[Chemical constituents of Tamarix chinensis].

OBJECTIVE: To study the chemical consistuents of Tamarix chinensis. METHODS: The compounds were isolated and purified by column chromatography and their structures were elucidated through spectroscopic analysis. RESULTS: Nine compounds were isolated and identified as isotamarixen(1), matairesinol(2), tetepathine(3), kaempferol(4), 4'-methylkaempferol(5),4',7-dimethylkaempferol (6), hexacosyl-3-caffeate(7), ferulic acid(8) and 3-methoxyl methyl gallate(9). CONCLUSION: Compounds 1-3,7 and 8 are isolated from this plant for the first time, compounds 1-3,7 are isolated from Tamarix genus for the first time.

Chlorine disinfection elevates the toxicity of polystyrene microplastics to human cells by inducing mitochondria-dependent apoptosis.

Microplastics (MPs) are ubiquitous in drinking water and pose potential threats to human health. Despite increasingly attentions on the toxicity of MPs, the deleterious effects of MPs after chlorine disinfection, which might be a more accessible form of MPs, has rarely been considered. Here, we first treated pristine polystyrene microplastics (PS-MPs) with chlorine to simulate the reactions that occur during drinking water treatment, and investigated and compared the cytotoxicity of chlorinated PS-MPs to those of pristine PS-MPs. Chlorine disinfection did not change the size of pristine PS-MPs, but increased the surface roughness. In addition, abundant carbon-chlorine bonds and persistent free radicals were generated on the surface of chlorinated PS-MPs. Compared with pristine PS-MPs, chlorinated PS-MPs markedly inhibited the cell proliferation, changed cellular morphology, destroyed cell membrane integrity, induced cell inflammatory response and apoptosis. Proteomics confirmed the difference in interactions with intracellular proteins between these particles. Furthermore, we found that the regulation of PI3K/AKT and Bcl-2/Bax pathways, oxidative stress-triggered mitochondrial depolarization, and the activation of caspase cascade were identified as the underlying mechanisms for the enhanced apoptosis ratio in GES-1 cells when exposed to chlorinated PS-MPs. This exacerbated cytotoxicity could be explained by the enhanced surface roughness and changed surface chemistry of these PS-MPs after chlorine disinfection. This work discloses the impacts of chlorine disinfection on the cytotoxicity of PS-MPs, which provides new insights for a more systematic risk assessment of MPs.

Low-level concentrations of aminoglycoside antibiotics induce the aggregation of cyanobacteria.

The interactions between antibiotics and microorganisms have attracted enormous research attentions. In this study, we investigated the effects of two typical aminoglycoside antibiotics on the aggregation of the model cyanobacterium, Synechococcus elongatus, and the dominating strain in algal blooms, Microcystis aeruginosa, via the analysis of zeta potentials, hydrophobicity, and extracellular polymeric substances (EPS) secretion. The results showed that low-level antibiotics promoted the aggregation of S. elongatus and M. aeruginosa by 40 and 18% under 0.10 and 0.02 µg/mL of kanamycin, respectively, which was mainly attributed to the combined effects of increased zeta potentials and the ratio between extracellular proteins and polysaccharides. Tobramycin exerted similar effects. Additionally, we discovered that at low pH (pH 5) and ionic strength (1 mM Na+ and 2 mM Mg2+), the inducing effects of antibiotics would be even larger than those with higher pH and ionic strength. As aggregation is important to cyanobacteria in either the basic physiology of biofilm formation or the algal bloom, our study demonstrated that low-level antibiotics exert ecological impacts via interfered aggregation. We believe this study will shed light on the mechanisms underlying antibiotic-induced biofilm formation and help with the evaluation of the environmental and ecological risks of antibiotics and other emerging pollutants.

[Preparation and evaluation of sustained-release microsphere of Sanguis Draconis in vitro].

OBJECTIVE: To prepare sustained-release microsphere containing extract of Sanguis Draconis and to measure its dissolution in vitro. METHOD: Sustained-release microsphere was prepared with polylactic acid (PLA) as carriers using the oil-in-water (O/W) emulsion solvent evaporation method. The powder particle's characteristics of sustainded-release microsphere were evaluated comprehensively, and its dissolution characteristics in vitro were studied. RESULT: The microsphere was round and its surface was smooth, drug-loading rate was 21.97% and the entrapment rate was 55.76%, the accumulative release percentage was 76. 71% in 16 hours. CONCLUSION: The sustained release effect of Sanguis Draconis microspheres was formed with potentially wide applications.

Influences of D-tyrosine on the stability of activated sludge flocs.

The sludge floc stability is essential for the solid/liquid separation in biological wastewater treatment. In this study, the effect of an exogenous d-tyrosine on the shear stability and surface characteristics of activated sludge flocs was investigated. Sludge flocs were found to be less stable in the addition of d-tyrosine. d-Tyrosine inhibited the production of extracellular polymeric substances (EPS) especially for the proteins. A high correlation coefficient was observed between the composition of EPS fraction and d-tyrosine content. In addition, the hydrophobicity of sludge flocs was reduced and the zeta potential was more negative with the content of d-tyrosine increased. A linear relationship between the extracellular polymeric substances and surface characteristics for sludge flocs indicated that the inhibited EPS production may be responsible for the instability of sludge upon the addition of d-tyrosine.