Enzyme-free impedimetric glucose sensor based on gold nanoparticles/polyaniline composite film

A non-enzymatic impedimetric glucose sensor was fabricated based on the adsorption of gold nanoparticles (GNPs) onto conductive polyaniline (PANI)-modified glassy carbon electrode (GCE). The modified electrode (GCE/PANI/GNPs) was characterized by using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and scanning electron microscopy (SEM). The determination of glucose concentration was based on the measurement of EIS with the mediation of electron transfer by ferricyanide ([Fe(CN)₆]^3?). The [Fe(CN)₆]^3? is reduced to ferrocyanide ([Fe(CN)₆]^4?), which in turn is oxidized at GCE/PANI/GNPs. An increase in the glucose concentration results in an increase in the diffusion current density of the [Fe(CN)₆]^4? oxidation, which corresponds to a decrease in the faradaic charge transfer resistance (R _ct). A wide linear concentration range from 0.3 to 10 mM with a lower detection limit of 0.1 mM for glucose was obtained. The proposed sensor shows high sensitivity, good reproducibility, and stability. In addition, the sensor exhibits no interference from common interfering substances such as ascorbic acid, acetaminophen, and uric acid.     

Beneficial Effects of Epigallocatechin-3-O-Gallate,Chlorogenic Acid,Resveratrol, and Curcumin on Neurodegenerative Diseases

Many observational and clinical studies have shown that consumption of diets rich in plant polyphenols have beneficial effects on various diseases such as cancer, obesity, diabetes, cardiovascular diseases, and neurodegenerative diseases (NDDs). Animal and cellular studies have indicated that these polyphenolic compounds contribute to such effects. The representative polyphenols are epigallocatechin-3-O-gallate in tea, chlorogenic acids in coffee, resveratrol in wine, and curcumin in curry. The results of human studies have suggested the beneficial effects of consumption of these foods on NDDs including Alzheimer’s and Parkinson’s diseases, and cellular animal experiments have provided molecular basis to indicate contribution of these representative polyphenols to these effects. This article provides updated information on the effects of these foods and their polyphenols on NDDs with discussions on mechanistic aspects of their actions mainly based on the findings derived from basic experiments.     

Iridoids and Cytotoxic Terpenes from Lindenbergia indica

Chemistry of Natural Compounds - A new iridoid aglycone, 1-acetylscyphiphin B2, along with two known iridoid aglycones and three triterpenes, was isolated from the whole plant of Lindenbergia...     

A Dispersion Corrected DFT Investigation of the Inclusion Complexation of Dexamethasone with β-Cyclodextrin and Molecular Docking Study of Its Potential Activity against COVID-19

The encapsulation mode of dexamethasone (Dex) into the cavity of β-cyclodextrin (β-CD), as well as its potential as an inhibitor of the COVID-19 main protease, were investigated using density functional theory with the recent dispersion corrections D4 and molecular docking calculations. Independent gradient model and natural bond orbital approaches allowed for the characterization of the host–guest interactions in the studied systems. Structural and energetic computation results revealed that hydrogen bonds and van der Waals interactions played significant roles in the stabilization of the formed Dex@β-CD complex. The complexation energy significantly decreased from −179.50 kJ/mol in the gas phase to −74.14 kJ/mol in the aqueous phase. A molecular docking study was performed to investigate the inhibitory activity of dexamethasone against the COVID-19 target protein (PDB ID: 6LU7). The dexamethasone showed potential therapeutic activity as a SARS CoV-2 main protease inhibitor due to its strong binding to the active sites of the protein target, with predicted free energy of binding values of −29.97 and −32.19 kJ/mol as calculated from AutoDock4 and AutoDock Vina, respectively. This study was intended to explore the potential use of the Dex@β-CD complex in drug delivery to enhance dexamethasone dissolution, thus improving its bioavailability and reducing its side effects.     

Isolation,Characterization and Pharmacological Investigations of a New Phenolic Compound along with Four Others Firstly Reported Phytochemicals from Glycosmis cyanocarpa (Blume) Spreng

Plants are serving the mankind with important bioactive phytochemicals from the very ancient ages to develop novel therapeutics against different disease states. Glycosmis cyanocarpa (Blume) Spreng is a plant from the Rutaceae family and a very less explored species from the Glycosmis genus. Thus, this present study was intended to present the chemical and biological investigation of Glycosmis cyanocarpa (Blume) Spreng. The chemical investigation resulted in the isolation of one new phenolic compound to the best of our knowledge which is (4-(3-hydroxy-2-methylpropyl)-2-methoxyphenol) (1) along with four known compounds that are isolated for the first time from this species- 3-methyl-1H-indole (2), Tri-transpoly-cis prenol-12 (3), Stigmasterol (4) and β-sitosterol (5). Their chemical structures were elucidated based on extensive spectroscopic methods, including 1D and 2D NMR, and comparison with the available literature data. Isolated phytochemicals were further investigated to unveil their antioxidant properties with IC₅₀ values (ranged from 9.97–75.48 µg/mL), cytotoxicity with LC₅₀ values (ranged from 1.02–1.92 µg/mL), and antibacterial properties against some selected Gram (+) ve and Gram (−) ve bacteria. Among the compounds, 3-methyl-1H-indole (2) was found to be the most active against Staphylococcus aureus. Moreover, the phenolic compound (1) and the alkaloid (2) revealed the highest antioxidant (9.97 µg/mL) and cytotoxic activities (1.02 µg/mL), respectively. Thus, the isolation of these bioactive phytochemicals from the plant revealed a new perception in the study arena of drug discovery and the findings may ease the development and discovery of novel therapeutics. Further investigations are still recommended to understand their exact molecular mechanism and toxicological impact.     

Isolation and In Silico Prediction of Potential Drug-like Compounds with a New Dimeric Prenylated Quinolone Alkaloid from Zanthoxylum rhetsa (Roxb.) Root Extracts Targeted against SARS-CoV-2 (Mpro)

A new dimeric prenylated quinolone alkaloid, named 2,11-didemethoxy-vepridimerine A, was isolated from the root bark of Zanthoxylum rhetsa, together with twelve known compounds. The structure of the new compound was elucidated on the basis of spectroscopic investigations (NMR and Mass). The interaction of the isolated compounds with the main protease of SARS-CoV-2 (Mpro) was evaluated using molecular docking followed by MD simulations. The result suggests that 2,11-didemethoxy-vepridimerine A, the new compound, has the highest negative binding affinity against the Mpro with a free energy of binding of −8.5 Kcal/mol, indicating interaction with the Mpro. This interaction was further validated by 100 ns MD simulation. This implies that the isolated new compound, which can be employed as a lead compound for an Mpro-targeting drug discovery program, may be able to block the action of Mpro.