Study of an inhibitory effect of plant polyphenolic compounds against digestive enzymes using bench-working experimental evidence predicted by molecular docking and dynamics.

The substantial nutritional content and diversified biological activity of plant-based nutraceuticals are due to polyphenolic chemicals. These chemicals are important and well-studied plant secondary metabolites. Their protein interactions are extensively studied. This relationship is crucial for the logical development of functional food and for enhancing the availability and usefulness of polyphenols. This study highlights the influence of protein types and polyphenols on the interaction, where the chemical bindings predominantly consist of hydrophobic interactions and hydrogen bonds. The interaction between polyphenolic compounds (PCs) and digestive enzymes concerning their inhibitory activity has not been fully studied. Therefore, we have examined the interaction of four digestive enzymes (α-amylase, pepsin, trypsin, and α-chymotrypsin) with four PCs (curcumin, diosmin, morin, and 2',3',4'-trihydroxychalcone) through in silico and in vitro approaches. In vitro plate assays, enzyme kinetics, spectroscopic assays, molecular docking, and simulations were performed. We observed all these PCs have significant docking scores and preferable interaction with the active site of the digestive enzymes, resulting in the reduction of enzyme activity. The enzyme-substrate binding mechanism was determined using the Lineweaver Burk plot, indicating that the inhibition occurred competitively. Among four PCs diosmin and morin has the highest interaction energy over digestive enzymes with IC50 value of 1.13 ± 0.0047 and 1.086 ± 0.0131 µM. Kinetic studies show that selected PCs inhibited pepsin, trypsin, and chymotrypsin competitively and inhibited amylase in a non-competitive manner, especially by 2',3',4'-trihydroxychalcone. This study offers insights into the mechanisms by which the selected PCs inhibit the enzymes and has the potential to enhance the application of curcumin, diosmin, morin, and 2',3',4'-trihydroxychalcone as natural inhibitors of digestive enzymes.

Comparative structural study of selective and non-selective NSAIDs against the enzyme cyclooxygenase-2 through real-time molecular dynamics linked to post-dynamics MM-GBSA and e-pharmacophores mapping.

BACKGROUND: Inflammation-provoked disorders including cancer are arbitrated by cyclooxygenase-2 (COX-2). Celecoxib and niflumic acid are among the potent and selective inhibitors of this enzyme while aspirin (acetylsalicylic acid) and sodium salicylate are its non-selective and lesser potent inhibitors. Despite these proven studies, the comparative structural study of these selective and non-selective molecules at atomistic scale in complex state with COX-2 that may answer this differential inhibitory behavior has not been accomplished spotlighting the imperative need of additional research in this area. Thus, this study was framed to provide a strong explanation for the enigma of higher inhibitory activity of celecoxib-niflumic acid duo in comparison to aspirin and sodium salicylate towards COX-2. METHODS: A contemporary approach including advanced molecular docking against COX2, molecular dynamics of receptor-ligand complexes, simulation-trajectory-backed MMGBSA for different time points, radius of gyration (Rg) calculations, and e-pharmacophores approach was employed to attain a rational conclusion. RESULTS: Our findings demonstrated the higher binding affinity of celecoxib and niflumic acid over aspirin and sodium salicylate against COX-2. Although both selective and non-selective COX-2 inhibitors manifested nearly the same stability in the active site of this enzyme but the e-pharmocophoric features found in the case of selective inhibitors scored over non-selective ones. Thus, our findings excluded the differential stability to be the cause of stronger potency of selective inhibitors but attributed their potency to greater number of complementary features present in these inhibitors against the active site of inflammation engendering COX-2.

Evaluation of free radical quenching, anti-inflammatory activity together with anticancer potential of Lychnis coronaria and characterization of novel molecules from its extract through high resolution-liquid chromatography mass spectrometry coupled to structural biochemistry approach.

Lychnis coronaria, a perennial (herbaceous) belonging to Caryophyllaceae has been traditionally used for treating different complications. However, the free radical scavenging effect, anti-inflammatory activity and anticancer property of methanolic extract of this plant has not been addressed. Most importantly, the chemical constituents present in the extract of Lychnis coronaria responsible for its diverse activities have not been scrutinized till date. Here, we used a complex approach for exploring the above mentioned effects of Lychnis coronaria. We performed rigorous phytochemical screening followed by quantification of tannins, phenols, alkaloids, quinones and sterols from the extract. Moreover we employed in vitro DPPH, ABTS , FRAP assay, albumin denaturation inhibition experiment, MTT assay, high resolution liquid chromatography mass spectrometry for measurng the reactive oxygen species quenching, anti-inflammatory and anticancer strength of Lychnis coronaria and for identifying the possible bioactive molecules. We identified two novel molecules panaxynol (polyacetylenic alcohol) and norharman (9H-Pyrido [3, 4-B] indole) following rigorous analysis of the extract. Following this, the binding affinity of these molecules was estimated using human cyclooxygenase (COX)-2 enzyme as target. Among the constituents of Lychnis coronaria norharman manifested stronger binding towards COX-2 compared to panaxynol. Most importantly, norharman showed high stability in the groove of COX2 as confirmed by molecular dynamics simulation. Collectively, Lychnis coronaria manifested free radical neutralizing, inflammation soothing and anticancer effect in concentration dependent manner and thus may serve as a promising phytotherapeutic in future.Communicated by Ramaswamy H. Sarma.

Functional Characterization, Mechanism, and Mode of Action of Putative Streptomycin Adenylyltransferase from Serratia marcescens.

Nosocomial infections are serious threats to the entire world in healthcare settings. The major causative agents of nosocomial infections are bacterial pathogens, among which Enterobacteriaceae family member Serratia marcescens plays a crucial role. It is a gram-negative opportunistic pathogen, predominantly affecting patients in intensive-care units. The presence of intrinsic genes in S. marcescens led to the development of resistance to antibiotics for survival. Complete scanning of the proteome, including hypothetical and partially annotated proteins, paves the way for a better understanding of potential drug targets. The targeted protein expressed in E. coli BL21 (DE3) pLysS cells has shown complete resistance to aminoglycoside antibiotic streptomycin (>256 MCG). The recombinant protein was purified using affinity and size-exclusion chromatography and characterized using SDS-PAGE, western blotting, and MALDI-TOF analysis. Free phosphate bound to malachite green was detected at 620 nm, evident of the conversion of adenosine triphosphate to adenosine monophosphate during the adenylation process. Similarly, in the chromatographic assay, adenylated streptomycin absorbed at 260 nm in AKTA (FPLC), confirming the enzyme-catalyzed adenylation of streptomycin. Further, the adenylated product of streptomycin was confirmed through HPLC and mass spectrometry analysis. In conclusion, our characterization studies identified the partially annotated hypothetical protein as streptomycin adenylyltransferase.

The Updated Review on Plant Peptides and Their Applications in Human Health.

Biologically active plant peptides, consisting of secondary metabolites, are compounds (amino acids) utilized by plants in their defense arsenal. Enzymatic processes and metabolic pathways secrete these plant peptides. They are also known for their medicinal value and have been incorporated in therapeutics of major human diseases. Nevertheless, its limitations (low bioavailability, high cytotoxicity, poor absorption, low abundance, improper metabolism, etc.) have demanded a need to explore further and discover other new plant compounds that overcome these limitations. Keeping this in mind, therapeutic plant proteins can be excellent remedial substitutes for bodily affliction. A multitude of these peptides demonstrates anti-carcinogenic, anti-microbial, anti-HIV, and neuro-regulating properties. This article's main aim is to list out and report the status of various therapeutic plant peptides and their prospective status as peptide-based drugs for multiple diseases (infectious and non-infectious). The feasibility of these compounds in the imminent future has also been discussed.

A Novel Prototype Biosensor Array Electrode System for Detecting the Bacterial Pathogen Salmonella typhimurium.

Salmonellosis caused by Salmonella sp. has long been reported all over the world. Despite the availability of various diagnostic methods, easy and effective detection systems are still required. This report describes a dialysis membrane electrode interface disc with immobilized specific antibodies to capture antigenic Salmonella cells. The interaction of a specific Salmonella antigen with a mouse anti-Salmonella monoclonal antibody complexed to rabbit anti-mouse secondary antibody conjugated with HRP and the substrate o-aminophenol resulted in a response signal output current measured using two electrode systems (cadmium reference electrode and glassy carbon working electrode) and an agilent HP34401A 6.5 digital multimeter without a potentiostat or applied potential input. A maximum response signal output current was recorded for various concentrations of Salmonella viz., 3, 30, 300, 3000, 30,000 and 300,000 cells. The biosensor has a detection limit of three cells, which is very sensitive when compared with other detection sensors. Little non-specific response was observed using Streptococcus, Vibrio, and Pseudomonas sp. The maximum response signal output current for a dialysis membrane electrode interface disc was greater than that for gelatin, collagen, and agarose. The device and technique have a range of biological applications. This novel detection system has great potential for future development and application in surveillance for microbial pathogens.

Computational identification of potential lead molecules targeting rho receptor of Neisseria gonorrhoeae.

Gonorrhea, one of the sexually transmitted disease caused by a gram negative diplococcus bacteria Neisseria gonorrhoeae. Rho protein is indispensable for bacterial viability due to its versatile functions in physiology apart from RNA dependent transcription termination. Based on conserved function and wider role in several cellular processes, inhibitors specifically targeting Rho proteins are largely in use these days to treat various bacterial infections. In this study, three dimensional structure of Rho protein was modeled using the template protein from E. coli and further the optimized model was simulated for 100 ns to understand the structural stability and compactness. Owing to the therapeutic potential of Rho, traditional structure-based virtual screening was applied to identify potential inhibitors for the selected target. Based on empirical glide scoring functions two potent lead molecules (ChemBridge_6121956 and ChemBridge_5232688) were selected from ChemBridge database. The pharmacokinetic properties of these lead molecules are within the permissible range. DFT descriptor revealed that the lead molecules are more reactive, which also supports the molecular docking studies. The stability of Rho and Rho-inhibitor complexes was studied using molecular dynamics simulation. Parameters include binding free energy calculation, RMSD, RMSF and hydrogen bond analysis depicts the stability of Rho and Rho-inhibitors throughout the simulation. Altogether, the identified lead molecules require further optimization towards the design and development of new antibiotics against N. gonorrhoeae.Communicated by Ramaswamy H. Sarma.