Psoriasis is a chronic inflammatory skin disease,which seriously affects the physical and mental health of patients.The progression of psoriasis is influenced by the excessive production of reactive oxygen species(ROS...Psoriasis is a chronic inflammatory skin disease,which seriously affects the physical and mental health of patients.The progression of psoriasis is influenced by the excessive production of reactive oxygen species(ROS)and inflammatory responses.In this paper,novel celastrol(Ce)-loaded metal-phenolic nanozymes(tannic acid-Fe^(3+))(TA-Fe)integrated microneedles(Ce@TA-Fe/MNs)were constructed to achieve the combined oxidative stress alleviation and anti-inflammatory therapy of psoriasis.Molecular dynamics simulations and structural characterization confirmed the successful fabrication of nanozymes.The Ce@TA-Fe/MNs system,characterized by its rapid dissolution kinetics and superior mechanical strength,enabled minimally invasive skin penetration for efficient nanozymes delivery.Nanozymes possessed superoxide dismutase and catalase mimetic enzyme activities,effectively eliminating excessive ROS in psoriatic skin lesions.Additionally,the release of Ce from Ce@TA-Fe provided strong antioxidant and anti-inflammatory effects.Based on these characteristics,Ce@TA-Fe/MNs could effectively alleviate the symptoms in psoriasis mice models.These findings demonstrated that the integration of Ce-equipped nanozymes within MNs holds great promise as a therapeutic strategy for the clinical management of psoriasis.展开更多
Infectious wound healing is complicated with and limited by infection and oxidative stress at the wound site.In recent years,various evidences suggest that nanozymes with multiple enzymatic activities have enabled the...Infectious wound healing is complicated with and limited by infection and oxidative stress at the wound site.In recent years,various evidences suggest that nanozymes with multiple enzymatic activities have enabled the development of novel strategies for infectious wound healing.In this study,epigallocatechin gallate loaded polydopamine(P@E)was developed to act as a potent reactive oxygen species(ROS)scavenger for scavenging ROS,alleviating inflammatory responses,and promoting infectious wound healing.Combining with near infrared(NIR)irradiation,P@E presented excellent antibacterial ability of Escherichia coli(E.coli,93.6%)and methicillin-resistant Staphylococcus aureus(MRSA,87.6%).Specifically,P@E+NIR exhibited the most potent antioxidant,anti-inflammatory and cell proliferation behaviors through downregulating intracellular ROS levels(81.9%and 94.3%for NIH3T3 and RAW264.7 respectively)and inducible nitric oxide synthase(iNOS)expression level(55.7%),and up-regulating the expression levels of arginase-1(Arg-1,71.4%),heat shock protein 70(HSP70,48.6%)and platelet endothelial cell adhesion molecule(CD31,35.3%)compared to control group.Meanwhile,it also efficiently induced M2 directional polarization of lipopolysaccharide induced murine macrophages to achieve anti-inflammation,indicated by the down-regulation of CD86(86.2%),and up-regulation of CD206(85.6%).Significantly,it was also observed that P@E+NIR presented the excellent behaviors of inhibiting wound infection,alleviating wound inflammation,as well as promoting skin tissue repairing.Altogether,it has developed the strategy of using P@E combining with NIR irradiation for the synergistic enhanced healing of infectious skin wound,which can serve as a promising therapeutic strategy for its clinical treatment.展开更多
Acute lung injury(ALI)was characterized by excessive reactive oxygen species(ROS)levels and inflammatory response in the lung.Scavenging ROS could inhibit the excessive inflammatory response,further treating ALI.Herei...Acute lung injury(ALI)was characterized by excessive reactive oxygen species(ROS)levels and inflammatory response in the lung.Scavenging ROS could inhibit the excessive inflammatory response,further treating ALI.Herein,we designed a novel nanozyme(P@Co)comprised of polydopamine(PDA)nanoparticles(NPs)loading with ultra-small Co,combining with near infrared(NIR)irradiation,which could efficiently scavenge intracellular ROS and suppress inflammatory responses against ALI.For lipopolysaccharide(LPS)induced macrophages,P@Co+NIR presented excellent antioxidant and anti-inflammatory capacities through lowering intracellular ROS levels,decreasing the expression levels of interleukin-6(IL-6)and tumor necrosis factor-α(TNF-α)as well as inducing macrophage M2 directional polarization.Significantly,it displayed the outstanding activities of lowering acute lung inflammation,relieving diffuse alveolar damage,and up-regulating heat shock protein 70(HSP70)expression,resulting in synergistic enhanced ALI therapy effect.It offers a novel strategy for the clinical treatment of ROS related diseases.展开更多
AIM To study the protective effects of tea polyphenol (TP) on cerebral ischemia reperfusion injury in rats and its scavenging oxygen free radical(OFR) activities and antilipid peroxidation in vitro . METHODS Cer...AIM To study the protective effects of tea polyphenol (TP) on cerebral ischemia reperfusion injury in rats and its scavenging oxygen free radical(OFR) activities and antilipid peroxidation in vitro . METHODS Cerebral ischemia reperfusion injury was produced by bilateral ligation of the common carotid arteries with vagus nerves and reperfusion for 45 min. The mitochondrial lipid peroxidation of rat brain induced by oxygen free radical was measured by thiobarbituric acid spectrophotometry. Superoxide anion (O 2) from xanthine xanthine oxidase system and hydroxyl radical (·OH) from Fe 2+ -H 2O 2 system were determined with spectrophotometry. RESULTS During Cerebral ischemia reperfusion,TP improved the activities of superoxide dismutase ( P 【0 05), GSH peroxidase( P 【0 01) and catalase( P 【0 01), while decreasing the maiondialdchyde content in the brain( P 【0 05) and brain water content ( P 【0 01). Tea polyphenol possessed significantly scavenging effects on ·OH produced by Fenton reaction and O 2 produced by xanthine xanthine oxidase system (the IC 50 were 2 2 mmol·L -1 and 1 9 mmol·L -1 respectively). Tea polyphenol could significant inhibit the lipid peroxidation of cerbral mitochondrial membrane induced by ·OH in a concentration dependent manner. CONCLUSION The results indicate that tea polyphenol could protect the injury on cerebral ischemia reperfusion in rats for OFR, these effects may be related to its scavenging effects on oxygen free radicals and antilipid peroxidant.展开更多
[ Objective ] The research aimed to provide reference for the application of extracts from sweet potato leaves in anti-aging cosmetics. [ Method ] The extraction and storage conditions for free radicals scavenging sub...[ Objective ] The research aimed to provide reference for the application of extracts from sweet potato leaves in anti-aging cosmetics. [ Method ] The extraction and storage conditions for free radicals scavenging substances from sweet potato leaves were optimized by orthogonal test and the bioactive components in extracts were investigated by correlation analysis. [ Result] Sweet potato leaves contain the bioactive substances scavenging DPPH free radical and hydroxyl free radical. Extracting solvent species is the most important factor that influencing extraction yield. The optimal extraction and storage conditions are as following： water as solvent, pH 8.0 of extracting liquid, storage at 25 ℃. There is a good positive linear relationship between the content of total phenols in sweet potato leaves and corresponding scavenging rates against both the DPPH free radical and hydroxyl free radical. For the content of total flavones in sweet potato leaves, just a correlation with scavenging rate against hydroxyl free radical shown in test. [ Conclusion] The phenols in ex- tracts could effectively scavenge both the DPPH free radical and hydroxyl free radical, whereas the flavones in extracts can only function on the hydroxyl free radical.展开更多
The below-cloud aerosol scavenging process by precipitation is one of the most important mechanisms to remove aerosols from the atmosphere.Due to its complexity and dependence on both aerosol and raindrop sizes,wet sc...The below-cloud aerosol scavenging process by precipitation is one of the most important mechanisms to remove aerosols from the atmosphere.Due to its complexity and dependence on both aerosol and raindrop sizes,wet scavenging process has been poorly treated,especially during the removal of fine particles.This makes the numerical simulation of below-cloud scavenging in large-scale aerosolmodels unrealistic.To consider the slip effects of submicron particles,a simplified expression for the diffusion scavenging was developed by approximating the Cunningham slip correction factor.The derived analytic solution was parameterized as a simple power function of rain intensity under the assumption of the lognormal size distribution of particles.The resultant approximated expression was compared to the observed data and the results of previous studies including a 3D atmospheric chemical transport model simulation.Compared with the default GEOS-Chem coefficient of 0.00106R0.61 and the observation-based coefficient of 0.0144R0.9268,the coefficient of a and b in∧m=aRb spread in the range of 0.0002-0.1959 for a and 0.3261-0.525 for b over a size distribution of GSD of 1.3–2.5 and a geometric mean diameter of 0.01-2.5μm.Overall,this study showed that the scavenging coefficient varies widely by orders of magnitude according to the size distribution of particles and rain intensity.This study also demonstrated that the obtained simplified expression could consider the theoretical approach of aerosol polydispersity.Our proposed analytic approach showed that results can be effectively applied for reduced computational burden in atmospheric modeling.展开更多
The molecular structure and radical scavenging activity of three novel antioxidants from Lespedeza Virgata, lespedezavirgatol, lespedezavirgatal, and lespedezacoumestan, have been studied using density functional theo...The molecular structure and radical scavenging activity of three novel antioxidants from Lespedeza Virgata, lespedezavirgatol, lespedezavirgatal, and lespedezacoumestan, have been studied using density functional theory with the B3LYP and BhandHLYP methods. The optimized geometries of neutral, radical cation, radical and anion forms were obtained at the B3LYP/6-31G（d） level, in which it was found that all the most stable conformations contain intramolecular hydrogen bonds. The same results were obtained from the MP2 method. The homolytic O-H bond dissociation enthalpy and the adiabatic ionization potential of neutral and anion forms for the three new antioxidants and adiabatic electron affinity and H-atom affinity for hydroxyl radical, superoxide anion radical, and hydrogen peroxide radical were determined both in gas phase and in aqueous solution using IEF-PCM and CPCM model with UAHF or Bondi cavity. The antioxidant activities and reactive oxygen species scavenging mechanisms were then discussed, and the results obtained from different methods are consistent. Furthermore, the antioxidant activities are consistent with the experimental findings of the compounds under investigation.展开更多
In order to investigate and compare the effects of Tetradium ruticarpum and Glycyrrhizae extracts in terms of scavenging sodium nitrite and inhibiting N-ni- troso compounds formation, the 1_9（3^3） orthogonal test wa...In order to investigate and compare the effects of Tetradium ruticarpum and Glycyrrhizae extracts in terms of scavenging sodium nitrite and inhibiting N-ni- troso compounds formation, the 1_9（3^3） orthogonal test was conducted to extract the active components. In addition, the capacities of scavenging sodium nitrite and of in- hibiting the N-nitroso compounds formation were measured to confirm the optimum condition of extracting. When the scavenging rate was considered as the main index, the maximum capacities of scavenging sodium nitrite by the extracts of Tetradi- urn ruticarpum and Glycyrrhizae were 0.836 5 and 0.558 0, respectively. Further- more, when the disconnection rate was considered as the main index, the maximum capacities of inhibiting the N-nitroso compounds formation by the extracts of Tetradi- urn ruticarpum and G/ycyrrhizae were 0.922 8 and 0.625 6, respectively. As a re- suit, the capacity of inhibiting nitrosation reaction by Tetradium ruticarpum was shown to be much stronger than G/ycyrrhizae, no matter the scavenging rate or the disconnection rate as the main index to be considered.展开更多
The DPPH scavenging ability of soymilk fermented with lactic acid bacteria under different fermentation conditions were investigated in this paper. According to the result, the optimal combination of starter species w...The DPPH scavenging ability of soymilk fermented with lactic acid bacteria under different fermentation conditions were investigated in this paper. According to the result, the optimal combination of starter species was S. thermophilus, L. plantarum and L. helveticus at a ratio of 2∶1.5∶1.5. The optimal fermentation parameters were temperature of 37 ℃, solids content of 12% and fermentation time of 6 h.Under above conditions, the fermented soymilk showed the highest ability to scavenge DPPH free radicals（84.3%）. Besides, the radical scavenging ability of fermented soymilk was compared with that of Baiyu lactone soymilk and bean curd which were coagulated by chemical method. The result indicated that the scavenging rate of lactone bean curd of Baiyu lactone soymilk and bean curd was only32.1% and 23.2%. According to the comparison, the free radical scavenging ability of soymilk was significantly improved by lactic acid fermentation. This product which had no beany flavor would be beneficial to human health.展开更多
A crude polysaccharide was extracted from Physalis alkekengi L. fruit. HPLC was used for the component analysis of the polysaccharide. The results indicate that Physalis alkekengi L. polysaccharide（PAP） was composed...A crude polysaccharide was extracted from Physalis alkekengi L. fruit. HPLC was used for the component analysis of the polysaccharide. The results indicate that Physalis alkekengi L. polysaccharide（PAP） was composed of rhamnose, xylose, arabinose, galactose, and glucose. Free radicals scavenging activity of PAP was studied through 3 free radicals scavenging tests. PAP exhibited high scavenging effects on OH and DPPH radicals, and both the scavenging rates were about 80%. The scavenging rate of O2^- radical was about 22%.展开更多
The Chinese dwarf cherry（Cerasus humilis（Bge.） Sok.） is a small shrub with edible fruits. It is native to northern and western China. This species was included as a medicinal plant in the ‘‘Chinese Pharmacopeia...The Chinese dwarf cherry（Cerasus humilis（Bge.） Sok.） is a small shrub with edible fruits. It is native to northern and western China. This species was included as a medicinal plant in the ‘‘Chinese Pharmacopeia’’ and has emerged as an economically important crop for fresh fruit consumption, processing into juice and wine and nutraceutical products as well. To gain a better understanding of flavonoid biosynthesis and help develop value added products and better cultivars with greater health benefits, we analyzed total flavonoid content（TFC）, composition, and radical scavenging activities in fruit extracts of 16 Chinese dwarf cherry genotypes. Fruit peel TFC ranged from 33.5 to72.8 mg/g REáFW（RE： rutin equivalent, FW： fresh weight）while fruit flesh TFC ranged from 4.3 to 16.9 mg/g REáFW.An HPLC analysis revealed that fruit extracts contained 14 flavonoids with considerable variation in their profiles across genotypes. The most abundant flavonoids in most genotypes were proanthocyanidin B1（PA-B1）, proanthocyanidin B2（PA-B2）, phloretin 20-O-glucoside（PG）, and phloretin 20,40-O-diglucoside（PDG）. Principal component analysis showed that PG, PA-B1, and PA-B2 had large,positive factor loading values in the first principal component for each genotype. Increased scavenging activity of2,2-diphenyl-1-picrylhydrazyl（DPPH） radicals was apparent in genotypes ‘Nongda 4’, ‘Nongda 3’, ‘Nongda 6’,‘Wenfenli’, and ’10-32’, suggesting promising applications in the production of nutraceutical products. In summary, our results will aid in breeding, fruit processing, and developing medicinal uses of the Chinese dwarf cherry.展开更多
Objective:To study the phytochemical screening of different extracts from Citrullus colocynthis(C.colocynthis)seeds extracts and to assess their antioxidant activity on the DPPH free radical scavenging.Methods:Phytoch...Objective:To study the phytochemical screening of different extracts from Citrullus colocynthis(C.colocynthis)seeds extracts and to assess their antioxidant activity on the DPPH free radical scavenging.Methods:Phytochemical screening,total content of polyphenols and flavonoids of C.colocynthis seeds extracts,including a crude aqueous extract(E1),a defatted aqueous extract(E2),a hydromethanolic extract(HM),an ethyl acetate extract(EA)and a n-butanol extract(n-B)was carried out according to the standard methods and to assess their corresponding effect on the antioxidant activity of this plant.Results:None of these extracts contained detectable amount of alkaloid,quinone,antraquinone,or reducing sugar.Catechic tannins and flavonoids were abundant in E1,MM and EA,whilst terpenoids were abundantly present in E1 and n-B but only weekly in HM.Coumarins were found in E2,EA and n-B.Polyphenols,expressed as gallic acid equivalent,amounted,per 100 g plant matter,to 329,1002 and 150 mg in EA,HM an E1 respectively.Flavonoids,expressed as catechin equivalent,amounted.per 100 g plant matter to 620,241 and 94 mg in EA,HM and E1 respectively.Comparable values were found in n-B and E1,with lower values in E2.Quercetin,myricetin and gallic acid were found in the EA and HM extracts by thin layer chromatography,The antioxidative effect of these extracts yielded,when tested at a concentration of 2000μg/mL in a 1,1-diphenyl-2-picrylhydrazyl assay,a reducing percentage of 88.8%with EA,74.5%with HM and 66.2%with E1,and corresponding IC_(50)of 350,580and 500μg/mL as compared to 1.1μg/mL for ascorbic acid.Conclusions:These qualitative and quantitative analytical data document the presence in C.colocynthis extracts of such chemical compounds as flavonoids responsible for the antioxidant activity,as well as other biological activities of this plant.展开更多
A number of studies have shown the existence of cross-tolerance in plants, but the physiological mechanism is poorly understood. In this study, we used the germination of barley seeds as a system to investigate the cr...A number of studies have shown the existence of cross-tolerance in plants, but the physiological mechanism is poorly understood. In this study, we used the germination of barley seeds as a system to investigate the cross-tolerance of low-temperature pretreatment to high-temperature stress and the possible involvement of reactive oxygen species （ROS） scavenging enzymes in the cross-tolerance. After pretreatment at 0 ℃ for different periods of time, barley seeds were germinated at 35 ℃, and the content of malondialdehyde （MDA） and the activities of ROS scavenging enzymes were measured by a spectrophotometer analysis. The results showed that barley seed germinated very poorly at 35 ℃, and this inhibitive effect could be overcome by pretreatment at 0 ℃. The MDA content varied, depending on the temperature at which seeds germinated, while barley seeds pretreated at 0 ℃ did not change the MDA content. Compared with seeds germinated directly at 35 ℃, the seeds pretreated first at 0 ℃ and then germinated at 35 ℃ had markedly increased activities of superoxide dismutase （SOD）, ascorbate peroxidase （APX）, catalase （CAT）, and glutathione reductase （GR）. The SOD and APX activities of seeds germinated at 35 ℃ after 0 ℃-pretreatment were even substantially higher than those at 25 ℃, and GR activity was similar to that at 25 ℃, at which the highest germination performance of barley seeds was achieved. These results indicate that low-temperature pretreatment can markedly increase the tolerance of barley seed to high temperature during germination, this being related to the increase in ROS scavenging enzyme activity. This may provide a new method for increasing seed germination under stress environments, and may be an excellent model system for the study of cross-tolerance.展开更多
A light purple organic active substance capable of scavenging hydroxyl radical（OH） with a high efficiency was extracted from Oyster shell at an extraction rate of 2.49%. It was found for the first time that this act...A light purple organic active substance capable of scavenging hydroxyl radical（OH） with a high efficiency was extracted from Oyster shell at an extraction rate of 2.49%. It was found for the first time that this active substance may scavenge OH with the efficiency far higher than that of vitamin C. This active substance may scavenge also superoxide radical（O2） although the scavenging efficiency is far lower than that of vitamin C. Infrared spectrometry and routine chemical analysis primarily reveal that this active substance belongs to glycoprotein.展开更多
Antioxidants have attracted the attention of researchers due to their beneficial effects as free radical scavengers. Application of a stable free radical named 1,1 diphenyl 2 picrylhydrazyl(DPPH) to screen the free ra...Antioxidants have attracted the attention of researchers due to their beneficial effects as free radical scavengers. Application of a stable free radical named 1,1 diphenyl 2 picrylhydrazyl(DPPH) to screen the free radical scavenging activity in 27 species of Chinese seaweed showed that 15 of them had significant activity in at least one of the organic solvent extracts. The most interesting seaweed species were Gelidium amansii, Gloiosiphonia capillaris, Polysiphonia urceolata, Sargassum kjellmanianum, Desmarestia viridis, and Rhodomela teres.展开更多
Echinops latifolius Tausch(ELT)is the traditional Mongolian medicine for the treatment of osteoporosis,and the ambiguous composition of active ingredients is an important factor in restricting the modernization and gl...Echinops latifolius Tausch(ELT)is the traditional Mongolian medicine for the treatment of osteoporosis,and the ambiguous composition of active ingredients is an important factor in restricting the modernization and globalization of this herb.Considering the traditional activity screening strategy is time-consuming and labor intensive,online HPLC active ingredient detection coupled with ESI-IT-TOF-MS^(n) strategy was employed in this study to isolate,identify and screen active compounds from the herbal medicines at the same time.The structure-activity relationship of these compounds was elucidated as well.Owing to the association of osteoporosis progression and oxidative stress,the antioxidants screening from ELT could be a good interpretive of the active substance in this herb.Meanwhile,DPPH equivalent method was an indicative of the most powerful antioxidant in ELT.Consequently,the screening and identification of the antioxidants in ELT was performed by using on-line HPLC-radical scavenging detection coupled with ESI-IT-TOF-MS^(n) strategy,and the structure-activity relationship was investigated based on DPPH equivalent method.Finally,20 constituents(including apigenin glucosides,caffeic acid,biscaffeoylquinic acids,biscaffeoylquinic acid methyl esters,ect.)were characterized in ELT extracts,and 18 components showed appreciable radical scavenging capacity.In addition,the structure-activity relationship study was carried out based on 14 compounds isolated from our laboratory,and the structural requirements of the compounds on antioxidant activity were obtained:(1)compounds with phenolic hydroxyl groups could have antioxidant activity;(2)the antioxidant activity could not be facilitated by the number of hydroxyl groups,but affected by the number of caffeoyl groups;(3)the substitution position of caffeoyl on quinic acid had a greater influence on DPPH activity;(4)methoxy groups could reduce the antioxidant activity.Collectively,this work provided the biochemical perspective to link active compounds and anti-osteoporosis action of ELT,and further explained how ELT worked in osteoporosis patients with bone loss.展开更多
The dynamics of Cd scavenging from solutions by Fe/Mn oxides in natural surface coatings （NSCs） was investigated under laboratory conditions. Selective extraction methods were employed to estimate the contributions ...The dynamics of Cd scavenging from solutions by Fe/Mn oxides in natural surface coatings （NSCs） was investigated under laboratory conditions. Selective extraction methods were employed to estimate the contributions of Fe/Mn oxides, where hydroxylamine hydrochloride （0.01 mol/L NH2OH-HCl ＋ 0.01 mol/L HNO3）, sodium dithionite （0.4 mol/L Na2S2O4） and nitric acid （10% HNO3） were used as extraction reagents. The Cd scavenging was accomplished with developing periods of the NSCs （totally 21 data sets）. The resulting process dynamics fitted well to the Elovich equation, demonstrating that the amount of Cd scavenged was proportional to the increments of Fe/Mn oxides that were accumulated in the NSCs. The amount of Cd bound to Fe oxides （MCdFe） and Mn oxides （MCdMn） could be quantified by solving two equations based on the properties of two extraction reagents. The amount of Cd scavenged by Fe/Mn oxides could also be estimated using MCdFe and MCdMn divided by the total amounts of Fe and Mn oxides in the NSCs, respectively. The results indicated that the Cd scavenging by Fe/Mn oxides was dominated by Fe oxides, with less roles attributed to Mn oxides. The estimated levels of Cd scavenging through Fe and Mn oxides agreed well with those predicted through additive-adsorption and linear-regression models.展开更多
Swirl-Loop Scavenging(SLS) improves the performance of 2-stroke aircraft diesel engine because the involved swirl may not only benefit the scavenging process, but also facilitate the fuel atomization and combustion. T...Swirl-Loop Scavenging(SLS) improves the performance of 2-stroke aircraft diesel engine because the involved swirl may not only benefit the scavenging process, but also facilitate the fuel atomization and combustion. The arrangement of scavenge port angles greatly influences incylinder flow distribution and swirl intensity, as well as the performance of the SLS engine. However, the mechanism of the effect and visualization experiment are rarely mentioned in the literature. To further investigate the SLS, Particle Image Velocimetry(PIV) experiment and Computational Fluid Dynamics(CFD) simulation are adopted to obtain its swirl distribution characteristics, and the effect of port angles on scavenging performance is discussed based on engine fired cycle simulation. The results illustrate that Reynolds Stress Turbulence model is accurate enough for in-cylinder flow simulation. Tangential and axial velocity distribution of the flow, as well as the scavenging performance, are mainly determined by geometric scavenge port angles ageom and βgeom . For reinforcement of scavenging on cross-sections and meridian planes, ageomvalue of27° and βgeom value of 60° are preferred, under which the scavenging efficiency reaches as high as 73.7%. Excessive swirl intensity has a negative effect on SLS performance, which should be controlled to a proper extent.展开更多
In vitro antioxidant activities of resveratrol and piceid against peroxynitrite（ONOO-） were examined by the inhibition of 3-nitrotyrosine formation.Trolox was used as a positive control.Resveratrol and piceid exhibi...In vitro antioxidant activities of resveratrol and piceid against peroxynitrite（ONOO-） were examined by the inhibition of 3-nitrotyrosine formation.Trolox was used as a positive control.Resveratrol and piceid exhibited high ONOO--scavenging activities in a concentration dependent manner.The antioxidant activities（the concentration of test compound required to yield a 50% inhibition of tyrosine nitration,IC 50） of resveratrol and piceid against ONOO-were（48.34±0.97） and（74.69±1.49） μmol/L,respectively.Compared with that of trolox[（105.40±1.16） μmol/L],their scavenging activities were 2.2-and 1.5-fold higher for resveratrol and piceid.Formation of nitroresveratrol as shown by UV-Vis spectroscopy and liquid chromatography-tandom mass spectrometry（LC-MS/MS） analysis indicates that resveratrol could directly scavenge ONOO-via nitration reaction.Our results demonstrate that foods and medicinal herbs with resveratrol and piceid as stronger ONOO-scavengers are valuable ingredients and have healthy application in preventing humans from peroxynitrite-mediated oxidative damage by scavenging peroxynitrite efficiently.展开更多
基金supported by Key Research Project of the Educational Department of Liaoning Province,China(JYTZD2023139).
文摘Psoriasis is a chronic inflammatory skin disease,which seriously affects the physical and mental health of patients.The progression of psoriasis is influenced by the excessive production of reactive oxygen species(ROS)and inflammatory responses.In this paper,novel celastrol(Ce)-loaded metal-phenolic nanozymes(tannic acid-Fe^(3+))(TA-Fe)integrated microneedles(Ce@TA-Fe/MNs)were constructed to achieve the combined oxidative stress alleviation and anti-inflammatory therapy of psoriasis.Molecular dynamics simulations and structural characterization confirmed the successful fabrication of nanozymes.The Ce@TA-Fe/MNs system,characterized by its rapid dissolution kinetics and superior mechanical strength,enabled minimally invasive skin penetration for efficient nanozymes delivery.Nanozymes possessed superoxide dismutase and catalase mimetic enzyme activities,effectively eliminating excessive ROS in psoriatic skin lesions.Additionally,the release of Ce from Ce@TA-Fe provided strong antioxidant and anti-inflammatory effects.Based on these characteristics,Ce@TA-Fe/MNs could effectively alleviate the symptoms in psoriasis mice models.These findings demonstrated that the integration of Ce-equipped nanozymes within MNs holds great promise as a therapeutic strategy for the clinical management of psoriasis.
基金financially supported by the Natural Science Foundation of Guangxi(Nos.2022GXNSFAA035505 and 2024GXNSFAA010164)the Key Research&Development Program of Guangxi(No.GuiKe2024AB08057)+1 种基金the Guangxi Medical and Health Suitable Technology Development and Popularization Applications Project(Nos.S2023093 and S2021084)the Major Talent Project of Guangxi Autonomous Region.
文摘Infectious wound healing is complicated with and limited by infection and oxidative stress at the wound site.In recent years,various evidences suggest that nanozymes with multiple enzymatic activities have enabled the development of novel strategies for infectious wound healing.In this study,epigallocatechin gallate loaded polydopamine(P@E)was developed to act as a potent reactive oxygen species(ROS)scavenger for scavenging ROS,alleviating inflammatory responses,and promoting infectious wound healing.Combining with near infrared(NIR)irradiation,P@E presented excellent antibacterial ability of Escherichia coli(E.coli,93.6%)and methicillin-resistant Staphylococcus aureus(MRSA,87.6%).Specifically,P@E+NIR exhibited the most potent antioxidant,anti-inflammatory and cell proliferation behaviors through downregulating intracellular ROS levels(81.9%and 94.3%for NIH3T3 and RAW264.7 respectively)and inducible nitric oxide synthase(iNOS)expression level(55.7%),and up-regulating the expression levels of arginase-1(Arg-1,71.4%),heat shock protein 70(HSP70,48.6%)and platelet endothelial cell adhesion molecule(CD31,35.3%)compared to control group.Meanwhile,it also efficiently induced M2 directional polarization of lipopolysaccharide induced murine macrophages to achieve anti-inflammation,indicated by the down-regulation of CD86(86.2%),and up-regulation of CD206(85.6%).Significantly,it was also observed that P@E+NIR presented the excellent behaviors of inhibiting wound infection,alleviating wound inflammation,as well as promoting skin tissue repairing.Altogether,it has developed the strategy of using P@E combining with NIR irradiation for the synergistic enhanced healing of infectious skin wound,which can serve as a promising therapeutic strategy for its clinical treatment.
基金financially supported by the Key Research&Development Program of Guangxi(No.GuiKeAB22080088)the Joint Project on Regional High-Incidence Diseases Research of Guangxi Natural Science Foundation(No.2023GXNSFDA026023)+3 种基金the Natural Science Foundation of Guangxi(No.2023JJA140322)the National Natural Science Foundation of China(No.82360372)the High-level Medical Expert Training Program of Guangxi“139 Plan Funding(No.G202003010)the Medical Appropriate Technology Development and Popularization and Application Project of Guangxi(No.S2020099)。
文摘Acute lung injury(ALI)was characterized by excessive reactive oxygen species(ROS)levels and inflammatory response in the lung.Scavenging ROS could inhibit the excessive inflammatory response,further treating ALI.Herein,we designed a novel nanozyme(P@Co)comprised of polydopamine(PDA)nanoparticles(NPs)loading with ultra-small Co,combining with near infrared(NIR)irradiation,which could efficiently scavenge intracellular ROS and suppress inflammatory responses against ALI.For lipopolysaccharide(LPS)induced macrophages,P@Co+NIR presented excellent antioxidant and anti-inflammatory capacities through lowering intracellular ROS levels,decreasing the expression levels of interleukin-6(IL-6)and tumor necrosis factor-α(TNF-α)as well as inducing macrophage M2 directional polarization.Significantly,it displayed the outstanding activities of lowering acute lung inflammation,relieving diffuse alveolar damage,and up-regulating heat shock protein 70(HSP70)expression,resulting in synergistic enhanced ALI therapy effect.It offers a novel strategy for the clinical treatment of ROS related diseases.
文摘AIM To study the protective effects of tea polyphenol (TP) on cerebral ischemia reperfusion injury in rats and its scavenging oxygen free radical(OFR) activities and antilipid peroxidation in vitro . METHODS Cerebral ischemia reperfusion injury was produced by bilateral ligation of the common carotid arteries with vagus nerves and reperfusion for 45 min. The mitochondrial lipid peroxidation of rat brain induced by oxygen free radical was measured by thiobarbituric acid spectrophotometry. Superoxide anion (O 2) from xanthine xanthine oxidase system and hydroxyl radical (·OH) from Fe 2+ -H 2O 2 system were determined with spectrophotometry. RESULTS During Cerebral ischemia reperfusion,TP improved the activities of superoxide dismutase ( P 【0 05), GSH peroxidase( P 【0 01) and catalase( P 【0 01), while decreasing the maiondialdchyde content in the brain( P 【0 05) and brain water content ( P 【0 01). Tea polyphenol possessed significantly scavenging effects on ·OH produced by Fenton reaction and O 2 produced by xanthine xanthine oxidase system (the IC 50 were 2 2 mmol·L -1 and 1 9 mmol·L -1 respectively). Tea polyphenol could significant inhibit the lipid peroxidation of cerbral mitochondrial membrane induced by ·OH in a concentration dependent manner. CONCLUSION The results indicate that tea polyphenol could protect the injury on cerebral ischemia reperfusion in rats for OFR, these effects may be related to its scavenging effects on oxygen free radicals and antilipid peroxidant.
基金Scientific Research Program of Beijing Municipal Commission of Education (KM200710011007)~~
文摘[ Objective ] The research aimed to provide reference for the application of extracts from sweet potato leaves in anti-aging cosmetics. [ Method ] The extraction and storage conditions for free radicals scavenging substances from sweet potato leaves were optimized by orthogonal test and the bioactive components in extracts were investigated by correlation analysis. [ Result] Sweet potato leaves contain the bioactive substances scavenging DPPH free radical and hydroxyl free radical. Extracting solvent species is the most important factor that influencing extraction yield. The optimal extraction and storage conditions are as following： water as solvent, pH 8.0 of extracting liquid, storage at 25 ℃. There is a good positive linear relationship between the content of total phenols in sweet potato leaves and corresponding scavenging rates against both the DPPH free radical and hydroxyl free radical. For the content of total flavones in sweet potato leaves, just a correlation with scavenging rate against hydroxyl free radical shown in test. [ Conclusion] The phenols in ex- tracts could effectively scavenge both the DPPH free radical and hydroxyl free radical, whereas the flavones in extracts can only function on the hydroxyl free radical.
基金supported by the FRIEND(Fine Particle Research Initiative in East Asia Considering National Differences)Project through the National Research Foundation of Korea(NRF)funded by the Ministry of Science and ICT(No.2020M3G1A1114617)the Technology Development Program to Solve Climate Changes through the National Research Foundation of Korea(NRF)funded by the Ministry of Science,ICT(No.2019M1A2A2103953)+1 种基金the National Research Foundation of Korea Grant from the Korean Government(MSIT)(Nos.NRF2021M1A5A1065672/PN22011,NRF2021R1F1A1046878,and NRF2020R1A2C1003215)This research was also supported by Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Education(No.2020R1A6A1A03044834).
文摘The below-cloud aerosol scavenging process by precipitation is one of the most important mechanisms to remove aerosols from the atmosphere.Due to its complexity and dependence on both aerosol and raindrop sizes,wet scavenging process has been poorly treated,especially during the removal of fine particles.This makes the numerical simulation of below-cloud scavenging in large-scale aerosolmodels unrealistic.To consider the slip effects of submicron particles,a simplified expression for the diffusion scavenging was developed by approximating the Cunningham slip correction factor.The derived analytic solution was parameterized as a simple power function of rain intensity under the assumption of the lognormal size distribution of particles.The resultant approximated expression was compared to the observed data and the results of previous studies including a 3D atmospheric chemical transport model simulation.Compared with the default GEOS-Chem coefficient of 0.00106R0.61 and the observation-based coefficient of 0.0144R0.9268,the coefficient of a and b in∧m=aRb spread in the range of 0.0002-0.1959 for a and 0.3261-0.525 for b over a size distribution of GSD of 1.3–2.5 and a geometric mean diameter of 0.01-2.5μm.Overall,this study showed that the scavenging coefficient varies widely by orders of magnitude according to the size distribution of particles and rain intensity.This study also demonstrated that the obtained simplified expression could consider the theoretical approach of aerosol polydispersity.Our proposed analytic approach showed that results can be effectively applied for reduced computational burden in atmospheric modeling.
基金ACKNOWLEDGMENTS This work was supported by the National Natural Science Foundation of China （No.20902056 and No.20973108）, the Innovation Foundation of Shanghai University, and the Leading Academic Discipline Project of Shanghai Municipal Education Commission （No.J50101）.
文摘The molecular structure and radical scavenging activity of three novel antioxidants from Lespedeza Virgata, lespedezavirgatol, lespedezavirgatal, and lespedezacoumestan, have been studied using density functional theory with the B3LYP and BhandHLYP methods. The optimized geometries of neutral, radical cation, radical and anion forms were obtained at the B3LYP/6-31G（d） level, in which it was found that all the most stable conformations contain intramolecular hydrogen bonds. The same results were obtained from the MP2 method. The homolytic O-H bond dissociation enthalpy and the adiabatic ionization potential of neutral and anion forms for the three new antioxidants and adiabatic electron affinity and H-atom affinity for hydroxyl radical, superoxide anion radical, and hydrogen peroxide radical were determined both in gas phase and in aqueous solution using IEF-PCM and CPCM model with UAHF or Bondi cavity. The antioxidant activities and reactive oxygen species scavenging mechanisms were then discussed, and the results obtained from different methods are consistent. Furthermore, the antioxidant activities are consistent with the experimental findings of the compounds under investigation.
基金Supported by National Natural Science Foundation of China(31372159)Scientific Research Foundation for The Junior Teachers in Beijing Normal University,Zhuhai(201353015)Innovative Foundation Project of Beijing Normal University,Zhuhai(1317713016)~~
文摘In order to investigate and compare the effects of Tetradium ruticarpum and Glycyrrhizae extracts in terms of scavenging sodium nitrite and inhibiting N-ni- troso compounds formation, the 1_9（3^3） orthogonal test was conducted to extract the active components. In addition, the capacities of scavenging sodium nitrite and of in- hibiting the N-nitroso compounds formation were measured to confirm the optimum condition of extracting. When the scavenging rate was considered as the main index, the maximum capacities of scavenging sodium nitrite by the extracts of Tetradi- urn ruticarpum and Glycyrrhizae were 0.836 5 and 0.558 0, respectively. Further- more, when the disconnection rate was considered as the main index, the maximum capacities of inhibiting the N-nitroso compounds formation by the extracts of Tetradi- urn ruticarpum and G/ycyrrhizae were 0.922 8 and 0.625 6, respectively. As a re- suit, the capacity of inhibiting nitrosation reaction by Tetradium ruticarpum was shown to be much stronger than G/ycyrrhizae, no matter the scavenging rate or the disconnection rate as the main index to be considered.
基金Supported by Key Technology Research and Development Program of Tianjin(11ZCKNC01800)~~
文摘The DPPH scavenging ability of soymilk fermented with lactic acid bacteria under different fermentation conditions were investigated in this paper. According to the result, the optimal combination of starter species was S. thermophilus, L. plantarum and L. helveticus at a ratio of 2∶1.5∶1.5. The optimal fermentation parameters were temperature of 37 ℃, solids content of 12% and fermentation time of 6 h.Under above conditions, the fermented soymilk showed the highest ability to scavenge DPPH free radicals（84.3%）. Besides, the radical scavenging ability of fermented soymilk was compared with that of Baiyu lactone soymilk and bean curd which were coagulated by chemical method. The result indicated that the scavenging rate of lactone bean curd of Baiyu lactone soymilk and bean curd was only32.1% and 23.2%. According to the comparison, the free radical scavenging ability of soymilk was significantly improved by lactic acid fermentation. This product which had no beany flavor would be beneficial to human health.
基金Supported by the Science and Technique Foundation of Jilin Province, China(No20020503-2)
文摘A crude polysaccharide was extracted from Physalis alkekengi L. fruit. HPLC was used for the component analysis of the polysaccharide. The results indicate that Physalis alkekengi L. polysaccharide（PAP） was composed of rhamnose, xylose, arabinose, galactose, and glucose. Free radicals scavenging activity of PAP was studied through 3 free radicals scavenging tests. PAP exhibited high scavenging effects on OH and DPPH radicals, and both the scavenging rates were about 80%. The scavenging rate of O2^- radical was about 22%.
基金financially supported by the Major Subject of Shanxi Science and Technology Research(Grant No.20121101010)the Platform Construction of Science and Technology of Shanxi Province(Grant No.2013091004-0101)the Doctoral Research Fund of Shanxi Agriculture University(Grant No.2015ZZ19)
文摘The Chinese dwarf cherry（Cerasus humilis（Bge.） Sok.） is a small shrub with edible fruits. It is native to northern and western China. This species was included as a medicinal plant in the ‘‘Chinese Pharmacopeia’’ and has emerged as an economically important crop for fresh fruit consumption, processing into juice and wine and nutraceutical products as well. To gain a better understanding of flavonoid biosynthesis and help develop value added products and better cultivars with greater health benefits, we analyzed total flavonoid content（TFC）, composition, and radical scavenging activities in fruit extracts of 16 Chinese dwarf cherry genotypes. Fruit peel TFC ranged from 33.5 to72.8 mg/g REáFW（RE： rutin equivalent, FW： fresh weight）while fruit flesh TFC ranged from 4.3 to 16.9 mg/g REáFW.An HPLC analysis revealed that fruit extracts contained 14 flavonoids with considerable variation in their profiles across genotypes. The most abundant flavonoids in most genotypes were proanthocyanidin B1（PA-B1）, proanthocyanidin B2（PA-B2）, phloretin 20-O-glucoside（PG）, and phloretin 20,40-O-diglucoside（PDG）. Principal component analysis showed that PG, PA-B1, and PA-B2 had large,positive factor loading values in the first principal component for each genotype. Increased scavenging activity of2,2-diphenyl-1-picrylhydrazyl（DPPH） radicals was apparent in genotypes ‘Nongda 4’, ‘Nongda 3’, ‘Nongda 6’,‘Wenfenli’, and ’10-32’, suggesting promising applications in the production of nutraceutical products. In summary, our results will aid in breeding, fruit processing, and developing medicinal uses of the Chinese dwarf cherry.
文摘Objective:To study the phytochemical screening of different extracts from Citrullus colocynthis(C.colocynthis)seeds extracts and to assess their antioxidant activity on the DPPH free radical scavenging.Methods:Phytochemical screening,total content of polyphenols and flavonoids of C.colocynthis seeds extracts,including a crude aqueous extract(E1),a defatted aqueous extract(E2),a hydromethanolic extract(HM),an ethyl acetate extract(EA)and a n-butanol extract(n-B)was carried out according to the standard methods and to assess their corresponding effect on the antioxidant activity of this plant.Results:None of these extracts contained detectable amount of alkaloid,quinone,antraquinone,or reducing sugar.Catechic tannins and flavonoids were abundant in E1,MM and EA,whilst terpenoids were abundantly present in E1 and n-B but only weekly in HM.Coumarins were found in E2,EA and n-B.Polyphenols,expressed as gallic acid equivalent,amounted,per 100 g plant matter,to 329,1002 and 150 mg in EA,HM an E1 respectively.Flavonoids,expressed as catechin equivalent,amounted.per 100 g plant matter to 620,241 and 94 mg in EA,HM and E1 respectively.Comparable values were found in n-B and E1,with lower values in E2.Quercetin,myricetin and gallic acid were found in the EA and HM extracts by thin layer chromatography,The antioxidative effect of these extracts yielded,when tested at a concentration of 2000μg/mL in a 1,1-diphenyl-2-picrylhydrazyl assay,a reducing percentage of 88.8%with EA,74.5%with HM and 66.2%with E1,and corresponding IC_(50)of 350,580and 500μg/mL as compared to 1.1μg/mL for ascorbic acid.Conclusions:These qualitative and quantitative analytical data document the presence in C.colocynthis extracts of such chemical compounds as flavonoids responsible for the antioxidant activity,as well as other biological activities of this plant.
基金Project (No. 30870223) supported by the National Natural Science Foundation of China
文摘A number of studies have shown the existence of cross-tolerance in plants, but the physiological mechanism is poorly understood. In this study, we used the germination of barley seeds as a system to investigate the cross-tolerance of low-temperature pretreatment to high-temperature stress and the possible involvement of reactive oxygen species （ROS） scavenging enzymes in the cross-tolerance. After pretreatment at 0 ℃ for different periods of time, barley seeds were germinated at 35 ℃, and the content of malondialdehyde （MDA） and the activities of ROS scavenging enzymes were measured by a spectrophotometer analysis. The results showed that barley seed germinated very poorly at 35 ℃, and this inhibitive effect could be overcome by pretreatment at 0 ℃. The MDA content varied, depending on the temperature at which seeds germinated, while barley seeds pretreated at 0 ℃ did not change the MDA content. Compared with seeds germinated directly at 35 ℃, the seeds pretreated first at 0 ℃ and then germinated at 35 ℃ had markedly increased activities of superoxide dismutase （SOD）, ascorbate peroxidase （APX）, catalase （CAT）, and glutathione reductase （GR）. The SOD and APX activities of seeds germinated at 35 ℃ after 0 ℃-pretreatment were even substantially higher than those at 25 ℃, and GR activity was similar to that at 25 ℃, at which the highest germination performance of barley seeds was achieved. These results indicate that low-temperature pretreatment can markedly increase the tolerance of barley seed to high temperature during germination, this being related to the increase in ROS scavenging enzyme activity. This may provide a new method for increasing seed germination under stress environments, and may be an excellent model system for the study of cross-tolerance.
基金Supported by the Natural Science Foundation of Fujian Province, China(NoC0510029)the Specialized Foundation for Creative Team of Young and Middle-aged Teachers of Jimei University, China(No2006A003)
文摘A light purple organic active substance capable of scavenging hydroxyl radical（OH） with a high efficiency was extracted from Oyster shell at an extraction rate of 2.49%. It was found for the first time that this active substance may scavenge OH with the efficiency far higher than that of vitamin C. This active substance may scavenge also superoxide radical（O2） although the scavenging efficiency is far lower than that of vitamin C. Infrared spectrometry and routine chemical analysis primarily reveal that this active substance belongs to glycoprotein.
文摘Antioxidants have attracted the attention of researchers due to their beneficial effects as free radical scavengers. Application of a stable free radical named 1,1 diphenyl 2 picrylhydrazyl(DPPH) to screen the free radical scavenging activity in 27 species of Chinese seaweed showed that 15 of them had significant activity in at least one of the organic solvent extracts. The most interesting seaweed species were Gelidium amansii, Gloiosiphonia capillaris, Polysiphonia urceolata, Sargassum kjellmanianum, Desmarestia viridis, and Rhodomela teres.
基金National Natural Science Foundation of China(Grant No.81860756,81960758)Natural Science Foundation of Inner Mongolia Autonomous Region(Grant No.2017MS08122,2019MS08111 and 2019MS08119)+2 种基金Inner Mongolia Science and Technology Innovation Guide Project(Grant No.02039001)Rolling Support Plan for Grassland Talents Project in Inner Mongolia Autonomous RegionInner Mongolia Autonomous Region Higher Education Science Research Project(Grant No.NJZY19099)。
文摘Echinops latifolius Tausch(ELT)is the traditional Mongolian medicine for the treatment of osteoporosis,and the ambiguous composition of active ingredients is an important factor in restricting the modernization and globalization of this herb.Considering the traditional activity screening strategy is time-consuming and labor intensive,online HPLC active ingredient detection coupled with ESI-IT-TOF-MS^(n) strategy was employed in this study to isolate,identify and screen active compounds from the herbal medicines at the same time.The structure-activity relationship of these compounds was elucidated as well.Owing to the association of osteoporosis progression and oxidative stress,the antioxidants screening from ELT could be a good interpretive of the active substance in this herb.Meanwhile,DPPH equivalent method was an indicative of the most powerful antioxidant in ELT.Consequently,the screening and identification of the antioxidants in ELT was performed by using on-line HPLC-radical scavenging detection coupled with ESI-IT-TOF-MS^(n) strategy,and the structure-activity relationship was investigated based on DPPH equivalent method.Finally,20 constituents(including apigenin glucosides,caffeic acid,biscaffeoylquinic acids,biscaffeoylquinic acid methyl esters,ect.)were characterized in ELT extracts,and 18 components showed appreciable radical scavenging capacity.In addition,the structure-activity relationship study was carried out based on 14 compounds isolated from our laboratory,and the structural requirements of the compounds on antioxidant activity were obtained:(1)compounds with phenolic hydroxyl groups could have antioxidant activity;(2)the antioxidant activity could not be facilitated by the number of hydroxyl groups,but affected by the number of caffeoyl groups;(3)the substitution position of caffeoyl on quinic acid had a greater influence on DPPH activity;(4)methoxy groups could reduce the antioxidant activity.Collectively,this work provided the biochemical perspective to link active compounds and anti-osteoporosis action of ELT,and further explained how ELT worked in osteoporosis patients with bone loss.
基金The National Basic Research Program (973) of China (No. 2004CB3418501)
文摘The dynamics of Cd scavenging from solutions by Fe/Mn oxides in natural surface coatings （NSCs） was investigated under laboratory conditions. Selective extraction methods were employed to estimate the contributions of Fe/Mn oxides, where hydroxylamine hydrochloride （0.01 mol/L NH2OH-HCl ＋ 0.01 mol/L HNO3）, sodium dithionite （0.4 mol/L Na2S2O4） and nitric acid （10% HNO3） were used as extraction reagents. The Cd scavenging was accomplished with developing periods of the NSCs （totally 21 data sets）. The resulting process dynamics fitted well to the Elovich equation, demonstrating that the amount of Cd scavenged was proportional to the increments of Fe/Mn oxides that were accumulated in the NSCs. The amount of Cd bound to Fe oxides （MCdFe） and Mn oxides （MCdMn） could be quantified by solving two equations based on the properties of two extraction reagents. The amount of Cd scavenged by Fe/Mn oxides could also be estimated using MCdFe and MCdMn divided by the total amounts of Fe and Mn oxides in the NSCs, respectively. The results indicated that the Cd scavenging by Fe/Mn oxides was dominated by Fe oxides, with less roles attributed to Mn oxides. The estimated levels of Cd scavenging through Fe and Mn oxides agreed well with those predicted through additive-adsorption and linear-regression models.
基金supported by the Basic Research Program of the National Natural Science Foundation of China (Nos. 51775025 and 51205015)China Key Research and Development Plan (No.2018YFB0104100)。
文摘Swirl-Loop Scavenging(SLS) improves the performance of 2-stroke aircraft diesel engine because the involved swirl may not only benefit the scavenging process, but also facilitate the fuel atomization and combustion. The arrangement of scavenge port angles greatly influences incylinder flow distribution and swirl intensity, as well as the performance of the SLS engine. However, the mechanism of the effect and visualization experiment are rarely mentioned in the literature. To further investigate the SLS, Particle Image Velocimetry(PIV) experiment and Computational Fluid Dynamics(CFD) simulation are adopted to obtain its swirl distribution characteristics, and the effect of port angles on scavenging performance is discussed based on engine fired cycle simulation. The results illustrate that Reynolds Stress Turbulence model is accurate enough for in-cylinder flow simulation. Tangential and axial velocity distribution of the flow, as well as the scavenging performance, are mainly determined by geometric scavenge port angles ageom and βgeom . For reinforcement of scavenging on cross-sections and meridian planes, ageomvalue of27° and βgeom value of 60° are preferred, under which the scavenging efficiency reaches as high as 73.7%. Excessive swirl intensity has a negative effect on SLS performance, which should be controlled to a proper extent.
基金Supported by the National Basic Research Program of China(Nos.2012CB721105,2011CBA00802,2007CB714301)the National Natural Science Foundation of China(No.30873400)the Specialized Research Fund for the Doctoral Program of Higher Education of China(No.20090032110015)
文摘In vitro antioxidant activities of resveratrol and piceid against peroxynitrite（ONOO-） were examined by the inhibition of 3-nitrotyrosine formation.Trolox was used as a positive control.Resveratrol and piceid exhibited high ONOO--scavenging activities in a concentration dependent manner.The antioxidant activities（the concentration of test compound required to yield a 50% inhibition of tyrosine nitration,IC 50） of resveratrol and piceid against ONOO-were（48.34±0.97） and（74.69±1.49） μmol/L,respectively.Compared with that of trolox[（105.40±1.16） μmol/L],their scavenging activities were 2.2-and 1.5-fold higher for resveratrol and piceid.Formation of nitroresveratrol as shown by UV-Vis spectroscopy and liquid chromatography-tandom mass spectrometry（LC-MS/MS） analysis indicates that resveratrol could directly scavenge ONOO-via nitration reaction.Our results demonstrate that foods and medicinal herbs with resveratrol and piceid as stronger ONOO-scavengers are valuable ingredients and have healthy application in preventing humans from peroxynitrite-mediated oxidative damage by scavenging peroxynitrite efficiently.
