Copper-catalyzed diastereoselective synthesis of ß-boryl-α-quaternary carbon carboxylic esters.

Cu(i)-Catalyzed diastereoselective carboboration of α-alkyl-substituted α,ß-unsaturated carboxylic esters to produce ß-boryl-α-quaternary carbon esters was developed. The carbon skeletons of dialkyl sulfates, primary allyl halides, and benzyl bromides were transferred to the α-position of the substrates to provide products in moderate to good yields with a diastereoselectivity of >95% in most cases. Substrates bearing a ß-(hetero)aryl substituent gave higher diastereoselectivities than those bearing a linear ß-alkyl substituent. The crystal structure of the potassium trifluoroborate derivative shows that the reactions probably go through a copper(i) enolate intermediate and the diastereoselectivity arises from the electrophilic attack of electrophiles to the less hindered side of the enolates.

Copper-catalyzed, stereoconvergent, cis-diastereoselective borylative cyclization of ω-mesylate-α,ß-unsaturated esters and ketones.

The Cu(i)-catalyzed stereoconvergent borylative cyclization of ω-mesylate-α,ß-unsaturated compounds is facilitated by a simple Cu-bisphosphine catalyst. This reaction provides a novel route to cis-ß-boron-substituted five- and six-membered carbocycle and heterocycle esters. Mechanistic studies indicate that stereoconvergence and cis-substitution likely stem from the rapid enolation of the borylcopper adduct with the substrate double bond and the formation of a five-membered intermediate, respectively.

Quantitative Methylation of Lignin Monomers Using Tetrabutylammonium Hydroxide and MeI and Applications in Organic Synthesis.

Efficient O-alkylation of phenols and carboxylic acids has essential applications in organic synthesis. A mild alkylation method for phenolic and carboxylic OH groups is developed using alkyl halides as alkylation reagents and tetrabutylammonium hydroxide as a base, and lignin monomers can be fully methylated in quantitative yields. Additionally, phenolic and carboxylic OH groups can be alkylated by different alkyl halides in one pot in different solvent systems.

Exploring the toxicity of biodegradable microplastics and imidacloprid to earthworms (Eisenia fetida) from morphological and gut microbial perspectives.

Biodegradable microplastics (BMPs) pose serious environmental problems to soil organisms, and their adsorption capacity might make pesticides more dangerous for soil organisms. Therefore, in this study, polylactic acid (PLA) BMPs and imidacloprid (IMI) were used as a representative of BMPs and pesticides, respectively. Eisenia fetida was used as a test animal to investigate the effects of environmentally relevant concentrations of single and compound contaminated PLA BMPs and IMI on mortality, growth, number of offspring, tissue damage, and gut microorganisms of E.fetida. Exposure to PLA BMPs treatment and PLA BMPs + IMI treatment resulted in a sustained increase in E.fetida mortality, reaching 16.7% and 26.7%, respectively. The growth inhibition rate of single treatments was significantly increased. The compound contamination had the greatest effect on E.fetida offspring compared to the control. PLA BMPs and IMI cause histological damage to E.fetida, with the compound treatment causing the most severe damage. Based on the results of 16S sequencing, the bacterial communities in E.fetida gut and soil treated to PLA BMPs and IMI were significantly different. PLA BMPs + IMI treatment suppresses the abundance and diversity of E.fetida gut microorganisms, disrupting the homeostasis of bacterial communities and causing immune and metabolic dysfunction. These findings highlight the more severe damage of combined PLA BMPs and IMI pollution to E.fetida, and help to assess the risk of earthworm exposure to environmentally relevant concentrations of PLA BMPs and IMI.

4-hydroxylonchocarpin and corylifol A: The potential hepatotoxic components of Psoralea corylifolia L.

Psoralea corylifolia L. (P. corylifolia) has attracted increasing attention because of its potential hepatotoxicity. In this study, we used network analysis (toxic component and hepatotoxic target prediction, proteinprotein interaction, GO enrichment analysis, KEGG pathway analysis, and molecular docking) to predict the components and mechanism of P. corylifolia-induced hepatotoxicity and then selected 4-hydroxylonchocarpin and corylifol A for experimental verification. HepG2 cells were treated with low, medium, and high concentrations of 4-hydroxylonchocarpin or corylifol A. The activities of ALT, AST, and LDH in cell culture media and the MDA level, SOD activity, and GSH level in cell extracts were measured. Moreover, apoptosis, ROS levels, and mitochondrial membrane potential were evaluated. The results showed that the activities of ALT, AST, and LDH in the culture medium increased, and hepatocyte apoptosis increased. The level of MDA increased, and the activity of SOD and level of GSH decreased, and the ROS level increased with 4-hydroxylonchocarpin and corylifol A intervention. Furthermore, the mitochondrial membrane potential decreased in the 4-hydroxylonchocarpin and corylifol A groups. This study suggests that 4-hydroxylonchocarpin and corylifol A cause hepatocyte injury and apoptosis by inducing oxidative stress and mitochondrial dysfunction, suggesting that these compounds may be the potential hepatotoxic components of P. corylifolia.

Potential of non-thermal discharge plasmas for activated sludge settling: effects and underlying mechanisms.

With increase in the construction of urban sewage treatment plants, the output of sludge also surges. Therefore, it is highly important to explore effective ways to reduce the production of sludge. In this study, non-thermal discharge plasmas were proposed to crack the excess sludge. High sludge settling performance was obtained, and the settling velocity (SV30) dramatically decreased from the initial value of 96% to 36% after 60 min of treatment at 20 kV, accompanied by 28.6%, 47.5%, and 76.7% decreases in mixed liquor suspended solids (MLSS), sludge volume index (SVI), and sludge viscosity, respectively. Acidic conditions improved the sludge settling performance. The presence of Cl- and NO3- slightly promoted the SV30, but CO32- has adverse effects. ·OH and O2˙- in the non-thermal discharge plasma system contributed to the sludge cracking, especially for ·OH. These reactive oxygen species destroyed the sludge floc structure; as a result, the total organic carbon and dissolved chemical oxygen demand obviously increased, the average particle size of the sludge decreased, and the number of coliform bacteria was also reduced. Furthermore, the microbial community abundance and diversity both decreased in the sludge after the plasma treatment.

Polygonatum sibiricum polysaccharide alleviates inflammatory cytokines and promotes glucose uptake in high­glucose­ and high­insulin­induced 3T3­L1 adipocytes by promoting Nrf2 expression.

Polygonatum sibiricum polysaccharide (PSP) has been shown to alleviate hyperglycemia and reduce oxidative stress to delay the progression of diabetic retinopathy and cataracts. However, its role and underlying mechanisms in regulating type 2 diabetes mellitus (T2DM) remain unclear. Nuclear factor erythroid 2­related factor 2 (Nrf2) activation plays a protective role in T2DM. The present study focused on the effect of PSP on inflammatory cytokine secretion and Nrf2 expression in the adipocytes of T2DM patients. In this study, high­glucose­ and high­insulin­induced 3T3­L1 adipocytes were used to mimic insulin­resistant (IR)­3T3­L1 adipocytes. Furthermore, the effect and underlying mechanisms of PSP on inflammation and glucose uptake in IR­3T3­L1 adipocytes were investigated. The present study found that proliferation after 50, 100 and 250 µg/ml PSP treatment had no significant change in normal 3T3­L1 adipocytes. A total of 50, 100 and 250 µg/ml of PSP also alleviated IL­1ß, IL­6, and TNF­α levels and promoted proliferation, glucose uptake, and glucose transporter 4 expression in IR­3T3­L1 adipocytes. Furthermore, 50, 100 and 250 µg/ml PSP promoted Nrf2 and HO­1 expression. However, silencing Nrf2 expression reversed the effect of 100 µg/ml PSP in IR­3T3­L1 adipocytes. In conclusion, these results suggest that PSP alleviates inflammatory cytokines and promotes glucose uptake in IR­3T3­L1 adipocytes by promoting Nrf2 expression. PSP may be a potential therapeutic agent for T2DM treatment by promoting Nrf2 expression.

Optimizing the synthetic nitrogen rate to balance residual nitrate and crop yield in a leguminous green-manured wheat cropping system.

Nitrate that originates from agriculture is linked to a series of deleterious environmental consequences that are closely related to human health. Therefore, it is vital to design cropping systems that can produce acceptable crop yields while minimizing the impact of surplus soil nitrate. To develop quantitative estimations, data from 2008 to 2016 were evaluated using multiple regression models. A split-plot field experiment was conducted, with the main treatments of growing Huai bean, soybean and mung bean in summer as leguminous green manure (LGM) while fallow as the control. Four synthetic N rates (0, 108, 135 and 162kgha-1) were applied as sub-treatments at wheat seeding. The N accumulation for LGMs ranged from 61 to 90kgha-1, and that of Huai bean was 46% higher than the average value of soybean and mung bean (P<0.05). The threshold of total N for wheat to produce the highest yields was 141kgha-1. For the LGM treatments, residual nitrate accumulated below the root-zone soil was not significantly increased even when their total N inputs were higher than that of fallow with 162kgha-1 of synthetic N. The estimated nitrate-holding capacity of the root-zone soil for the LGM treatments ranged from 104 to 117kgha-1, and the corresponding synthetic N limits were 97-130kgha-1. Considering the target of producing high wheat yields while keeping the residual nitrate in the root-zone soil, the optimal synthetic N rates for LGM treatments were 52-80kgha-1. In conclusion, growing LGMs can maintain high crop yield and mitigate the environmental impact of residual nitrate by substantially replacing the synthetic N to avoid nitrate leaching to deeper soils.