Targeting tyrosinase in hyperpigmentation: Current status, limitations and future promises.

Hyperpigmentation is a common and distressing dermatologic condition. Since tyrosinase (TYR) plays an essential role in melanogenesis, its inhibition is considered a logical approach along with other therapeutic methods to prevent the accumulation of melanin in the skin. Thus, TYR inhibitors are a tempting target as the medicinal and cosmetic active agents of hyperpigmentation disorder. Among TYR inhibitors, hydroquinone is a traditional lightening agent that is commonly used in clinical practice. However, despite good efficacy, prolonged use of hydroquinone is associated with side effects. To overcome these shortcomings, new approaches in targeting TYR and treating hyperpigmentation are desperately requiredessentialneeded. In line with this purpose, several non-hydroquinone lightening agents have been developed and suggested as hydroquinone alternatives. In addition to traditional approaches, nanomedicine and nanotheranostic platforms have been recently proposed in the treatment of hyperpigmentation. In this review, we discuss the available strategies for the management of hyperpigmentation with a focus on TYR inhibition. In addition, alternative treatment options to hydroquinone are discussed. Finally, we present nano-based strategies to improve the therapeutic effect of drugs prescribed to patients with skin disorders.

Evaluation of the interaction between potent small molecules against the Nipah virus Glycoprotein in Malaysia and Bangladesh strains, accompanied by the human Ephrin-B2 and Ephrin-B3 receptors; a simulation approach.

Malaysia reported the first human case of Nipah virus (NiV) in late September 1998 with encephalitis and respiratory symptoms. As a result of viral genomic mutations, two main strains (NiV-Malaysia and NiV-Bangladesh) have spread around the world. There are no licensed molecular therapeutics available for this biosafety level 4 pathogen. NiV attachment glycoprotein plays a critical role in viral transmission through its human receptors (Ephrin-B2 and Ephrin-B3), so identifying small molecules that can be repurposed to inhibit them is crucial to developing anti-NiV drugs. Consequently, in this study annealing simulations, pharmacophore modeling, molecular docking, and molecular dynamics were used to evaluate seven potential drugs (Pemirolast, Nitrofurantoin, Isoniazid Pyruvate, Eriodictyol, Cepharanthine, Ergoloid, and Hypericin) against NiV-G, Ephrin-B2, and Ephrin-B3 receptors. Based on the annealing analysis, Pemirolast for efnb2 protein and Isoniazid Pyruvate for efnb3 receptor were repurposed as the most promising small molecule candidates. Furthermore, Hypericin and Cepharanthine, with notable interaction values, are the top Glycoprotein inhibitors in Malaysia and Bangladesh strains, respectively. In addition, docking calculations revealed that their binding affinity scores are related to efnb2-pem (- 7.1 kcal/mol), efnb3-iso (- 5.8 kcal/mol), gm-hyp (- 9.6 kcal/mol), gb-ceph (- 9.2 kcal/mol). Finally, our computational research minimizes the time-consuming aspects and provides options for dealing with any new variants of Nipah virus that might emerge in the future.

An overview of the vaccine platforms to combat COVID-19 with a focus on the subunit vaccines.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is an emerging virus that has caused the recent coronavirus disease (COVID-19) global pandemic. The current approved COVID-19 vaccines have shown considerable efficiency against hospitalization and death. However, the continuation of the pandemic for more than two years and the likelihood of new strain emergence despite the global rollout of vaccination highlight the immediate need for the development and improvement of vaccines. mRNA, viral vector, and inactivated virus vaccine platforms were the first members of the worldwide approved vaccine list. Subunit vaccines. which are vaccines based on synthetic peptides or recombinant proteins, have been used in lower numbers and limited countries. The unavoidable advantages of this platform, including safety and precise immune targeting, make it a promising vaccine with wider global use in the near future. This review article summarizes the current knowledge on different vaccine platforms, focusing on the subunit vaccines and their clinical trial advancements against COVID-19.

Computational repurposing approach for targeting the critical spike mutations in B.1.617.2 (delta), AY.1 (delta plus) and C.37 (lambda) SARS-CoV-2 variants using exhaustive structure-based virtual screening, molecular dynamic simulations and MM-PBSA methods.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent of the contagious coronavirus disease 2019 (COVID-19) which was first identified in Wuhan, China, in December 2019. Around the world, many researchers focused their research on identifying inhibitors against the druggable SARS-CoV-2 targets. The reported genomic mutations have a direct effect on the receptor-binding domain (RBD), which interacts with host angiotensin-converting enzyme 2 (ACE-2) for viral cell entry. These mutations, some of which are variants of concern (VOC), lead to increased morbidity and mortality rates. The newest variants including B.1.617.2 (Delta), AY.1 (Delta plus), and C.37 (Lambda) were considered in this study. Thus, an exhaustive structure-based virtual screening of a ligand library (in which FDA approved drugs are also present) using the drug-likeness screening, molecular docking, ADMET profiling was performed followed by molecular dynamics (MD) simulation, and Molecular Mechanics-Poisson Boltzmann Surface Area (MM-PBSA) calculation to identify compounds or drugs can be repurposed for inhibiting the wild type, Delta, Delta plus and Lambda variants of RBD of the spike protein. Based on the virtual screening steps, two FDA approved drugs, Atovaquone (atv) and Praziquantel (prz), were selected and repurposed as the best candidates of SARS-CoV-2 RBD inhibitors. Molecular docking results display that both atv and prz contribute in different interaction with binding site residues (Gln493, Asn501 and Gly502 in the hydrogen bond formation, Phe490 and Tyr505 in the π- π stacking and Tyr449, Ser494, and Phe497 in the vdW interactions) in the wild type, Delta, Delta plus and Lambda variants of RBD of the spike protein. MD simulations revealed that among the eight studied complexes, the wild type-atv and Delta-prz complexes have the most structural stability over the simulation time. Furthermore, MM-PBSA calculation showed that in the atv containing complexes, highest binding affinity is related to the wild type-atv complex and in the prz containing complexes, it is related to the Delta-prz complex. The validation of docking results was done by comparing with experimental data (heparin in complex with wild type and Delta variants). Also, comparison of the obtained results with the result of simulation of the k22 with the studied proteins showed that atv and prz are suitable inhibitors for these proteins, especially wild type t and Delta variant, respectively. Thus, we found that atv and prz are the best candidate for inhibition of wild type and Delta variant of the spike protein. Also, atv can be an appropriate inhibitor for the Lambda variant. Obtained in silico results may help the development of new anti-COVID-19 drugs.

Process Development for the Production and Purification of PEGylated RhG-CSF Expressed in Escherichia coli.

BACKGROUND AND OBJECTIVES: Recombinant human granulocyte-colony stimulating factor (rhG-CSF) and its PEGylated form (PEG-GCSF) are used in cancer therapy. Thus, developing a more cost-effectively method for expressing rhG-CSF and the PEGylation optimization of rhG-CSF by reaction engineering and subsequent purification strategy is necessary. METHODS: RhG-CSF expression in Escherichia coli BL21 (DE3) was carried out by auto-induction batch fermentation and improved for maximizing rhG-CSF productivity. After that, purified rhGCSF was PEGylated using methoxy polyethylene glycol propionaldehydes (mPEG20-ALD). The various conditions effect of extraction and purification of rhG-CSF and PEG-GCSF were assayed. RESULTS: The assessment results revealed that the auto-induction batch cultivation strategy had maximum productivity, and rhG-CSF purity was more than 99%. The obtained data of rhG-CSF PEGylation displayed that the optimized conditions of rhG-CSF PEGylation and purification enhanced homogeneity PEG-GCSF and managed reaction toward optimal yield of PEG-GCSF (70%) and purity of 99.9%. Findings from FTIR, CD, fluorescence spectroscopy, and bioassay revealed that PEGylation was executed exactly in the rhG-CSF N-terminus, and products maintained their conformation properties. CONCLUSION: Overall, the developed approach expanded strategies for high yield rhG-CSF by simplified auto-induction batch fermentation system and rhG-CSF PEGylation, which are simple and timesaving, economical, and high efficiency.

Artificial Muscles Powered by Glucose.

Untethered actuation is important for robotic devices to achieve autonomous motion, which is typically enabled by using batteries. Using enzymes to provide the required electrical charge is particularly interesting as it will enable direct harvesting of fuel components from a surrounding fluid. Here, a soft artificial muscle is presented, which uses the biofuel glucose in the presence of oxygen. Glucose oxidase and laccase enzymes integrated in the actuator catalytically convert glucose and oxygen into electrical power that in turn is converted into movement by the electroactive polymer polypyrrole causing the actuator to bend. The integrated bioelectrode pair shows a maximum open-circuit voltage of 0.70 ± 0.04 V at room temperature and a maximum power density of 0.27 µW cm-2 at 0.50 V, sufficient to drive an external polypyrrole-based trilayer artificial muscle. Next, the enzymes are fully integrated into the artificial muscle, resulting in an autonomously powered actuator that can bend reversibly in both directions driven by glucose and O2 only. This autonomously powered artificial muscle can be of great interest for soft (micro-)robotics and implantable or ingestible medical devices manoeuvring throughout the body, for devices in regenerative medicine, wearables, and environmental monitoring devices operating autonomously in aqueous environments.

Assay of bacteriorhodopsin stability on polycarbonate surface by using of FTIR-ATR: a model of disk-based bioassays.

Bacteriorhodopsin (BR) is a transmembrane protein which able to transport protons through cell membrane and thus converting solar energy to electrical energy. Up to now different strategies have been used to immobilize BR. In the present study the BR has been immobilized on polycarbonate surface with two different methods. The functional groups of polycarbonate were modified in two ways (sulfuric acid, PDAC and HNO3) and then the BR was immobilized on two different modified polycarbonate surfaces. The modified surfaces were characterized by ATR-FTIR and AFM techniques. Afterward the activity of bounded BR to two different modified polycarbonate surfaces was measured. Our results show that BR bounded to modified polycarbonate surface with HNO3 (nitrated polycarbonate) has higher activity in comparison to modified with sulfuric acid (electrostatically bounded BR). Also the activities of both types of Bounded BR after 10 days were measured. The results showed that unlike electrostatically bounded BR, bounding BR to nitrated polycarbonate keeps its activity after 10 days. In conclusion, nitrated polycarbonate surface is a suitable candidate due to immobilizing BR in order to manufacture of BioCDs.

Inhibition of mushroom tyrosinase by a newly synthesized ligand: inhibition kinetics and computational simulations.

Alterations in the synthesis of melanin contribute to a number of diseases; therefore, the design of new tyrosinase inhibitors is very important. Mushroom tyrosinase (MT) is a metalloenzyme, which plays an important role in melanin biosynthesis. In this study, the inhibitory effect of a novel designed compound, i.e. 2-((1Z)-(2-(2,4-dinitrophenyl)hydrazin-1-ylidene)methyl)phenol, as a specific ligand which can bind to the copper ion of MT, has been assessed. The ligand was found to competitively inhibit both the cresolase and catecholase activities of MT, with small inhibition constants of 2.8 and 2.6 µM, respectively. Intrinsic fluorescence studies were performed to gain more information on the binding constants. Docking results indicated that the ligand binds to copper ions in the active site of MT via the OH group of the ligand. The ligand makes four hydrogen bonds with aspartic acid and one hydrogen bond with the histidine residue in the active site. Molecular dynamics results show that ligand binds to the MT via both electrostatic and hydrophobic interactions with its different parts.

The inhibitory effect of ethylenediamine on mushroom tyrosinase.

The inhibitory effect of ethylenediamine on both activities of mushroom tyrosinase (MT) at 20 °C in a 10 mM phosphate buffer solution (pH 6.8), was studied. L-DOPA and L-tyrosine were used as substrates of catecholase and cresolase activities, respectively. The results showed that ethylenediamine competitively inhibits both activities of the enzyme with inhibition constants (K(i)) of 0.18±0.05 and 0.14±0.01 µM for catecholase and cresolase respectively, which are lower than the reported values for other MT inhibitors. For further insight a docking study between tyrosinase and ethylenediamine was performed. The docking simulation showed that ethylenediamine binds in the active site of the enzyme near the Cu atoms and makes 3 hydrogen bonds with two histidine residues of active site.

The role of alkyl chain length in the inhibitory effect n-alkyl xanthates on mushroom tyrosinase activities.

Sodium salts of four n-alkyl xanthate compounds, C2H5OCS2Na (I), C3H7OCS2Na (II), C4H9OCS2Na (III), and C6H13OCS2Na (IV) were synthesized and examined for inhibition of both cresolase and catecholase activities of mushroom tyrosinase (MT) in 10 mM sodium phosphate buffer, pH 6.8, at 293 K using UV spectrophotometry. 4-[(4-Methylbenzo)azo]-1,2-benzendiol (MeBACat) and 4-[(4-methylphenyl)azo]-phenol (MePAPh) were used as synthetic substrates for the enzyme for catecholase and cresolase reactions, respectively. Lineweaver-Burk plots showed different patterns of mixed, competitive or uncompetitive inhibition for the four xanthates. For the cresolase activity, I and II showed uncompetitive inhibition but III and IV showed competitive inhibition pattern. For the catecholase activity, I and II showed mixed inhibition but III and IV showed competitive inhibition. The synthesized compounds can be classified as potent inhibitors of MT due to their Ki values of 13.8, 11, 8 and 5 microM for the cresolase activity, and 1.4, 5, 13 and 25 microM for the catecholase activity for I, II, III and IV, respectively. For the catecholase activity both substrate and inhibitor can be bound to the enzyme with negative cooperativity between the binding sites (alpha > 1) and this negative cooperativity increases with increasing length of the aliphatic tail of these compounds. The length of the hydrophobic tail of the xanthates has a stronger effect on the Ki values for catecholase inhibition than for cresolase inhibition. Increasing the length of the hydrophobic tail leads to a decrease of the Ki values for cresolase inhibition and an increase of the Ki values for catecholase inhibition.