Potential anti-viral compounds from Malaysian Plant Natural Product Repository and Database (MyNature50000) for DENV2

Evaluation of the inhibitory potency of anti-dengue phytocompounds against DENV-2 NS2B-NS3 protease: virtual screening, ADMET profiling and molecular dynamics simulation investigations

Dengue fever has been a worldwide concern, with 50-100 million new infections each year mainly due to five different serotypes of the Dengue virus (DENV). Designing a perfect anti-dengue agent that can inhibit all the serotypes by distinguishing antigenic differences is quite difficult. Previous anti-dengue researches have included chemical compounds screening against DENV enzymes. The ongoing analysis is meant for investigation of the plant-based compounds as antagonistic to DENV-2 focusing on the specific NS2B-NS3Pro target, a trypsin like serine protease that cuts the DENV polyprotein into separate proteins crucial for viral reproduction. Initially, a virtual library of more than 130 phytocompounds was prepared from previously published reports of plants with anti-dengue properties, which were then virtually screened and shortlisted against the WT, H51N and S135A mutant of DENV-2 NS2B-NS3Pro. The three top-most compounds were viewed as Gallocatechin (GAL), Flavokawain-C (FLV), and Isorhamnetin (ISO) showing docking scores of -5.8, -5.7, -5.7 kcal/mol for WT, -7.5, -6.8, -7.6 kcal/mol for the H51N, and -6.9, -6.5, -6.1 kcal/mol for the S135A mutant protease, respectively. 100 ns long MD simulations and MM-GBSA based free energy calculations were performed on the NS2B-NS3Pro complexes to witness the relative binding affinity of the compounds and favourable molecular interactions network. A comprehensive analysis of the study reveals some promising outcomes with ISO as the topmost compound with favourable pharmacokinetic properties for the WT and mutants (H51N and S135A) as well, suggesting as a novel anti-NS2B-NS3Pro agent with better adapting characters in both the mutants.Communicated by Ramaswamy H. Sarma.

Potential medicinal plants to combat viral infections: A way forward to environmental biotechnology

The viral diseases encouraged scientific community to evaluate the natural antiviral bioactive components rather than protease inhibitors, harmful organic molecules or nucleic acid analogues. For this purpose, medicinal plants have been gaining tremendous importance in the field of attenuating the various kinds of infectious and non-infectious diseases. Most of the commonly used medicines contains the bioactive components/phytoconstituents that are generally extracted from medicinal plants. Moreover, the medicinal plants offer many advantages for the recovery applications of infectious disease especially in viral infections including HIV-1, HIV-2, Enterovirus, Japanese Encephalitis Virus, Hepatitis B virus, Herpes Virus, Respiratory syncytial virus, Chandipura virus and Influenza A/H1N1. Considering the lack of acceptable drug candidates and the growing antimicrobial resistance to existing drug molecules for many emerging viral diseases, medicinal plants may offer best platform to develop sustainable/efficient/economic alternatives against viral infections. In this regard, for exploring and analyzing large volume of scientific data, bibliometric analysis was done using VOS Viewer shedding light on the emerging areas in the field of medicinal plants and their antiviral activity. This review covers most of the plant species that have some novel bioactive compound like gnidicin, gniditrin, rutin, apigenin, quercetin, kaempferol, curcumin, tannin and oleuropin which showed high efficacy to inhibit the several disease causing virus and their mechanism of action in HIV, Covid-19, HBV and RSV were discussed. Moreover, it also delves the in-depth mechanism of medicinal with challenges and future prospective. Therefore, this work delves the key role of environment in the biological field.

Recent advances in natural products as potential inhibitors of dengue virus with a special emphasis on NS2b/NS3 protease

Dengue virus (DENV) is an arbovirus widespread through tropical and subtropical areas. It is transmitted to humans through Aedes mosquitoes. Infections with DENV can lead to a series of complications, including dengue fever, dengue haemorrhagic fever, or dengue shock syndrome, which might manifest through secondary infections because of a vulnerable immune system. To date, only one tetravalent DENV vaccine is approved to be administered to children whom have been previously DENV-infected and between 9 and 16 years of age. One of the key targets in discovering DENV antiviral agents is the NS2b/NS3 protease. This protease is a crucial enzyme complex for the proteolytic and cleavage activities of the translated polyprotein during DENV life cycle. Several studies were conducted to discover potential antivirals from natural sources or synthetic compounds and peptides. In this review, we describe the recent studies from the past five years dealing with isolated natural products as potential inhibitors of DENV with a greater focus on inhibiting the NS2b/NS3 protease. This review describes recent discoveries in anti-DENV potential of isolated phytochemicals belonging to different groups including fatty acids, glucosides, terpenes and terpenoids, flavonoids, phenolics, chalcones, acetamides, and peptides. Curcumin, quercetin, and myricetin were found to act as non-competitive inhibitors for the NS2b/NS3 protease enzyme. In some studies, the molecular targets of some of these compounds are yet to be identified using in-silico and in-vitro approaches. So far, none of the isolated natural products was tested clinically for the management of DENV infections. The discussed studies demonstrate that natural products are a rich source of potential anti-DENV compounds. However, not all of these compounds were studied for their kinetic molecular mechanism and type of inhibition. In-silico studies provided an ample number of phytochemical hits to be tested experimentally as DENV protease inhibitors. In conclusion, derivatives of these natural products can be designed and synthesised, which could enhance their specificity and efficacy towards the protease. Other sources of natural products, such as fungi, bacterial toxins, marine organisms, and animals, should also be explored towards discovering more potential and effective DENV NS2b/NS3 protease inhibitors.

In Silico Elucidation of Potent Inhibitors from Natural Products for Nonstructural Proteins of Dengue Virus

Medicinal plants have been used from the beginning of human civilization against various health complications. Dengue virus (DENV) has emerged as one of the most widespread viruses in tropical and subtropical countries. Yet no clinically approved antiviral drug is available to combat DENV infection. Consequently, the search for novel antidengue agents from medicinal plants has assumed more insistence than in previous days. This study has focused on 31 potential antidengue molecules from secondary metabolites to examine their inhibitory activity against DENV nonstructural proteins through molecular docking and pharmacokinetics studies. In this research, the wet lab experiments were tested on a computational platform. Agathisflavone and pectolinarin are the top-scored inhibitors of DENV NS2B/NS3 protease and NS5 polymerase, respectively. Epigallocatechin gallate, Pinostrobin, Panduratin A, and Pectolinarin could be potential lead compounds against NS2B/NS3 protease, while acacetin-7-O-rutinoside against NS5 polymerase. Moreover, agathisflavone (LD50= 1430 mg/kg) and pectolinarin (LD50= 5000 mg/kg) exhibited less toxicity than nelfinavir (LD50= 600 mg/kg) and balapiravir (LD50 = 824 mg/kg), and the reference drugs. Further research on clinical trials is required to analyze the therapeutic efficacy of these metabolites to develop new potential drug candidates against different serotypes of DENV.

Chemical composition, antioxidant, antimicrobial and antiviral activities of the leaf extracts of Syzygium myrtifolium

This study was conducted to evaluate the chemical composition and biological activities of the leaf extracts of Syzygium myrtifolium Walp. (Myrtaceae). The results indicate that the leaf extracts of S. myrtifolium contain various classes of phytochemicals (alkaloids, anthraquinones, flavonoids, phenolics, saponins, tannins and triterpenoids) and possess antioxidant, antibacterial, antifungal and antiviral activities. Ethyl acetate, ethanol, methanol, and water extracts exhibited significantly higher (p < 0.05) oxygen radical absorbance capacity and ferric-reducing antioxidant power than the hexane and chloroform extracts. However, all extracts exhibited stronger inhibitory activity against four tested species of yeasts (minimal inhibitory concentration: 0.02-0.31 mg mL^-1) than against six tested species of bacteria (minimal inhibitory concentration: 0.16-1.25 mg mL^-1). The ethanolic extract offered the highest protection of Vero cells (viability > 70 %) from the cytopathic effect caused by the Chikungunya virus while the ethyl acetate extract showed significant replication inhibitory activity against the virus (p < 0.001) using the replicon-enhanced green fluorescent protein reporter system.

Plant-Based Natural Products and Extracts: Potential Source to Develop New Antiviral Drug Candidates

Viral infections are among the most complex medical problems and have been a major threat to the economy and global health. Several epidemics and pandemics have occurred due to viruses, which has led to a significant increase in mortality and morbidity rates. Natural products have always been an inspiration and source for new drug development because of their various uses. Among all-natural sources, plant sources are the most dominant for the discovery of new therapeutic agents due to their chemical and structural diversity. Despite the traditional use and potential source for drug development, natural products have gained little attention from large pharmaceutical industries. Several plant extracts and isolated compounds have been extensively studied and explored for antiviral properties against different strains of viruses. In this review, we have compiled antiviral plant extracts and natural products isolated from plants reported since 2015.