The synthesis, carbonic anhydrase and acetylcholinesterase inhibition effects of sulfonyl chloride moiety containing oxazolidinones using an intramolecular aza-Michael addition

Oxazolidinones are used as various potent antibiotics, in organisms it acts as a protein synthesis inhibitor, focusing on an initial stage that encompasses the tRNA binding process. Novel intramolecular aza-Michael reactions devoid of metal catalysts have been introduced in an oxazolidone synthesis pathway, different from α,β-unsaturated ketones. Oxazolidinone derivatives were tested against acetylcholinesterase (AChE), carbonic anhydrase I and II (hCA I and hCA II) enzymes. All the synthesized compounds had potent inhibition effects with Ki values in the range of 13.57 ± 0.98 - 53.60 ± 6.81 µM against hCA I and 9.96 ± 1.02 - 46.35 ± 3.83 µM against hCA II in comparison to the acetazolamide (AZA) (Ki = 50.46 ± 6.17 µM for hCA I) and for hCA II (Ki = 41.31 ± 5.05 µM). Also, most of the compounds demonstrated potent inhibition ability towards AChE enzyme with Ki values 78.67-231.75 nM and compared to tacrine (TAC) as standard clinical inhibitor (Ki = 142.48 nM). Furthermore, ADMET analysis and molecular docking were calculated using the AChE, hCA I and hCA II enzyme proteins to correlate the data with the experimental data. In this work, recent applications of a stereoselective aza-Michael reaction as an efficient tool for of nitrogen-containing heterocyclic scaffolds and their useful to pharmacology analogs are reviewed and summarized.Communicated by Ramaswamy H. Sarma.

A safe alternative synthesis of primary carbamates from alcohols; in vitro and in silico assessments as an alternative acetylcholinesterase inhibitors

Carbamates are important molecules because they are used in various biochemical processes. In this study, effective alternative method for the synthesis of primary carbamates from alcohols was developed in the presence of chlorosulfonyl isocyanate (CSI) in pyridine at room temperature in mild conditions. The primary carbamates were synthesized excellent yield. This method is easy, practical, and inexpensive without any additive, metal, or catalyst. Alzheimer's disease (AD) is a neurodegenerative disease and has been reported to affect approximately 50 million people worldwide in 2020. Drugs that reversibly inhibit the acetylcholinesterase (AChE) activity are used for the treatment of AD. For this reason, there is a growing interest in developing alternative AChE inhibitors. Concordantly, Anti-anticholinesterase activity of synthesized carbamate derivatives was investigated as an alternative AChE inhibitors. In order to determine the inhibitory effect of these molecules, IC50, and Ki values and inhibition types were determined. According to the Ki results, the most effective inhibitors were 3 b and 3e with the Ki values of 22 and 38 µM, respectively. It was found that all molecules showed competitive inhibition type. For clarify the inhibitors-enzyme interactions, molecular docking studies were performed and possible binding interactions between the synthesized molecules and AChE were determined. Additionally, the pharmacokinetic and properties of the synthesized molecules were evaluated in silico.Communicated by Ramaswamy H. Sarma.

Characterization and kinetics analysis of the thermal decomposition of the humic substance from hazelnut husk

A humic substance was obtained from hazelnut husk using an alkali extraction. The chemical and morphological structure of the humic matter was characterized via elemental analysis, Fourier transform infrared spectrometry (FTIR), nuclear magnetic resonance, Brunauer-Emmet-Teller (BET) analysis, scanning electron microscopy (SEM), and thermogravimetric-FTIR (TG-FTIR). In addition, thermal analysis measurements TG analysis-differential thermogravimetry/differential scanning calorimetry (TGA-DTG/DSC) were performed under dynamic air conditions to better determine the origin, physical and chemical structure, and decomposition process of the humic matter. The Kissinger-Akahira-Sunose (KAS) and Flynn-Wall-Ozawa (FWO) methods were used to calculate the kinetic parameters of the high-temperature decomposition process. It was observed that the activation energy values were almost constant at certain conversion and temperature intervals. In addition, the structure of the humic substance at different temperatures was also investigated via FTIR analysis. It was found that the obtained humic substance had a very stable structure and decomposed at a high temperature. The stability of the humic matter can be a useful tool in the environmental quality research of soil.

One-pot synthesis of oxazolidinones and five-membered cyclic carbonates from epoxides and chlorosulfonyl isocyanate: theoretical evidence for an asynchronous concerted pathway

The one-pot reaction of chlorosulfonyl isocyanate (CSI) with epoxides having phenyl, benzyl and fused cyclic alkyl groups in different solvents under mild reaction conditions without additives and catalysts was studied. Oxazolidinones and five-membered cyclic carbonates were obtained in ratios close to 1:1 in the cyclization reactions. The best yields of these compounds were obtained in dichloromethane (DCM). Together with 16 known compounds, two novel oxazolidinone derivatives and two novel cyclic carbonates were synthesized with an efficient and straightforward method. Compared to the existing methods, the synthetic approach presented here provides the following distinct advantageous: being a one-pot reaction with metal-free reagent, having shorter reaction times, good yields and a very simple purification method. Moreover, using the density functional theory (DFT) method at the M06-2X/6-31+G(d,p) level of theory the mechanism of the cycloaddition reactions has been elucidated. The further investigation of the potential energy surfaces associated with two possible channels leading to oxazolidinones and five-membered cyclic carbonates disclosed that the cycloaddition reaction proceeds via an asynchronous concerted mechanism in gas phase and in DCM.

Synthesis of oxazolidinone from enantiomerically enriched allylic alcohols and determination of their molecular docking and biologic activities

Enantioselective synthesis of functionalized cyclic allylic alcohols via kinetic resolution in transesterifcation with different lipase enzymes has been developed. The influence of the enzymes and temperature activity was studied. By determination of ideal reaction conditions, byproduct formation is minimized; this made it possible to prepare enantiomerically enriched allylic alcohols in high ee's and good yields. Enantiomerically enriched allylic alcohols were used for enantiomerically enriched oxazolidinone synthesis. Using benzoate as a leaving group means that 1 mol % of potassium osmate is necessary and can be obtained high yields 98%. Inhibitory activities of enantiomerically enriched oxazolidinones (8, 10 and 12) were tested against human carbonic anhydrase I and II isoenzymes (hCA I and hCA II), acetylcholinesterase (AChE), and α-glycosidase (α-Gly) enzymes. These enantiomerically enriched oxazolidinones derivatives had K_i values in the range of 11.6 ± 2.1-66.4 ± 22.7 nM for hCA I, 34.1 ± 6.7-45.2 ± 12.9 nM for hCA II, 16.5 ± 2.9 to 35.6 ± 13.9 for AChE, and 22.3 ± 6.0-70.9 ± 9.9 nM for α-glycosidase enzyme. Moreover, they had high binding affinity with -5.767, -6.568, -9.014, and -8.563 kcal/mol for hCA I, hCA II, AChE and α-glycosidase enzyme, respectively. These results strongly supported the promising nature of the enantiomerically enriched oxazolidinones as selective hCA, AChE, and α-glycosidase inhibitors. Overall, due to these derivatives' inhibitory potential on the tested enzymes, they are promising drug candidates for the treatment of diseases like glaucoma, leukemia, epilepsy; Alzheimer's disease; type-2 diabetes mellitus that are associated with high enzymatic activity of CA, AChE, and α-glycosidase.