Exploration of Binding Mechanism of a Potential Streptococcus pneumoniae Neuraminidase Inhibitor from Herbaceous Plants by Molecular Simulation

Receptor modulators associated with the hypothalamus -pituitary-thyroid axis

The hypothalamus-pituitary-thyroid (HPT) axis maintains normal metabolic balance and homeostasis in the human body through positive and negative feedback regulation. Its main regulatory mode is the secretion of thyrotropin (TSH), thyroid hormones (TH), and thyrotropin-releasing hormone (TRH). By binding to their corresponding receptors, they are involved in the development and progression of several systemic diseases, including digestive, cardiovascular, and central nervous system diseases. The HPT axis-related receptors include thyrotropin receptor (TSHR), thyroid hormone receptor (TR), and thyrotropin-releasing hormone receptor (TRHR). Recently, research on regulators has become popular in the field of biology. Several HPT axis-related receptor modulators have been used for clinical treatment. This study reviews the developments and recent findings on HPT axis-related receptor modulators. This will provide a theoretical basis for the development and utilisation of new modulators of the HPT axis receptors.

ZnO-chlorogenic acid nanostructured complex inhibits Covid-19 pathogenesis and increases hydroxychloroquine efficacy

Objective

The study purpose was to compare the anti- novel coronavirus disease 2019 (COVID-19) property of chlorogenic acid (CGA) and Zinc oxide nanoparticles (ZnO-NP) with the new valid synthesized complex of ZnO /CGA-NPs.

Methods

The facile mixing method was utilized to prepare ZnO/CGA-NPs. The in vitro effect of different ZnO/CGA-NPs concentrations on papain-like protease (PL^pro) and spike protein- receptor-binding domain (RBD) was measured by ELISA technique. The compounds effects on SARS-CoV2 were determined on viral entry, replication, and assembly by using plaque reduction assay, qPCR, and ELISA techniques. Their individual effects or mixed with hydroxychloroquine (HCQ) on erythrocytes (RBCs) and leukocytes (WBCs) were evaluated by routine cell culture technique. Finally, turbidity and agar well diffusion assays were done to evaluate their antimicrobial properties against Escherichia. coli, klebsila pneumonia, Streptococcus pyogenes, Staphylococcus aureus, and Candida albicans.

Results

The results confirmed that the uniformly dispersed ZnO-NPs were converted to aggregated form of ZnO/CGA-NPs upon the addition of CGA. The inhibitory concentration 50 (IC₅₀) of ZnO /CGA-NPs against RBD, angiotensin-converting enzyme 2 (ACE2) and PL^pro were 1647.7, 323.3 µg/mL and 38.7 µg/mL, respectively. Also, it inhibited E-gene, RdRp gene, E-protein, and spike protein with an IC₅₀ of 0.11, 0.13, 0.48, and 0.37 µg/mL, respectively. It acted as an antimicrobial against all tested organisms with a minimum inhibitory concentration (MIC) of 26 µg/mL. Finally, ZnO/CGA-NPs Complex (0.1 IC₅₀) prevented the cytotoxic effect of HCQ on RBCs and WBC by 92.3 and 90 %, respectively.

Conclusion

ZnO/CGA-NPs Complex can be considered as a new anti- severe acute respiratory syndrome coronavirus 2 (SARS-CoV2) compound.

Phenolic Secondary Metabolites and Antiradical and Antibacterial Activities of Different Extracts of Usnea barbata (L.) Weber ex F.H.Wigg from Călimani Mountains, Romania

Phenolic compounds represent an essential bioactive metabolites group with numerous pharmaceutical applications. Our study aims to identify and quantify phenolic constituents of various liquid and dry extracts of Usnea barbata (L.) Weber ex F.H. Wigg (U. barbata) from Calimani Mountains, Romania, and investigate their bioactivities. The extracts in acetone, 96% ethanol, and water with the same dried lichen/solvent ratio (w/v) were obtained through two conventional techniques: maceration (mUBA, mUBE, and mUBW) and Soxhlet extraction (dUBA, dUBE, and dUBW). High-performance liquid chromatography with diode-array detection (HPLC-DAD) was performed for usnic acid (UA) and different polyphenols quantification. Then, the total phenolic content (TPC) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) free-radical scavenging activity (AA) were determined through spectrophotometric methods. Using the disc diffusion method (DDM), the antibacterial activity was evaluated against Gram-positive and Gram-negative bacteria known for their pathogenicity: Staphylococcus aureus (ATCC 25923), Streptococcus pneumoniae (ATCC 49619), Pseudomonas aeruginosa (ATCC 27853), and Klebsiella pneumoniae (ATCC 13883). All extracts contain phenolic compounds expressed as TPC values. Five lichen extracts display various UA contents; this significant metabolite was not detected in dUBW. Six polyphenols from the standards mixture were quantified only in ethanol and water extracts; mUBE has all individual polyphenols, while dUBE shows only two. Three polyphenols were detected in mUBW, but none was found in dUBW. All U. barbata extracts had antiradical activity; however, only ethanol and acetone extracts proved inhibitory activity against P. aeruginosa, S. pneumoniae, and S. aureus. In contrast, K. pneumoniae was strongly resistant (IZD = 0). Data analysis evidenced a high positive correlation between the phenolic constituents and bioactivities of each U. barbata extract. Associating these extracts’ properties with both conventional techniques used for their preparation revealed the extraction conditions’ significant influence on lichen extracts metabolites profiling, with a powerful impact on their pharmacological potential.

Exploration of the Interactions between Maltase–Glucoamylase and Its Potential Peptide Inhibitors by Molecular Dynamics Simulation

Diabetes mellitus, a chronic metabolic disorder, represents a serious threat to human health. The gut enzyme maltase–glucoamylase (MGAM) has attracted considerable attention as a potential therapeutic target for the treatment of type 2 diabetes. Thus, developing novel inhibitors of MGAM holds the promise of improving clinical management. The dipeptides, Thr-Trp (TW) and Trp-Ala (WA), are known inhibitors of MGAM; however, studies on how they interact with MGAM are lacking. The work presented here explored these interactions by utilizing molecular docking and molecular dynamics simulations. Results indicate that the active center of the MGAM could easily accommodate the flexible peptides. Interactions involving hydrogen bonds, cation-π, and hydrophobic interactions are predicted between TW/WA and residues including Tyr1251, Trp1355, Asp1420, Met1421, Glu1423, and Arg1510 within MGAM. The electrostatic energy was recognized as playing a dominant role in both TW-MGAM and WA-MGAM systems. The binding locations of TW/WA are close to the possible acid-base catalytic residue Asp1526 and might be the reason for MGAM inhibition. These findings provide a theoretical structural model for the development of future inhibitors.

Tannic Acid with Antiviral and Antibacterial Activity as A Promising Component of Biomaterials-A Minireview

As a phenolic acid, tannic acid can be classified into a polyphenolic group. It has been widely studied in the biomedical field of science because it presents unique antiviral as well as antibacterial properties. Tannic acid has been reported to present the activity against Influeneza A virus, Papilloma viruses, noroviruses, Herpes simplex virus type 1 and 2, and human immunodeficiency virus (HIV) as well as activity against both Gram-positive and Gram-negative bacteria as Staphylococcus aureus, Escherichia coli, Streptococcus pyogenes, Enterococcus faecalis, Pseudomonas aeruginosa, Yersinia enterocolitica, Listeria innocua. Nowadays, compounds of natural origin constitute fundaments of material science, and the trend is called "from nature to nature". Although biopolymers have found a broad range of applications in biomedical sciences, they do not present anti-microbial activity, and their physicochemical properties are rather poor. Biopolymers, however, may be modified with organic and inorganic additives which enhance their properties. Tannic acid, like phenolic acid, is classified into a polyphenolic group and can be isolated from natural sources, e.g., a pure compound or a component of a plant extract. Numerous studies have been carried out over the application of tannic acid as an additive to biopolymer materials due to its unique properties. On the one hand, it shows antimicrobial and antiviral activity, while on the other hand, it reveals promising biological properties, i.e., enhances the cell proliferation, tissue regeneration and wound healing processes. Tannic acid is added to different biopolymers, collagen and polysaccharides as chitosan, agarose and starch. Its activity has been proven by the determination of physicochemical properties, as well as the performance of in vitro and in vivo studies. This systematics review is a summary of current studies on tannic acid properties. It presents tannic acid as an excellent natural compound which can be used to eliminate pathogenic factors as well as a revision of current studies on tannic acid composed with biopolymers and active properties of the resulting complexes.