New N-acetyl-L-cysteine derivatives synthesized by the degradation of proanthocyanidins as high biological activity antioxidants

A novel degradation method was investigated to synthesize highly biologically active flavan-3-ol derivatives in the presence of N-acetyl-L-cysteine(NAC)as a nucleophile under acidic conditions for polymerized proanthocyanidins degradation.The reaction conditions were optimized by the combination of single-factor test and central composite experimental design(CCD).Grape seed proanthocyanidins were reacted with NAC at a ratio of 1:3 with 0.3 M methanolic HC1,a temperature of 55°C,and a reaction time of 50 mins.Most of the degradation products were separated and prepared by one-step high-speed countercurrent chromatography(HSCCC)and preparative high-performance liquid chromatography(prep-HPLC).Three monomeric pro anthocyanidins and four new N-acetyl-L-cysteine derivatives were isolated from degradation products with total degradation yield of 55.44%and high purity over 95%.Furthermore,the neuroprotective abilities of these compounds to H2O2-treated PC-12 neuroblastoma cells were evaluated.NAC derivatives showed better antioxidant activity than their corresponding underivatized monomers and NAC,indicating that they had a better performance in protecting PC-12 cells from oxidative stress damage.

Short-term effects of fine particulate matter constituents on myocardial infarction death

Existing evidence suggested that short-term exposure to fine particulate matter(PM_(2.5))may increase the risk of death from myocardial infarction(MI),while PM_(2.5) constituents responsible for this association has not been determined.We collected 12,927 MI deaths from 32 counties in southern China during 2011–2013.County-level exposures of ambient PM_(2.5) and its 5 constituents(i.e.,elemental carbon(EC),organic carbon(OC),sulfate(SO_(4)^(2-)),ammonium(NH_(4)^(+)),and nitrate(NO_(3)^(-)))were aggregated from gridded datasets predicted by Community Multiscale Air Quality Modeling System.We employed a space-time-stratified casecrossover design and conditional logistic regression models to quantify the association of MI mortality with short-term exposure to PM_(2.5) and its constituents across various lag days.Over the study period,the daily mean PM_(2.5) mass concentration was 77.8(standard deviation(SD)=72.7)μg/m^(3).We estimated an odds ratio of 1.038(95%confidence interval(CI):1.003-1.074),1.038(1.013-1.063)and 1.057(1.023-1.097)for MI mortality associated with per interquartile range(IQR)increase in the 3-day moving-average exposure to PM_(2.5)(IQR=76.3μg/m 3),EC(4.1μg/m^(3))and OC(9.1μg/m^(3)),respectively.We did not identify significant association between MI death and exposure to water-soluble ions(SO_(4)^(2-),NH_(4)^(+)and NO_(3)^(-)).Likelihood ratio tests supported no evident violations of linear assumptions for constituents-MI associations.Subgroup analyses showed stronger associations between MI death and EC/OC exposure in the elderly,males and cold months.Short-term exposure to PM_(2.5) constituents,particularly those carbonaceous aerosols,was associated with increased risks of MI mortality.

Short-term exposure to fine particulate matter constituents and mortality:case-crossover evidence from 32 counties in China

A growing number of studies associated increased mortality with exposures to specific fine particulate(PM_(2.5))constituents,while great heterogeneity exists between locations.In China,evidence linking PM_(2.5)constituents and mortality was extensively sparse.This study primarily aimed to quantify short-term associations between PM_(2.5)constituents and non-accidental mortality among the Chinese population.We collected daily mortality records from 32 counties in China between January 1,2011,and December 31,2013.Daily concentrations of main PM_(2.5)constituents(organic carbon(OC),elemental carbon(EC),nitrate(NO_(3)^(-)),sulfate(SO_(4)^(2−)),and ammonium(NH_(4)^(+)))were estimated using the modified Community Multiscale Air Quality model.Time-stratified case-crossover design with conditional logistic regression models was adopted to estimate mortality risks associated with short-term exposures to PM_(2.5)mass and its constituents.Stratification analyses were done by sex,age,and season.A total of 116,959 non-accidental deaths were investigated.PM_(2.5)concentrations on the day of death were averaged at 75.7μg m^(−3)(control day:75.6μg m^(−3)),with an interquartile range(IQR)of 65.2μg m^(−3).Per IQR rise in PM_(2.5),EC,OC,NO_(3)^(-),SO_(4)^(2−),and NH_(4)^(+)at lag-04 day was associated with an increase in non-accidental mortality of 2.4%(95%confidence interval,(1.0–3.7),1.7%(0.8–2.7),2.9%(1.6–4.3),2.1%(0.4–3.9),1.0%(0.2–1.9),and 1.6%(0.3–2.9),respectively.Both PM_(2.5)mass and its constituents were strongly associated with elevated cardiovascular mortality risks,but only PM_(2.5),EC,and OC were positively associated with respiratory mortality at lag-3 day.PM_(2.5)mass and its constituents associated effects on mortality varied among sex-and age-specific subpopulations.Differences in the seasonal pattern of associations exist among PM_(2.5)constituents,with stronger effects related to EC and NO_(3)^(-)in warm months but SO_(4)^(2−)and NH_(4)^(+)in cold months.Short-term exposures to PM_(2.5)compositions were positively associated with increased risks of mortality,particularly those constituents from combustion-related sources.