant power assay (FRAP). Total phenolic content (TPC) was determined using Folin-Ciocalteu reagent while quantitative determination of total flavonoid content (TFC) was conducted using aluminium trichloride colorimetric method. Betacyanin content (BC) was measured by spectrophotometer. Red dragon fruit was extracted using conventional (CV) and ultrasonic-assisted extraction (UE) technique to determine the most efficient way of extracting its antioxidant components. Results indicated that UE increased TFC, reduced the extraction yield, BC, and TPC, but exhibited the strongest scavenging activity for the peel of red dragon fruit. In contrast, UE reduced BC, TFC, and scavenging activity but increased the yield for the flesh. Nonetheless, UE slightly increases TPC in flesh. Scavenging activity and reducing power were highly correlated with phenolic and flavonoid compounds. Conversely, the scavenging activity and reducing power were weakly correlated with betacyanin content. This work gives scientific evidences for the consideration of the type of extraction techniques for the peel and flesh of red dragon fruit in applied research and food industry.

Screening of antioxidant activity in microalgae

Event Abstract Back to Event Screening of antioxidant activity in microalgae Mariana F.G. Assunção1*, Sandrine Da Ressurreição2, Joana D. Ferreira1, Clara B. Martins1, Raquel Amaral1, Sandra Dias Santos2, Lilia M.A. Santos1 and Jorge M.T.B. Varejão2 1 Algoteca de Coimbra (ACOI), Department of Life Sciences, University of Coimbra, Portugal 2 Instituto Politécnico de Coimbra, ESAC, CERNAS, Bencanta, 3045-601 Coimbra, Portugal Due to the toxicity of synthetic antioxidants, the demand for alternative sources of antioxidants over the years has increased. The interest in such compounds is related to their importance in human health and food quality. Microalgae, a group of organisms with high morphological diversity and able to produce a wide variety of biochemical compounds are considered a promising, non expensive source of antioxidant compounds (Guedes et al., 2013a). This work reports the screening of several different species of microalgae for their antioxidant behavior using the 2,2’-azino-bis-3-ethylbenzthiazoline-6-sulphonic acid radical cation (ABTS•+) spectrophotometric assay for antioxidant activity (Guedes et al., 2013b) to 50 microalgae from the Coimbra Collection of Algae (ACOI). This method is based on the discoloration of a radical solution expressed as a radical inhibition activity. Recorded values obtained varied between 0.19 and 12.31 mg.L1 equivalent ascorbic acid concentration. In order to confirm the results, the initial screening was followed by the application of the ABTS•+ assay and another common method for antioxidant activity namely that using 2,2-diphenyl-1-picrylhydrazyl (DPPH•) to 8 selected strains from the first 50 and belonging to different taxonomic groups. The DPPH• method consists on the decrease of absorbance of a solution containing the radical in the presence of antioxidants (Brand-Williams et al., 1994). The results obtained for these 8 strains ranged from 2 to 30 mg.L-1 equivalent ascorbic acid concentration for the ABTS•+ assay and from 7 to 13% inhibition of DPPH•. Both sets of results indicate an interesting antioxidant potential in microalgae belonging to the groups Eustigmatophyceae and Chlorophyceae. Tested species of these groups showed ABTS•+ values comparable to grape and raspberry ethanolic extracts, confirmed also by the DPPH• method. References Guedes, A. C., Gião, M. S., Seabra, R., Ferreira, A. C. S., Tamagnini, P., Moradas-Ferreira, P. and Malcata, X. (2013a). Evaluation of the Antioxidant Activity of Cell Extracts from Microalgae. Marine Drugs, 11, 1256-1270. Guedes, A. C., Amaro, H. M., Gião, M. S. and Malcata, X. (2013b). Optimization of ABTS radical cation assay specifically for determination of antioxidant capacity of intracellular extracts of microalgae and cyanobacteria. Food Chemistry, 138, 638–643. Brand-Williams, W., Cuvelier, M. E. and Berset, C. (1994). Use of free radical method to evaluate antioxidant activity. Lebensmittel-Wissenschaft & Technologie, 28, 25-30. Keywords: ACOI, Microalgae, Antioxidants, ABTS, DPPH radical scavengers Conference: IMMR | International Meeting on Marine Research 2014, Peniche, Portugal, 10 Jul - 11 Jul, 2014. Presentation Type: Poster Presentation Topic: BLUE BIOTECH Citation: Assunção M, Ressurreição S, Ferreira JD, Martins CB, Amaral R, Santos S, Santos L and Varejão J (2014). Screening of antioxidant activity in microalgae. Front. Mar. Sci. Conference Abstract: IMMR | International Meeting on Marine Research 2014. doi: 10.3389/conf.fmars.2014.02.00060 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 08 May 2014; Published Online: 18 Jul 2014. * Correspondence: Ms. Mariana F.G. Assunção, Algoteca de Coimbra (ACOI), Department of Life Sciences, University of Coimbra, Coimbra, Portugal, mariana.f.g.assuncao@gmail.com Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Mariana F.G. Assunção Sandrine Da Ressurreição Joana D Ferreira Clara B Martins Raquel Amaral Sandra Dias Santos Lilia M.A. Santos Jorge M.T.B. Varejão Google Mariana F.G. Assunção Sandrine Da Ressurreição Joana D Ferreira Clara B Martins Raquel Amaral Sandra Dias Santos Lilia M.A. Santos Jorge M.T.B. Varejão Google Scholar Mariana F.G. Assunção Sandrine Da Ressurreição Joana D Ferreira Clara B Martins Raquel Amaral Sandra Dias Santos Lilia M.A. Santos Jorge M.T.B. Varejão PubMed Mariana F.G. Assunção Sandrine Da Ressurreição Joana D Ferreira Clara B Martins Raquel Amaral Sandra Dias Santos Lilia M.A. Santos Jorge M.T.B. Varejão Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Chemical composition and antioxidant activity of the ethanol extract and purified fractions of cadillo (Pavonia sepioides)

Background: Bioactive plant compounds can contribute to prevent diseases related to oxidative stress. Some of these compounds are water soluble and fat soluble vitamins, carotenoids and a huge variety of phenolic compounds associated with the antioxidant activity (AOA). Objective: The aim of this study was to study the antioxidant activity of Pavonia sepioides. Methods: The AOA was evaluated by spectrophotometric methods using the free radical DPPH* and the ABTS*þ radical cation assays. Total phenolic content (TPC) was determined by FolineCiocalteu method and total flavonoid content (TFC) was determined by direct reaction with aluminum trichloride. The phenolic content was evaluated by GC/MS technique. Results: The greatest antioxidant activity was found in ethyl acetate fraction (Fea), The total ethanol extract (TE) showed good AOA in comparison with hexane fraction (Fhx), dichloromethane fraction (Fdc) and aqueous fraction (Faq). The TPC and TFC analyses provided results consistent with the AOA with highest values for Fea and ET respectively. Different phenolic compounds of low molecular weight were identified by GC/MS (Salicylic acid, cinnamic acid, p-hydroxybenzoic acid, p-hydroxyphenylacetic acid, phydrocinnamic acid, vanillic acid, gentisic acid, p-cinnamic acid, o-Cinnamic acid, protocatechuic acid, syringic acid, m-cinnamic acid, ferulic acid, and caffeic acid). These compounds could be associated with the named activity. The Pearson and Spearman association tests indicated a positive linear correlation between the AOA and TPC and TFC results, showing correlation coefficients greater than 0.810 in the Pearson test and greater than 0.700 in the Spearman test (p < 0.05). Conclusion: The AAO of P. sepioides (ET and purified fractions) was confirmed. The study provides evidence that P. sepioides is potential source of natural antioxidants showing positive correlations between phenolic contents and the AAO.