Antioxidative and anti-inflammatory properties of Citrus sulcata extracts

Citrus sulcata was subjected to ultrasound, high-pressure, and Soxhlet extractions. The antioxidant and anti-inflammatory activities of the extracts were evaluated qualitatively and quantitatively. The antioxidant content of the peel extract was twice that of the fruit extract. The quantitative analysis showed that the narirutin and hesperidin contents in the peel extracts were 8.8 and 7.5 mg/100 g, respectively. These extracts had a total phenolic content of 112.22 ± 2.89 gallic acid equivalent (GAE) mg/100 g, a total flavonoid content of 54.09 ± 1.01 rutin equivalent (RE) mg/100 g, DPPH radical scavenging activity of 46%, and antioxidant activity of 213.25 ± 2.82 μM of Trolox equivalents (TEAC). C. sulcata extracts could prevent hydrogen peroxide (H₂O₂)-induced oxidative stress, reduce expression of the inflammatory markers nuclear Factor kappa B (NFκB) and phosphorylated IκBα (p-IκBα) in A549 human lung carcinoma cells, and inhibit Lipopolysaccharide (LPS)-induced THP-1 monocyte differentiation to an extent of 85%.     

Curcumin protects mouse neuroblastoma Neuro-2A cells against hydrogen-peroxide-induced oxidative stress

Curcumin has been traditionally used in China and India for food and medicinal purposes. It has been shown to possess potent antioxidative activity both in vitro and in vivo. In the present study, the neuroprotective effects and the potential mechanisms of curcumin against H₂O₂-induced oxidative stress in mouse neuroblastoma Neuro-2A cells were investigated. Treatment with curcumin at 20 and 25 μg/mL for 1 h prior to H₂O₂ exposure significantly attenuated cell viability loss, reduced apoptosis, suppressed the elevation of intracellular reactive oxygen species (ROS) and calcium levels, and stabilised mitochondrial membrane potential. Furthermore, curcumin could block H₂O₂-mediated degradation of the protein IκBα and subsequent activation of nuclear factor κB, thus inhibiting the expression of its target gene cyclooxygenase 2. These results indicate that curcumin has potential protective effects against H₂O₂-induced oxidative stress in neuron cells, which might make curcumin a suitable therapeutic agent for prevention and treatment of neurodegenerative diseases associated with oxidative stress.     

Cytoprotective effect of white tea against H2O2-induced oxidative stress in vitro

The protective effect of water extracts of white tea (WEWT) on oxidative stress in vitro is investigated. WEWT, like water extracts of green tea (WEGT) and water extracts of Pu-erh tea (WEPT), demonstrates a marked inhibition of the oxidation of liposome, albumin and LDLmodel systems. WEWT protects against H₂O₂-induced cytotoxicity, in a dose-dependent manner. The inhibition of ROS generation and MDA formation by WEWT in H₂O₂-induced Clone 9 cells parallels the effects on cell viability. Moreover, GSH and antioxidant enzymes may play an important role in the protective effect that is associated with H₂O₂-induced oxidative stress. The HPLC-DAD and HPLC–MS/MS analysis, shows that sixteen bioactive compounds are present in WEWT, which may partially account for its protective effect against oxidative insult. These results suggest that the mechanism of the protective actions of WEWT is related to its antioxidant potential and the maintenance of the normal redox status of the cell.     

Neuroprotective effect of blackberry (Rubus sp.) polyphenols is potentiated after simulated gastrointestinal digestion

Blackberry ingestion has been demonstrated to attenuate brain degenerative processes in rodents with the benefits ascribed to the (poly)phenolic components. The aim of this work was to assess the efficacy of blackberry polyphenolics in a neurodegeneration cell model before and after simulated gastrointestinal digestion.Digested blackberry metabolites protected neuroblastoma cells from H₂O₂-induced death at low, non-toxic levels that approach physiologically-relevant serum concentrations. However, the original extracts were not protective even at fivefold higher concentrations. This potentiation may reflect alterations in the polyphenolic composition caused by the digestion procedure, as detected by liquid-chromatography-mass spectrometric analysis. This protection was not caused by modulation of the intracellular antioxidant capacity or through alteration of glutathione levels, although the original extract influenced both of these parameters. This work reinforces the importance of evaluating digested metabolites in disease cell models and highlights the possible involvement of other mechanisms beyond antioxidant systems.     

Antioxidant Activities of Polyphenolic Compounds Isolated from Antidesma thwaitesianum Müll. Arg. Seeds and Marcs

ABSTRACT: Antidesma thwaitesianum Müll. Arg. or mao is widely used as commercial products of juice and wine in Thailand. As a result, waste products from the mao plant, such as mao seeds (MS) and mao marcs (MM), are plentiful. We aimed to purify and analyze polyphenolic content in both MS and MM and to investigate the radical scavenging activities of these polyphenolics against 1,1‐diphenyl‐2‐picryl‐hydrazyl (DPPH) and 2,2′‐Azinobis (3‐ethylbenzothiazoline 6‐sulphonate) (ABTS) radicals and thiobarbituric acid reactive products (TBARP). The results showed MS and MM to be an abundant source of polyphenols (97.32 to 130 mg gallic acid equivalents [GAE]/g) and proanthocyanidins. The radical scavenging activities of MS/MM against DPPH and ABTS radicals (IC₅₀ of 0.85 to 1.21 μg/mL) were significantly higher (P < 0.05) than that of standard trolox (IC₅₀ of 5.05 μg/mL). Activity of MS/MM extracts were 3.74 and 3.80 μg/mL trolox eq/g f.w. for the DPPH and ABTS assays, respectively. The oxidation of erythrocyte membranes using 2‐thiobarbituric acid demonstrated that the protective effect of MS/MM on lipid peroxidation is as strong as grape seed proanthocyanidin extract. These findings suggest that polyphenolic compounds and proanthocyanidins isolated from these mao extracts had much higher antioxidant activities than those of standard trolox and exhibited similar antioxidant potential to grape seed proanthocyanidin extract. These findings may also increase value of mao waste products and allow development of commercial health products.     

Phenolic extracts of brewers’ spent grain (BSG) as functional ingredients – Assessment of their DNA protective effect against oxidant-induced DNA single strand breaks in U937 cells

Brewers’ spent grain (BSG), a by-product of the brewing industry, contains high amounts of phenolic acids, which have antioxidant effects. The present study examined the ability of BSG extracts to protect against the genotoxic effects of oxidants, hydrogen peroxide (H₂O₂), 3-morpholinosydnonimine hydrochloride (SIN-1), 4-nitroquinoline 1-oxide (4-NQO) and tert-butylhydroperoxide (t-BOOH) in U937 cells. Four pale (P1–P4) and four black (B1–B4) BSG extracts were investigated. U937 cells were pre-incubated with BSG extracts, exposed to the oxidants and the DNA damage was measured by the Comet assay. The black BSG extracts (B1–B4) significantly protected against H₂O₂-induced DNA damage. Extract B2, which had the highest phenol content, provided the greatest protection. Extracts P2, B2, B3 and B4 provided significant protection against SIN-1-induced DNA damage. None of the extracts protected against DNA damage induced by t-BOOH and 4-NQO. The DNA protective effects of the BSG phenolic extracts may be related to iron chelation.     

Neuroprotective effects of N-acetylglucosamine against hydrogen peroxide-induced apoptosis in human neuronal SK-N-SH cells by inhibiting the activation of caspase-3, PARP, and p38

Neuroprotective effects of N-acetylglucosamine (GlcNAc), a monosaccharide derivative of glucose, against H₂O₂-induced neurotoxicity and its underlying mechanism in human SK-N-SH neuroblastoma cells were investigated. Pretreatment of GlcNAc prior to exposure of cells to H₂O₂ stress significantly reduced the H₂O₂-mediated neuronal cell death and apoptosis. The GlcNAc dose-dependently decreased the level of intracellular reactive oxygen species (ROS) in H₂O₂-treated cells and also effectively inhibited H₂O₂-induced apoptotic features such as DNA fragmentation, caspase-3, and poly ADP-ribose polymerase (PARP) cleavages, and p38 phosphorylation. These results suggested that GlcNAc might potentially serve as agents for prevention of neurodegenerative diseases caused by oxidative stresses and this effect may be associated with the suppression of caspase-3, PARP, and p38 activation.     

Free radical scavenging activity and comparative proteomic analysis of antioxidative protein against H2O2-induced oxidative stress in neuronal cells

Artemisia annua was enzymatically hydrolyzed by five proteases and seven carbohydrases. All enzymatic extracts scavenged DPPH, hydroxyl and alkyl radicals. Especially, the Protamex among the various proteases and Maltogenase among the various carbohydrases extracts exhibited the highest scavenging activity on hydroxyl radical. The extracts of A. annua clearly reduced neuronal cell death from H₂O₂-induced damage. In addition, a proteomic analysis, two-dimensional electrophoresis (2-DE) and matrix assisted laser desorption ionisation-time of flight/time of flight (MALDI-TOF/TOF) was used to identify the proteins of the neuronal cells whose expressions were or were not altered by the treatment of the Maltogenase extracts which showed the highest hydroxyl radical scavenging activity among all enzymatic extracts for 24 h. The protein characterisation revealed that translation elongation factor Tu (EF-Tu), Immunoglobulin E (IgE) and voltage-dependent anion channel 1 (VDAC-1) were involved in the cell survival effects against H₂O₂-induced apoptosis. These results suggest that EF-Tu, IgE and VDAC-1 have an important role in the reduction of neuronal apoptosis by oxidative stress, and the enzymatic extracts of A. annua shows potent antioxidative activities by regulating EF-Tu, IgE and VDAC-1.     

The component of green tea,L-theanine protects human hepatic L02 cells from hydrogen peroxide-induced apoptosis

L-theanine is a natural amino acid in green tea and it has been well known for its activities of relieving depression and neuroprotection. However, cytoprotective effect and its mechanism of L-theanine on hepatocytes have not been reported. The objective of this work was to investigate the hepatoprotective effect of L-theanine as well as its mechanism by using the human hepatic L02 cells injured by hydrogen peroxide (H₂O₂). Results showed that L-theanine dose dependently decreased H₂O₂-induced cell viability loss and lactate dehydrogenase (LDH) release. L-theanine pretreatment improved nuclear morphology of the cells injured by H₂O₂. By using flow cytometric analysis, we found that L-theanine significantly inhibited H₂O₂-induced cell apoptosis. Further, L-theanine attenuated H₂O₂-induced reduction in pro-caspase3 and cleavage of poly (adenosine diphosphate-ribose) polymerase (PARP). H₂O₂-activated p38 mitogen-activated protein kinase (MAPK) was also inhibited by L-theanine. These data suggest that L-theanine could protect L02 cells against H₂O₂-induced apoptosis via suppression of p38 MAPK. L-theanine might potentially be useful in the prevention and treatment of liver diseases.     

Oryzadine,a new alkaloid of Oryza sativa cv. Heugjinjubyeo, attenuates oxidative stress-induced cell damage via a radical scavenging effect

The antioxidant properties of oryzadine, a new alkaloid, obtained from Oryza sativa cv. Heugjinjubyeo was investigated by applying various methods based on cell-free and cell experiments. Oryzadine showed scavenging effects on the hydroxyl radical, superoxide radical, and intracellular reactive oxygen species (ROS). Oryzadine inhibited H₂O₂-induced DNA damage, which was demonstrated by DNA tail formation, lipid peroxidation which was demonstrated by the formation of thiobarbituric acid reactive substance (TBARS), and protein oxidation which was demonstrated by protein carbonyl formation. Therefore, oryzadine protected H₂O₂-induced cell damage. Our results show that the cytoprotective effects of oryzadine stem from its ability to inhibit H₂O₂-induced apoptosis, as demonstrated by a decrease in apoptotic body formation and the inhibition of mitochondrial membrane potential (ΔΨ) loss. Taken together, these findings suggest that oryzadine protected cells against H₂O₂-induced cell damage via ROS scavenging effect. Therefore, oryzadine could be considered a significant natural source of antioxidant.     

Protective effects of the crude extracts from yam (Dioscorea alata) peel on tert-butylhydroperoxide-induced oxidative stress in mouse liver cells

Researchers have shown that yam extracts contain antioxidative activity; however, there are few reports regarding the antioxidant activities of yam peel. The effects of water and 50% ethanolic extracts from Darsan yam (Dioscorea alata) peel on the oxidative status of tert-butylhydroperoxide (t-BHP)-treated mouse Hepa 1–6 and FL83B liver cell lines were investigated. The cytosols were analysed for H₂O₂ and malondialdehyde (MDA) levels and antioxidative enzymes activities, including superoxide dismutase, glutathione peroxidase (GPx) and catalase activities. Both water and 50% ethanolic extracts from yam peel did not affect cellular MDA level in t-BHP-treated cells, but they altered the level of H₂O₂. Water extract from yam peel amplified the t-BHP-induced cytotoxicity in Hepa 1–6 whilst the ethanolic extract showed protection in FL83B cells. GPx activity might play an important role in the protective effect associated with t-BHP-induced oxidative stress.     

s‐Ethyl Cysteine and s‐Methyl Cysteine Protect Human Bronchial Epithelial Cells Against Hydrogen Peroxide Induced Injury

Protective effects and actions from s‐ethyl cysteine (SEC) and s‐methyl cysteine (SMC) for BEAS‐2B cells were examined. BEAS‐2B cells were pretreated with SEC or SMC at 4, 8, or 16 μmol/L, and followed by hydrogen peroxide (H₂O₂) treatment. Data showed that H₂O₂ enhanced Bax, caspase‐3 and caspase‐8 expression, and declined Bcl‐2 expression. However, SEC or SMC dose‐dependently decreased caspase‐3 expression and reserved Bcl‐2 expression. H₂O₂ increased reactive oxygen species (ROS) production, and lowered glutathione level, glutathione peroxide, and glutathione reductase activities in BEAS‐2B cells. SEC or SMC pretreatments reduced ROS generation, and maintained glutathione redox cycle in those cells. H₂O₂ upregulated the expression of both p47^phox and gp91^phox. SEC and SMC downregulated p47^phox expression. SEC or SMC at 8 and 16 μmol/L decreased H₂O₂‐induced release of inflammatory cytokines. H₂O₂ stimulated the activation of nuclear factor‐κB (NF‐κB) and mitogen‐activated protein kinase. SEC and SMC pretreatments dose‐dependently downregulated NF‐κB p65 and p‐p38 expression. Pyrrolidine dithiocarbamate or SB203580 inhibited NF‐κB activation and p38 phosphorylation; thus, SEC or SMC pretreatments failed to affect protein expression of these factors. These novel findings suggest that SEC or SMC could protect bronchial cells and benefit respiratory epithelia stability and functions.     

Apple extracts attenuate tumor necrosis factor-α-induced nuclear factor-κB activation by inhibiting IκB kinase and proteasome in A549 human non-small lung carcinoma cells

Apples contain a variety of phytochemicals and health benefits of apple consumption are widely recognized in reducing the risks of chronic diseases such as cancer. However, the mechanisms of apples in inhibiting lung cancer cell proliferation are not fully understood. The present study examined the role of apple extracts in suppressing nuclear factor (NF)-κB activation in A549 human lung cancer cells. Incubation with apple extracts at doses of 10 and 20 mg(fresh apple)/mL significantly inhibited tumor necrosis factor (TNF)-α-induced NF-κB activation in A549 cells (p<0.05). Apple extracts suppressed phosphorylation of inhibitor of NF-κB (IκB-α) at doses of 10 and 20 mg (fresh apple)/mL and inhibited proteasomal activity at doses of 5, 10, and 20 mg(fresh apple)/mL (p<0.05). These results indicate that apple extracts inhibit TNF-α-induced NF-κB activation in A549 lung cancer cells by suppressing both of IκB kinase (IKK) activity and proteasomal activity.     

Antioxidant activity of Mammea longifolia bud extracts

Mammea longifolia buds (nagkesar) are extensively used in India as a minor spice. The antioxidant activity of its methanol (NM) and aqueous-ethanol (NW) extracts were evaluated by several in vitro experiments, e.g., DPPH, hydroxyl, superoxide radicals and H₂O₂-scavenging assays as well as inhibition of Fe(II)-induced lipid peroxidation of rat liver mitochondria. The extracts were found to possess impressive antioxidant activity in all the tests, the activity of NW being higher than that of NM in most of the assays. The differential activities of NW and NM could be correlated with their respective total phenolic, flavonoid and proanthocyanidin contents.     

Antioxidant activity of Nyctanthes arbor-tristis leaf extract

Nyctanthes arbor-tristis (Harsingar) leaf extracts are extensively used in Indian traditional medicine. The acetone-soluble fraction of its ethyl acetate extract showed impressive antioxidant activity as revealed by several in vitro experiments, e.g., DPPH, hydroxyl and superoxide radicals, as well as H₂O₂ scavenging assays. Moreover, its preventive capacity against Fe(II)-induced lipid peroxidation of liposomes and γ-ray-induced DNA damage also confirmed this. The strong reducing power and high phenolics and flavonoids contents could be responsible for the antioxidant activity.     

Antioxidant properties of 1,2,3,4,6-penta-O-galloyl-β-d-glucose from Elaeocarpus sylvestris var. ellipticus

The antioxidant potential of 1,2,3,4,6-penta-O-galloyl-β-d-glucose (PGG), isolated from Elaeocarpus sylvestris var. ellipticus, was investigated by various established systems based on cell-free and cell system experiments, such as radical detection, antioxidant enzyme assay, lipid peroxidation detection, and cell viability assay. PGG was found to quench the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical and intracellular reactive oxygen species. PGG recovered the cellular antioxidant enzyme activities of superoxide dismutase, catalase, and glutathione peroxidase, which were reduced by H₂O₂ treatment, thereby resulting in the inhibition of lipid peroxidation. Cytoprotective effects of PGG were based on the results of DNA fragmentation, mitochondrial membrane potential (Δψ), apoptotic body formation, and caspase-3 activity. The results suggest that PGG protects cells against H₂O₂-induced cell damage via antioxidant properties.     

Analysis of phenolic compounds and antioxidant activity with H4IIE cells of three different rice grain varieties

The phenolic content and the antioxidant capacity of ethanolic extract of rice grains were examined using three different rice (Oryza sativa L. var. japonica) varieties, Jakwangchalbyeo (red pericarp glutinous rice), Hwasunchalbyeo (white pericarp glutinous rice), and Ilpumbyeo (white pericarp non-glutinous rice). Quantitative high performance liquid chromatography (HPLC) analyses showed that Jakwangchalbyeo contains the highest amount of total phenolic substances. Radical scavenging activities measured by the 1,1-diphenyl-2-picryl hydrazyl (DPPH) assay were 87.5% (Jakwangchalbyeo), 45.0% (Hwasunchalbyeo), and 50.0% (Ilpumbyeo). The results suggest a positive correlation between the phenolic content and the antioxidation capacity. Antioxidant activity in the ethanolic extract of rice grain was further assessed with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) cell viability assay and fluorescence-activated cell sorting (FACS) analysis of H4IIE cells treated with hydrogen peroxide (H₂O₂). Hwasunchalbyeo and Ilpumbyeo extracts showed no significant effects on H₂O₂-induced oxidative stress. Jakwangchalbyeo extract increased cell viability by up to 82% and 74% after 5- and 24-h treatments at 100 μg/mL, respectively. Consistent with the results of DPPH and MTT assays, dichlorofluorescein (DCF) fluorescence was further reduced when H₂O₂ was applied with Jakwangchalbyeo extract. In conclusion, red pericarp Jakwangchalbyeo grain extracts exerted significantly higher inhibitory effects on H₂O₂-induced oxidative stress in H4IIE cells than did other white pericarp rice grain extracts.     

Antioxidant activity and antiproliferative action of methanol extracts of 4 different colored bell peppers (Capsicum annuum l.)

Methanol extracts of 4 different colored (red, orange, yellow, and green) bell peppers (Capsicum annuum L.) were examined to (1) determine the total phenolic content (TPC), (2) compare the antioxidant activities, (3) assess the protective effects of extracts on H₂O₂-induced and 4-hydroxy-2-nonenal (HNE)-induced DNA damage using the Comet assay, and (4) examine the antiproliferative action of their extracts on HT-29 cells. Red and orange bell peppers had significantly higher levels of TPC than yellow or green bell peppers. Orange bell pepper exhibited the highest level of radical scavenging activity and total antioxidant activity, while green bell pepper exhibited the highest superoxide dismutase-like activity. These results suggest that the difference in antioxidant activities may depend on the kinds of antioxidant compounds related to the color of the pepper. It was found a significant negative correlation between TPC and radical scavenging activity inhibiting capacity (IC)₅₀, and a significant positive corretation between TPC and total antioxidant activity. All extracts of bell pepper inhibited H₂O₂-induced and 4-hydroxy-2-nonenal-induced DNA damage in human leukocytes and showed potential toxicity on HT-29 cells. These findings suggest that the 4 different colored bell peppers may be useful as antioxidants and cancer prevention in food.