Entry to new spiroheterocycles via tandem Rh(II)-catalyzed O-H insertion/base-promoted cyclization involving diazoarylidene succinimides

A facile approach to novel medicinally relevant spiro heterocyclic scaffolds (namely furan-2(5H)-ones, tetrahydrofurans and pyrans spiro-conjugated with the succinimide ring) has been developed. The protocol consists of Rh(II)-catalyzed insertion of heterocyclic carbenes derived from diazoarylidene succinimides (DAS) into the O-H bond of propiolic/allenic acids or brominated alcohols, followed by base-promoted cyclization to afford the target spirocyclic compounds in good to high yields.

Absolute Configuration of 12S-Deoxynortryptoquivaline from Ascidian-Derived Fungus Aspergillus clavatus Determined by Anisotropic NMR and Chiroptical Spectroscopy

Tryptoquivalines are highly toxic metabolites initially isolated from the fungus Aspergillus clavatus. The relative and absolute configuration of tryptoquivaline derivates was primarily established by comparison of the chemical shifts, NOE data, and ECD calculations. A de novo determination of the complete relative configuration using NMR spectroscopy was challenging due to multiple spatially separated stereocenters, including one nonprotonated carbon. In this study, we isolated a new tryptoquivaline derivative, 12S-deoxynortryptoquivaline (1), from the marine ascidian-derived fungus Aspergillus clavatus AS-107. The correct assignment of the relative configuration of 1 was accomplished using anisotropic NMR spectroscopy, while the absolute configuration was determined by comparing calculated and experimental ECD spectra. This case study highlights the effectiveness of anisotropic NMR parameters over isotropic NMR parameters in determining the relative configuration of complex natural products without the need for crystallization.

A review on the effective natural compounds of medicinal plants on the COVID-19

In this review out of 300 selected articles 70 articles were evaluated, and the most significant compounds impacting COVID-19 and their mechanism of action were introduced. The compounds belong to four categories as follow: Phenolic, Flavonoid, Terpenoid, and Alkaloid compounds. In the phenol groups, the most effective compounds are scutellarin (suppressor of COVID-19 virus), thymol and carvacrol (the most inhibitory effect on COVID-19 virus), in the flavonoid groups, hesperdin (a strong inhibitor on COVID-19), in the terpenoids, methyl tanshinonate and sojil COVID-19 inhibitory effect) and 1,8-cineol (COVID-19 inhibitory effect) and in the last group, niglidine and quinoline alkaloid compounds (COVID-19 inhibitory effect) have been identified and introduced. These compounds have shown promising results due to their structure and effective mechanisms on COVID-19, so it can be an idea for researchers in this field to try to produce drugs by using natural compounds against the COVID-19 and Corona viruses.

Therapeutic Management with Repurposing Approaches: A Mystery During COVID-19 Outbreak

The ubiquitous pandemic that emerged due to COVID-19 affected the whole planet. People all over the globe became vulnerable to the unpredictable emergence of coronavirus. The sudden emergence of respiratory disease in coronavirus infected several patients. This affected human life drastically, from mild symptoms to severe illness, leading to mortality. COVID-19 is an exceptionally communicable disease caused by SARS-CoV-2. According to a genomic study, the viral spike RBD interactions with the host ACE2 protein from several coronavirus strains and the interaction between RBD and ACE2 highlighted the potential change in affinity from the virus causing the COVID-19 outbreak to a progenitor type of SARS-CoV-2. SARS-CoV-2, which could be the principal reservoir, is phylogenetically related to the SARS-like bat virus. Other research works reported that intermediary hosts for the transmission of viruses to humans could include cats, bats, snakes, pigs, ferrets, orangutans, and monkeys. Even with the arrival of vaccines and individuals getting vaccinated and treated with FDAapproved repurposed drugs like Remdesivir, the first and foremost steps aimed towards the possible control and minimization of community transmission of the virus include social distancing, self-realization, and self-health care. In this review paper, we discussed and summarized various approaches and methodologies adopted and proposed by researchers all over the globe to help with the management of this zoonotic outbreak by following repurposed approaches.

Novel Multi-Target Agents Based on the Privileged Structure of 4-Hydroxy-2-quinolinone

In this work, the privileged scaffold of 4-hydroxy-2quinolinone is investigated through the synthesis of carboxamides and hybrid derivatives, as well as through their bioactivity evaluation, focusing on the ability of the molecules to inhibit the soybean LOX, as an indication of their anti-inflammatory activity. Twenty-one quinolinone carboxamides, seven novel hybrid compounds consisting of the quinolinone moiety and selected cinnamic or benzoic acid derivatives, as well as three reverse amides are synthesized and classified as multi-target agents according to their LOX inhibitory and antioxidant activity. Among all the synthesized analogues, quinolinone-carboxamide compounds 3h and 3s, which are introduced for the first time in the literature, exhibited the best LOX inhibitory activity (IC50 = 10 μM). Furthermore, carboxamide 3g and quinolinone hybrid with acetylated ferulic acid 11e emerged as multi-target agents, revealing combined antioxidant and LOX inhibitory activity (3g: IC50 = 27.5 μM for LOX inhibition, 100% inhibition of lipid peroxidation, 67.7% ability to scavenge hydroxyl radicals and 72.4% in the ABTS radical cation decolorization assay; 11e: IC50 = 52 μM for LOX inhibition and 97% inhibition of lipid peroxidation). The in silico docking results revealed that the synthetic carboxamide analogues 3h and 3s and NDGA (the reference compound) bind at the same alternative binding site in a similar binding mode.

Arq Ajīb - a wonder Unani formulation for inhibiting SARS-CoV-2 spike glycoprotein and main protease - an in silico approach

OBJECTIVES

The current pandemic caused by Severe Acute Respiratory Syndrome Corona-Virus 2 (SARS-CoV-2) has become a global health menace with significant morbidity and mortality besides huge socioeconomic implications. Despite the approval of few vaccines for the prevention of the disease, the discovery of safe and effective countermeasures especially from natural sources is of paramount importance, as the number of cases continues escalating. Arq Ajīb has long been used for various diseases and its ingredients have been reported for antiviral, antimicrobial, antipyretic, anti-inflammatory, antioxidant activities. The present study investigates the inhibitory effect of phytocompound of Arq Ajīb on potential drug targets of SARS-CoV-2.

METHODS

The structures of phytocompounds present in Arq Ajīb were retrieved from PubChem database and some were illustrated using Marvin Sketch. SARS-CoV-2 S glycoprotein (PDB ID: 6LZG) and 3CLpro (PDB ID: 7BQY) were selected as the target protein. Dock Prep module in UCSF Chimera software was used for receptor structure processing. AutoDock Vina was used to calculate the binding affinities between the protein and ligands and to predict most promising compounds with best scores.

RESULTS

Molecular docking results predicted that the phytocompounds of Arq Ajīb had good binding affinity and interaction with S glycoprotein and 3CLpro. Quercetin and Isorhoifolin from Mentha arvensis were identified as promising candidates with the potential to interact with 3CLpro and spike glycoprotein and inhibit the viral replication and its entry into the host.

CONCLUSIONS

Arq Ajīb may prove valuable for developing novel therapeutic candidate for COVID-19; however, it has to be substantiated further with in-vitro and in-vivo studies.

Photosensitization of TiO2 microspheres by novel Quinazoline-derivative as visible-light-harvesting antenna for enhanced Rhodamine B photodegradation

Water pollution is one of the global threats severely affecting our planet and human health. Organic textile dyes are one of the common organic water pollutants that are presentient to degradation by traditional physical methods. Semiconductor-assisted photocatalysis is considered a green, efficient, and sustainable technology for wastewater treatment. To maximize the efficient utilization of solar radiation, it is of pivotal significance to explore novel organic molecules to be employed as efficient dye sensitizers for wide-bandgap semiconductors to extend their performance to the Visible-light region. Hence, in this work, we are proposing the design and synthesis of novel structures of QAD molecule as a dye photosensitizer with extended visible light absorptivity due to the extended π-π/n-π conjugations, to promote the performance of TiO2 nanoparticles to the visible-light region and enhance the charge separation. The physicochemical characterizations confirmed the successful synthesis of QAD, TiO2, and QAD/TiO2 samples with the proposed structures. The anchoring of QAD molecules on the surface of TiO2 caused a substantial improvement in the optical characteristics of TiO2 as well as overcoming its common drawbacks by decreasing its bandgap energy to 2.6 eV, a remarkable reduction of PL intensity indicating reducing the e-h recombination and enhancing the charge separation, and creation of efficient visible light-harvesting antenna in the range of 400-600 nm. Besides, the QAD/TiO2 sample achieved a 3-fold enhancement in the observed rate constant of the photodegradation of Rhodamine B dye compared to the bare TiO2. The parameters affecting the photodegradation process were optimized and the sample displayed outstanding stability after 4 consecutive cycles. Finally, the effect of the scavengers was investigated and [Formula: see text] was proposed to be the most reactive species and the mechanism of the enhancement was suggested based on the electron injection from the QAD's HOMO level to the TiO2's CB. Finally, this work opens the door for various studies for the investigation of the proposed structures or similar structures in various photocatalytic/biomedical applications.

Emerging quinoline- and quinolone-based antibiotics in the light of epidemics

Pandemics are large-scale outbreaks of infectious disease that can greatly increase morbidity and mortality all the globe. Since past 1990 till twentieth century, these infectious diseases have been major threat all over the globe associated with poor hygiene and sanitation. In light of these epidemics, researches have gained enormous rise in the developing the potential therapeutic treatment. Thus, revolutionized antibiotics have led to the near eradication of such ailments. Around 50 million prescription of antibiotics written in US per year according to center for disease control and prevention (CDC) report. There is a wide range of antibiotics available which differ in their usage and their mechanism of action. Among these quinoline and quinolone class of antibiotics get attention as they show tremendous potential in fighting the epidemics. Quinoline and quinolone comprise of two rings along with substitutions at different positions which is synthetically obtained by structural modifications of quinine. Quinoline and quinolone antibiotics exhibit extensive activities approved by FDA in the treatment of the several ailments such as gastrointestinal infections, urinary tract infections, prostate inflammation, malaria, gonorrhea, skin infection, colorectal cancer, respiratory tract infections. These are active against both gram-negative and gram-positive bacteria. This basic core of quinoline and quinolone is vital due to its capability of targeting the pathogen causing disease and beneficial in treating the infectious disease. They inhibit the synthesis of nucleic acid of bacteria which results in the rupture of bacterial chromosome due to the interruption of enzymes such as DNA gyrase and topoisomerase IV. There are various quinoline and quinolone compounds that are synthetically derived by applying different synthesis approaches which show a wide range of pharmacological activities in several diseases. The most commonly used are fluoro, chloro, and hydroxychloro derivatives of quinoline and quinolone. These compounds are helpful in the treatment of numerous epidemics as a chief and combination therapy. These quinoline and quinolone pharmacophore fascinate the interest of researchers as they inhibit the entry of virus in host cell and cease its replication by blocking the host receptor glycosylation and proteolytic processing. They act as immune modulator by inhibiting autophagy and reduction of both lysosomal activity and production of cytokine. Therefore, quinoline and quinolone derivatives attain significance in area of research and treatment of various life-threatening epidemics such as SARS, Zika virus, Ebola virus, dengue, and COVID-19 (currently). In this chapter, the research and advancements of quinoline- and quinolone-based antibiotics in epidemic management are briefly discussed.

A Review on Herbal Secondary Metabolites Against COVID-19 Focusing on the Genetic Variants of SARS-CoV-2

Context: An outbreak of the new coronavirus disease 2019 (COVID-19) was reported in Wuhan, China, in December 2019, subsequently affecting countries worldwide and causing a pandemic. Although several vaccines, such as mRNA vaccines, inactivated vaccines, and adenovirus vaccines, have been licensed in several countries, the danger of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants persists. To date, Alpha (B.1.1.7), Beta (B.1.351, B.1.351.2, B.1.351.3), Delta (B.1.617.2, AY.1, AY.2, AY. 3), Gamma (P.1, P.1.1, P.1.2), and Iota (B.1 .526) circulating in the United States, Kappa (B.1.617.1) in India, Lambda (C.37) in Peru and Mu (B.1.621) in Colombia are considered the variants of concern and interest. Evidence Acquisition: Data were collected through the end of August 2021 by searching PubMed, Scopus, and Google Scholar databases. There were findings from in silico, in vitro cell-based, and non-cell-based investigations. Results: The potential and safety profile of herbal medicines need clarification to scientifically support future recommendations regarding the benefits and risks of their use. Conclusions: Current research results on natural products against SARS-CoV-2 and variants are discussed, and their specific molecular targets and possible mechanisms of action are summarized.

The naturally-derived alkaloids as a potential treatment for COVID-19: A scoping review

Coronavirus disease 2019 (COVID-19) is caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), which has a high mortality rate and transmissibility. In this context, medicinal plants have attracted attention due to the wide availability and variety of therapeutic compounds, such as alkaloids, a vast class with several proven pharmacological effects, like the antiviral and anti-inflammatory activities. Therefore, this scoping review aimed to summarize the current knowledge of the potential applicability of alkaloids for treating COVID-19. A systematic search was performed on PubMed and Scopus, from database inception to August 2021. Among the 63 eligible studies, 65.07% were in silico model, 20.63% in vitro and 14.28% clinical trials and observational studies. According to the in silico assessments, the alkaloids 10-hydroxyusambarensine, cryptospirolepine, crambescidin 826, deoxynortryptoquivaline, ergotamine, michellamine B, nigellidine, norboldine and quinadoline B showed higher binding energy with more than two target proteins. The remaining studies showed potential use of berberine, cephaeline, emetine, homoharringtonine, lycorine, narciclasine, quinine, papaverine and colchicine. The possible ability of alkaloids to inhibit protein targets and to reduce inflammatory markers show the potential for development of new treatment strategies against COVID-19. However, more high quality analyses/reviews in this field are necessary to firmly establish the effectiveness/safety of the alkaloids here described.

Deep-Sea Natural Products from Extreme Environments: Cold Seeps and Hydrothermal Vents

The deep sea has been proven to be a great treasure for structurally unique and biologically active natural products in the last two decades. Cold seeps and hydrothermal vents, as typical representatives of deep-sea extreme environments, have attracted more and more attention. This review mainly summarizes the natural products of marine animals, marine fungi, and marine bacteria derived from deep-sea cold seeps and hydrothermal vents as well as their biological activities. In general, there were 182 compounds reported, citing 132 references and covering the literature from the first report in 1984 up to March 2022. The sources of the compounds are represented by the genera Aspergillus sp., Penicillium sp., Streptomyces sp., and so on. It is worth mentioning that 90 of the 182 compounds are new and that almost 60% of the reported structures exhibited diverse bioactivities, which became attractive targets for relevant organic synthetic and biosynthetic studies.

Cuspareine as alkaloid against COVID-19 designed with ionic liquids: DFT and docking molecular approaches

Cuspareine as an antiviral alkaloid can be used in the treatment of COVID-19. In this study, we introduced the ionic liquids (ILs) concluded cuspareinium as a cation with CH₃COO^-, CF₃COO^-, and PF₆ as anions. The optimized geometry, thermodynamic parameters, and reactivity descriptors were calculated with density functional theory (DFT) approach and time-dependent density functional theory (TD-DFT) using B3LYP/6-311G. In addition, the UV and IR spectra of the introduced ILs were investigated. Based on DFT calculation, the designed IL CH₃COO^- can be to the most suitable anions due to most solubility in the water. DFT studies displayed that all the introduced ILs have more polarity than pristine cuspareine and CH3COO^--cuspareine is the most polarity due to high dipole moment. Also, the thermo- chemical data of the designed ionic liquids revealed that PF6-cuspareine is distinguished to be stable. A molecular docking study of the designed ILs with 6 LU7 protease was performed to display interactions and binding energy. Results of molecular docking displayed that CH₃COO^- ion liquid has the highest binding energy (- 7.20 kcal/mol) and Ala7, and Lys 5 residues are involved in an interaction. DFT and molecular docking studies of cuspareine as alkaloid based on ionic liquids can be helpful to for more pharmaceutical and biological researches of cuspareine as an antiviral agent against COVID-19.

Potential of Natural Alkaloids From Jadwar (Delphinium denudatum) as Inhibitors Against Main Protease of COVID-19: A Molecular Modeling Approach

The ongoing pandemic coronavirus disease (COVID-19) caused by a novel corona virus, namely, severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), has had a major impact on global public health. COVID-19 cases continue to increase across the globe with high mortality rates in immunocompromised patients. There is still a pressing demand for drug discovery and vaccine development against this highly contagious disease. To design and develop antiviral drugs against COVID-19, the main protease (M^pro) has emerged as one of the important drug targets. In this context, the present work explored Jadwar (Delphinium denudatum)-derived natural alkaloids as potential inhibitors against M^pro of SARS-CoV-2 by employing a combination of molecular docking and molecular dynamic simulation-based methods. Molecular docking and interaction profile analysis revealed strong binding on the M^pro functional domain with four natural alkaloids viz. panicutine (-7.4 kcal/mol), vilmorrianone (-7.0 kcal/mol), denudatine (-6.0 kcal/mol), and condelphine (-5.9 kcal/mol). The molecular docking results evaluated by using the MD simulations on 200 nanoseconds confirmed highly stable interactions of these compounds with the M^pro. Additionally, mechanics/generalized Born/Poisson-Boltzmann surface area (MM/G/P/BSA) free energy calculations also affirmed the docking results. Natural alkaloids explored in the present study possess the essential drug-likeness properties, namely, absorption, distribution, metabolism, and excretion (ADME), and are in accordance with Lipinski's rule of five. The results of this study suggest that these four bioactive molecules, namely, condelphine, denudatine, panicutine, and vilmorrianone, might be effective candidates against COVID-19 and can be further investigated using a number of experimental methods.

Implication of in silico studies in the search for novel inhibitors against SARS-CoV-2

Corona Virus Disease-19 (COVID-19) is a pandemic disease mainly caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). It had spread from Wuhan, China, in late 2019 and spread over 222 countries and territories all over the world. Earlier, at the very beginning of COVID-19 infection, there were no approved medicines or vaccines for combating this disease, which adversely affected a lot of individuals worldwide. Although frequent mutation leads to the generation of more deadly variants of SARS-CoV-2, researchers have developed several highly effective vaccines that were approved for emergency use by the World Health Organization (WHO), such as mRNA-1273 by Moderna, BNT162b2 by Pfizer/BioNTech, Ad26.COV2.S by Janssen, AZD1222 by Oxford/AstraZeneca, Covishield by the Serum Institute of India, BBIBP-CorV by Sinopharm, coronaVac by Sinovac, and Covaxin by Bharat Biotech, and the first US Food and Drug Administration-approved antiviral drug Veklury (remdesivir) for the treatment of COVID-19. Several waves of COVID-19 have already occurred worldwide, and good-quality vaccines and medicines should be available for ongoing as well as upcoming waves of the pandemic. Therefore, in silico studies have become an excellent tool for identifying possible ligands that could lead to the development of safer medicines or vaccines. Various phytoconstituents from plants and herbs with antiviral properties are studied further to obtain inhibitors of SARS-CoV-2. In silico screening of various molecular databases like PubChem, ZINC, Asinex Biol-Design Library, and so on has been performed extensively for finding effective ligands against targets. Herein, in silico studies carried out by various researchers are summarized so that one can easily find the best molecule for further in vitro and in vivo studies.

Newly Identified COVID-19 Drug Candidates Based on Computational Strategies

The COVID-19 has raised a public health catastrophe in early 2020 worldwide. Despite several approved vaccines that have repressed the pandemic and decreased the mortality rate since then, attempts to discover an effective antiviral drug have not indicated reliable results. In this research, in silico studies (virtual screening and molecular docking) were performed based on quinoline structure to identify novel drug candidates against SARS-CoV-2 before laboratory evaluations. A chemical library consisting of 548 compounds was collected from literature mining of five databases to select the best ligands interacting with three target proteins of SARS-CoV-2, including the main protease, spike protein, and chimeric receptor-binding domain in a complex of human angiotensin-converting enzyme 2. The top five compounds that presented suitable binding energy against each target protein are reported in detail for the first time. Notably, new compound N-4-(6-methyl-3-pyridinyl) phenyl)-9-acridinamine showed high affinity to all selected proteins. These identified compounds will help in speeding up the drug development against COVID-19.

α-Glucosidase inhibitory activity of cannabidiol, tetrahydrocannabinol and standardized cannabinoid extracts from Cannabis sativa

Two major cannabinoids of cannabis, namely cannabidiol (CBD) and tetrahydrocannabinol (THC) have been reportedly used as alternative medicine for diabetes treatment in both pre-clinical and clinical research. However, their mechanisms of action still remain unclear. Therefore, this study aimed to evaluate the α-glucosidase inhibitory activity of THC, CBD and the standardized cannabinoid extracts. Based on in silico studies, THC generated hydrogen bonding and Van der Waals interactions, while CBD exhibited only Van der Waals interactions with functional residues of target α-glucosidase protein, with good binding energies of −7.5 and −6.9 kcal/mol, respectively. In addition, both of them showed excellent pharmacokinetic profiles with minor toxicity in terms of tumorigenic and reproductive effects. In addition, the enzyme based in vitro assay on α-glucosidase revealed that THC and CBD exhibited good inhibitory activity, with the IC₅₀ values of 3.0 ± 0.37 and 5.5 ± 0.28 μg/ml, respectively. These were better than the standard drug, acarbose (IC₅₀ of 488.6 ± 10.23 μg/ml). Furthermore, two standardized cannabinoid extracts, SCE-I (C. sativa leaf extract) and SCE-II (C. sativa inflorescence extract) exhibited stronger inhibitory activity than THC and CBD, with the IC₅₀ values of 1.2 ± 0.62 and 0.16 ± 0.01 μg/ml, respectively. The present study provides the first evidence that the standardized cannabinoid extracts containing THC and CBD have greater potential than CBD and THC in application as an α-glucosidase inhibitor.

•

In silico study illustrated the inhibitory action of THC and CBD on α-glucosidase.

•

THC and CBD exhibited good pharmacokinetic profiles with low toxicity.

•

In vitro study confirmed the inhibitory effect of THC and CBD against α-glucosidase.

•

Standardized cannabinoid extracts showed higher inhibitory effect than THC and CBD.

Alkaloids as Potential Phytochemicals against SARS-CoV-2: Approaches to the Associated Pivotal Mechanisms

Since its inception, the coronavirus disease 2019 (COVID-19) pandemic has infected millions of people around the world. Therefore, it is necessary to find effective treatments against Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2), as it is the viral source of COVID-19. Alkaloids are one of the most widespread plant-derived natural compounds with prominent antiviral effects. Accordingly, these phytochemicals have been promising candidates towards discovering effective treatments for COVID-19. Alkaloids have shown potential anti-SARS-CoV activities via inhibiting pathogenesis-associated targets of the Coronaviridae family that are required for the virus life cycle. In the current study, the chemistry, plant sources, and antiviral effects of alkaloids, as well as their anti-SARS-CoV-2 effect with related mechanisms, are reviewed towards discovering an effective treatment against COVID-19.