Polymer solubility mechanism in ionic liquids: 1H-NMR spectra and two-parameter hydrogen bonding analysis.

Understanding the polymer solubility in ionic liquids (ILs) is important for polymer processing or polymeric material preparation. Previously, two-parameter H-bonding analysis has been proposed to clarify that polymer solubility in ILs is dominated by H-bonding interactions (Y. F. Yuan et al., Phys. Chem. Chem. Phys., 2021, 23, 21893-21900). In the present work, 1H-NMR spectra are adopted to characterize the H-bonding interactions between polymers and ILs, which provide a microscopic relation between polymer solubility and two-parameter H-bonding analysis.

Expression, purification and refolding of pro-MMP-2 from inclusion bodies of E. coli.

MMP-2 has been reported as the most validated target for cancer progression and deserves further investigation. However, due to the lack of methods for obtaining large amounts of highly purified and bioactive MMP-2, identifying specific substrates and developing specific inhibitors of MMP-2 remains extremely difficult. In this study, the DNA fragment coding for pro-MMP-2 was inserted into plasmid pET28a in an oriented manner, and the resulting recombinant protein was effectively expressed and led to accumulation as inclusion bodies in E. coli. This protein was easy to purify to near homogeneity by the combination of common inclusion bodies purification procedure and cold ethanol fractionation. Then, our results of gelatin zymography and fluorometric assay revealed that pro-MMP-2 at least partially restored its natural structure and enzymatic activity after renaturation. We obtained approximately 11 mg refolded pro-MMP-2 protein from 1 L LB broth, which was higher than other strategies previously reported. In conclusion, a simple and cost-effective procedure for obtaining high amounts of functional MMP-2 was developed, which would contribute to the progress of studies on the gamut of biological action of this important proteinase. Furthermore, our protocol should be appropriate for the expression, purification, and refolding of other bacterial toxic proteins.

Polymer solubility in ionic liquids: dominated by hydrogen bonding.

Polymer solubility in ionic liquids (ILs) cannot be predicted by the solubility parameter approach based on the "like dissolves like" principle. According to the Kamlet-Abraham-Taft (KAT) multi-parameter polarity scale, ILs can be categorized on the basis of hydrogen-bond acidity or basicity ones. The experimental observations, that acidic ILs easily dissolve basic polymers and basic ILs dissolve acidic polymers, reflect the complementary nature of hydrogen-bonding interactions. A quantitative hydrogen-bonding analysis is proposed for predicting the solubility by taking the product of ΔαΔß as an indicator of the competition between cross-association and self-association hydrogen bonding (H-bonding), where Δα is the difference of acidity parameters between the polymer and IL, and Δß is the difference of basicity. This solubility criterion has been validated by the solubility data of 19 polymers (11 acidic and 8 basic) in 11 ILs (7 acidic and 4 basic). These principles based on KAT parameters can be applied to other systems dominated by hydrogen bonding.

Plasma metabolite profiles of Alzheimer's disease and mild cognitive impairment.

Previous studies have demonstrated altered metabolites in samples of Alzheimer's disease (AD) patients. However, the sample size from many of them is relatively small and the metabolites are relatively limited. Here we applied a comprehensive platform using ultraperformance liquid chromatography-time-of-flight mass spectrometry and gas chromatography-time-of-flight mass spectrometry to analyze plasma samples from AD patients, amnestic mild cognitive impairment (aMCI) patients, and normal controls. A biomarker panel consisting of six plasma metabolites (arachidonic acid, N,N-dimethylglycine, thymine, glutamine, glutamic acid, and cytidine) was identified to discriminate AD patients from normal control. Another panel of five plasma metabolites (thymine, arachidonic acid, 2-aminoadipic acid, N,N-dimethylglycine, and 5,8-tetradecadienoic acid) was able to differentiate aMCI patients from control subjects. Both biomarker panels had good agreements with clinical diagnosis. The 2 panels of metabolite markers were all involved in fatty acid metabolism, one-carbon metabolism, amino acid metabolism, and nucleic acid metabolism. Additionally, no altered metabolites were found among the patients at different stages, as well as among those on anticholinesterase medication and those without anticholinesterase medication. These findings provide a comprehensive global plasma metabolite profiling and may contribute to making early diagnosis as well as understanding the pathogenic mechanism of AD and aMCI.

[Chemical constituents in Thunbergia from Africa].

OBJECTIVE: To investigate the chemical compounds from the ethanol extract with inhibitory effects against aldose reductase from Thunbergia. METHOD: Guided by anti-aldose reductase assay, compounds from the bioactive fraction (ethyl acetate extract) were separated and purified by various chromatographic methods including silica gel, Sephadex LH-20, and reversed-phase HPLC. Their structures were indentified based on analysis of the spectroscopic data including 1D and 2D NMR data. RESULT: Eight compounds were obtained and identified as 8-hydroxy-8-methyl-9-methene-cyclopentane [7,11] -1,4, 6-trihydroxy-tetrahydronaphthalene-12-one, named as thunbergia A (1), 3,4-dihydro-4,5,8-trihydroxy-2-(3-methyl-2-butenyl) naphtha[2,3-b] oxiren-1(2H)-one (2), 8-(beta-gluco pyranosyloxy)-3,4-dihydro-2-(3-methyl-2-butenyl)naphtha [2,3-b] oxiren-1(2H)-one (3), galangin (4), quercetin (5), luteolin (6), 5,6,3',4'-tetrahydroxy -3,7-dimethoxy-flavone (7) and upeol (8). CONCLUSION: Thunbergia A was a new derivative of tetrahydronaphthalene, and compounds 2 and 3 were separated from the genus Thunbergia for the first time.

[Effects of drug serum of plantaginis semen on bone formation function of rat osteoblast in vitro].

OBJECTIVE: To study the influence of Plantaginis Semen on cell proliferation, differentiation and function of rat osteoblasts, and investigate the regulation effects of rat osteoblast epithelial sodium channel (ENaC) on bone formation. METHODS: The animal serum was prepared by serum pharmacology means. The cells were got by separating and inducing the SD neonatal rat's skull bone. Cell proliferation and differentiation were evaluated by CCK-8 assay kit and AKP assay kit respectively. Regulation effects on mRNA expression of ENaC and osteogenesis gene were investigated by semi-quantitative PCR. RESULTS: Plantaginis Semen stimulated the osteoblasts proliferation and differentiation,the difference between treatment group and control group had statistical significance (P < 0.01) in a dose-dependent manner. The effects of Plantaginis Semen serum on alpha-ENaC gene expression paralleled those on osteogenic gene (OC, ALP, OP) expression level. CONCLUSION: Plantaginis Semen stimulates proliferation, differentiation and the mRNA expression of ENaC and osteogenesis gene in rat osteoblasts. Our results suggest that ENaC participate in the effects of Plantaginis Semen serum on osteoblast bone formation. Regulation of ENaC channel expression and function may provide a new clue for research on treatment of osteoporosis with traditional Chinese medicine.

[Adventitious root induction and in vitro culture of Panax notoginseng].

OBJECTIVE: To investigate the induction and culture of adventitious root of Panax notoginseng. METHOD: Three ways, induction from the explants of three-year-old P. notoginseng. The explants of regenerated shoots and calluses, were used to induce adventitious roots. The effects of 2, 4-dichlorophenoxyacetic acid, indole-3-butyric acid and naphthylacetic acid on adventitious root induction were investigated respectively. The effects of four modes of separating adventitious roots from the parent tissues on culture in vitro were compared. RESULT: Adventitious roots were successfully induced by three methods, of which the young flower bud callus was the best material for the induction of adventitious root. Indole-3-butyric acid possessed the strongest potency for induction. The liquid culture system was established by continuous culture of adventitious roots together with their parent tissues before separated. CONCLUSION: The acquisition and culture in vitro in liquid culture system of adventitious roots of P. notoginseng lay a foundation for the next investigation.