Current Molecular Pharmacology - Volume 15, Issue 2, 2022

The emergence of communicable and non-communicable diseases has posed a health challenge for millions of people worldwide and is a major threat to the economic and social development in the coming century. The occurrence of the recent pandemic, SARS-CoV-2, caused by lethal severe acute respiratory syndrome coronavirus 2, is one such example. Rapid research and development of drugs for the treatment and management of these diseases have become an incredibly challenging task for the pharmaceutical industry. Although, substantial attention has been paid to the discovery of therapeutic compounds from natural sources having significant medicinal potential, their synthesis has made a slow progress. Hence, the discovery of new targets by the application of the latest biotechnological and synthetic biology approaches is very much the need of the hour. Polyketides (PKs) and non-ribosomal peptides (NRPs) found in bacteria, fungi and plants are a diverse family of natural products synthesized by two classes of enzymes: polyketide synthases (PKS) and non-ribosomal peptide synthetases (NRPS). These enzymes possess immense biomedical potential due to their simple architecture, catalytic capacity, as well as diversity. With the advent of the latest in-silico and in-vitro strategies, these enzymes and their related metabolic pathways, if targeted, can contribute highly towards the biosynthesis of an array of potentially natural drug leads that have antagonist effects on biopolymers associated with various human diseases. In the face of the rising threat from multidrug-resistant pathogens, this will further open new avenues for the discovery of novel and improved drugs by combining natural and synthetic approaches. This review discusses the relevance of polyketides and non-ribosomal peptides and the improvement strategies for the development of their derivatives and scaffolds, and how they will be beneficial for future bioprospecting and drug discovery.

Hormonal coordination is tightly regulated within the human body and thus regulates human physiology. The parathyroid hormone (PTH), a member of the endocrine system, regulates the calcium and phosphate level within the human body. Under non-physiological conditions, PTH levels get upregulated (hyperparathyroidism) or downregulated (hypoparathyroidism) due to external or internal factors. In case of hyperparathyroidism, elevated PTH stimulates cellular receptors present in the bones, kidneys, and intestines to increase the blood calcium level, leading to calcium deposition. This eventually causes various symptoms, including kidney stones. Currently, there is no known medication that directly targets PTH in order to suppress its function. Therefore, it is of great interest to find novel small molecules or any other means that can modulate PTH function. The molecular signaling of PTH starts by binding its N-terminus to the G-protein coupled PTH1/2 receptor. Therefore, any intervention that affects the N-terminus of PTH could be a lead candidate for treating hyperparathyroidism. As a proof-of-concept, there are various possibilities to inhibit molecular PTH function by (i) a small molecule, (ii) N-terminal PTH phosphorylation, (iii) fibril formation and (iv) residue-specific mutations. These modifications put PTH into an inactive state, which will be discussed in detail in this review article. We anticipate that exploring small molecules or other means that affect the N-terminus of PTH could be lead candidates in combating hyperparathyroidism.

The smallest of all the pathogens, viruses, have continuously been the foremost strange microorganisms. Viral infections can cause extreme sicknesses as evidenced by the HIV/AIDS widespread or the later Ebola or Zika episodes. Apprehensive framework distortions are also regularly observed as consequences of numerous viral infections. Besides, numerous viral infections are of oncoviruses, which can trigger different types of cancer. Nearly every year, a modern infectious species emerges, debilitating the world population with an annihilating episode. Subsequently, there is a need to create antivirals to combat such rising infections. From the discovery of the antiviral drug Idoxuridine in 1962 to the revelation of Baloxavir marboxil (Xofluza) that was approved by the FDA in 2018, the whole process and criteria of creating antivirals have changed significantly. In this article, different auxiliary science strategies are described that can serve as a referral for therapeutic innovation.

Background: Glioblastoma Multiforme (GBM) is one of the most heterogeneous primary brain tumors with high mortality. In spite of the current therapeutic approaches, the survival rate remains poor, with death occurring within 12 to 15 months after the preliminary diagnosis. This warrants the need for an effective treatment modality. The Wnt/β-catenin pathway is presumably the most noteworthy pathway upregulated in almost 80% of GBM cases, contributing to tumor initiation, progression, and survival. Therefore, therapeutic strategies targeting key components of the Wnt/β-catenin cascade using established genotoxic agents like temozolomide and pharmacological inhibitors would be an effective approach to modulate the Wnt/β-catenin pathway. Recently, drug repurposing by means of effective combination therapy has gained importance in various solid tumors, including GBM, by targeting two or more proteins in a single pathway, thereby possessing the ability to overcome the hurdle implicated by chemoresistance in GBM. Objective: In this context, by employing computational tools, an attempt has been made to find out the novel combinations against the Wnt/β-catenin signalling pathway. Methods: We have explored the binding interactions of three conventional drugs - namely temozolomide, metformin and chloroquine - along with three natural compounds, viz. epigallocatechin gallate, naringenin and phloroglucinol, on the major receptors of Wnt/β-catenin signalling. Results: It was noted that all the experimental compounds showed profound interaction with two major receptors of the Wnt/β-catenin pathway. Conclusion: To the best of our knowledge, this study is the first of its kind to characterize the combined interactions of the aforementioned drugs with the Wnt/β-catenin signalling in silico, and this will putatively open up new avenues for combination therapies in GBM treatment.

Alzheimer’s disease (AD), a major form of dementia, has been reported to affect more than 50 million people worldwide. It is characterized by the presence of amyloid-β (Aβ) plaques and hyperphosphorylated Tau-associated neurofibrillary tangles in the brain. Apart from AD, microtubule (MT)-associated protein Tau is also involved in other neurodegenerative diseases called tauopathies, including Pick’s disease, frontotemporal lobar degeneration, progressive supranuclear palsy, and corticobasal degeneration. The recent unsuccessful phase III clinical trials related to Aβ- targeted therapeutic drugs have indicated that alternative targets, such as Tau, should be studied to discover more effective and safer drugs. Recent drug discovery approaches to reduce AD-related Tau pathologies are primarily based on blocking Tau aggregation, inhibiting Tau phosphorylation, compensating impaired Tau function with MT-stabilizing agents, and targeting the degradation pathways in neuronal cells to degrade Tau protein aggregates. Owing to several limitations of the currently available Tau-directed drugs, further studies are required to generate further effective and safer Tau-based disease-modifying drugs. Here, we review the studies focused on medicinal plant- derived compounds capable of modulating the Tau protein, which is significantly elevated and hyperphosphorylated in AD and other tauopathies. We have mainly considered the studies focused on Tau protein as a therapeutic target. We have reviewed several pertinent papers retrieved from PubMed and ScienceDirect using relevant keywords, with a primary focus on the Tau-targeting compounds from medicinal plants. These compounds include indolines, phenolics, flavonoids, coumarins, alkaloids, and iridoids, which have been scientifically proven to be Tau-targeting candidates for the treatment of AD.

The cytochrome bc1-aa3 supercomplex plays an essential role in the cellular respiratory system of Mycobacterium Tuberculosis. It transfers electrons from menaquinol to cytochrome aa3 (Complex IV) via cytochrome bc1 (Complex III), which reduces the oxygen. The electron transfer from a variety of donors into oxygen through the respiratory electron transport chain is essential to pump protons across the membrane creating an electrochemical transmembrane gradient (proton motive force, PMF) that regulates the synthesis of ATP via the oxidative phosphorylation process. Cytochrome bc1-aa3 supercomplex in M. tuberculosis is, therefore, a major drug target for antibiotic action. In recent years, several respiratory chain components have been targeted for developing new candidate drugs, illustrating the therapeutic potential of obstructing energy conversion of M. tuberculosis. The recently available cryo-EM structure of mycobacterial cytochrome bc1-aa3 supercomplex with open and closed conformations has opened new avenues for understanding its structure and function for developing more effective, new therapeutics against pulmonary tuberculosis. In this review, we discuss the role and function of several components, subunits, and drug targeting elements of the supercomplex cytochrome bc1-aa3 and its potential inhibitors in detail.

Corona viruses are enveloped, single-stranded RNA (Ribonucleic acid) viruses, and they cause pandemic diseases having a devastating effect on both human healthcare and the global economy. To date, six corona viruses have been identified as pathogenic organisms, which are significantly responsible for the infection and cause severe respiratory diseases. Among them, the novel SARS-CoV-2 (Severe Acute Respiratory Syndrome coronavirus 2) caused a major outbreak of coronavirus diseases in 2019 (COVID-19). Coronaviridae family members can affect both humans and animals. In humans, coronaviruses cause a severe acute respiratory syndrome with mild to severe outcomes. Several structural and genomics aspects have been investigated, and the genome encodes about 30 proteins most of them with unknown function though they share remarkable sequence identity with other proteins. There are no potent drugs against SARS-CoV-2 and several trials are underway to investigate the possible therapeutic agents against viral infection. However, some of the antiviral drugs that have been investigated against SARS-CoV-2 are under clinical trials. In the current review, we comparatively emphasize the emergence and pathogenicity of the SARS-CoV-2 and their infection, and discuss the various putative drug targets of both viral and host receptors for developing effective vaccines and therapeutic combinations to overcome the viral outbreak.

The pandemic, caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARSCoV- 2), is responsible for multiple worldwide lockdowns, an economic crisis, and a substantial increase in hospitalizations for viral pneumonia along with respiratory failure and multiorgan dysfunctions. Recently, the first few vaccines were approved by World Health Organization (WHO) and can eventually save millions of lives. Even though, few drugs are used in emergency like Remdesivir and several other repurposed drugs, still there is no approved drug for COVID-19. The coronaviral encoded proteins involved in host-cell entry, replication, and host-cell invading mechanism are potential therapeutic targets. This perspective review provides the molecular overview of SARS-CoV-2 life cycle for summarizing potential drug targets, structural insights, active site contour map analyses of those selected SARS-CoV-2 protein targets for drug discovery, immunology, and pathogenesis.

Background: Tacrolimus is a calcineurin inhibitor widely used for immunological disorders. However, there is significant controversy regarding its effect on the liver. The present study was conducted to evaluate the anticancer effects of tacrolimus on an induced murine hepatocellular carcinoma (HCC) model and its possible hepatotoxicity at standard therapeutic doses. Methods: Fifty-four male mice were divided into five groups: a control healthy group, control HCC group, tacrolimus-treated group, doxorubicin (DOXO)-treated group, and combined tacrolimus- and DOXO-treated group. The activity of liver enzymes, including alkaline phosphatase, gamma- glutamyl transferase, lactate dehydrogenase, alanine transaminase, and aspartate transaminase, was determined. Serum vascular endothelial growth factor (VEGF) was measured using an enzyme- linked immunosorbent assay. A quantitative real time- polymerase chain reaction (qRTPCR) was conducted to measure the expression of proliferating cell nuclear antigen (PCNA), Bax, and p53 mRNA. Immunohistochemical staining for cyclin D1 and VEGF was performed. Results: Mice that received combined treatment with tacrolimus and DOXO exhibited the best improvement in all parameters when compared with the groups that received DOXO or tacrolimus alone (p < 0.001). Conclusion: The combination of DOXO and tacrolimus was more effective in the management of HCC compared with either agent alone. This improvement was detected by the reduction of liver enzymes and the improvement of the histopathological profile. The involved mechanisms included significant apoptosis induction demonstrated by upregulation of bax along with a reduction in angiogenesis demonstrated by downregulation of VEGF. This was accompanied by inhibition of cell cycle progression mediated by upregulated p53 and downregulated PCNA and cyclin D1.

Objective: The present study aims to evaluate the antioxidant effect of beta-glucan on oxidative DNA damage by comet assay. Methods: A total of 19 adult females and males diagnosed with stage 3-4 colorectal cancer and a control group of 20 age-matched healthy subjects were enrolled in the study. Blood samples of the participants were analyzed using Comet Assay for the parameters of DNA damage. Results: Significantly increased DNA damage was observed in patients versus the control group as indicated by greater values of tail moment, tail percent DNA and tail length. Following incubation with β-glucan, a substantial reduction was found in the aforementioned parameters of DNA damage. Comet assay revealed significant levels of endogenous DNA damage in patients as shown by remarkable increases in the tail moment, the percentage of DNA in the tail and the tail length values, in comparison with the control group. Following treatment of fresh whole blood with β-glucan incubation, DNA damages were significantly reduced, but lower values were observed after β-glucan incubation in the patient group versus control group. Conclusion: β-Glucan was found to reduce DNA damage substantially in colorectal cancer patients and show antimutagenic effects. Our results suggested that dietary β-glucan intake might be important in the genesis of colorectal cancer tumors.

Background: Collagen production by activated hepatic stellate cells (HSCs) to encapsulate injury is part of the natural wound-healing response in injured liver. However, persistent activation of HSCs can lead to pathological fibrogenesis. Such persistent HSC activation could be mediated by norepinephrine (NE), a reaction product of dopamine beta-hydroxylase (DBH). Objective: To investigate the potential paracrine role of NE in hepatotoxin thioacetamide (TAA)-induced liver fibrosis. Methods: In TAA-treated mice, fibrotic liver tissue showed significant increases in the mRNA expression of DBH up to 14-fold and collagen up to 7-fold. Immunohistochemical staining showed increased DBH protein expression in fibrotic liver tissue. Parenchymal hepatocyte cell line HepG2 expressed DBH and secreted NE, and the conditioned medium of HepG2 cells promoted collagenesis in nonparenchymal HSC cell line LX-2. TAA treatment increased DBH expression by 170% in HepG2 cells, as well as increased NE by 120% in the conditioned medium of HepG2 cells. The conditioned medium of TAA-treated HepG2 cells was used to culture LX-2 cells, and was found to increase collagen expression by 80% in LX-2 cells. Collagen expression was reduced by pre-treating HepG2 cells with siRNA targeting DBH or by adding NE antagonists to the conditioned medium. Results: Finally, TAA-induced oxidative stress in HepG2 cells was associated with induction of DBH expression. Collectively, our results suggest a potential role for DBH/NE-mediated crosstalk between hepatocytes and HSCs in fibrogenesis. Conclusion: From a therapeutic standpoint, antagonism of DBH/NE induction in hepatocytes might be a useful strategy to suppress pathological fibrogenesis.