Octyl 6-O-hexanoyl-β-D-glucopyranosides: Synthesis, PASS, antibacterial, in silico ADMET, and DFT studies

Chemical composition, pesticidal activities and in-silico investigation of Hedychium spicatum Sm. chloroform extract

The present study aimed to identify the bioactive constituents in the chloroform extract of H. spicatum rhizomes (HS-RCLE), further evaluated for its in-vitro pesticidal activities validating via molecular docking techniques. GC/MS analysis of HS-RCLE identified 14 compounds contributing 84.1 % of the total composition. The extract was dominated by oxygenated sesquiterpenes (43.1 %) with curcumenone (25.2 %) and coronarin E (14.8 %) as the major compounds. The extract recorded 89.4 % egg hatchability inhibition and 82.6 % immobility of Meloidogyne incognita, 66.7 % insecticidal activity on Spodoptera litura, 100 % phytotoxic activity on Raphanus raphanistrum seeds, and 74.7 % anti-fungal activity on Curvularia lunata at the respective highest dose studied. The biological activities were furthermore validated by using docking studies on certain proteins/enzymes namely acetylcholinesterase (PBD ID: IC2O), carboxylesterase (PDB ID: 1CI8), acetohydroxyacid synthase (PBD ID: 1YHZ) and trihydroxy naphthalene reductase (PBD ID: 3HNR). The bioactivity of the major constituents of the extract was predicted with the help of in silico PASS studies. HS-RCLE was observed to be a viable alternative source of natural pesticidal agents and paves the way for further studies on its mechanistic approaches and field trials to ascertain its pesticidal studies.

In Silico Testing of Some Protected Galactopyranose as SARS-CoV-2 Main Protease Inhibitors

An outbreak of novel Coronavirus disease (COVID-19 or 2019-nCoV) due to the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) has already demonstrated a fatal death toll all over the world. To cure this viral infection, a number of compounds of different categories have been investigated in silico. Some of the compounds showed better binding energy with COVID-19-related proteins. However, until now there is no appropriate drug except a vaccine. It was found that many antifungal drugs are used for COVID-19 patients in hospitals. Many monosaccharide esters have been reported to have antifungal potential. Thus, in the present study, some protected galactopyranose esters are chosen for molecular docking with SARS-CoV-2 main proteases (PDB id: 7BQY and 6LU7). A docking study revealed that galactopyranose esters 5-8 have very good docking scores (-8.4 to -6.5 kcal/mol) compared to the standard drugs azithromycin, remdesivir, and hydroxychloroquine. To explain such good scores interaction between amino acid residues of proteins and compounds in their docked complexes are calculated and duly discussed in this study.

DFT Based Comparative Studies of Some Glucofuranose and Glucopyranoside Esters and Ethers

Carbohydrate-based molecular scaffolding received significant interest due to its impact on the drug discovery and development in synthetic carbohydrate chemistry during the last couple of decades. In this respect, four glucose compounds in the furanose and pyranose forms with ester and ether functionality were selected for their structural, thermodynamic and chemical reactivity studies. PASS predication indicated that the glucose in the six-membered pyranose form was more prone to biological properties compared to their five-membered furanose form. Also, in the pyranose form acetate ester (3) had more potentiality than the ethyl ether (4). The HOMO-LUMO energy gaps were almost similar for both monosubstituted furanose and pyranose glucose indicating their almost similar reactivities. It was also inferred that these 6-O-substituted compounds followed Lipinski’s rule with the acceptable range of ADMET levels, and hence, safe from lethal proarrhythmic risks. Hopefully, these results can be used in the near future for their probable pharmaceutical use without any remarkable toxicity.

Chemical Reactivity Descriptors and Molecular Docking Studies of Octyl 6-O-hexanoyl-β-D-glucopyranosides

The present study describes different chemical reactivity predictions of 6-O-hexanoylation of octyl β-D-glucopyranosides prepared from octyl β-D-glucopyranoside (OBG). Also, molecular docking of the OBGs was conducted against SARS-CoV-2 main protease (6LU7), urate oxidase (Aspergillus flavus; 1R51) and glucoamylase (Aspergillus niger; 1KUL). DFT optimization indicated that glucoside 1 and its ester derivatives 2-7 exist in 4C1 conformation with C1 symmetry. Interestingly, the addition of ester group(s) decreased the HOMO-LUMO gap (Δԑ) of glucosides indicating their good chemical reactivities, whereas the other chemical reactivity descriptors indicated their moderate reactive nature. This fact of moderate reactivity was confirmed by their molecular docking with 6LU7, 1R51 and 1KUL. All the esters showed a moderate binding affinity with these three proteins. More importantly, incorporation of the ester group(s) increased binding affinity with 6LU7 and 1R51, whereas decreased with 1KUL as compared to non-ester OBG 1.

Octyl 6-O-hexanoyl-β-D-glucopyranosides: Synthesis, PASS, antibacterial, in silico ADMET, and DFT studies

An analytical procedure for the analysis of carotenoids in marine sediments rich in organic matter has been developed. Analysis of these compounds is difficult; the application of methods used by other authors required optimization for the samples studied here. The analytical procedure involved multiple ultrasound-assisted extraction with acetone followed by liquid-liquid extraction (acetone extract:benzene:water - 15:1:10 v/v/v) and HPLC analysis. The influence of column temperature on pigment separation and the quantification method were investigated – a temperature of 5 °C was selected for the Lichrospher 100 RP-18e column. The pigments in the sediment extract were quantified using a method based on HPLC analysis (at 450 nm) and spectrophotometric measurements (at 450 nm), and extinction coefficients were determined for standard solutions at this wavelength. It is very important to use the value of the extinction coefficient appropriate to the wavelength at which the detection of carotenoids was carried out.