The Rise and Fall of Chloroquine/Hydroxychloroquine as Compassionate Therapy of COVID-19.

The emergence and rapid spread of novel coronavirus disease (COVID-19) has posed a serious challenge to global public health in 2020. The speed of this viral spread together with the high mortality rate has caused an unprecedented public health crisis. With no antivirals or vaccines available for the treatment of COVID-19, the medical community is presently exploring repositioning of clinically approved drugs for COVID-19. Chloroquine (CQ) and hydroxychloroquine (HCQ) have emerged as potential candidates for repositioning as anti-COVID-19 therapeutics and have received FDA authorization for compassionate use in COVID-19 patients. On March 28, 2020, the U.S. Food and Drug Administration (FDA) issued an Emergency Use Authorization (EUA) for HCQ in the treatment of COVID-19. However, it was later revoked by the FDA on June 15, 2020, after analyzing the emerging scientific data from ongoing clinical trials. Similarly, the World Health Organization (WHO) also conducted a Solidarity trial of chloroquine, hydroxychloroquine, remdesivir, lopinavir, and ritonavir. However, on May 23, 2020, the executive body of the "Solidarity trial" decided to put a temporary hold on the HCQ trial. On June 17, 2020, the WHO abruptly stopped the Solidarity trial of HCQ. The current review strives to examine the basis of compassionate use of CQ and HCQ for the treatment of COVID-19 in terms of literature evidence, establishing the antiviral efficacy of these drugs against corona and related viruses. Furthermore, the review presents a critical analysis of the clinical trial findings and also provides an insight into the dynamically changing decision on the authorization and withdrawal of HCQ as anti-COVID-19 therapy by the U.S. FDA and the WHO. Ultimately, our study necessitates an evidenced-based treatment protocol to confront the ongoing COVID-19 pandemic and not the mere observational study that mislead the public healthcare system, which paralyzes the entire world.

Mutational analysis of structural proteins of SARS-CoV-2.

SARS-CoV-2 transmissibility is higher than that of other human coronaviruses; therefore, it poses a threat to the populated communities. We investigated mutations among envelope (E), membrane (M), and spike (S) proteins from different isolates of SARS-CoV-2 and plausible signaling influenced by mutated virus in a host. We procured updated protein sequences from the NCBI virus database. Mutations were analyzed in the retrieved sequences of the viral proteins through multiple sequence alignment. Additionally, the data was subjected to ScanPROSITE to analyse if the mutations generated a relevant sequence for host signaling. Unique mutations in E, M, and S proteins resulted in modification sites like PKC phosphorylation and N-myristoylation sites. Based on structural analysis, our study revealed that the D614G mutation in the S protein diminished the interaction with T859 and K854 of adjacent chains. Moreover, the S protein of SARS-CoV-2 consists of an Arg-Gly-Asp (RGD) tripeptide sequence, which could potentially interact with various members of integrin family receptors. RGD sequence in S protein might aid in the initial virus attachment. We speculated crucial host pathways which the mutated isolates of SARS-CoV-2 may alter like PKC, Src, and integrin mediated signaling pathways. PKC signaling is known to influence the caveosome/raft pathway which is critical for virus entry. Additionally, the myristoylated proteins might activate NF-κB, a master molecule of inflammation. Thus the mutations may contribute to the disease pathogenesis and distinct lung pathophysiological changes. Further the frequently occurring mutations in the protein can be studied for possible therapeutic interventions.

An Update on Antiviral Therapy Against SARS-CoV-2: How Far Have We Come?

COVID-19 pandemic has spread worldwide at an exponential rate affecting millions of people instantaneously. Currently, various drugs are under investigation to treat an enormously increasing number of COVID-19 patients. This dreadful situation clearly demands an efficient strategy to quickly identify drugs for the successful treatment of COVID-19. Hence, drug repurposing is an effective approach for the rapid discovery of frontline arsenals to fight against COVID-19. Successful application of this approach has resulted in the repurposing of some clinically approved drugs as potential anti-SARS-CoV-2 candidates. Several of these drugs are either antimalarials, antivirals, antibiotics or corticosteroids and they have been repurposed based on their potential to negate virus or reduce lung inflammation. Large numbers of clinical trials have been registered to evaluate the effectiveness and clinical safety of these drugs. Till date, a few clinical studies are complete and the results are primary. WHO also conducted an international, multi-country, open-label, randomized trials-a solidarity trial for four antiviral drugs. However, solidarity trials have few limitations like no placebos were used, additionally any drug may show effectiveness for a particular population in a region which may get neglected in solidarity trial analysis. The ongoing randomized clinical trials can provide reliable long-term follow-up results that will establish both clinical safety and clinical efficacy of these drugs with respect to different regions, populations and may aid up to worldwide COVID-19 treatment research. This review presents a comprehensive update on majorly repurposed drugs namely chloroquine, hydroxychloroquine, remdesivir, lopinavir-ritonavir, favipiravir, ribavirin, azithromycin, umifenovir, oseltamivir as well as convalescent plasma therapy used against SARS-CoV-2. The review also summarizes the data recorded on the mechanism of anti-SARS-CoV-2 activity of these repurposed drugs along with the preclinical and clinical findings, therapeutic regimens, pharmacokinetics, and drug-drug interactions.

Bax/Tubulin/Epithelial-Mesenchymal Pathways Determine the Efficacy of Silybin Analog HM015k in Colorectal Cancer Cell Growth and Metastasis.

The inhibition of apoptosis, disruption of cellular microtubule dynamics, and over-activation of the epithelial mesenchymal transition (EMT), are involved in the progression, metastasis, and resistance of colorectal cancer (CRC) to chemotherapy. Therefore, the design of a molecule that can target these pathways could be an effective strategy to reverse CRC progression and metastasis. In this study, twelve novel silybin derivatives, HM015a-HM015k (15a-15k) and compound 17, were screened for cytotoxicity in CRC cell lines. Compounds HM015j and HM015k (15k and 15j) significantly decreased cell proliferation, inhibited colony formation, and produced cell cycle arrest in CRC cells. Furthermore, 15k significantly induced the formation of reactive oxygen species and apoptosis. It induced the cleavage of the intrinsic apoptotic protein (Bax p21) to its more efficacious fragment, p18. Compound 15k also inhibited tubulin expression and disrupted its structure. Compound 15k significantly decreased metastatic LOVO cell migration and invasion. Furthermore, 15k reversed mesenchymal morphology in HCT116 and LOVO cells. Additionally, 15k significantly inhibited the expression of the mesenchymal marker N-cadherin and upregulated the expression of the epithelial marker, E-cadherin. Compound 15k inhibited the expression of key proteins known to induce EMT (i.e., DVL3, ß-catenin, c-Myc) and upregulated the anti-metastatic protein, cyclin B1. Overall, in vitro, 15k significantly inhibited CRC progression and metastasis by inhibiting apoptosis, tubulin activity and the EMT pathways. Overall, these data suggest that compound 15k should be tested in vivo in a CRC animal model for further development.

Blocking oestradiol synthesis pathways with potent and selective coumarin derivatives.

A comprehensive set of 3-phenylcoumarin analogues with polar substituents was synthesised for blocking oestradiol synthesis by 17-ß-hydroxysteroid dehydrogenase 1 (HSD1) in the latter part of the sulphatase pathway. Five analogues produced ≥62% HSD1 inhibition at 5 µM and, furthermore, three of them produced ≥68% inhibition at 1 µM. A docking-based structure-activity relationship analysis was done to determine the molecular basis of the inhibition and the cross-reactivity of the analogues was tested against oestrogen receptor, aromatase, cytochrome P450 1A2, and monoamine oxidases. Most of the analogues are only modestly active with 17-ß-hydroxysteroid dehydrogenase 2 - a requirement for lowering effective oestradiol levels in vivo. Moreover, the analysis led to the synthesis and discovery of 3-imidazolecoumarin as a potent aromatase inhibitor. In short, coumarin core can be tailored with specific ring and polar moiety substitutions to block either the sulphatase pathway or the aromatase pathway for treating breast cancer and endometriosis.

Structure-Activity Relationship Analysis of 3-Phenylcoumarin-Based Monoamine Oxidase B Inhibitors.

Monoamine oxidase B (MAO-B) catalyzes deamination of monoamines such as neurotransmitters dopamine and norepinephrine. Accordingly, small-molecule MAO-B inhibitors potentially alleviate the symptoms of dopamine-linked neuropathologies such as depression or Parkinson's disease. Coumarin with a functionalized 3-phenyl ring system is a promising scaffold for building potent MAO-B inhibitors. Here, a vast set of 3-phenylcoumarin derivatives was designed using virtual combinatorial chemistry or rationally de novo and synthesized using microwave chemistry. The derivatives inhibited the MAO-B at 100 nM-1 µM. The IC50 value of the most potent derivative 1 was 56 nM. A docking-based structure-activity relationship analysis summarizes the atom-level determinants of the MAO-B inhibition by the derivatives. Finally, the cross-reactivity of the derivatives was tested against monoamine oxidase A and a specific subset of enzymes linked to estradiol metabolism, known to have coumarin-based inhibitors. Overall, the results indicate that the 3-phenylcoumarins, especially derivative 1, present unique pharmacological features worth considering in future drug development.

HM015k, a Novel Silybin Derivative, Multi-Targets Metastatic Ovarian Cancer Cells and Is Safe in Zebrafish Toxicity Studies.

This study was designed to determine the in vitro mechanisms by which the novel silybin derivative, (E)-3-(3-(benzyloxy) phenyl)-1-(4-hydroxyphenyl)prop-2-en-1-one (HM015k or 15k), produces its anticancer efficacy in ovarian cancer cells. Compound 15k induced apoptosis in ovarian cancer cells in a time-dependent manner by significantly upregulating the expression of Bax and Bak and downregulating the expression of Bcl-2. Interestingly, 15k induced the cleavage of Bax p21 into its more efficacious cleaved form, Bax p18. In addition, caspase 3 and caspase 9 were cleaved to their active forms, inducing the cleavage of poly ADP ribose polymerase (PARP) and ß-catenin. Furthermore, in OV2008 cells, 15k induced significant cleavage in nuclear ß-catenin to primarily inactive fragments of lower molecular weight. Furthermore, 15k reversed the metastatic potential of OV2008 cells by inhibiting their migration and invasiveness. The mesenchymal phenotype in OV2008 was reversed by 15k, causing cells to be rounder with epithelial-like phenotypes. The 15k-induced reversal was further confirmed by significant upregulation of the E-cadherin expression, an epithelial marker, while N-cadherin, a mesenchymal marker, was downregulated in OV2008 cells. Compound 15k inhibited the expression of the oncogenic c-Myc protein, downregulated proteins DVL3 and DVL2 and significantly upregulated cyclin B1. Also, 15k significantly downregulated the expression levels of ABCG2 and ABCB1 transporters in resistant ABCG2 overexpressing H460/MX20 and resistant ABCB1 overexpressing MDCK/MDR1 cells, respectively. Finally, 15k was safe in zebrafish in vivo model at concentrations up to 10 µM and induced no major toxicities in cardiac, morphology and swimming position parameters. Overall, 15k is a multi-targeted inhibitor with efficacy against metastatic and resistant ovarian cancer. Future in vivo studies will be conducted to determine the efficacy of 15k in tumor-bearing animals.

Design and discovery of silybin analogues as antiproliferative compounds using a ring disjunctive - Based, natural product lead optimization approach.

The present study reports the synthesis and anticancer activity evaluation of twelve novel silybin analogues designed using a ring disjunctive-based natural product lead (RDNPL) optimization approach. All twelve compounds were tested against a panel of cancer cells (i.e. breast, prostate, pancreatic, and ovarian) and compared with normal cells. While all of the compounds had significantly greater efficacy than silybin, derivative 15k was found to be highly potent (IC50 < 1 µM) and selective against ovarian cancer cell lines, as well as other cancer cell lines, compared to normal cells. Preliminary mechanistic studies indicated that the antiproliferative efficacy of 15k was mediated by its induction of apoptosis, loss of mitochondrial membrane potential and cell cycle arrest at the sub-G1 phase. Furthermore, 15k inhibited cellular microtubules dynamic and assembly by binding to tubulin and inhibiting its expression and function. Overall, the results of the study establish 15k as a novel tubulin inhibitor with significant activity against ovarian cancer cells.

Inhibition of Aβ(1-42)Oligomerization, Fibrillization and Acetylcholinesterase Activity by Some Anti-Inflammatory Drugs: An in vitro Study.

BACKGROUND: Number of contradictory reports are available on the effects of antiinflammatory drugs on Alzheimer's disease (AD) including beneficial, adverse and stage dependent effects. We provide insights of the effects exerted by some anti-inflammatory drugs on the chemistry of AD. METHODS: Three different doses of dexamethasone (0.015, 0.030, 0.060 µM), piroxicam (5, 7.5, 10 µM), indomethacin (1, 1.25, 1.50 µM), diclofenac (0.6, 0.8, 1.0 µM), aspirin (90, 120, 150 µM) and celecoxib (30, 45, 60 µM) were used. Rivastigmine, methylene blue and butylated hydroxyanisole were used as standard drug, oligomerization inhibitor and antioxidant, respectively. Oligomerization and fibrillization reactions were performed using Aß1-42 peptides. Results-Indomethacin and aspirin mainly inhibited oligomerization, while rivastigmine and piroxicam inhibited fibrillization. Diclofenac and celecoxib inhibited both oligomerization and fibrillization almost equally. Dexamethasone showed poor efficiency on both the processes, but exert comparably more inhibition of oligomerization than fibrillization. Inhibition of acetylcholinesterase activity was also potent and was in the following order: celecoxib> piroxicam> diclofenac> aspirin> indomethacin> dexamethasone. Strong radical scavenging (More than 50%) activity was showed by indomethacin and aspirin for NO radicals. CONCLUSION: Present study consistently revealed that anti-inflammatory drugs have potential to Modulate chemistry of AD progression. Inclusion of anti-inflammatory drugs in low doses along with routine therapies may provide therapeutically and economically more efficient therapies for AD. However, further studies are warranted, because the overall therapeutic effect seems to be the function of stage of disease, dose of drug, main underlying mechanism of action(s).

Identification of estrogen receptor α ligands with virtual screening techniques.

Utilization of computer-aided molecular discovery methods in virtual screening (VS) is a cost-effective approach to identify novel bioactive small molecules. Unfortunately, no universal VS strategy can guarantee high hit rates for all biological targets, but each target requires distinct, fine-tuned solutions. Here, we have studied in retrospective manner the effectiveness and usefulness of common pharmacophore hypothesis, molecular docking and negative image-based screening as potential VS tools for a widely applied drug discovery target, estrogen receptor α (ERα). The comparison of the methods helps to demonstrate the differences in their ability to identify active molecules. For example, structure-based methods identified an already known active ligand from the widely-used bechmarking decoy molecule set. Although prospective VS against one commercially available database with around 100,000 drug-like molecules did not retrieve many testworthy hits, one novel hit molecule with pIC50 value of 6.6, was identified. Furthermore, our small in-house compound collection of easy-to-synthesize molecules was virtually screened against ERα, yielding to five hit candidates, which were found to be active in vitro having pIC50 values from 5.5 to 6.5.

Advances in chalcones with anticancer activities.

Chalcones are naturally occurring compounds exhibiting broad spectrum biological activities including anticancer activity through multiple mechanisms. Literature on anticancer chalcones highlights the employment of three pronged strategies, namely; structural manipulation of both aryl rings, replacement of aryl rings with heteroaryl scaffolds, molecular hybridization through conjugation with other pharmacologically interesting scaffolds for enhancement of anticancer properties. Methoxy substitutions on both the aryl rings (A and B) of the chalcones, depending upon their positions in the aryl rings appear to influence anticancer and other activities. Similarly, heterocyclic rings either as ring A or B in chalcones, also influence the anticancer activity shown by this class of compounds. Hybrid chalcones formulated by chemically linking chalcones to other prominent anticancer scaffolds such as pyrrol[2,1-c][1,4]benzodiazepines, benzothiazoles, imidazolones have demonstrated synergistic or additive pharmacological activities. The successful application of these three pronged strategies for discovering novel anticancer agents based on chalcone scaffold has resulted in many novel and chemically diverse chalcones with potential therapeutic application for many types of cancer. This review summarizes the concerted efforts expended on the design and development of anticancer chalcones recorded in recent literature and also provides an overview of the patents published in this area between 2007 and 2014 (WO2013022951, WO201201745 & US2012029489).

QSAR analysis of some fused pyrazoles as selective cyclooxygenase-2 inhibitors: a Hansch approach.

Quantitative structure activity relationships (QSAR) for two unique series of centrally fused pyrazole ring systems have been studied for selective cyclooxygenase-2 inhibitory activity. Several statistically significant QSAR models were developed and suggest that hydrophobicity of entire molecules and a fluorine atom substitution at position 8 of the non benzene sulphonyl ring fused with central pyrazole core of series 1 compounds is crucial for improved COX-2 selectivity. Various structural and physicochemical stipulations to improve the inhibitory activities of the enzymes among individual series of compounds are also discussed. The conclusions derived may serve as an example to advance the design of new selective COX-2 inhibitors.