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A novel esterase (est3S) gene, 1026 bp in size, was cloned from a metagenomic library made of uncultured microorganisms from the contents of cow rumen. The esterolytic enzyme (Est3S) is composed of 342 amino acids and shows the highest identity with EstGK1 (71.7%) and EstZ3 (63.78%) esterases from the uncultured bacterium. The Est3S did not cluster in any up-to-date classes (I to XVIII) of esterase and lipase. Est3S protein molecular weight was determined to be 38 kDa by gel electrophoresis and showed optimum activity at pH 7.0 and 40 °C and is partially resistant to organic solvents. Est3S activity was enhanced by K+, Na+, Mg2+, and Ca2+ and its highest activity was observed toward the short-chain p-nitrophenyl esters. Additionally, Est3S can degrade chlorpyrifos (CP) and methyl parathion (70% to 80%) in an hour. A mutated Est3S (Ser132-Ala132) did not show any activity toward CP and ester substrates. Notably, the GHS132QG motif is superimposed with the homolog esterase and cutinase-like esterase. Therefore, Ser132 is the critical amino acid like other esterases. The Est3S is relatively stable with ester compounds, and the methyl parathion complex was confirmed by molecular dynamics simulation. Novelty statement A novel esterase gene (est3S) expressing esters and organophosphorus insecticide degradation traits was isolated from the uncultured bacterium in the contents of cow rumen. The Est3S protein did not cluster in any up-to-date classes (I to XVIII) of esterase/lipase proteins. Est3S was stable with the ligands up to 100 ns during the molecular dynamic simulations.

The near future of drug delivery system would lie in the search of a versatile and innocuous material, based mostly on the natural resources. The tamarind seed xyloglucan (XG) is a natural neutral hemicellulose and a hydrophilic polysaccharide consisting of a main chain of glucan backbone with xylose and galactose side chains. XG is endowed with idiosyncratic mucoadhesive and in situ gelling properties which rated XG as an attractive, functional polymer for numerous drug delivery applications. In milieu of this, the present review is designed to underline the plausible potential of XG or XG-based systems in drug delivery. The feasibility of surface-tailoring, the flexibility of chemical-modification, and the possibility as ligand-conjugations grant XG an extraordinary consideration in the scientific territory. The authors are hopeful that the versatility of XG would meet the expectations of regulatory authorities and the XG-based products will serve the therapeutic needs of the community in the future, if sufficiently investigated and promising outcomes are obtained in human subjects.

Although chitosan (CHT, a linear cationic polysaccharide) is biodegradable, biocompatible, non-toxic, and mucoadhesive in nature, the low solubility of CHT in aqueous and alkaline media limits its applicability in pharmaceutical and biomedical field. This necessitate the introduction of new chemically-modified derivatives of CHT those can surmount the solubility barrier. Herein, N,N,N-trimethyl chitosan (TMC), a quaternized hydrophilic derivative of CHT, was synthesized by two-step reductive methylation of CHT and characterized for 1H NMR and zeta potential measurements. Polyelectrolyte complexes (PECs) based on TMC and dextran sulfate (DS) were prepared via ionic interactions between charged functional groups of former polysaccharides at different pH conditions (pH 5, 8, 10, and 12) and characterized for physicochemical (particle size and zeta potential) and solid- state characterizations (HR-TEM, SEM, FTIR, TGA and XRD). At alkaline pH conditions, the participant polymer chains (TMC and DS) are sufficiently close to form more stable PECs. The release efficiency was assessed after loading a model drug into optimized PEC formulation. Data indicated that the PECs fabricated at alkaline pH presents a reliable formulation for pharmaceutical and biomedical applications.