Antioxidants

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Open AccessArticle

Krebs Cycle Intermediates Protective against Oxidative Stress by Modulating the Level of Reactive Oxygen Species in Neuronal HT22 Cells

by Kenta Sawa, Takumi Uematsu, Yusuke Korenaga, Ryuya Hirasawa, Masatoshi Kikuchi, Kyohei Murata, Jian Zhang, Xiaoqing Gai, Kazuichi Sakamoto, Tomoyuki Koyama and Takumi Satoh

Antioxidants 2017, 6(1), 21; https://doi.org/10.3390/antiox6010021 - 16 Mar 2017

Cited by 34 | Viewed by 9905

Abstract

Krebs cycle intermediates (KCIs) are reported to function as energy substrates in mitochondria and to exert antioxidants effects on the brain. The present study was designed to identify which KCIs are effective neuroprotective compounds against oxidative stress in neuronal cells. Here we found [...] Read more.

Krebs cycle intermediates (KCIs) are reported to function as energy substrates in mitochondria and to exert antioxidants effects on the brain. The present study was designed to identify which KCIs are effective neuroprotective compounds against oxidative stress in neuronal cells. Here we found that pyruvate, oxaloacetate, and α-ketoglutarate, but not lactate, citrate, iso-citrate, succinate, fumarate, or malate, protected HT22 cells against hydrogen peroxide-mediated toxicity. These three intermediates reduced the production of hydrogen peroxide-activated reactive oxygen species, measured in terms of 2′,7′-dichlorofluorescein diacetate fluorescence. In contrast, none of the KCIs—used at 1 mM—protected against cell death induced by high concentrations of glutamate—another type of oxidative stress-induced neuronal cell death. Because these protective KCIs did not have any toxic effects (at least up to 10 mM), they have potential use for therapeutic intervention against chronic neurodegenerative diseases. Full article

(This article belongs to the Special Issue Oxidative Stress and Cancer: The Nrf2 Enigma)

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Open AccessReview

Vitamin E Nicotinate

by Kimbell R. Duncan and Yuichiro J. Suzuki

Antioxidants 2017, 6(1), 20; https://doi.org/10.3390/antiox6010020 - 13 Mar 2017

Cited by 19 | Viewed by 8899 | Correction

Abstract

Vitamin E refers to a family of compounds that function as lipid-soluble antioxidants capable of preventing lipid peroxidation. Naturally occurring forms of vitamin E include tocopherols and tocotrienols. Vitamin E in dietary supplements and fortified foods is often an esterified form of α-tocopherol, [...] Read more.

Vitamin E refers to a family of compounds that function as lipid-soluble antioxidants capable of preventing lipid peroxidation. Naturally occurring forms of vitamin E include tocopherols and tocotrienols. Vitamin E in dietary supplements and fortified foods is often an esterified form of α-tocopherol, the most common esters being acetate and succinate. The vitamin E esters are hydrolyzed and converted into free α-tocopherol prior to absorption in the intestinal tract. Because its functions are relevant to many chronic diseases, vitamin E has been extensively studied in respect to a variety of diseases as well as cosmetic applications. The forms of vitamin E most studied are natural α-tocopherol and the esters α-tocopheryl acetate and α-tocopheryl succinate. A small number of studies include or focus on another ester form, α-tocopheryl nicotinate, an ester of vitamin E and niacin. Some of these studies raise the possibility of differences in metabolism and in efficacy between vitamin E nicotinate and other forms of vitamin E. Recently, through metabolomics studies, we identified that α-tocopheryl nicotinate occurs endogenously in the heart and that its level is dramatically decreased in heart failure, indicating the possible biological importance of this vitamin E ester. Since knowledge about vitamin E nicotinate is not readily available in the literature, the purpose of this review is to summarize and evaluate published reports, specifically with respect to α-tocopheryl nicotinate with an emphasis on the differences from natural α-tocopherol or α-tocopheryl acetate. Full article

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Open AccessArticle

Effect of Leaves of Caesalpinia decapetala on Oxidative Stability of Oil-in-Water Emulsions

by María Gabriela Gallego, Monika Skowyra, Michael H. Gordon, Nurul Aini Mohd Azman and María Pilar Almajano

Antioxidants 2017, 6(1), 19; https://doi.org/10.3390/antiox6010019 - 04 Mar 2017

Cited by 11 | Viewed by 7218

Abstract

Caesalpinia decapetala (Roth) Alston (Fabaceae) (CD) is used in folk medicine to prevent colds and treat bronchitis. This plant has antitumor and antioxidant activity. The antioxidant effects of an extract from Caesalpinia decapetala (Fabaceae) were assessed by storage of model food oil-in-water emulsions [...] Read more.

Caesalpinia decapetala (Roth) Alston (Fabaceae) (CD) is used in folk medicine to prevent colds and treat bronchitis. This plant has antitumor and antioxidant activity. The antioxidant effects of an extract from Caesalpinia decapetala (Fabaceae) were assessed by storage of model food oil-in-water emulsions with analysis of primary and secondary oxidation products. The antioxidant capacity of the plant extract was evaluated by the diphenylpicrylhydrazyl (DPPH), Trolox equivalent antioxidant capacity (TEAC), oxygen radical absorbance capacity (ORAC) and ferric reducing antioxidant power (FRAP) assays and by electron paramagnetic resonance (EPR) spectroscopy. Lyophilized extracts of CD were added at concentrations of 0.002%, 0.02% and 0.2% into oil-in-water emulsions, which were stored for 30 days at 33 ± 1 °C, and then, oxidative stability was evaluated. The CD extract had high antioxidant activity (700 ± 70 µmol Trolox/g dry plant for the ORAC assay), mainly due to its phenolic components: gallic acid, quercetin, catechin, 4-hydroxybenzoic acid and p-coumaric acid. At a concentration of 0.2%, the extract significantly reduced the oxidative deterioration of oil-in-water emulsions. The results of the present study show the possibility of utilizing CD as a promising source of natural antioxidants for retarding lipid oxidation in the food and cosmetic industries. Full article

(This article belongs to the Special Issue Feature Papers 2016)

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Open AccessReview

Na/K-ATPase Signaling and Salt Sensitivity: The Role of Oxidative Stress

by Jiang Liu, Yanling Yan, Ying Nie and Joseph I. Shapiro

Antioxidants 2017, 6(1), 18; https://doi.org/10.3390/antiox6010018 - 02 Mar 2017

Cited by 8 | Viewed by 7576

Abstract

Other than genetic regulation of salt sensitivity of blood pressure, many factors have been shown to regulate renal sodium handling which contributes to long-term blood pressure regulation and have been extensively reviewed. Here we present our progress on the Na/K-ATPase signaling mediated sodium [...] Read more.

Other than genetic regulation of salt sensitivity of blood pressure, many factors have been shown to regulate renal sodium handling which contributes to long-term blood pressure regulation and have been extensively reviewed. Here we present our progress on the Na/K-ATPase signaling mediated sodium reabsorption in renal proximal tubules, from cardiotonic steroids-mediated to reactive oxygen species (ROS)-mediated Na/K-ATPase signaling that contributes to experimental salt sensitivity. Full article

(This article belongs to the Special Issue Oxidative Stress and Salt-Sensitive Hypertension)

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Open AccessReview

Current Insights to Regulation and Role of Telomerase in Human Diseases

by Mert Burak Ozturk, Yinghui Li and Vinay Tergaonkar

Antioxidants 2017, 6(1), 17; https://doi.org/10.3390/antiox6010017 - 28 Feb 2017

Cited by 52 | Viewed by 10359

Abstract

The telomerase ribonucleoprotein complex has a pivotal role in regulating the proliferation and senescence of normal somatic cells as well as cancer cells. This complex is comprised mainly of telomerase reverse transcriptase (TERT), telomerase RNA component (TERC) and other associated proteins that function [...] Read more.

The telomerase ribonucleoprotein complex has a pivotal role in regulating the proliferation and senescence of normal somatic cells as well as cancer cells. This complex is comprised mainly of telomerase reverse transcriptase (TERT), telomerase RNA component (TERC) and other associated proteins that function to elongate telomeres localized at the end of the chromosomes. While reactivation of telomerase is a major hallmark of most cancers, together with the synergistic activation of other oncogenic signals, deficiency in telomerase and telomeric proteins might lead to aging and senescence-associated disorders. Therefore, it is critically important to understand the canonical as well as non-canonical functions of telomerase through TERT to develop a therapeutic strategy against telomerase-related diseases. In this review, we shed light on the regulation and function of telomerase, and current therapeutic strategies against telomerase in cancer and age-related diseases. Full article

(This article belongs to the Special Issue Role of Telomerase in Aging and Cancer)

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Open AccessArticle

The Effect of Gender and Menstrual Phase on Serum Creatine Kinase Activity and Muscle Soreness Following Downhill Running

by Tanja Oosthuyse and Andrew N. Bosch

Antioxidants 2017, 6(1), 16; https://doi.org/10.3390/antiox6010016 - 23 Feb 2017

Cited by 32 | Viewed by 8181

Abstract

Serum creatine kinase (CK) activity reflects muscle membrane disruption. Oestrogen has antioxidant and membrane stabilising properties, yet no study has compared the CK and muscle soreness (DOMS) response to unaccustomed exercise between genders when all menstrual phases are represented in women. Fifteen eumenorrhoeic [...] Read more.

Serum creatine kinase (CK) activity reflects muscle membrane disruption. Oestrogen has antioxidant and membrane stabilising properties, yet no study has compared the CK and muscle soreness (DOMS) response to unaccustomed exercise between genders when all menstrual phases are represented in women. Fifteen eumenorrhoeic women (early follicular, EF (n = 5); late follicular, LF (n = 5); mid-luteal, ML (n = 5) phase) and six men performed 20 min of downhill running (−10% gradient) at 9 km/h. Serum CK activity and visual analogue scale rating of perceived muscle soreness were measured before, immediately, 24-h, 48-h and 72-h after exercise. The 24-h peak CK response (relative to pre-exercise) was similar between women and men (mean change (95% confidence interval): 58.5 (25.2 to 91.7) IU/L; 68.8 (31.3 to 106.3) IU/L, respectively). However, serum CK activity was restored to pre-exercise levels quicker in women (regardless of menstrual phase) than men; after 48-h post exercise in women (16.3 (−4.4 to 37.0) IU/L; 56.3 (37.0 to 75.6) IU/L, respectively) but only after 72-h in men (14.9 (−14.8 to 44.6) IU/L). Parallel to the CK response, muscle soreness recovered by 72-h in men. Conversely, the women still reported muscle soreness at 72-h despite CK levels being restored by 48-h; delayed recovery of muscle soreness appeared mainly in EF and LF. The CK and DOMS response to downhill running is gender-specific. The CK response recovers quicker in women than men. The CK and DOMS response occur in concert in men but not in women. The DOMS response in women is prolonged and may be influenced by menstrual phase. Full article

(This article belongs to the Special Issue Exercise Induced Muscle Damage and Oxidative Stress)

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Open AccessReview

Treating Cancer by Targeting Telomeres and Telomerase

by Marko Ivancich, Zachary Schrank, Luke Wojdyla, Brandon Leviskas, Adijan Kuckovic, Ankita Sanjali and Neelu Puri

Antioxidants 2017, 6(1), 15; https://doi.org/10.3390/antiox6010015 - 19 Feb 2017

Cited by 69 | Viewed by 12669

Abstract

Telomerase is expressed in more than 85% of cancer cells. Tumor cells with metastatic potential may have a high telomerase activity, allowing cells to escape from the inhibition of cell proliferation due to shortened telomeres. Human telomerase primarily consists of two main components: [...] Read more.

Telomerase is expressed in more than 85% of cancer cells. Tumor cells with metastatic potential may have a high telomerase activity, allowing cells to escape from the inhibition of cell proliferation due to shortened telomeres. Human telomerase primarily consists of two main components: hTERT, a catalytic subunit, and hTR, an RNA template whose sequence is complimentary to the telomeric 5′-dTTAGGG-3′ repeat. In humans, telomerase activity is typically restricted to renewing tissues, such as germ cells and stem cells, and is generally absent in normal cells. While hTR is constitutively expressed in most tissue types, hTERT expression levels are low enough that telomere length cannot be maintained, which sets a proliferative lifespan on normal cells. However, in the majority of cancers, telomerase maintains stable telomere length, thereby conferring cell immortality. Levels of hTERT mRNA are directly related to telomerase activity, thereby making it a more suitable therapeutic target than hTR. Recent data suggests that stabilization of telomeric G-quadruplexes may act to indirectly inhibit telomerase action by blocking hTR binding. Telomeric DNA has the propensity to spontaneously form intramolecular G-quadruplexes, four-stranded DNA secondary structures that are stabilized by the stacking of guanine residues in a planar arrangement. The functional roles of telomeric G-quadruplexes are not completely understood, but recent evidence suggests that they can stall the replication fork during DNA synthesis and inhibit telomere replication by preventing telomerase and related proteins from binding to the telomere. Long-term treatment with G-quadruplex stabilizers induces a gradual reduction in the length of the G-rich 3’ end of the telomere without a reduction of the total telomere length, suggesting that telomerase activity is inhibited. However, inhibition of telomerase, either directly or indirectly, has shown only moderate success in cancer patients. Another promising approach of targeting the telomere is the use of guanine-rich oligonucleotides (GROs) homologous to the 3’ telomere overhang sequence (T-oligos). T-oligos, particularly a specific 11-base oligonucleotide (5’-dGTTAGGGTTAG-3’) called T11, have been shown to induce DNA damage responses (DDRs) such as senescence, apoptosis, and cell cycle arrest in numerous cancer cell types with minimal or no cytostatic effects in normal, non-transformed cells. As a result, T-oligos and other GROs are being investigated as prospective anticancer therapeutics. Interestingly, the DDRs induced by T-oligos in cancer cells are similar to the effects seen after progressive telomere degradation in normal cells. The loss of telomeres is an important tumor suppressor mechanism that is commonly absent in transformed malignant cells, and hence, T-oligos have garnered significant interest as a novel strategy to combat cancer. However, little is known about their mechanism of action. In this review, we discuss the current understanding of how T-oligos exert their antiproliferative effects in cancer cells and their role in inhibition of telomerase. We also discuss the current understanding of telomerase in cancer and various therapeutic targets related to the telomeres and telomerase. Full article

(This article belongs to the Special Issue Role of Telomerase in Aging and Cancer)

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Open AccessArticle

Inorganic Reactive Sulfur-Nitrogen Species: Intricate Release Mechanisms or Cacophony in Yellow, Blue and Red?

by Marian Grman, Muhammad Jawad Nasim, Roman Leontiev, Anton Misak, Veronika Jakusova, Karol Ondrias and Claus Jacob

Antioxidants 2017, 6(1), 14; https://doi.org/10.3390/antiox6010014 - 15 Feb 2017

Cited by 12 | Viewed by 6313

Abstract

Since the heydays of Reactive Sulfur Species (RSS) research during the first decade of the Millennium, numerous sulfur species involved in cellular regulation and signalling have been discovered. Yet despite the general predominance of organic species in organisms, recent years have also seen [...] Read more.

Since the heydays of Reactive Sulfur Species (RSS) research during the first decade of the Millennium, numerous sulfur species involved in cellular regulation and signalling have been discovered. Yet despite the general predominance of organic species in organisms, recent years have also seen the emergence of inorganic reactive sulfur species, ranging from inorganic polysulfides (HS_x⁻/S_x²⁻) to thionitrous acid (HSNO) and nitrosopersulfide (SSNO⁻). These inorganic species engage in a complex interplay of reactions in vitro and possibly also in vivo. Employing a combination of spectrophotometry and sulfide assays, we have investigated the role of polysulfanes from garlic during the release of nitric oxide (^•NO) from S-nitrosoglutathione (GSNO) in the absence and presence of thiol reducing agents. Our studies reveal a distinct enhancement of GSNO decomposition by compounds such as diallyltrisulfane, which is most pronounced in the presence of cysteine and glutathione and presumably proceeds via the initial release of an inorganic mono- or polysulfides, i.e., hydrogen sulfide (H₂S) or HS_x⁻, from the organic polysulfane. Albeit being of a preliminary nature, our spectrophotometric data also reveals a complicated underlying mechanism which appears to involve transient species such as SSNO⁻. Eventually, more in depth studies are required to further explore the underlying chemistry and wider biological and nutritional implications of this interplay between edible garlic compounds, reductive activation, inorganic polysulfides and their interplay with ^•NO storage and release. Full article

(This article belongs to the Special Issue Think Yellow: Reactive Sulfur Species in Redox Biology, Medicine and Agriculture)

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Open AccessArticle

Selenium- and Tellurium-Based Antioxidants for Modulating Inflammation and Effects on Osteoblastic Activity

by Xi Lu, Gemma Mestres, Vijay Pal Singh, Pedram Effati, Jia-Fei Poon, Lars Engman and Marjam Karlsson Ott

Antioxidants 2017, 6(1), 13; https://doi.org/10.3390/antiox6010013 - 14 Feb 2017

Cited by 22 | Viewed by 6445

Abstract

Increased oxidative stress plays a significant role in the etiology of bone diseases. Heightened levels of H2O2 disrupt bone homeostasis, leading to greater bone resorption than bone formation. Organochalcogen compounds could act as free radical trapping agents or glutathione peroxidase mimetics, reducing oxidative [...] Read more.

Increased oxidative stress plays a significant role in the etiology of bone diseases. Heightened levels of H2O2 disrupt bone homeostasis, leading to greater bone resorption than bone formation. Organochalcogen compounds could act as free radical trapping agents or glutathione peroxidase mimetics, reducing oxidative stress in inflammatory diseases. In this report, we synthesized and screened a library of organoselenium and organotellurium compounds for hydrogen peroxide scavenging activity, using macrophagic cell lines RAW264.7 and THP-1, as well as human mono- and poly-nuclear cells. These cells were stimulated to release H2O2, using phorbol 12-myristate 13-acetate, with and without organochalogens. Released H2O2 was then measured using a chemiluminescent assay over a period of 2 h. The screening identified an organoselenium compound which scavenged H2O2 more effectively than the vitamin E analog, Trolox. We also found that this organoselenium compound protected MC3T3 cells against H2O2-induced toxicity, whereas Trolox did not. The organoselenium compound exhibited no cytotoxicity to the cells and had no deleterious effects on cell proliferation, viability, or alkaline phosphatase activity. The rapidity of H2O2 scavenging and protection suggests that the mechanism of protection is due to the direct scavenging of extracellular H2O2. This compound is a promising modulators of inflammation and could potentially treat diseases involving high levels of oxidative stress. Full article

(This article belongs to the Special Issue Selenium and Selenoproteins for Optimal Health)

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Open AccessArticle

Proanthocyanidin Characterization and Bioactivity of Extracts from Different Parts of Uncaria tomentosa L. (Cat’s Claw)

by Mirtha Navarro-Hoyos, Rosa Lebrón-Aguilar, Jesús E. Quintanilla-López, Carolina Cueva, David Hevia, Silvia Quesada, Gabriela Azofeifa, M. Victoria Moreno-Arribas, María Monagas and Begoña Bartolomé

Antioxidants 2017, 6(1), 12; https://doi.org/10.3390/antiox6010012 - 04 Feb 2017

Cited by 27 | Viewed by 8919

Abstract

Apart from alkaloids, bioactive properties of Uncaria tomentosa L. have been attributed to its phenolic constituents. Although there are some reports concerning low-molecular-weight polyphenols in U. tomentosa, its polymeric phenolic composition has been scarcely studied. In this study, phenolic-rich extracts from leaves, [...] Read more.

Apart from alkaloids, bioactive properties of Uncaria tomentosa L. have been attributed to its phenolic constituents. Although there are some reports concerning low-molecular-weight polyphenols in U. tomentosa, its polymeric phenolic composition has been scarcely studied. In this study, phenolic-rich extracts from leaves, stems, bark and wood (n = 14) of Uncaria tomentosa plants from several regions of Costa Rica were obtained and analysed in respect to their proanthocyanidin profile determined by a quadrupole-time-of-flight analyser (ESI-QTOF MS). Main structural characteristics found for U. tomentosa proanthocyanidins were: (a) monomer composition, including pure procyanidins (only composed of (epi)catechin units) and propelargonidins (only composed of (epi)afzelechin units) as well as mixed proanthocyanidins; and (b) degree of polymerization, from 3 up to 11 units. In addition, U. tomentosa phenolic extracts were found to exhibit reasonable antioxidant capacity (ORAC (Oxygen Radical Absorbance Capacity) values between 1.5 and 18.8 mmol TE/g) and antimicrobial activity against potential respiratory pathogens (minimum IC₅₀ of 133 µg/mL). There were also found to be particularly cytotoxic to gastric adenocarcinoma AGS and colon adenocarcinoma SW620 cell lines. The results state the particularities of U. tomentosa proanthocyanidins and suggest the potential value of these extracts with prospective use as functional ingredients. Full article

(This article belongs to the Special Issue Dietary Antioxidants and Health Promotion)

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Open AccessArticle

In Vitro Lipophilic Antioxidant Capacity, Antidiabetic and Antibacterial Activity of Citrus Fruits Extracts from Aceh, Indonesia

by Ernawita, Ruri Agung Wahyuono, Jana Hesse, Uta-Christina Hipler, Peter Elsner and Volker Böhm

Antioxidants 2017, 6(1), 11; https://doi.org/10.3390/antiox6010011 - 03 Feb 2017

Cited by 41 | Viewed by 8018

Abstract

This study reports in vitro lipophilic antioxidant, inhibition of α-amylase and antibacterial activities of extracts of peel and pulp of citrus samples from Aceh, Indonesia. HPLC (high-performance liquid chromatography), phytochemical, and FTIR (fourier transform infrared) analysis detected carotenoids, flavonoids, phenolic acids and terpenoids, [...] Read more.

This study reports in vitro lipophilic antioxidant, inhibition of α-amylase and antibacterial activities of extracts of peel and pulp of citrus samples from Aceh, Indonesia. HPLC (high-performance liquid chromatography), phytochemical, and FTIR (fourier transform infrared) analysis detected carotenoids, flavonoids, phenolic acids and terpenoids, contributing to the biological potencies. Most peel and pulp extracts contained lutein and lower concentrations of zeaxanthin, α-carotene, β-carotene and β-cryptoxanthin. The extracts also contained flavanone glycosides (hesperidin, naringin and neohesperidin), flavonol (quercetin) and polymethoxylated flavones (sinensetin, tangeretin). L-TEAC (lipophilic trolox equivalent antioxidant capacity) test determined for peel extracts higher antioxidant capacity compared to pulp extracts. All extracts presented α-amylase inhibitory activity, pulp extracts showing stronger inhibitory activity compared to peel extracts. All extracts inhibited the growth of both gram (+) and gram (−) bacteria, with peel and pulp extracts of makin showing the strongest inhibitory activity. Therefore, local citrus species from Aceh are potential sources of beneficial compounds with possible health preventive effects. Full article

(This article belongs to the Special Issue Feature Papers 2016)

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Open AccessCommunication

Antioxidant Compound Extraction from Maqui (Aristotelia chilensis [Mol] Stuntz) Berries: Optimization by Response Surface Methodology

by Issis Quispe-Fuentes, Antonio Vega-Gálvez and Víctor H. Campos-Requena

Antioxidants 2017, 6(1), 10; https://doi.org/10.3390/antiox6010010 - 02 Feb 2017

Cited by 24 | Viewed by 5975

Abstract

The optimum conditions for the antioxidant extraction from maqui berry were determined using a response surface methodology. A three level D-optimal design was used to investigate the effects of three independent variables namely, solvent type (methanol, acetone and ethanol), solvent concentration and extraction [...] Read more.

The optimum conditions for the antioxidant extraction from maqui berry were determined using a response surface methodology. A three level D-optimal design was used to investigate the effects of three independent variables namely, solvent type (methanol, acetone and ethanol), solvent concentration and extraction time over total antioxidant capacity by using the oxygen radical absorbance capacity (ORAC) method. The D-optimal design considered 42 experiments including 10 central point replicates. A second-order polynomial model showed that more than 89% of the variation is explained with a satisfactory prediction (78%). ORAC values are higher when acetone was used as a solvent at lower concentrations, and the extraction time range studied showed no significant influence on ORAC values. The optimal conditions for antioxidant extraction obtained were 29% of acetone for 159 min under agitation. From the results obtained it can be concluded that the given predictive model describes an antioxidant extraction process from maqui berry. Full article

(This article belongs to the Special Issue Extraction of Antioxidants: Innovative and Intensification Methods, Activity Enhancement and Degradations)

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Open AccessArticle

Hydroxybenzoic Acids Are Significant Contributors to the Antioxidant Effect of Borututu Bark, Cochlospermum angolensis Welw. ex Oliv

by Ehab A. Abourashed and Hao Wen Fu

Antioxidants 2017, 6(1), 9; https://doi.org/10.3390/antiox6010009 - 28 Jan 2017

Cited by 5 | Viewed by 6796

Abstract

Borututu (Cochlospermum angolensis) is an African tree whose bark has recently emerged as a herbal dietary supplement with claims for antioxidant activity. In order to substantiate the claimed activity of borututu supplements, we performed an activity-guided fractionation of the total extract [...] Read more.

Borututu (Cochlospermum angolensis) is an African tree whose bark has recently emerged as a herbal dietary supplement with claims for antioxidant activity. In order to substantiate the claimed activity of borututu supplements, we performed an activity-guided fractionation of the total extract utilizing a 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging assay. Subsequent flash and centrifugal chromatography resulted in the isolation of gallic acid (1) and protocatechuic acid (2) as the main antioxidant constituents. Two apocarotenoids and one flavonoid were also isolated from the chloroform fraction and were identified as cochloxanthin (3), dihydrocochloxanthin (4), and 7,4′-dimethyltaxifolin (5), respectively. A High-performance liquid chromatography (HPLC) method was also developed for fingerprinting borututu samples, with Compounds 1–4 suggested as chemical markers for quality control purposes. Full article

(This article belongs to the Special Issue Feature Papers 2016)

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Open AccessArticle

A Comparative Study of the Phenolic and Technological Maturities of Red Grapes Grown in Lebanon

by Hiba N. Rajha, Nada El Darra, Sally El Kantar, Zeina Hobaika, Nicolas Louka and Richard G. Maroun

Antioxidants 2017, 6(1), 8; https://doi.org/10.3390/antiox6010008 - 26 Jan 2017

Cited by 18 | Viewed by 5171

Abstract

Grape harvest date is determined according to the technological and phenolic maturities. These parameters were calculated for different red grape (Vitis vinifera L.) varieties (Cabernet Sauvignon, Merlot, Syrah, Cabernet Franc) over four years (2008, 2009, 2010, and 2011) (642 samples). Titratable acidity and [...] Read more.

Grape harvest date is determined according to the technological and phenolic maturities. These parameters were calculated for different red grape (Vitis vinifera L.) varieties (Cabernet Sauvignon, Merlot, Syrah, Cabernet Franc) over four years (2008, 2009, 2010, and 2011) (642 samples). Titratable acidity and sugar content of the grapes were used to determine the technological maturity, whereas Glories (1 and 2) and ITV (Institut Technique de la Vigne et du Vin) methods were used to monitor their phenolic maturity. The ITV method allows the monitoring of phenolic maturity by the quantiﬁcation of total polyphenol index and anthocyanins, while the Glories method enables the quantitative evolution of extractable anthocyanins and tannins of the grapes. A correlation was shown between the harvest dates obtained by both ITV and Glories (R2 = 0.7 – 0.93). Phenolic maturity of grapes can, therefore, be optimized by the application of both ITV and Glories. Similarly, a correlation was observed between technological and phenolic harvest dates. The effect of climate on the phenolic content of grapes was also studied. The highest temperatures(up to 25◦C)accompanied by the lowest rainfall (null value), induced the maximal concentration of polyphenols in grapes. Thermal and water stresses were also shown to enhance the grapes’ polyphenolic production. Full article

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Open AccessReview

Red Fruits: Extraction of Antioxidants, Phenolic Content, and Radical Scavenging Determination: A Review

by Gádor-Indra Hidalgo and María Pilar Almajano

Antioxidants 2017, 6(1), 7; https://doi.org/10.3390/antiox6010007 - 19 Jan 2017

Cited by 144 | Viewed by 18379

Abstract

Red fruits, as rich antioxidant foods, have gained over recent years capital importance for consumers and manufacturers. The industrial extraction of the phenolic molecules from this source has been taking place with the conventional solvent extraction method. New non-conventional extraction methods have been [...] Read more.

Red fruits, as rich antioxidant foods, have gained over recent years capital importance for consumers and manufacturers. The industrial extraction of the phenolic molecules from this source has been taking place with the conventional solvent extraction method. New non-conventional extraction methods have been devised as environmentally friendly alternatives to the former method, such as ultrasound, microwave, and pressure assisted extractions. The aim of this review is to compile the results of recent studies using different extraction methodologies, identify the red fruits with higher antioxidant activity, and give a global overview of the research trends regarding this topic. As the amount of data available is overwhelming, only results referring to berries are included, leaving aside other plant parts such as roots, stems, or even buds and flowers. Several researchers have drawn attention to the efficacy of non-conventional extraction methods, accomplishing similar or even better results using these new techniques. Some pilot-scale trials have been performed, corroborating the applicability of green alternative methods to the industrial scale. Blueberries (Vaccinium corymbosum L.) and bilberries (Vaccinium myrtillus L.) emerge as the berries with the highest antioxidant content and capacity. However, several new up and coming berries are gaining attention due to global availability and elevated anthocyanin content. Full article

(This article belongs to the Special Issue Feature Papers 2016)

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Graphical abstract

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Open AccessReview

Exercise-Induced Oxidative Stress Responses in the Pediatric Population

by Alexandra Avloniti, Athanasios Chatzinikolaou, Chariklia K. Deli, Dimitris Vlachopoulos, Luis Gracia-Marco, Diamanda Leontsini, Dimitrios Draganidis, Athanasios Z. Jamurtas, George Mastorakos and Ioannis G. Fatouros

Antioxidants 2017, 6(1), 6; https://doi.org/10.3390/antiox6010006 - 17 Jan 2017

Cited by 26 | Viewed by 6814

Abstract

Adults demonstrate an upregulation of their pro- and anti-oxidant mechanisms in response to acute exercise while systematic exercise training enhances their antioxidant capacity, thereby leading to a reduced generation of free radicals both at rest and in response to exercise stress. However, less [...] Read more.

Adults demonstrate an upregulation of their pro- and anti-oxidant mechanisms in response to acute exercise while systematic exercise training enhances their antioxidant capacity, thereby leading to a reduced generation of free radicals both at rest and in response to exercise stress. However, less information exists regarding oxidative stress responses and the underlying mechanisms in the pediatric population. Evidence suggests that exercise-induced redox perturbations may be valuable in order to monitor exercise-induced inflammatory responses and as such training overload in children and adolescents as well as monitor optimal growth and development. The purpose of this review was to provide an update on oxidative stress responses to acute and chronic exercise in youth. It has been documented that acute exercise induces age-specific transient alterations in both oxidant and antioxidant markers in children and adolescents. However, these responses seem to be affected by factors such as training phase, training load, fitness level, mode of exercise etc. In relation to chronic adaptation, the role of training on oxidative stress adaptation has not been adequately investigated. The two studies performed so far indicate that children and adolescents exhibit positive adaptations of their antioxidant system, as adults do. More studies are needed in order to shed light on oxidative stress and antioxidant responses, following acute exercise and training adaptations in youth. Available evidence suggests that small amounts of oxidative stress may be necessary for growth whereas the transition to adolescence from childhood may promote maturation of pro- and anti-oxidant mechanisms. Available evidence also suggests that obesity may negatively affect basal and exercise-related antioxidant responses in the peripubertal period during pre- and early-puberty. Full article

(This article belongs to the Special Issue Exercise Induced Muscle Damage and Oxidative Stress)

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Open AccessReview

Use of Saliva Biomarkers to Monitor Efficacy of Vitamin C in Exercise-Induced Oxidative Stress

by Levi W. Evans and Stanley T. Omaye

Antioxidants 2017, 6(1), 5; https://doi.org/10.3390/antiox6010005 - 12 Jan 2017

Cited by 26 | Viewed by 12322

Abstract

Saliva is easily obtainable for medical research and requires little effort or training for collection. Because saliva contains a variety of biological compounds, including vitamin C, malondialdehyde, amylase, and proteomes, it has been successfully used as a biospecimen for the reflection of health [...] Read more.

Saliva is easily obtainable for medical research and requires little effort or training for collection. Because saliva contains a variety of biological compounds, including vitamin C, malondialdehyde, amylase, and proteomes, it has been successfully used as a biospecimen for the reflection of health status. A popular topic of discussion in medical research is the potential association between oxidative stress and negative outcomes. Systemic biomarkers that represent oxidative stress can be found in saliva. It is unclear, however, if saliva is an accurate biospecimen as is blood and/or plasma. Exercise can induce oxidative stress, resulting in a trend of antioxidant supplementation to combat its assumed detriments. Vitamin C is a popular antioxidant supplement in the realm of sports and exercise. One potential avenue for evaluating exercise induced oxidative stress is through assessment of biomarkers like vitamin C and malondialdehyde in saliva. At present, limited research has been done in this area. The current state of research involving exercise-induced oxidative stress, salivary biomarkers, and vitamin C supplementation is reviewed in this article. Full article

(This article belongs to the Special Issue Feature Papers 2016)

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Open AccessEditorial

Acknowledgement to Reviewers of Antioxidants in 2016

by Antioxidants Editorial Office

Antioxidants 2017, 6(1), 4; https://doi.org/10.3390/antiox6010004 - 11 Jan 2017

Cited by 2 | Viewed by 3376

Abstract

The editors of Antioxidants would like to express their sincere gratitude to the following reviewers for assessing manuscripts in 2016.[...] Full article

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Open AccessReview

Think Yellow and Keep Green—Role of Sulfanes from Garlic in Agriculture

by Awais Anwar, Emma Gould, Ryan Tinson, Murree Groom and Chris J. Hamilton

Antioxidants 2017, 6(1), 3; https://doi.org/10.3390/antiox6010003 - 30 Dec 2016

Cited by 18 | Viewed by 8046

Abstract

Reactive sulfur species from garlic have long been renowned for their health benefits and antimicrobial properties. In agriculture the subject matter is now gathering momentum in the search for new bio-pesticides to addressing emerging environmental concerns and tighter restrictions on the use of [...] Read more.

Reactive sulfur species from garlic have long been renowned for their health benefits and antimicrobial properties. In agriculture the subject matter is now gathering momentum in the search for new bio-pesticides to addressing emerging environmental concerns and tighter restrictions on the use of many conventional chemical pesticides. Although the precise modes of action of these garlic-derived bioactives is complex, recent research has provided a number of new insights that deepen our understanding of garlic-derived products, such as garlic extracts and oils. Herein, their activity against various crop-damaging pests is reviewed. In many cases, there seems to be a broad range of activity associated with the sulfur-containing compounds derived from Allium species, which manifests itself in diverse insecticidal, antifungal, and nematicidal activities. These activities open a new understanding to develop this natural chemistry as a “green pesticide”. Full article

(This article belongs to the Special Issue Think Yellow: Reactive Sulfur Species in Redox Biology, Medicine and Agriculture)

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Open AccessReview

Green Tea and Other Tea Polyphenols: Effects on Sebum Production and Acne Vulgaris

by Suzana Saric, Manisha Notay and Raja K. Sivamani

Antioxidants 2017, 6(1), 2; https://doi.org/10.3390/antiox6010002 - 29 Dec 2016

Cited by 43 | Viewed by 26047

Abstract

Polyphenols are antioxidant molecules found in many foods including nuts, fruits, vegetables, chocolate, wine, and tea. Polyphenols have antimicrobial, anti-inflammatory, and antineoplastic properties. Recent studies suggest that tea polyphenols may be used for reducing sebum production in the skin and for treatment of [...] Read more.

Polyphenols are antioxidant molecules found in many foods including nuts, fruits, vegetables, chocolate, wine, and tea. Polyphenols have antimicrobial, anti-inflammatory, and antineoplastic properties. Recent studies suggest that tea polyphenols may be used for reducing sebum production in the skin and for treatment of acne vulgaris. This review examines the evidence for use of topically and orally ingested tea polyphenols against sebum production and for acne treatment and prevention. The PubMed database was searched for studies on tea polyphenols, sebum secretion, and acne vulgaris. Of the 59 studies found, eight met the inclusion criteria. Two studies evaluated tea polyphenol effects on sebum production; six studies examined tea polyphenol effects on acne vulgaris. Seven studies evaluated topical tea polyphenols; one study examined systemic tea polyphenols. None of the studies evaluated both topical and systemic tea polyphenols. Tea polyphenol sources included green tea (six studies) and tea, type not specified (two studies). Overall, there is some evidence that tea polyphenols in topical formulation may be beneficial in reducing sebum secretion and in treatment of acne. Research studies of high quality and with large sample sizes are needed to assess the efficacy of tea polyphenols in topical and oral prevention of acne vulgaris and lipid synthesis by the sebaceous glands. Full article

(This article belongs to the Special Issue Tea Polyphenols and Antioxidants: Analysis, Chemistry and Biotechnological Applications)

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Open AccessArticle

The Effects of Allicin, a Reactive Sulfur Species from Garlic, on a Selection of Mammalian Cell Lines

by Martin C. H. Gruhlke, Carole Nicco, Frederic Batteux and Alan J. Slusarenko

Antioxidants 2017, 6(1), 1; https://doi.org/10.3390/antiox6010001 - 26 Dec 2016

Cited by 71 | Viewed by 11493

Abstract

Garlic (Allium sativum L.) has been used as a spice and medicinal plant since ancient times. Garlic produces the thiol-reactive defence substance, allicin, upon wounding. The effects of allicin on human lung epithelium carcinoma (A549), mouse fibroblast (3T3), human umbilical vein endothelial [...] Read more.

Garlic (Allium sativum L.) has been used as a spice and medicinal plant since ancient times. Garlic produces the thiol-reactive defence substance, allicin, upon wounding. The effects of allicin on human lung epithelium carcinoma (A549), mouse fibroblast (3T3), human umbilical vein endothelial cell (HUVEC), human colon carcinoma (HT29) and human breast cancer (MCF7) cell lines were tested. To estimate toxic effects of allicin, we used a standard MTT-test (methylthiazoltetrazolium) for cell viability and ³H-thymidine incorporation for cell proliferation. The glutathione pool was measured using monobromobimane and the formation of reactive species was identified using 2′,7′-dichlorofluoresceine-diacetate. The YO-PRO-1 iodide staining procedure was used to estimate apoptosis. Allicin reduced cell viability and cell proliferation in a concentration dependent manner. In the bimane test, it was observed that cells treated with allicin showed reduced fluorescence, suggesting glutathione oxidation. The cell lines tested differed in sensitivity to allicin in regard to viability, cell proliferation and glutathione oxidation. The 3T3 and MCF-7 cells showed a higher proportion of apoptosis compared to the other cell types. These data show that mammalian cell lines differ in their sensitivity and responses to allicin. Full article

(This article belongs to the Special Issue Think Yellow: Reactive Sulfur Species in Redox Biology, Medicine and Agriculture)

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