Starch swelling and its role in modern ceramic shaping technology

A microscopic real-time visualisation of potato starch swelling in aqueous media at 56°C is performed. The viscosity increase of a starch-water mixture during the swelling step is documented by viscometric measurements. The mechanism of ceramic green-body formation in a new ceramic shaping process, called “starch consolidation”, is discussed. In particular, the rheological changes during swelling and their concomitant structural background can explain certain discrepancies between model predictions and experimental findings observed in previous work.     

Selective covalent targeting of SARS-CoV-2 main protease by enantiopure chlorofluoroacetamide

The coronavirus disease 2019 (COVID-19) pandemic has necessitated the development of antiviral agents against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The main protease (M^pro) is a promising target for COVID-19 treatment. Here, we report an irreversible SARS-CoV-2 M^pro inhibitor possessing chlorofluoroacetamide (CFA) as a warhead for the covalent modification of M^pro. Ugi multicomponent reaction using chlorofluoroacetic acid enabled the rapid synthesis of dipeptidic CFA derivatives that identified 18 as a potent inhibitor of SARS-CoV-2 M^pro. Among the four stereoisomers, (R,R)-18 exhibited a markedly higher inhibitory activity against M^pro than the other isomers. Reaction kinetics and computational docking studies suggest that the R configuration of the CFA warhead is crucial for the rapid covalent inhibition of M^pro. Our findings highlight the prominent influence of the CFA chirality on the covalent modification of proteinous cysteines and provide the basis for improving the potency and selectivity of CFA-based covalent inhibitors.

Chlorofluoroacetamide (CFA) was used as the warhead for covalent targeting of SARS-CoV-2 M^pro. The chirality at CFA showed marked influence on inhibitory activity, suggesting stereospecific activation of CFA for cysteine modification in the protein.     

Thiazolidinedione Derivatives: In Silico,In Vitro,In Vivo,Antioxidant and Anti-Diabetic Evaluation

This work aimed to synthesize a new antihyperglycemic thiazolidinedione based on the spectral data. The DFT\B3LYP\6-311G** level of theory was used to investigate the frontier molecular orbitals (FMOs), chemical reactivity and map the molecular electrostatic potentials (MEPs) to explain how the synthesized compounds interacted with the receptor. The molecular docking simulations into the active sites of PPAR-γ and α-amylase were performed. The in vitro potency of these compounds via α-amylase and radical scavenging were evaluated. The data revealed that compounds (4–6) have higher potency than the reference drugs. The anti-diabetic and anti-hyperlipidemic activities for thiazolidine-2,4-dione have been investigated in vivo using the alloxan-induced diabetic rat model along with the 30 days of treatment protocol. The investigated compounds didn’t show obvious reduction of blood glucose during pre-treatments compared to diabetic control, while after 30 days of treatments, the blood glucose level was lower than that of the diabetic control. Compounds (4–7) were able to regulate hyperlipidemia levels (cholesterol, triglyceride, high-density lipoproteins and low- and very-low-density lipoproteins) to nearly normal value at the 30th day.     

Ethylene polymerizations with novel tantalum(V) aminopyridinato complex/MAO systems

The use of two kinds of tantalum(V) aminopyridinato complexes, bis(2-benzylaminopyridinato)trichlorotantalum(V) and trichlorobis[2,6-di(phenylamino)pyridinato-N,N′]-tantalum(V), activated by methylaluminoxane was studied in polymerization of ethylene. The activities of these homogeneous catalyst systems are comparable to those of metallocenes. The weight-average molecular weights (M̄_w) of the produced polyethylenes are between 60 000 and 200 000 and M̄_w/M̄_n ≈ 2.     

Asymmetric Markovian analysis of the polymerization mechanism of propene by ziegler-natta catalysis and external alkoxysilane donors

The formulae for conditional probabilities are derived with the term of NMR triad tacticities for the polymers whose polymerization process is described by an asymmetric Markovian process. The formulae obtained are applied to the polypropylene polymerized by Ziegler-Natta catalysis with external alkoxysilane donors. For both, unfractionated samples and heptane-insoluble fractions, four evidences are clarified as follows: Don the transformation from symmetric to (fluctuating) asymmetric sites the transformation of one (hereafter, L) site is much more enhanced than that of the other (D) site, 2) monotonous increase of isotacticity with an increase of the concentration of the donor is due to the increase of p_LL, 3) aromatic donors are more effective than aliphatic ones for the improvement of isotacticity, and 4) the improvement of isotacticity after an addition of alkoxysilane is not due to the contribution from both of L and D sites, but the competition between the larger positive contribution from the former and the smaller negative one from the latter.     

Polarity Directed Appraisal of Pharmacological Potential and HPLC-DAD Based Phytochemical Profiling of Polygonum glabrum Willd

The present study was designed to evaluate polarity-dependent extraction efficiency and pharmacological profiling of Polygonum glabrum Willd. Crude extracts of leaves, roots, stems, and seeds, prepared from solvents of varying polarities, were subjected to phytochemical, antioxidant, antibacterial, antifungal, antidiabetic, and cytotoxicity assays. Maximum extraction yield (20.0% w/w) was observed in the case of an acetone:methanol (AC:M) root extract. Distilled water:methanol (W:M) leaves extract showed maximum phenolic contents. Maximum flavonoid content and free radical scavenging potential were found in methanolic (M) seed extract. HPLC-DAD quantification displayed the manifestation of substantial quantities of quercetin, rutin, gallic acid, quercetin, catechin, and kaempferol in various extracts. The highest ascorbic acid equivalent total antioxidant capacity and reducing power potential was found in distilled water roots and W:M leaf extracts, respectively. Chloroform (C) seeds extract produced a maximum zone of inhibition against Salmonella typhimurium. Promising protein kinase inhibition and antifungal activity against Mucor sp. were demonstrated by C leaf extract. AC:M leaves extract exhibited significant cytotoxic capability against brine shrimp larvae and α-amylase inhibition. Present results suggest that the nature of pharmacological responses depends upon the polarity of extraction solvents and parts of the plant used. P. glabrum can be considered as a potential candidate for the isolation of bioactive compounds with profound therapeutic importance.     

27 Years of Catalytic Carbonylative Coupling Reactions in Hungary (1994–2021)

Palladium-catalyzed carbonylation reactions, in the presence of nucleophiles, serve as very potent tools for the conversion of aryl and alkenyl halides or halide equivalents to carboxylic acid derivatives or to other carbonyl compounds. There are a vast number of applications for the synthesis of simple building blocks as well as for the functionalization of biologically important skeletons. This review covers the history of carbonylative coupling reactions in Hungary between the years 1994 and 2021.