Peroxynitrite Scavenging Activity Research Articles

Revisit the E2 Domain of Amyloid Precursor Protein: Ferroxidase, Superoxide and Peroxynitrite Scavenging Activities.

Amyloid precursor protein (APP) is the biological precursor of β-amyloids, a known histopathological hallmark associated with Alzheimer's disease (AD). The function of APP is of great interest yet remains elusive. One of the extracellular domains of APP, the E2 domain, has been proposed to possess ferroxidase activity and affect neuronal iron homeostasis. However, contradicting evidence has been reported, and its precise role remains inconclusive. Here, we studied the Cu-binding site of the E2 domain using extended X-ray absorption fine structure (EXAFS), UV-vis, and electron paramagnetic resonance (EPR) and discovered that a new labile water ligand coordinates to the Cu(II) cofactor in addition to the four known histidines. We explored the proposed ferroxidase activity of the Cu(II)-E2 domain through reactions with ferrous iron and observed single-turnover ferrous oxidation activity with a rate up to 1.0 × 102 M-1 s-1. Cu(I)-E2 reacted with molecular oxygen at a rate of only 5.3 M-1 s-1, which would restrict any potential multiturnover ferroxidase activity to this slow rate and prevents observation of activity under multiturnover conditions. The positive electrostatic potential surface of the protein indicates possible reactivity with negatively charged small substrates such as superoxide radicals (O2•-) and peroxynitrite (ONOO-) that are major contributors to the oxidative stress prevalent in the extracellular environment. Our assays showed that Cu(I)-E2 can remove O2•- at a rate of 1.6 × 105 M-1 s-1, which is slower than the rates of native SODs. However, the reaction between Cu(I)-E2 and ONOO- achieved a rate of 1.1 × 105 M-1 s-1, comparable to native ONOO- scavenger peroxiredoxins (105-107 M-1 s-1). Therefore, the E2 domain of APP can serve as an enzymatic site that may function as a ferroxidase under substrate-limiting conditions, a supplemental O2•- scavenger, and an ONOO- remover in the vicinity of the cellular iron efflux channel and protect neuron cells from reactive oxygen species (ROS) and reactive nitrogen species (RNS) damage.

Generation of novel antioxidant peptides from silver carp muscle hydrolysate: Gastrointestinal digestion stability and transepithelial absorption property

Oxidative stress is a major cause of cardiovascular diseases (CVDs). Antioxidant peptides have potential to improve CVDs. The aim of this study was to develop novel antioxidant peptides from silver carp muscle hydrolysates (SCHs) and investigate their gastrointestinal digestion (GID) stability, and bioavailability. Results showed that SCHs generated by Alcalase and Papain exhibited the highest free radical scavenging activity, peroxynitrite scavenging activity and low density lipoprotein (LDL) oxidation inhibitory capacity. All these antioxidant activities were enhanced in different SCHs after GID. Notably, the GID products of Papain-SCH and Alcalase-SCH possessed potent ameliorating effects on oxidative stress injury in endothelial cells. After transepithelial transport, total of nine peptides was identified from permeates of GID products of Papain-SCH and Alcalase-SCH. The VKVGNEF and MEAPPH were both novel peptides in the current study that possess the highest activities in scavenging free radicals, inhibiting LDL oxidation and alleviating oxidative stress injury in endothelial cells.

Peroxynitrite-Promoted Persulfide Prodrugs with Protective Potential against Paracetamol Poisoning.

The newly emerging persulfide prodrugs provide additional options for the profound study of persulfide, a fascinating molecule expected to intervene in biological functions and even diseases. Peroxynitrite is often the culprit in pathological processes characterized by oxidative stress, while the persulfide prodrug responsive to it is still pending. To enrich the family of redox-activated prodrugs, we designed prodrugs with a 2-oxo-2-phenylacetamide trigger, which achieved the release of persulfide via 1, 6-N, S-relay. The degradation of prodrugs and the formation of persulfides were confirmed to be peroxynitrite-responsible by the qualitative and quantitative studies based on LC-MS/MS methods and a spectrophotometry-based tag-switch strategy. Furthermore, these prodrugs showed potent peroxynitrite scavenging activity, cellular therapeutic potential against paracetamol poisoning in HepG2 and oxidative stress in H9c2, as well as desirable in vitro metabolic properties.

Angong Niuhuang Wan reduces hemorrhagic transformation and mortality in ischemic stroke rats with delayed thrombolysis: involvement of peroxynitrite-mediated MMP-9 activation

BackgroundHemorrhagic transformation (HT) is a common complication of delayed tissue plasminogen activator (t-PA) treatment for ischemic stroke. Peroxynitrite plays an important role in the breakdown of blood–brain barrier (BBB) and the development of HT. We tested the hypothesis that Angong Niuhuang Wan (AGNHW), a traditional Chinese medicinal formula, could be used in conjunction with t-PA to protect the BBB, minimize HT, and improve neurological function by suppressing peroxynitrite-mediated matrix metalloproteinase-9 (MMP-9) activation.MethodsWe first performed quality control study and chemical identification of AGNHW by using UPLC. In animal experiments, male Sprague–Dawley rats were subjected to 5 h of middle cerebral artery occlusion (MCAO) followed by 19 h of reperfusion plus t-PA infusion (10 mg/kg) at 5 h of cerebral ischemia. AGNHW (257 mg/kg) was given orally at 2 h after MCAO. Hemorrhagic transformation was measured using hemorrhagic scores and hemoglobin levels in ischemic brains. Evans blue leakage was utilized to assess the severity of the blood–brain barrier (BBB) damage. The modified neurologic severity score (mNSS) test was used to assess neurological functions. Peroxynitrite and superoxide was detected by using fluorescent probes. MMP-9 activity and expression were examined by gelatin zymography and immunostaining. The antioxidant effects were also studied by using brain microvascular endothelial b.End3 cells exposed to 5 h of oxygen and glucose deprivation (OGD) plus 5 h of reoxygenation with t-PA treatment (20 µg/ml).ResultsAGNHW significantly reduced the BBB damage, brain edema, reduced hemorrhagic transformation, enhanced neurological function, and reduced mortality rate in the ischemic stroke rats with t-PA treatment. AGNHW reduced peroxynitrite and superoxide in vivo and in vitro and six active chemical compounds were identified from AGNHW with peroxynitrite scavenging activity. Furthermore, AGNHW inhibited MMP-9 activity, and preserved tight junction protein claudin-5 and collagen IV in the ischemic brains.ConclusionAGNHW could be a potential adjuvant therapy with t-PA to protect the BBB integrity, reduce HT, and improve therapeutic outcome in ischemic stroke treatment via inhibiting peroxynitrite-mediated MMP-9 activation.Graphical

토마토 추출물의 라디칼 소거 및 항염증 활성

This study compares the antioxidant and anti-inflammatory capacities of acetone extracts obtained from commercially available tomatoes (gangwon chal, wansuk, cherry, daechu cherry, plum, and campari). Campari and cherry tomatoes had the highest levels of 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical, 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS) radical, and hydroxyl radical scavenging activities, as well as cupric reducing antioxidant capacity (CUPRAC), followed sequentially by gangwon chal, daechu cherry, plum and wansuk varieties. Highest peroxynitrite scavenging activity, oxygen radical absorbance capacity (ORAC), and total phenolic contents were obtained in campari tomatoes, followed by cherry, gangwon chal, daechu cherry, plum and wansuk varieties. Lycopene contents were highest in cherry tomato, followed by daechu cherry and campari, and were lowest in the gangwon chal, plum and wansuk varieties. Maximum inhibition of the lipopolysaccharide-induced nitric oxide production in RAW 264.7 cells was observed in campari tomatoes, followed by cherry, daechu cherry, gangwon chal, plum and wansuk varieties. Antioxidant activities, including hydroxyl radical and peroxynitrite scavenging, ORAC, and CUPRAC, showed a high correlation with the total phenolic or lycopene contents. Anti-inflammatory capacity was highly correlated with antioxidant activities, total phenolic, and lycopene contents. Taken together, findings of the current study demonstrate that campari and cherry tomatoes have the most potent antioxidant and anti-inflammatory effects, which are closely related to the lycopene as well as polyphenolic contents.

Ballodiolic Acid A and B: Two New ROS, (•OH), (ONOO-) Scavenging and Potent Antimicrobial Constituents Isolated from Ballota pseudodictamnus (L.) Benth.

Bioassays guided phytochemical investigations on the ethyl acetate-soluble fraction of the root material of Ballota pseudodictamnus (L.) Benth. led to the isolation of two new compounds, ballodiolic acid A (1) and ballodiolic acid B (2), along with three known compounds ballodiolic acid (3), ballotenic acid (4), and β-amyrin (5), which were also isolated for the first time from this species by using multiple chromatographic techniques. The structures of the compounds (1–5) were determined by modern spectroscopic analysis including 1D and 2D NMR techniques and chemical studies. In three separate experiments, the isolated compounds (1–5) demonstrated potent antioxidant scavenging activity, with IC50 values ranging from 07.22–34.10 μM in the hydroxyl radical (•OH) inhibitory activity test, 58.10–148.55 μM in the total ROS (reactive oxygen species) inhibitory activity test, and 6.23–69.01 μM in the peroxynitrite (ONOO−) scavenging activity test. With IC50 values of (07.22 ± 0.03, 58.10 ± 0.07, 6.23 ± 0.04 μM) for •OH, total ROS, and scavenge ONOO−, respectively, ballodiolic acid B (2) showed the highest scavenging ability. Antibacterial and antifungal behaviors were also exposed to the pure compounds 1–5. In contrast to compounds 4 and 5, compounds 1–3 were active against all bacterial strains studied, with a good zone of inhibition proving these as a potent antibacterial agent. Similarly, compared to compounds 3–5, compounds 1 and 2 with a 47 percent and 45 percent respective inhibition zone were found to be more active against tested fungal strains.

Entacapone scavenges peroxynitrite and protects against kidney and liver injuries induced by renal ischemia/reperfusion in rats.

Acute kidney injury (AKI), secondary to renal ischemia/reperfusion (I/R), is a serious problem associated with high mortality. The pathophysiology of AKI after renal I/R involves peroxynitrite production; hence, scavenging this metabolite may rescue AKI. Entacapone is a catechol-O-methyl transferase (COMT) inhibitor which elicits antioxidant activity by scavenging peroxynitrite. Therefore, we hypothesized that the peroxynitrite scavenging activity of entacopone protects against AKI after renal I/R injury in rats. Male Wistar rats were given either entacapone or a well-known peroxynitrite scavenger (FeTPPS) daily for 10days before I/R procedures. I/R was induced by occluding both renal pedicles for 45min followed by reperfusion for 24h. Pre-treatment with either entacapone or FeTPPS improved renal function as indicated by a significant reduction in serum creatinine and urea when compared to I/R group (P < 0.05). I/R injury increased renal levels of NO (4-folds, P < 0.05), iNOS (4-folds, P < 0.05), and 3-nitrotyrosine (5-folds, P < 0.05) compared to sham control. These effects were abrogated in animals pre-treated with entacapone or FeTPPS before being subjected to I/R (P < 0.05). In addition, entacapone or FeTPPS significantly inhibited I/R-induced elevation in renal TNF-α levels (78% and 58%, respectively) and caspase-3 activity (72% and 56%, respectively) indicating the reduction of both inflammation and apoptosis in the kidney (P < 0.05). The two drugs also improved kidney and liver functions in rats with renal I/R injury. Our study showed that entacapone and FeTPPS protected against AKI and remote liver damage associated with renal I/R and this effect might be due to scavenging peroxynitrite and reducing nitrosative stress.

2,4-Dihydroxyphenyl-benzo[d]thiazole (MHY553), a synthetic PPARα agonist, decreases age-associated inflammatory responses through PPARα activation and RS scavenging in the skin.

We previously reported that 2,4-dihydroxyphenyl-benzo[d]thiazole (MHY553) is a PPARα agonist, which has been shown to inhibit tyrosinase activity in murine melanocyte and alleviate hepatic steatosis in aged rats. This study investigated the effects of MHY553 on the age-related occurrence of inflammatory responses via the molecular modulation of the nuclear factor-κB (NF-κB) signaling pathway in the skin of aged rats and skin fibroblast cells. Moreover, we investigated the antioxidant effect of MHY553 via in vitro assays of reactive oxygen species (ROS) and peroxynitrite (ONOO-) scavenging activities. We also scrutinized the ability of MHY553 as a PPARα activator in aged rat skin and H2O2-induced Hs27 fibroblast cells. In vivo experiments were performed in young, aged, and MHY553-fed aged rats (3mg or 5mg∙kg -1∙day -1 for 4weeks). MHY553 dose-dependently scavenged ROS and ONOO-. Furthermore, we found that MHY553 suppressed the NF-κB transcription factor and downregulated mitogen-activated protein kinase (MAPK)/activator protein-1 (AP-1) signaling. MHY553 also inhibited the expression of pro-inflammatory cytokines including COX-2, iNOS, IL-1β, and IL-6. Our findings indicate the MHY553 scavenges ROS/reactive nitrogen species and inhibits inflammatory cytokines through PPARα activation in the skin. Thus, these results suggest that MHY553 may be of therapeutic interest for protecting skin from oxidative stress-induced damage and intrinsic aging.

콩 추출물의 라디칼 소거 및 항염증 활성

This study compared the antioxidant and anti-inflammatory capacities of acetone extracts from commercially available soybeans with reddish (Gangnang-kong, Ultari-kong, and Lentils), black (Heuk-tae, Seori-tae, and Seomok-tae), and yellow (Baek-tae and Chickpea) seed coats. Reddish soybeans had the highest 2,2- diphenyl-1-picrylhydrazyl (DPPH) radical-, superoxide-, and peroxynitrite-scavenging activities as well as the highest cupric reducing antioxidant capacities, followed by black soybeans; yellow soybeans showed the lowest value. The oxygen radical absorbance capacities and total phenolic contents of reddish and black soybeans were similar and higher than those of yellow soybeans were. Supercoiled DNA strand breakage induced by the hydroxyl radical was inhibited more by reddish soybeans compared to black or yellow soybeans. Lipopolysaccharide-induced NO production in RAW 264.7 cells was inhibited more by reddish or black soybeans than yellow soybeans. The antioxidant activities, including DPPH radical scavenging, superoxide scavenging, and cupric reducing antioxidant capacity, were strongly correlated with the total phenolic and total flavonoid contents. The anti-inflammatory capacity was strongly correlated with the total flavonoid content. Therefore, these findings show that reddish or black soybeans had more potent antioxidant and anti-inflammatory effects than yellow soybeans, possibly due to their high phenolic contents.

Root Bark of Paeonia suffruticosa Extract and Its Component Methyl Gallate Possess Peroxynitrite Scavenging Activity and Anti-inflammatory Properties through NF-κB Inhibition in LPS-treated Mice.

A peroxynitrite (ONOO−)-generating system induced by 3-morpholinosydnonimine, was used to evaluate the ONOO− scavenging properties of plants that have been widely used as traditional medicine in Korea for the treatment of several diseases. The most effective medicinal plants were Paeonia suffruticosa Andrew, followed in order by Lonicera japonica Thunb., Curcuma zedoaria (Christm.) Roscoe, and Pueraria thunbergiana Benth. In addition, root bark of P. suffruticosa was partitioned with organic solvents of different polarities, and the ethyl acetate (EtOAc) fraction showed the strongest ONOO− scavenging activity. Methyl gallate, a plant-derived phenolic compound identified from the EtOAc fraction, exerted strong ONOO− scavenging activity. The in vivo therapeutic potential of methyl gallate was investigated using lipopolysaccharide-treated mice. Oral administration of methyl gallate protected against acute renal injury and exhibited potential anti-inflammatory properties through an increase in antioxidant activity and decrease in nuclear factor-kappa B activity.

Identification and quantification of flavonoids in Carica papaya leaf and peroxynitrite-scavenging activity

ObjectiveTo characterize the types, contents, and peroxynitrite-scavenging activities of flavonoids in the leaf of Carica papaya (C. papaya). MethodsChromatographic and spectroscopic techniques along with high performance liquid chromatography quantitative analysis and peroxynitrite-scavenging assay were performed to isolate and quantify flavonoid compounds in the flavonoid-rich fraction (BuOH fraction) derived from MeOH extract of C. papaya leaves and evaluate their peroxynitrite-scavenging activities. ResultsSeven flavonoids were isolated from the leaves of C. papaya, including quercetin 3-(2G-rhamnosylrutinoside), kaempferol 3-(2G-rhamnosylrutinoside), quercetin 3-rutinoside, myricetin 3-rhamnoside, kaempferol 3-rutinoside, quercetin, and kaempferol. All of the substances exhibited potent activities on peroxynitrite scavenging (IC50 ≤ 4.15 μmol/L), which were stronger than the positive control, l-penicillamine (6.90 μmol/L). The content of kaempferol 3-(2G-rhamnosylrutinoside) was significantly higher than other identified compounds (123.18 mg/g BuOH fraction and 7.23 mg/g MeOH extract). ConclusionsThe results of the present study demonstrate the potent antioxidant flavonoids of C. papaya leaf, with kaempferol 3-(2G-rhamnosylrutinoside) as the major one.

BACE1 molecular docking and anti-Alzheimer's disease activities of ginsenosides

Ethnopharmacological relevanceGinsenosides are natural product steroid glycosides and triterpene saponins obtained from the Panax species. Panax ginseng has been widely used as a traditional Chinese medicine (TCM) for around a thousand years, especially in East Asian countries. Ginseng, the root and rhizome of the most popular species P. ginseng, used as tonic, prophylactic agent and restorative. In TCM, ginseng is highly valued herb and has been applied to a variety of pathological conditions and illnesses such as hypodynamia, anorexia, shortness of breath, palpitation, insomnia, impotence, hemorrhage and diabetes. Aim of the studyThe basic aim of this study was to evaluate the anti-Alzheimer's disease activities of selected ginsenosides (Rb1, Rb2, Rc, Re, Rg1, and Rg3) according to peroxynitrite (ONOO‒) scavenging activity and inhibitory activity of ONOO−-mediated nitrotyrosine formation as a measure of changes in oxidative stress. In addition, molecular docking simulation studies were performed to predict binding energies of the ginsenosides with β-site amyloid precursor protein cleaving enzyme 1 (BACE1, β-secretase) and identify the interacting residues. Materials and methodsIn vitro cholinesterase enzyme assays by using acetylcholinesterase (AChE), butyrylcholinesterase (BChE), and BACE1 were performed. In vitro authentic peroxynitrite scavenging activity and inhibitory activity against ONOO−-mediated nitrotyrosine formation were also performed. Molecular docking simulation studies were performed with Autodock Vina software and Discovery studio 4.1. ResultsIn vitro enzyme assays demonstrated that ginsenosides have significant inhibitory potential against AChE, BChE, and BACE1, as well as ONOO− and nitrotyrosine formation. Most importantly, significant AChE inhibitory activities were observed for Re; BChE for Rg3; and BACE1 for Rc, with IC50 values of 29.86±3.20, 16.80±0.36, and 59.81±2.74μg/mL, respectively. Among the tested ginsenosides, Rb1 exhibited a higher scavenging activity against ONOO− with an IC50 value of 27.86±1.34μg/mL, while Rc and Rg3 exhibited impressive inhibitory activity against the formation of nitrotyrosine. In addition, molecular docking studies revealed potential BACE1 inhibitory activity of ginsenosides, especially Rb1 and Rb2, which exhibited good binding affinities towards BACE1, with docking scores of −10kcal/mol. ConclusionThe findings of the present study suggest the potential of ginsenosides (Rb1, Rb2, Rc, Re, Rg1, and Rg3) for use in the development of therapeutic or preventive agents for Alzheimer's disease, especially through inhibition of AChE, BChE and BACE1 activities, as well as scavenging of ONOO− and inhibition of nitrotyrosine formation.

Serum uric acid levels in patients with myasthenia gravis are inversely correlated with disability.

Uric acid (UA), the final product of purine metabolism, has been reported to be reduced in patients with various neurological disorders and is considered to be a possible indicator for monitoring the disability and progression of multiple sclerosis. However, it remains unclear whether there is a close relationship between UA and myasthenia gravis (MG), or whether UA is primarily deficient or secondarily reduced because of its peroxynitrite scavenging activity. We investigated the correlation between serum UA levels and the clinical characteristics of MG. We assessed 338 serum UA levels obtained in 135 patients with MG, 47 patients with multiple sclerosis, and 156 healthy controls. In addition, we compared serum UA levels when MG patients were stratified according to disease activity and classifications performed by the Myasthenia Gravis Foundation of America, age of onset, duration, and thymus histology (by means of MRI or computed tomography). MG patients had significantly lower serum UA levels than the controls (P<0.001). Moreover, UA levels in patients with MG were inversely correlated with disease activity and disease progression (P=0.013). However, UA levels did not correlate significantly with disease duration, age of onset, and thymus histology. Our findings suggest that serum level of UA was reduced in patients with MG and serum UA might be considered a surrogate biomarker of MG disability and progression.

HPLC analysis of Phenolic Substances and Anti-Alzheimer's Activity of KoreanQuercusSpecies

This study aimed to establish the quantitative method to analyze the content of peroxynitrite-scavengers belonging to polyphenols in six Korean Quercus species (Quercus mongolica, Q. dentata, Q. acutissima, Q. alienta, Q. serrata, and Q. variabilis) by HPLC. The twelve peroxynitrite-scavengers, flavanols (catechins: (+)-catechin, (−)-epicatechin, and (−)-epigallocatechin), flavonols (kaempferol and quercetin), flavonol glycosides (astragalin, quercitrin, and isoquercitrin), flavonol acylated glycosides (astragalin 6''-gallate and isoquercitrin 6''-gallate), gallic acid and its dimer (ellagic acid) were analyzed by HPLC. Further, anti-Alzheimer's activity was assayed in a passive avoidance testusing mice by measuring the retention latency (sec), the concentration of acetylcholine (ACh), and acetylcholinesterase (AChE) activity. Simultaneous analysis of the extracts of the six Quercus leaves was achieved on a Capcell C18 column (5 µm, 250 mm × 4.6 mm i.d.) with a gradient elution of 0.05% HAc and 0.05% HAc in CH3CN. In the extract of Q. mongolica leaves, the content of gallic acid (32.53 mg/g), (+)-catechin (28.78 mg/g), (−)-epicatehin (22.03 mg/g), astragalin 6''-gallate (20.94 mg/g), and isoquercitrin 6''-gallate (44.11 mg/g) and peroxynitrite-scavenging activity (IC50, 0.831 µg/ml) were high. This extract delayed the retention latency and inhibited acetylcholinesterase activity in scopolamine-induced memory impairment of mice, suggesting that it has anti-Alzheimer's activity.

Effects of methanolic extracts from edible plants on endogenous secretory receptor for advanced glycation end products induced by the high glucose incubation in human endothelial cells

Background:In diabetic populations, endogenous secretory receptor for advanced glycation end products (esRAGE) levels may be related to the degree of diabetic complications or to the protection from diabetic complications.Objective:We investigated the impact of 29 methanolic extracts from edible plants on esRAGE production in human umbilical vein endothelial cells (HUVECs) cultured in high (4.5 g/L) glucose.Materials and Methods:Edible plants were minced, and extracts were obtained with methanol overnight. The methanolic extracts from 29 edible plants were evaporated in a vacuum. For screening study purposes, HUVECs were seeded in culture dishes (1.5 × 105 cells). Then, HUVECs were incubated with 1 g/L or 4.5 g/L of glucose in SFM CS-C medium treated with methanolic extracts from edible plants (MEEP) for 96 h. Determination of esRAGE production in the cell culture-derived supernatants was performed by colorimetric ELISA. The 8-hydroxydeoxyguanosine (8-OHdG) level was determined by using the 8-OHdG Check ELISA kit. Peroxynitrite-dependent oxidation of 2’, 7’-dichlorodihydrofluorescein to 2’, 7’-dichlorofluorescein was estimated based on the method described by Crow. Because MEEP were methanolic extracts, we measured their total phenolic content (TPC). TPC was measured with a modified version of the Folin–Ciocalteu method.Results:The results showed eight extracts increased esRAGE production. The extract from white radish sprouts showed the highest esRAGE production activity, and then eggplant, carrot peel, young sweet corn, Jew's marrow, broad bean, Japanese radish and cauliflower. In order to understand the mechanism of esRAGE production, the eight extracts were examined for DNA damage, peroxynitrite scavenging activity, and TPC in correlation with their esRAGE production. The results showed esRAGE production correlates with the peroxynitrite level and TPC.Conclusion:This study supports the utilization of these eight extracts in folk medicine for improved treatment of diabetic complications.

Antioxidant Properties of Tripeptides Revealed by a Comparison of Six Different Assays

Free radical scavenging activities of two series of tripeptide libraries were investigated using ABTS, DPPH, and ORAC assays. Two Tyr-containing tripeptides showed higher scavenging activities against the hydrophilic ABTS and AAPH radicals than two His-containing tripeptides, showing that Tyr residues play important roles in free radical scavenging activity. Higher concentrations of tripeptides were required to reveal apparent DPPH radical scavenging activity. The antioxidant activities of the tripeptide libraries obtained from this study were compared with previous results obtained using several assays, including antioxidant activity against the peroxidation of linoleic acid, FRAP assay, and peroxynitrite (PN) scavenging activity. The antioxidant activity of the tripeptides against the peroxidation of linoleic acid showed high correlations with the ABTS and ORAC assays (correlation coefficients (R) = 0.725 and 0.731, respectively), and low correlations with FRAP, PN scavenging, and DPPH assays. The highest correlation was found between the ABTS and ORAC assays (R = 0.905).

Simultaneous quantification and validation of new peroxynitrite scavengers from Artemisia iwayomogi

Context: Artemisia iwayomogi Kitamura (Compositae) has been very widely used for the treatment of acute or chronic hepatitis, jaundice, and gastritis. In the course of our continuing efforts to identify and quantify peroxynitrite scavengers from Compositae plants, A. iwayomogi was used in this study.Objective: The present study was aimed to identify and quantify the peroxynitrite scavengers of A. iwayomogi.Materials and methods: Silica gel and ODS were used for column chromatography. The isolated compounds were quantified using an HPLC equipped with a Capcell Pak C18 column (5 μm, 250 mm × 4.6 mm i.d.), and the method was validated for the quality control. Peroxynitrite (ONOO−)-scavenging activities of the compounds and extracts were evaluated on the measurement of highly fluorescent rhodamine 123 converted from non-fluorescent dihydrorhodamine (DHR)-123 under the presence of peroxynitrite.Results: Based on the spectroscopic evidences, a new compound, 2″-O-caffeoylrutin (2″-O-trans-caffeic acid ester of quercetin 3-O-α-l-rhamnopyranosyl(1 → 6)-β-d-glucopyranoside) was isolated and determined together with patuletin 3-O-glucoside, scopolin, scopoletin, rutin, 3,4-dicaffeoylquinic acid, and chlorogenic acid. All of them were potent peroxynitrite scavengers (IC50 ≤ 1.88 μg/mL).Discussion and conclusion: The peroxynitrite scavengers were mainly distributed in the EtOAc fraction rather than the ether and BuOH fractions. The 70% MeOH extract exhibited a high peroxynitrite-scavenging activity. Through the validation, the present HPLC method was verified to be sufficiently sensitive, accurate, precise, and stable. Therefore, this method can be used for the quality control of A. iwayomogi.

Characteristics and in vitro Anti-diabetic Properties of the Korean Rice Wine, Makgeolli Fermented with Laminaria japonica.

New in vitro anti-diabetes makgeolli was produced from rice by adding various quantities of Laminaria japonica, and the fermentation characteristics of the L. japonica makgeolli during the fermentation process were investigated. The contents of alcohol and reducing sugar, and viable count of yeast, of L. japonica makgeolli were not significantly changed when the proportion of L. japonica was increased. The total acid content decreased with an increase in L. japonica concentration; the pH and total bacterial cell count increased in proportion with the increase in L. japonica concentration. The L. japonica makgeolli contents of free sugars, such as fructose, glucose, and sucrose, and of organic acids, such as acetic acid, citric acid, succinic acid, and lactic acid, were altered during fermentation and showed various patterns. The effects of the quantity of L. japonica added on the acceptability and anti-diabetes activities of L. japonica makgeolli were also investigated. In a sensory evaluation, L. japonica makgeolli brewed by adding 2.5 or 5% L. japonica to the mash showed the best overall acceptability; the 12.5% L. japonica sample was least favored due to its seaweed flavor. L. japonica addition did not increase the peroxynitrite-scavenging activity of makgeolli. L. japonica makgeolli showed potent anti-diabetes activity, particularly that containing >7.5% L. japonica. Therefore, L. japonica makgeolli may represent a new functional makgeolli with anti-diabetes properties.

Striped, bioactive Ce-TiO2 materials with peroxynitrite-scavenging activity.

Controlling aligned fiber micro-architectures to simulate the extracellular matrix for inducing important biological functions is a key challenge with regard to successful tissue regeneration. Here we present a bottom-up microemulsion-mediated strategy to obtain highly bioactive and biocompatible, striped Ce-TiO2 nano-crystalline superstructures with ONOO- scavenging activity. The employment of a bulkier organic ceria precursor in the material synthesis has several concurrent effects: (I) influencing the interfacial microemulsion droplet elasticity to create an aligned distribution of prismatic anatase nanoparticles causing the final lined morphology, (II) stabilizing the anatase active phase in a fine dispersed state and improving its resistance to the thermal anatase-rutile conversion, (III) indirectly favoring the rapid formation on the material surface of a hydroxyapatite layer composed of sphere-like globules of 3-5 μm in diameter essential for bone-bonding, and finally (IV) accelerating the ONOO- degradation into less harmful species NO2 - and O2.

Functional hybrids of layered double hydroxides with hemin: synergistic effect for peroxynitrite-scavenging activity

The interaction between heme and LDHs results in a synergistic effect, which leads to an efficient ONOO−scavenging ability.