Marsectohexol and other pregnane phytochemicals derived from Gongronema latifolium as α-amylase and α-glucosidase inhibitors: in vitro and molecular docking studies

Aristolochia bracteolata flower extract based phytosynthesis and characterization of AgNPs: Antimicrobial, antidiabetic, and antioxidant activities potential assessment

The study was carried out to evaluate the effectiveness of the Aristolochia bracteolata water flower extract-mediated AgNPs synthesis and assess their antimicrobial potential. According to the experimental and analytical results, A. bracteolata flower extract can produce valuable AgNPs. The characteristic features of these AgNPs were assessed with UV-visible spectrophotometer, Fourier transform-infrared spectroscopy, Transmission Electron Microscope, Scanning Electron Microscopy, as well as. Under UV-vis. spectrum results, showed major peak at 430 nm and recorded essential functional groups responsible for reducing, capping, and stabilizing AgNPs by FT-IR analysis. In addition, the size and shape of the synthesized AgNPs were found as 21.11-25.17 nm and spherical/octahedral shape. The A. bracteolata fabricated NPs showed remarkable antimicrobial activity against fish bacterial pathogens (V. parahaemolytics, Serratia sp., B. subtilis, and E. coli) as well as common fungal pathogens (A. niger, C. albicans, A. flavus, and A. terreus) at the quantity of 100 μg mL-1 than positive controls. Nevertheless, it was not effective against human bacterial pathogens. It concludes that AgNPs synthesized from A. bracteolata aqueous flower extract have excellent antimicrobial activity and may have a variety of biomedical applications.

Identification of potential inhibitors of cholinergic and β-secretase enzymes from phytochemicals derived from Gongronema latifolium Benth leaf: an integrated computational analysis

Neurodegenerative disorders (NDDs) are associated with increased activities of the brain acetylcholinesterase (AChE), butyrylcholinesterase (BChE) and β-secretase enzyme (BACE1). Inhibition of these enzymes affords therapeutic option for managing NDDs such as Alzheimer's disease (AD) and Parkinson's disease (PD). Although, Gongronema latifolium Benth (GL) has been widely documented in ethnopharmacological and scientific reports for the management of NDDs, there is paucity of information on its underlying mechanism and neurotherapeutic constituents. Herein, 152 previously reported Gongronema latifolium derived-phytochemicals (GLDP) were screened against hAChE, hBChE and hBACE-1 using molecular docking, molecular dynamics (MD) simulations, free energy of binding calculations and cluster analysis. The result of the computational analysis identified silymarin, alpha-amyrin and teraxeron with the highest binding energies (-12.3, -11.2, -10.5 Kcal/mol) for hAChE, hBChE and hBACE-1 respectively as compared with those of the reference inhibitors (-12.3, -9.8 and - 9.4 for donepezil, propidium and aminoquinoline compound respectively). These best docked phytochemicals were found to be orientated in the hydrophobic gorge where they interacted with the choline-binding pocket in the A-site and P-site of the cholinesterase and subsites S1, S3, S3' and flip (67-75) residues of the pocket of the BACE-1. The best docked phytochemicals complexed with the target proteins were stable in a 100 ns molecular dynamic simulation. The interactions with the catalytic residues were preserved during the simulation as observed from the MMGBSA decomposition and cluster analyses. The presence of these phytocompounds most notably silymarin, which demonstrated dual high binding tendencies to both cholinesterases, were identified as potential neurotherapeutics subject to further investigation.

Exploration of human pancreatic alpha-amylase inhibitors from Physalis peruviana for the treatment of type 2 diabetes

Type 2 Diabetes (T2D), a chronic metabolic disorder characterized by persistent hyperglycemia, accounts for ∼90% of all types of diabetes. Pancreatic α-amylase is a potential drug target for preventing postprandial hyperglycemia and inhibiting T2D in humans. Although many synthetic drugs have been identified against pancreatic α-amylase, however, reported several side effects, and plant-derived natural products are less explored against T2D. This study tested 34 flavonoids derived from the plant Physalis peruviana against the human pancreatic α-amylase (HPA) using in silico computational approaches such as molecular docking and molecular dynamics simulation approaches. Schrödinger, a drug discovery package with modules applicable for molecular docking, protein-ligand interaction analysis, molecular dynamics, post-dynamics simulation, and binding free energy calculation, was employed for all computational studies. Four flavonoids, namely, Chlorogenic acid, Withaperuvin F, Withaperuvin H, and Rutin, were picked based on their docking score ranging between -7.03 kcal/mol and -11.35 kcal/mol compared to the docking score -7.3 kcal/mol of reference ligand, i.e. Myricetin. The molecular dynamics analysis suggested that all flavonoids showed considerable stability within the protein's catalytic pocket, except chlorogenic acid, which showed high deviation during the last 15 ns. However, the interactions observed in initial docking and extracted from the simulation trajectory involved > 90% identical residues, indicating the affinity and stability of the docked flavonoids with the protein. Therefore, all four compounds identified in this study are proposed as promising antidiabetic candidates and should be further considered for their in vitro and in vivo validation.Communicated by Ramaswamy H. Sarma.

Identification of promising multi-targeting inhibitors of obesity from Vernonia amygdalina through computational analysis

Vernonia amygdalina, a widely consumed West African food herb, can be a boon in the discovery of safe anti-obesity agents given the extensive reports on its anti-obesity and antidiabetic potentials. The main aim of this study was to screen 78 Vernonia-Derived Phytocompounds (VDPs) against the active site regions of Human Pancreatic Lipase (HPL), Human Pancreatic Amylase and Human Glucosidase (HG) as drug targets associated with obesity in silico. Structure-based virtual screening helped to identify Luteolin 7-O-glucuronoside and Andrographidoid D2 as hit compounds with dual targeting tendency towards the HPL and HG. Analysis of the molecular dynamic simulation trajectory files of the ligand-receptor complexes as computed from the thermodynamic parameters plots showed not only increased flexibility and greater interaction potential of the active site residues of the receptor towards the VDPs as indicated by the root mean square fluctuation but also higher stability as indicated by the root mean square deviation, radius of gyration and number of hydrogen bonds. The cluster analysis further showed that the interactions with important residues were preserved in the dynamic environment. These observations were further verified from Molecular Mechanics Generalized Born Surface Area Analysis, which also showed that residual contributions to the binding free energies were mainly from catalytic residues at the active sites of the enzymes. The hit compounds also feature desirable physicochemical properties and drug-likeness. This study provides in silico evidence for the inhibitory potential of phytochemicals from Vernonia amygdalina against two target enzymes in obesity.

Rhus coriaria L. (Sumac), a Versatile and Resourceful Food Spice with Cornucopia of Polyphenols

In recent years, utilization of Rhus coriaria L. (sumac) is upgrading not only in their culinary use and human nutrition, but also in the pharmaceutical industry, food industry and veterinary practices. This is driven by accumulating evidence that support the ethnobotanical use of this plant; in particular, advanced knowledge of the content of nutritional, medicinal and techno-functional bioactive ingredients. Herein, we discuss polyphenolic compounds as the main bioactive ingredients in Rhus coriaria L., which contribute mainly to the significance and utility of this spice. Most of the antioxidant potential and therapeutic roles of sumac are increasingly attributed to its constituent tannins, flavonoids, and phenolic acids. Hydroxyphenyl pyranoanthocyanins and other anthocynins are responsible for the highly desired red pigments accounting for the strong pigmentation capacity and colorant ability of sumac. Certain polyphenols and the essential oil components are responsible for the peculiar flavor and antimicrobial activity of sumac. Tannin-rich sumac extracts and isolates are known to enhance the food quality and the oxidative stability of animal products such as meat and milk. In conclusion, polyphenol-rich sumac extracts and its bioactive ingredients could be exploited towards developing novel food products which do not only address the current consumers' interests regarding organoleptic and nutritional value of food, but also meet the growing need for 'clean label' as well as value addition with respect to antioxidant capacity, disease prevention, and health promotion in humans.

Inhibition mechanism of alpha-amylase, a diabetes target, by a steroidal pregnane and pregnane glycosides derived from Gongronema latifolium Benth

Alpha-amylase is widely exploited as a drug target for preventing postprandial hyperglycemia in diabetes and other metabolic diseases. Inhibition of this enzyme by plant-derived pregnanes is not fully understood. Herein, we used in vitro, in silico, and in vivo studies to provide further insights into the alpha-amylase inhibitory potential of selected pregnane-rich chromatographic fractions and four steroidal pregnane phytochemicals (SPPs), viz: marsectohexol (P1), 3-O-[6-deoxy-3-O-methyl-β-D-allopyranosyl-(1→14)-β-D-oleandropyranosyl]-11,12-di-O-tigloyl-17β-marsdenin (P2), 3-O-[6-deoxy-3-O-methyl-β-D-allopyranosyl-(1→4)-β-D-oleandropyranosyl]-17β-marsdenin (P3), and 3-O-[6-deoxy-3-O-methyl-β-D-allopyranosyl-(1→4)-β-D-canaropyranosyl]-17β-marsdenin (P4) derived from Gongronema latifolium Benth. The results revealed that the SPPs source pregnane-rich chromatographic fractions and the SPPs (P1–P4) exhibited inhibitory potential against porcine pancreatic alpha-amylase in vitro. Compounds P1 and P2 with IC50 values 10.01 and 12.10 µM, respectively, showed greater inhibitory potential than the reference acarbose (IC50 = 13.47 µM). Molecular docking analysis suggests that the SPPs had a strong binding affinity to porcine pancreatic alpha-amylase (PPA), human pancreatic alpha-amylase (HPA), and human salivary alpha-amylase (HSA), interacting with the key active site residues through an array of hydrophobic interactions and hydrogen bonds. The strong interactions of the SPPs with Glu233 and Asp300 residues may disrupt their roles in the acid-base catalytic mechanism and proper orientation of the polymeric substrates, respectively. The interactions with human pancreatic amylase were maintained in a dynamic environment as indicated by the root mean square deviation, radius of gyration, surface accessible surface area, and number of hydrogen bonds computed from the trajectories obtained from a 100-ns molecular dynamics simulation. Key loop regions of HPA that contribute to substrate binding exhibited flexibility and interaction potential toward the compounds as indicated by the root mean square fluctuation. Furthermore, P1 significantly reduced blood glucose levels and area under the curve in albino rats which were orally challenged with starch. Therefore, Gongronema latifolium and its constituent SPPs may be exploited as inhibitors of pancreatic alpha-amylase as an oral policy for impeding postprandial blood glucose rise.