Antioxidant potential of sesamol and its role on radiation-induced DNA damage in whole-body irradiated Swiss albino mice

Sesamol (SM) is a dietary phytochemical present in the processed sesame oil. In this present study we have evaluated the antioxidant potential of SM and its role in the protection of radiation-induced DNA damage in γ-irradiated mice. The antioxidant properties of SM were evaluated by using different in vitro antioxidant assays. SM shows scavenging effect against hydroxyl (OH), superoxide anion (O₂⁻), nitric oxide, 2,2-azino-bis-3-ethylbenzothiazoline-6-sulphonic acid radical cation (ABTS⁺) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals. Our results demonstrate that SM exhibits strong antioxidant property in all the in vitro assays. When mice were exposed to 7 Gy γ-radiations there was an increase in % tail DNA, tail length, tail moment and Olive tail moment in blood lymphocytes. SM (100 mg/kg b.wt) pretreatment significantly decreased the % tail DNA, tail length, tail moment and Olive tail moment in irradiated mice lymphocytes. These results suggest that SM protects γ-radiation-induced DNA damage in mice lymphocytes, which may be attributed to its antioxidant property.     

Antioxidant evaluation of O-methylated metabolites of catechin, epicatechin and quercetin

Catechins and quercetin are major polyphenols in many plant foods that have been related to health promotion. In the human organism they are largely metabolized to different metabolites, which are further found in plasma and should contribute to the biological effects associated to the intake of the parent compounds. An important step in quercetin and catechins metabolism is the O-methylation of the catechol group, which can be expected to have an effect on their antioxidant and scavenging properties. In the present work, the 3′- and 4′-methylethers of catechin and epicatechin have been prepared and characterised and their antioxidant activity evaluated and compared to that of the corresponding quercetin derivatives. The antioxidant activity was assessed using the ferric reducing power (FRAP) assay and two methods based on the ability to scavenge the ABTS⁺ radical cation at different pH values. In these assays the three flavonoids behave as better radical scavengers and reducing compounds than usually recognised antioxidants like α-tocopherol. The O-methylation of the hydroxyls of the catechol B-ring resulted in a decrease of the antioxidant activity with regard to the parent compounds. However, the methylated metabolites still retain significant radical scavenging activity at pH 7.4, suggesting that they could act as potential antioxidants in physiological conditions. Quercetin and its methylated metabolites showed, in general, greater activity than (epi)catechin and their O-methyl derivatives, although a relatively high antioxidant activity was found in the case of 3′-O-methyl catechin at pH 7.4, comparable to those of its parent compound and the quercetin metabolites. It was confirmed that the antioxidant activity of the flavonoids assayed was strongly dependent on the pH of the medium, showing higher activity at greater pH values. The results obtained are expected to contribute to the understanding of the mechanisms involved in the biological effects attributed to the intake of flavonoid-rich diets.     

Epigallocatechin-3-gallate induces cytokine production in mast cells by stimulating an extracellular superoxide-mediated calcium influx

The green tea polyphenol (−)-epigallocatechin-3-O-gallate (EGCG) has various biological activities, including anti-inflammatory, anti-neoplastic, anti- and pro-apoptotic, and neuroprotective effects. Although these are often associated with increased intracellular reactive oxygen species (ROS) and Ca²⁺ levels, their involvement in biological effects is poorly understood. Here we report that EGCG induces cytokine production in mast cells via Ca²⁺ influx and ROS generation. EGCG at concentrations of ≥50 μM induced interleukin-13 and tumor necrosis factor-α production in RBL-2H3 and bone marrow-derived mast cells. The effects were dependent on extracellular Ca²⁺, and EGCG induced Ca²⁺ release from intracellular stores and Ca²⁺ influx. Ca²⁺ influx was suppressed by 2-aminoethoxydiphenyl borate, an inhibitor of store-operated Ca²⁺ (SOC) channels, including Ca²⁺ release-activated Ca²⁺ channels and transient receptor potential canonical channels. EGCG failed to induce Ca²⁺ influx through SOC channels. EGCG-activated Ca²⁺ channels were genetically and pharmacologically distinct from Ca_v1.2 L-type Ca²⁺ channels, another route of Ca²⁺ influx into mast cells. EGCG evoked release of superoxide (O₂⁻) into the extracellular space. Exogenous superoxide dismutase, but not catalase, inhibited EGCG-evoked Ca²⁺ influx and cytokine production, indicating that extracellular O₂⁻ regulates these events. EGCG can serve as a powerful tool for studying O₂⁻-regulated Ca²⁺ channels, which may be selectively involved in the regulation of cytokine production but have yet to be elucidated.     

Chemical composition and bioactivities of flavonoids-rich extract from Davallia cylindrica Ching

The flavonoids profiles and bioactivities of flavonoids-rich extract from Davallia cylindrica Ching were investigated. The total flavonoids content in D. cylindrica was determined as about 164.41 mg/g. The main flavonoids in D. cylindrica were tentatively identified as quercetin-3-O-rutinoside, quercetin 7-O-glucoside, quercetin 7-O-glucoside, kaempferol 3-O-rutinoside, and quercitrin by UV and ESI-MS spectra. Flavonoids-rich extract (0.258 mg/ml) from D. cylindrica showed similar or higher free radical (O₂⁻, DPPH and ABTS) scavenging potential with that of rutin (0.25 mg/ml). The reducing power of flavonoids-rich extract (0.258 mg/ml) was slightly stronger than that of 0.25 mg/ml rutin. The flavonoids extract from D. cylindrica exhibited cytotoxic effects on A549 cells. It exhibited a dose-dependent inhibition against acetylcholinesterase.     

Characterization of flavonoids from Dryopteris erythrosora and evaluation of their antioxidant,anticancer and acetylcholinesterase inhibition activities

The profiles and bioactivities of flavonoids extracted from Dryopteris erythrosora were investigated. The total flavonoid content in full plant of D. Erythrosora is about 14.33%. The main flavonoids in D. Erythrosora were identified as gliricidin 7-O-hexoside, apigenin7-O-glucoside, quercetin 7-O-rutinoside, quercetin 7-O-galactoside, keampferol 7-O-gentiobioside, keampferol-3-O-rutinoside, myricetin 3-O-rhamnoside and quercitrin by means of HPLC-DAD–ESI-MS. Flavonoids (0.36 mg/ml) extract from D. erythrosora showed similar 2,2-diphenyl-1-picrylhydrazyl free radical (DPPH), 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) radical (ABTS), superoxide anion scavenging potential and ferric reducing antioxidant potential (FRAP) with that of rutin (0.80 mg/ml). However, the antioxidant power by FRAP assay of 0.36 mg/ml flavonoids extract from D. erythrosora was much weaker than that of 0.80 mg/ml rutin. Moreover, the flavonoids extract from D. erythrosora showed obvious cytotoxic effects on A549 cells. The antioxidant activities of flavonoids extracts from 69 ferns showed a significant reciprocal proportion to the total flavonoids contents. The flavonoids extract from D. erythrosora exhibited a dose-dependent inhibition against acetylcholinesterase. Moreover, the anticancer activity slightly increased with improving antioxidant potential of fern flavonoids. Fern flavonoids are excellent function foods.     

In vitro and in vivo antioxidant properties of different fractions of Moringa oleifera leaves

The antioxidant potency of different fractions of Moringa oleifera leaves were investigated by employing various established in vitro systems, such as β-Carotene bleaching, reducing power, DPPH/superoxide/hydroxyl radical scavenging, ferrous ion chelation and lipid peroxidation. On the basis of in vitro antioxidant properties polyphenolic fraction of M. oleifera leaves (MOEF) was chosen as the potent fraction and used for the DNA nicking and in vivo antioxidant properties. MOEF shows concentration dependent protection of oxidative DNA damage induced by HO and also found to inhibit the toxicity produced by CCl₄ administration as seen from the decreased lipid peroxides (LPO) and increased glutathione (GSH) levels. Among the antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT) levels were restored to almost normal levels compared to CCl₄ intoxicated rats. The HPLC analysis indicated the presence of phenolic acids (gallic, chlorogenic, ellagic and ferulic acid) and flavonoids (kaempferol, quercetin and rutin). Thus, it may be concluded that the MOEF possess high phenolic content and potent antioxidant properties, which may be mediated through direct trapping of the free radicals and also through metal chelation.     

Generation of reactive oxygen species induced by gold nanoparticles under x-ray and UV Irradiations

The radiosensitizing effect of 5--250 nm diameter Au nanoparticles (AuNPs) in water was investigated under irradiations of diagnostic x-ray and UV light. Enhanced generations of hydroxyl radical (OH) and superoxide anion (O₂⁻) were confirmed from their dependencies on the absorbed energy, ethanol concentration and AuNPs' concentration. Two kinds of fluorescent probes revealed that the reactive oxygen species (ROS) generation rate under x-ray irradiation was enhanced by factors of 1.46 for OH and 7.68 for O₂⁻. Photo- and Auger electron charge transfer is possibly relevant to generation of O₂⁻ near the particle surface, whereas fluorescent x-rays are involved in generation of OH in the secondary water radiolysis. Smaller diameter AuNPs with larger surface area showed a greater yield of ROS. An inverse proportion of ROS generation to the AuNPs' diameter suggests a catalytic function of AuNPs' surface for enhanced ROS generation.

From the Clinical Editor

This paper investigates the effects of UV and X-ray irradiation on reactive oxygen species induction of gold nanoparticles, concluding that smaller diameter AuNPs with larger surface area lead to a greater yield of ROS probably due to catalytic effects. The paper may be important for the development of novel non-toxic radiation sensitizers.     

Flavonoids profiles,antioxidant, acetylcholinesterase inhibition activities of extract from Dryoathyrium boryanum (Willd.) Ching

The profiles and bioactivities of flavonoids extracted from Dryoathyrium boryanum (Willd.) Ching were investigated. The total flavonoids content in extract from D. boryanum is about 145.8 mg/g. By means of HPLC–DAD–ESI–MS, the main flavonoids in D. boryanum were tentatively identified as 3-hydroxyphloretin 6′-O-hexoside, quercetin-7-hexoside, apigenin7-O-glucoside, luteolin 7-O-glucoside, apigenin 7-O-galactoside, acacetin 7-O-(α-D-apio-furanosyl) (1 → 6)-β-d-glucoside, 3-hydroxy phloretin 6-O-hexoside, luteolin-6-C-glucoside. 0.21 mg/ml flavonoids extract from D. boryanum showed very strong superoxide anion radical scavenging potential, which is higher than that of rutin (0.25 mg/ml). The extract (0.21 mg/ml of flavonoids) from D. boryanum exhibited similar DPPH scavenging potential with that of rutin (0.25 mg/ml). However, rutin (0.25 mg/ml) showed a significantly higher reducing power and ABTS scavenging potential than that of 0.21 mg/ml flavonoids extract from D. boryanum. It had no effect on acetylcholinesterase. D. boryanum can be considered as a medicinal plant and the flavonoids from D. boryanum are excellent antioxidants.     

On the antioxidant properties of kynurenic acid: Free radical scavenging activity and inhibition of oxidative stress

Kynurenic acid (KYNA) is an endogenous metabolite of the kynurenine pathway for tryptophan degradation and an antagonist of both N-methyl-d-aspartate (NMDA) and alpha-7 nicotinic acetylcholine (α7nACh) receptors. KYNA has also been shown to scavenge hydroxyl radicals (OH) under controlled conditions of free radical production. In this work we evaluated the ability of KYNA to scavenge superoxide anion (O₂⁻) and peroxynitrite (ONOO⁻). The scavenging ability of KYNA (expressed as IC₅₀ values) was as follows: OH = O₂⁻ > ONOO⁻. In parallel, the antiperoxidative and scavenging capacities of KYNA (0-150 μM) were tested in cerebellum and forebrain homogenates exposed to 5 μM FeSO₄ and 2.5 mM 3-nitropropionic acid (3-NPA). Both FeSO₄ and 3-NPA increased lipid peroxidation (LP) and ROS formation in a significant manner in these preparations, whereas KYNA significantly reduced these markers. Reactive oxygen species (ROS) formation were determined in the presence of FeSO₄ and/or KYNA (0-100 μM), both at intra and extracellular levels. An increase in ROS formation was induced by FeSO₄ in forebrain and cerebellum in a time-dependent manner, and KYNA reduced this effect in a concentration-dependent manner. To further know whether the effect of KYNA on oxidative stress is independent of NMDA and nicotinic receptors, we also tested KYNA (0-100 μM) in a biological preparation free of these receptors - defolliculated Xenopus laevis oocytes - incubated with FeSO₄ for 1 h. A 3-fold increase in LP and a 2-fold increase in ROS formation were seen after exposure to FeSO₄, whereas KYNA attenuated these effects in a concentration-dependent manner. In addition, the in vivo formation of OH evoked by an acute infusion of FeSO₄ (100 μM) in the rat striatum was estimated by microdialysis and challenged by a topic infusion of KYNA (1 μM). FeSO₄ increased the striatal OH production, while KYNA mitigated this effect. Altogether, these data strongly suggest that KYNA, in addition to be a well-known antagonist acting on nicotinic and NMDA receptors, can be considered as a potential endogenous antioxidant.     

Signaling mechanisms of inhibition of phospholipase D activation by CHS-111 in formyl peptide-stimulated neutrophils

A selective phospholipase D (PLD) inhibitor 5-fluoro-2-indolyl des-chlorohalopemide (FIPI) inhibited the O₂⁻ generation and cell migration but not degranulation in formyl-Met-Leu-Phe (fMLP)-stimulated rat neutrophils. A novel benzyl indazole compound 2-benzyl-3-(4-hydroxymethylphenyl)indazole (CHS-111), which inhibited O₂⁻ generation and cell migration, also reduced the fMLP- but not phorbol ester-stimulated PLD activity (IC₅₀ 3.9 ± 1.2 μM). CHS-111 inhibited the interaction of PLD1 with ADP-ribosylation factor (Arf) 6 and Ras homology (Rho) A, and reduced the membrane recruitment of RhoA in fMLP-stimulated cells but not in GTPγS-stimulated cell-free system. CHS-111 reduced the cellular levels of GTP-bound RhoA, membrane recruitment of Rho-associated protein kinase 1 and the downstream myosin light chain 2 phosphorylation, and attenuated the interaction between phosphatidylinositol 4-phosphate 5-kinase (PIP5K) and Arf6, whereas it only slightly inhibited the guanine nucleotide exchange activity of human Dbs (DH/PH) protein and did not affect the arfaptin binding to Arf6. CHS-111 inhibited the interaction of RhoA with Vav, the membrane association and the phosphorylation of Vav. CHS-111 had no effect on the phosphorylation of Src family kinases (SFK) but attenuated the interaction of Vav with Lck, Hck, Fgr and Lyn. CHS-111 also inhibited the interaction of PLD1 with protein kinase C (PKC) α, βI and βII isoenzymes, and the phosphorylation of PLD1. These results indicate that inhibition of fMLP-stimulated PLD activity by CHS-111 is attributable to the blockade of RhoA activation via the interference with SFK-mediated Vav activation, attenuation of the interaction of Arf6 with PLD1 and PIP5K, and the activation of Ca²⁺-dependent PKC in rat neutrophils.     

Comparative study on antioxidant activity of different varieties of commonly consumed legumes in India

Legumes are rich source of proteins, dietary fiber, micronutrients and bioactive phytochemicals. Thirty different varieties of commonly consumed legumes in India, were screened for phenolic content and antioxidant activity using, radical scavenging [(1,1-diphenyl-2-picryl-hydrazyl (DPPH) and 2,2′-azino-bis (3-ethylbenz-thiazoline-6-sulfonic acid, (ABTS⁺)], Ferric Reducing Antioxidant Power (FRAP) and metal ion (Fe²⁺) chelation assays. Legumes varied largely in their antioxidant activity. Horse gram, common beans, cowpea (brown and red) and fenugreek showed high DPPH radical scavenging activity (>400 units/g), while lablab bean (cream and white), chickpea (cream and green), butter bean and pea (white and green) showed low antioxidant activity (<125 units/g). Green gram, black gram, pigeon pea, lentils, cowpea (white) and common bean (maroon) showed intermediate activity. Similar trend was observed when the activity was assessed with ABTS⁺ and FRAP assays. Thus most of the varieties having light color seed coat, except soybean exhibited low antioxidant activity. While legumes having dark color seed coat did not always possessed high antioxidant activity (e.g. moth bean, black pea, black gram, lentils). Antioxidant activity showed positive correlation (r² > 0.95) with phenolic contents, in DPPH, ABTS⁺ and FRAP assays, whereas poor correlation (r² = 0.297) was observed between Fe²⁺ chelating activity of the legumes and phenolic contents.     

Pharmacopeial compliance of fish oil-containing parenteral lipid emulsion mixtures: Globule size distribution (GSD) and fatty acid analyses

Recently, the United States Pharmacopeia (USP) has established Chapter 729 with GSD limits for all lipid emulsions where the mean droplet size (MDS) must be <500 nm and the percent of fat larger than 5 μm (PFAT₅) must be <0.05%, irrespective of the final lipid concentration. As well, the European Pharmacopeia (EP) Monograph no. 1352 specifies n3-fatty acid (FA) limits (EPA + DHA ≥ 45%; total n3 or T-n3 ≥ 60%) for fish oil. We assessed compliance with USP physical and EP chemical limits of two fish oil-containing lipid emulsion mixtures. All lipid emulsions passed USP 729 limits. No samples tested had an MDS >302 nm or a PFAT₅ value >0.011%. Only one product met EP limits while the other failed. All emulsions tested were extremely fine dispersions and easily met USP 729 GSD limits. The n3-FAs profiles were lower in one, despite being labeled to contain 50% more fish oil than the other product. This latter finding suggests the n3-FA content of the fish oil source and/or the applied manufacturing processes in these products is different.     

Mechanisms involved in the in vitro contractile dysfunction induced by different concentrations of ferrous iron in the rat myocardium

Iron intoxication is related to reactive oxygen species (ROS) production and organic damage including the cardiovascular system, and is a leading cause of poisoning deaths in children. In this study we examined whether a range of ferrous iron (Fe(2 +)) concentrations can interfere differently on the myocardial mechanics, investigating the ROS-mediated effects. Developed force of isolated rat papillary muscles was depressed with a concentration- and time-dependency by Fe(2 +) 100–1000 μM. The contractile response to Ca(2 +) was reduced, but it was partially reversed by co-incubation with catalase and DMSO, but not TEMPOL. In agreement, in situ detection of OH was increased by Fe(2 +) whereas O₂⁻ was unchanged. The myosin-ATPase activity was significantly decreased. Contractions dependent on the sarcolemal Ca(2 +) influx were impaired only by Fe(2 +) 1000 μM, and antioxidants had no effect. In skinned fibers, Fe(2 +) reduced the pCa-force relationship, and pCa50 was right-shifted by 0.55. In conclusion, iron overload can acutely impair myocardial contractility by reducing myosin-ATPase activity and myofibrillar Ca(2 +) sensitivity. These effects are mediated by local production of OH and H₂O₂. Nevertheless, in a such high concentration as 1000 μM, Fe(2 +) appears to depress force also by reducing Ca(2 +) influx, probably due to a competition at Ca(2 +) channels.     

Arsenic alters monocyte superoxide anion and nitric oxide production in environmentally exposed children

Arsenic (As) exposure has been associated with alterations in the immune system, studies in experimental models and adults have shown that these effects involve macrophage function; however, limited information is available on what type of effects could be induced in children. The aim of this study was to evaluate effects of As exposure, through the association of inorganic As (iAs) and its metabolites [monomethylated arsenic (MMA) and dimethylated arsenic (DMA)] with basal levels of nitric oxide (NO⁻) and superoxide anion (O₂⁻), in peripheral blood mononuclear cells (PBMC) and monocytes, and NO⁻ and O₂⁻ produced by activated monocytes. Hence, a cross-sectional study was conducted in 87 children (6-10 years old) who had been environmentally exposed to As through drinking water. Levels of urinary As species (iAs, MMA and DMA) were determined by hydride generation atomic absorption spectrometry, total As (tAs) represents the sum of iAs and its species; tAs urine levels ranged from 12.3 to 1411 μg/g creatinine. Using multiple linear regression models, iAs presented a positive and statistical association with basal NO⁻ in PBMC (β = 0.0048, p = 0.049) and monocytes (β = 0.0044, p = 0.044), while basal O₂⁻ had a significant positive association with DMA (β = 0.0025, p = 0.046). In activated monocytes, O₂⁻ showed a statistical and positive association with iAs (β = 0.0108, p = 0.023), MMA (β = 0.0066, p = 0.022), DMA (β = 0.0018, p = 0.015), and tAs (β = 0.0013, p = 0.015). We conclude that As exposure in the studied children was positively associated with basal levels of NO⁻ and O₂⁻ in PBMC and monocytes, suggesting that As induces oxidative stress in circulating blood cells. Additionally, this study showed a positive association of O₂⁻ production with iAs and its metabolites in stimulated monocytes, supporting previous data that suggests that these cells, and particularly the O₂⁻ activation pathway, are relevant targets for As toxicity.     

In vitro antioxidant, anticholinesterase and antimicrobial activity studies on three Agaricus species with fatty acid compositions and iron contents: A comparative study on the three most edible mushrooms

The fatty acids of Agaricus essettei, Agaricus bitorquis and Agaricus bisporus were investigated by using GC and GC-MS. The dominant fatty acids were found to be linoleic (61.82-67.29%) and palmitic (12.67-14.71%) acids among the 13 fatty acids detected in the oils. Total unsaturation for the oils was calculated as 77.50%, 77.44%, and 79.72%, respectively. In vitro antioxidant, anticholinesterase and antimicrobial activities were also studied. The ethyl acetate extract of Agaricus bitorquis showed the highest activity in β-carotene-linoleic acid, DPPH and ABTS⁺ assays, while the hexane extract of Agaricus bisporus exhibited the best metal chelating activity. The ethyl acetate and hexane extract of Agaricus bitorquis and the hexane extract of Agaricus essettei showed meaningful butyrylcholinesterase activity being close to that of galantamine. The extracts were found to be effective on Gram (+) bacteria, especially against Micrococcus luteus, Micrococcus flavus, Bacillus subtilis and Bacillus cereus. In conclusion, Agaricus bitorquis and Agaricus essettei demonstrated higher iron content, and better antioxidant, anticholinesterase and antimicrobial activities than those of Agaricus bisporus commonly consumed mushroom. Hence, Agaricus species, particularly Agaricus bitorquis might be useful as antioxidant agents and moderate anticholinesterase agents, and their extracts will probably be used for development of dietary foods, food products and additives.