Notable biological activities including brains protective activities have made carbohydrate esters as a topic of great interest over the past several decades. In this context, unimolecular treatment of methyl α-L-rhamnopyranoside with dibutyltin oxide gave the corresponding 2,3-O-(dibutylstannylene) derivative which was then allowed to react with 3-chlorobenzoyl chloride. The reaction regioselectively furnished the 3-O-substitution product in excellent yield. To get newer rhamnopyranoside esters chlorobenzoate was further converted into four 2,4-di-O-substituted products with other acylating agents using direct acylation technique. Moreover, thermodynamic properties indicated that these sugar esters (SEs) possess better stability, suitable polar nature and higher binding affinity than the non-ester rhamnopyranoside. Prediction of Activity Spectra for Substances (PASS) predication showed that these SEs should be more potent against fungal pathogens than the bacterial organisms. With these encouraging results absorption, distribution, metabolism, excretion, and toxicity (ADMET) and drug-likeness properties of the SEs are also discussed.

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.

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.

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