Poly(methylene blue)-modified electrode for indirect electrochemical sensing of OH radicals and radical scavengers

ABSTRACT A new modified electrode for indirect sensing of OH· and radical scavengers was described. The electrochemical polymerization of methylene blue in aqueous solutions and the properties of the resulting films on a glassy carbon electrode were carried out using cyclic voltammetry. A surface coverage of 1.11 × 109mol cm2 was obtained, revealing a complete surface coverage of the polymeric film on the electrode surface. OH· was able to destroy the poly(methylene blue) film by exposure to a Fenton solution. The loss of the electrochemical signal of the residual polymeric film attached to the electrode surface was related to the extent of its dissolution. The applicability of the sensor was demonstrated by evaluating the OH radical scavenging effect on different concentrations of ascorbic acid. The obtained radical scavenging capacity were 31.4%, 55.7%, 98.9% and 65.7% for the ascorbic acid concentrations of 5, 10, 30 and 50 mM, respectively.

Citotoxicidad/capacidad antiradicalaria in-vitro y caracterización estructural por GC-MS/1H-13C-RMN de los aceites esenciales de hojas de árboles joven/adulto de annona purpurea Moc. & Sessé ex Dunal de Repelón (Atlántico, Colombia) / [in-vitro Cytotoxicity/Anti-Radical Capability and structural characterization by GC-MS/1H13C-NMR of theleaves essential oils of young/old trees of Annona purpurea Moc. & Sessé ex Dunal from Repelón (Atlántico,Colombia]

Annona purpurea es una planta empleada en etnomedicina, en la región norte de Colombia, que no tiene reportes científicos relacionados con la composición de su AE y sus actividades biológicas. En este trabajo, los AE de hojas de árboles joven/adulto se caracterizaron por GC-MS y RMN y se evaluaron sus propiedades antiradicalarias/citotóxicas. Los AE de hojas de árboles joven/adulto estuvieron representados por beta-eudesmol (68.9 por ciento) y alfa-eudesmol (16.8 por ciento), y germacreno D (55.6 por ciento) y biciclogermacreno (20.3 por ciento), respectivamente. El análisis por RMN mostró las señales distintivas de los constituyentes mayoritarios identificados. Los valores de TAA (mmol Trolox®/kg SE) obtenidos por los AE de árboles joven/adulto fueron 165 +/- 8 y 602 +/- 38. Los AE de árboles joven/adulto evaluados sobre linfocitos humanos fueron “moderadamente tóxicos” con valores de CL50 (ug/mL) de 145.5 +/- 0.7 y 346 +/- 8. Finalmente, la citotoxicidad en eritrocitos humanos reveló que el AE de árbol adulto no fue hemolítico (CL50 > 1000 μg/mL, 4.3 +/- 0.6 por ciento); mientras que, el AE de árbol joven fue hemolítico (CL50 490 +/- 48 ug/mL).

Annona purpurea is a plant used in ethnomedicine in the northern region of Colombia, which has no scientific reports on the composition of their essential oil (EO) and biological activities. In this work, the leaves EO of young/old trees were characterized by GC- MS and NMR, and their antiradical/cytotoxic properties were evaluated. beta-Eudesmol (68.9 percent) and alpha-eudesmol (16.8 percent), and germacrene D (55.6 percent) and bicyclogermacrene (20.3 percent), were the representative compounds of the leaves EO of young/old trees, respectively. The NMR analysis showed the distinctive signals of the main constituents identified. The TAA values (mmol Trolox®/kg ES) obtained from the EO of young/old trees were 165 +/- 8 and 602 +/- 38. The EO of young/old trees evaluated on human lymphocytes were “moderately toxic” with LC50 (μg/mL) of 145.5 +/- 0.7 and 346 +/- 8. Finally, the cytotoxicity in human erythrocytes revealed that the old tree EO was not haemolytic (LC50 > 1000 ug/mL, 4.3 +/- 0.6 percent); while the young tree EO was hemolytic (LC50 490 +/- 48 ug/mL).

Caracterización química y cuantificación de fructooligosacáridos, compuestos fenólicos y actividad antirradical de tubérculos y raíces andinos cultivados en el noroeste de Argentina / Chemical characterization and quantification of fructooligosaccharides, phenolic compounds and antiradical activity of Andean roots and tubers grown in Northwest of Argentina

Existe un creciente interés por consumir alimentos que además de aportar los componentes básicos para una buena nutrición provean otros compuestos benéficos para la salud. El objetivo del trabajo fue determinar la composición química de alimentos autóctonos de la región andina y cuantificar algunos componentes funcionales. Se determinó composición centesimal, contenido de vitamina C y compuestos fenólicos totales, actividad antirradical (DPPH) en cáscara y pulpa, fibra dietaria soluble e insoluble, fructooligosacáridos (FOS), almidón total y resistente (en tubérculos y raíces crudos, hervidos y hervidos y almacenados) de 6 variedades de Ocas (Oxalis tuberosa), 4 clones de Mandiocas (Manihot esculenta Crantz) y Yacón (Smallanthus sonchifolius). Los resultados mostraron mayor cantidad de compuestos bioactivos y actividad antirradical en la cáscara de ocas. En todos los casos el contenido de fibra insoluble fue mayor que la soluble. Las mandiocas tuvieron mayor contenido de almidón total que las raíces y tubérculos andinos. El proceso de ebullición disminuyó el contenido de almidón resistente en ocas y mandiocas pero cuando éstas se almacenaron por 48h a 5°C, el contenido de almidón resistente aumentó nuevamente. El contenido de FOS en ocas fue similar para todas las variedades (Aproximadamente 7%). El principal componente de los carbohidratos del yacón fueron los FOS (8,89%). Se puede concluir que las raíces y tubérculos estudiados, además de aportar nutrientes, contienen compuestos funcionales que les confieren un valor adicional como alimentos útiles para la prevención de algunas enfermedades no trasmisibles.

There is great interest in consuming foods that can provide the nutrients for a good nutrition and other health beneficial compounds. The aim of this work was to determine the chemical composition of native foods of the Andean region and to quantify some functional components. Proximal composition, vitamin C, total phenolic compounds, antiradical activity (DPPH) in peel and pulp, dietary fiber soluble and insoluble, fructooligosaccharides (FOS), total and resistant starch (in tubers and raw roots, boiled and boiled and stored) of 6 varieties of Oca (Oxalis tuberosa), 4 clones of manioc (Manihot esculenta Crantz) and yacon (Smallanthus sonchifolius were determined. The results showed greater amount of bioactive compounds and antiradical activity in the skin of these products. The highest content was found in the oca peel. In all cases, the content of insoluble fiber was greater than the soluble. The manioc had higher total starch than Andean roots and tubers. The boiling process decreased the resistant starch content of ocas and maniocs, but when these are stored for 48 h at 5 ° C, the resistant starch content increased. The FOS content of the ocas was similar for all varieties (7%). The main component of yacon carbohydrates were FOS (8,89%). The maniocs did not contain FOS. It can be concluded that the roots and tubers studied, in addition to provide nutrients, contain functional compounds that confer additional helpful value for preventing no communicable diseases.

Oil, protein, antioxidants and free radical scavenging activity of stone from wild olive trees [Olea europaea L.]

The wild olive trees or oleaster [var. sylvestris] and the cultivated olive trees [var. europaea] constitute the two botanical varieties of Olea europaea L. from Mediterranean. In this study, a partial chemical profile was conducted including the total lipids, the fatty acid profiles, soluble proteins, polyphenols, flavanoids contents and antioxidants activities of stone from six oleaster trees. The comparison was made by two olive cultivars cultivated in the same region. The oleaster and cultivar stones were richer in oil content having an average of 8.99 and 7.38% dry weight basis [DW], respectively. Qualitatively, all studied oils have the same fatty acids profile with the oleic acid C18:1n-9 as the major fatty acid. The oleaster stone oils were richer in monounsaturated fatty acids having an average of 64.87%. They, also, richer in protein content with an average of 198.86 mg/g DW.The globulin is the major fraction, followed by the albumin, the prolamin and the glutemin fractions. The oleaster stone extracts contain polyphenols, flavonoids with an average of 151.14 and 11.91 mg gallic acid equivalent/100g of DW, respectively. The studied extracts showed antioxidant activity using the free radical scavenging activity determined by DPPH and ABTS. The unexploited oleaster stone seems to be a source of oil with good fatty acids balance, in protein and antioxidants metabolites and would be useful for the formulation of supplements and/or pharmaceutical ingredients

In vitro antioxidant activity of banana (Musa spp. ABB cv. Pisang Awak).

The methanolic extract of Musa ABB cv Pisang Awak was investigated for the polyphenolic contents and antioxidant activity. The total phenol and flavonoid contents of the fruit extract were found to be 120 mg gallic acid equivalents (GAE) and 440 mg quercetin equivalents (QE)/100 g of sample dry weight, respectively. The antioxidant activity of the Pisang Awak methanol extract (PAME) (20-500 µg/ml) was determined using 1,1-diphenyl-2-picryl hydrazyl (DPPH) radical scavenging activity, reducing capacity, 2-2’-azinobis-3-ethylbenzothiozoline-6-sulfonic acid (ABTS) radical cation decolourization and hydroxyl radical scavenging capacity (OH·). The EC50 values of DPPH, ABTS and OH· activities of the PAME and butylated hydroxy toluene (BHT) were found to be 65 and 9 µg/ml, 29 and 6 µg/ml, 36 and 42 µg/ml respectively. The reducing capacity increased with increasing concentration (31.5-1000 mg/ml) of the fruit extract and the activity was comparable with the standard BHT. The high performance thin layer chromatography (HPTLC) analysis of the extract revealed the presence of polyphenols. The strong and positive correlations were obtained between total phenol/flavonoid contents (R2 = 0.693-1.0) and free radical scavenging ability was attributed to the polyphenols as the major antioxidants.

Antioxidant activity by DPPH assay of potential solutions to be applied on bleached teeth

The aim of this study was to assess, using the DPPH assay, the antioxidant activity of several substances that could be proposed to immediately revert the problems caused by bleaching procedures. The percentage of antioxidant activity (AA percent) of 10 percent ascorbic acid solution (AAcidS), 10 percent ascorbic acid gel (AAcidG), 10 percent sodium ascorbate solution (SodAsS), 10 percent sodium ascorbate gel (SodAsG), 10 percent sodium bicarbonate (Bicarb), Neutralize® (NE), Desensibilize® (DES), catalase C-40 at 10 mg/mL (CAT), 10 percent alcohol solution of alpha-tocopherol (VitE), Listerine® (LIS), 0.12 percent chlorhexidine (CHX), Croton Lechleri (CL), 10 percent aqueous solution of Uncaria Tomentosa (UT), artificial saliva (ArtS) and 0.05 percent sodium fluoride (NaF) was assessed in triplicate by 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) free radical assay. All substances exhibited antioxidant activity, except for CL. AAcidS, AAcidG and VitE exhibited the highest AA percent (p<0.05). On the contrary, CHX, NE, LIS and NaF showed the lowest AA percent (p<0.05). In conclusion, AAcidS, AAcidG, SodAsS, SodAsG and VitE presented the highest antioxidant activity among substances tested in this study. The DPPH assay provides an easy and rapid way to evaluate potential antioxidants.

O objetivo deste estudo foi avaliar, por meio do DPPH, a atividade antioxidante de substâncias que poderiam ser propostas para reverter de imediato os problemas causados pelos procedimentos de clareamento. A porcentagem de atividade antioxidante (AA por cento) da solução de acido ascórbico 10 por cento (AAcidS), gel de ácido ascórbico a 10 por cento (AAcidG), solução de ascorbato de sódio 10 por cento (SodAsS), gel de ascorbato de sódio 10 por cento (SodAsG), bicarbonato de sódio 10 por cento (Bicarb), Neutralize® (NE), Desensibilize® (DES), catalase C-40 10 mg/mL (CAT), solução alcoólica 10 por cento de alfa-tocoferol (VitE), Listerine® (LIS), clorexidina 0,12 por cento (CHX), CrotonLechleri (CL), solução aquosa 10 por cento de Uncaria Tomentosa (UT), saliva artificial (ArtS) e fluoreto de sódio 0,05 por cento (NaF) foi avaliada em triplicata pelo teste de radicais livres 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH). Todas as substâncias apresentaram atividade antioxidante, exceto a CL. AAcidS, AAcidG e VitE mostraram os maiores valores de AA por cento (p<0,05). Por outro lado, CHX, NE, LIS e NaF mostraram os valores mais baixos de AA por cento (p<0,05). Em conclusão, AAcidS, AAcidG, SodAsS, SodAsG e VitE apresentaram os mais altos valores de atividade antioxidante entre as substâncias testadas. O teste DPPH é um método rápido e fácil para avaliar o potencial antioxidante.

Antioxidant activities of the leaves Chrysophyllum albidum G.

Chrysophyllum albidum G. is a tropical plant and commonly found in Nigeria. It belongs to the sapotaceae family and used in folklore in the treatment of yellow fever, malaria, diarrhea, vaginal and dermatological infections. The study was aimed at investigating the antioxidant properties of this plant by employing the in vitro and in vivo experimental models. The effect of DPPH free radical scavenging activity on the fractions of petroleum ether, ethanol, butanol, ethylacetate, and water of C. albidum was determined. The ethyl acetate fraction was purified in column chromatography to obtain myricetin rhamnoside. Structure elucidation was done by NMR and mass spectroscopic techniques. Furthermore, ethanol extract was administered to five groups of eight rats per group. The animals in the normal group were administered with vehicle alone for 7 days. The positive control animals were given vehicle on the first four days, and with the vehicle and hepatotoxin [CC1[4]] on the fifth, sixth and seventh day. The animals in the treatment category were respectively administered with 500, 1000 and 1500 mg/kg b.w. of extract and distilled water for the first four days, and with distilled water, extract and CC1[4] on the last three days. Animals were subsequently anaesthetized and blood samples were collected for catalase [CAT], malondialdehyde [MDA], reduced gluthathione [GSH] and superoxide dismutase [SOD] assays. The petroleum ether fraction showed the least antiradical activity [4057.5 +/- 809.6 g/kg] while ethyl ether exhibited the highest activity [414.4 +/- 92.0 g/kg]. Myricetin rhamnoside also exhibited an excellent radical scavenging activity [314.1 +/- 60.2] which was comparable to the positive control. Result from animal study showed that C. albidum exhibited significant [p < 0.05] differences on the activity of CAT, MDA and GSH. The plant could therefore be employed as sources of natural antioxidant boosters and for the treatment of some oxidative stress disorders in which free radicals are implicated

Nutrient composition, phenolic content and free radical scavenging activity of some uncommon vegetables of Pakistan

Vegetables play a vital role in the prevention of human disease and in the improvement of general health as these contain vitamins, amino acids, fiber, antioxidants and minerals. In the present study, some less familiar vegetables of Pakistan namely chickpea [leaves], chungah [shoots], drumstick tree [inflorescences], radish [fruit pods], mountain ebony [flower buds], mustard [leaves], purslane [leaves] and white goosefoot [leaves and shoots] were evaluated for proximate composition, mineral content, phenolic content and free radical scavenging activity. The protein, fat, fiber, carbohydrate and ash contents of the selected vegetables were in the range of 2.9 to 6.6%, 0.2 to 2.5%, 2.4 to 8.6%, 9.7 to 20.1% and 1.0 to 2.3%, respectively. The concentration of vitamin C ranged between 32.6 to 120.1 mg/100 g. The phosphorus, calcium, iron, zinc, manganese, magnesium and copper were 190 to 3400, 103 to 987, 19 to 93, 12 to 47, 9 to 121, 299 to 1635 and non detectable level to 42 mg/kg, respectively. The amount of total phenolic content varied from 55.3 to 221.0 mg/g in the dry methanolic extracts of the studied plants. The EC[50] values were below 1400 [ig/ml, indicating that all the studied vegetables have good scavenging effect on DPPH radical

Antioxidant activity of acetone extract/fractions of Terminalia bellerica Roxb. fruit.

Terminalia bellerica Roxb. (Family: Combretaceae) has been valued in Indian system of medicine for treatment of wide range of diseases and reported to have antioxidant properties. In the present study, the free radical scavenging activity and antioxidant potential of acetone extract/fractions of its fruit was investigated using in vitro assays, including scavenging ability against 2,2′-diphenyl-2-picrylhydrazyl (DPPH), β-carotene bleaching inhibition, reducing power and chelating ability on Fe2+ ions. The fruit powder was extracted at room temperature with different solvents in the order of increasing and decreasing polarity to obtain crude acetone extract which was further partitioned with ethyl acetate and water (1:1). It was found that ethyl acetate fraction was more effective than crude acetone extract in all antioxidant assays, except chelating power which was highest in water fraction. Maximum antioxidant activities (expressed as EC50 values) observed were 14.56 μg/ml, 27.81 μg/ml and 67.8 μg/ml in DPPH, β-carotene bleaching and reducing power assays, respectively. The antioxidant potential was compared with known antioxidant (butylated hydroxyl toluene) and correlated with total phenolic and flavonoid content in crude extract and fractions. Fractions rich in polyphenolic content were more effective than the crude extract.

Phytochemical and antioxidant studies of Laurera benguelensis growing in Thailand

The aim of this study was to investigate metabolites of the lichen Laurera benguelensis. A high-performance liquid chromatographic (HPLC) method has been developed for the characterization of xanthones and anthraquinones in extracts of this lichen. Lichexanthone, secalonic acid D, norlichexanthon, parietin, emodin, teloschistin and citreorosein were detected in the lichen samples, which were collected from two places in Thailand. Components of the lichen were identifed by relative retention time and spectral data. This is the frst time that a detailed phytochemical analysis of the lichen L. benguelensis was reported and this paper has chemotaxonomic signifcance because very little has been published on the secondary metabolites present in Laurera species. Some of the metabolites were detected for the frst time in the family Trypetheliaceae. The results of preliminary testing of benzene extract and its chloroform and methanol fractions showed that all samples showed a weak radical scavenging activity. The chloroform extract showed the highest antioxidant activity.

Scavenging effect of Indian grape polyphenols on 2,2'-diphenyl-1-picrylhydrazyl(DPPH) radical by electron spin resonance spectrometry.

Antioxidant potency of Indian grape cultivars varying in their skin color, seed and polyphenol content (Bangalore blue, Pandhari sahebi, Sharad seedless and Thompson seedless) and their components (whole grapes, pulp with skin and seeds) was examined as 2,2'-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity using electron spin resonance spectrometry. The total polyphenols in Indian grapes ranged between 3-51%. Extracted polyphenols caused a concentration dependent and significant loss in DPPH radical signal, similar to known antioxidants-Vitamin C, catechin and procyanidin B3 used as references. Among seedless cultivars, polyphenols from Sharad was more potent as antioxidant than Thompson, showing IC50 values of 1250 +/- 30 and 2650 +/- 125 microg/ml, respectively. The inhibitory effect of polyphenols from seedless grape cultivars was as effective as that of seeded variety. The results indicate that polyphenols extracted from Indian grapes/ components (with /without seeds) exhibited free radical scavenging activity and their chemopreventive properties need to be exploited by in vivo model system.

Methyl gallate and chemicals structurally related tomethyl gallate protect human umbilical vein endothelial cells from oxidative stress

Methyl gallate (meGAL) is known as one of major antioxidants. To investigate whether meGAL protects human cells from oxidative stress, meGAL extracted from Korean medicinal plant, Cercis chinensis leaves, was primarily screened using cell viability assay against oxidative stress. Human umbilical vein endothelial cells (HUVECs) were treated with three different concentrations of meGAL for indicated time. After or during meGAL treatment, H2O2 was added and incubated. meGAL showed free radical scavenging effect at low concentration (0.02 mM) and cell protective effect against H2O2-mediated oxidative stress. meGAL recovered viability of HUVECs damaged by H2O2-treatment, reduced the lipid peroxidation (LPO) and decreased the internal reactive oxygen species (ROS) level elevated by H2O2-treatment. Free radical scavenging effect of meGAL was proven to be very high. Differential display reverse transcription-PCR analysis showed that meGAL upregulated the levels of regulator of chromatin condensation 1, type 1 sigma receptor and phosphate carrier protein expressions, respectively. Based on structural similarity compared with meGAL, 14 chemicals were chosen and viability assay was performed. Four chemicals, haematommic acid (56.2% enhancement of viability), gallic acid (35.0%), methylorsellinic acid (23.7%), and syringic acid (20.8%), enhanced more potent cell viability than meGAL, which showed only 18.1% enhancement of cell viability. These results suggest that meGAL and four meGAL-related chemicals protect HUVECs from oxidative stress.

Free radical scavenging and antioxidant enzyme fortifying activities of extracts from Smilax china root

The extract from Smilax china root has been used as medicinal remedy and reported to retain antimicrobial and antimutagenic acitivities. In this study, a possible presence of antioxidant activity of Smilax china root extract was investigated. Methanol extract (Me) revealed the presence of high 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging activity (IC50 7.4 microg/ml) and protective property of cell's viability. Further fractionation with various solvent extraction and assay showed high levels of DPPH free radical scavenging activity in the ethyl acetate, butanol and water extracted fractions. In addition, V79-4 cells treated with Me of Smilax china root induced an increase of superoxide dismutase, catalase and glutathione peroxidase activities in a dose-dependent manner between 4-100 microg/ml. These results suggest that the medicinal component of the root of Smilax china extracts also contains antioxidant activity.

Free radical scavenging and antioxidant enzyme fortifying activities of extracts from Smilax china root

The extract from Smilax china root has been used as medicinal remedy and reported to retain antimicrobial and antimutagenic acitivities. In this study, a possible presence of antioxidant activity of Smilax china root extract was investigated. Methanol extract (Me) revealed the presence of high 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging activity (IC50 7.4 microg/ml) and protective property of cell's viability. Further fractionation with various solvent extraction and assay showed high levels of DPPH free radical scavenging activity in the ethyl acetate, butanol and water extracted fractions. In addition, V79-4 cells treated with Me of Smilax china root induced an increase of superoxide dismutase, catalase and glutathione peroxidase activities in a dose-dependent manner between 4-100 microg/ml. These results suggest that the medicinal component of the root of Smilax china extracts also contains antioxidant activity.

Biologically active free radicals and their scavengers: a review

Free radicals are continuously generated in almost all aerobic cells. If they are not scavenged by the integrated comprehensive array of endogenous antioxidant mechanisms, tissue damage occurs. It has been widely accepted that free radicals are implicated in a large number of medical disorders including cancer, inflammation, atherosclerosis, coronary heart disease and diabetes. Low levels of one or more of the essential antioxidants have been shown to be associated with many of these disorders. Thus, in such cases, the administration of exogenous antioxidants seems to be salutary. Nowadays, a great deal of effort being expended to find effective antioxidants for the treatment or prevention of free radical-mediated deleterious effects. The effectiveness of currently used exogenous antioxidant therapy stems most probably from the augmentation of the endogenous free radical scavengers such as enzymes [superoxide dismutase and selenium-dependent glutathione peroxidase] and vitamins [alpha-tocopherol, ascorbic acid and beta-carotene]. Many drugs have been also found to possess free radical scavenging activity. Among these are probucol, gliclazide, allopurinol and some calcium channel blockers. The free radical scavenging property exerted by drugs might account, at least in part, for some of their beneficial pharmacological actions