Anti-Neuraminidase Bioactives from Manggis Hutan (Garcinia celebica L.) Leaves: Partial Purification and Molecular Characterization

Phytochemical profile and diverse pharmacology of Garcinia celebica L

Garcinia celebica L. syn. Garcinia hombroniana Pierre belongs to the family Clusiaceae, is indigenous to Southeast Asian countries. This review aims to provide updated, comprehensive and categorized information on the phytoconstituents and pharmacological effects of this species. The data collection mainly involved searches through databases named Scopus, Google Scholar, Pubmed and Springer Link. Approximately 100 phytochemicals were recorded in this review, with various classes of compounds such as triterpenoids, flavonoids, benzophenones, xanthones, depsidones and sterols identified. The most abundant compounds isolated belong to two chemical classes: triterpenoids and xanthones. Their extracts and pure compounds have been reported for their antibacterial, antiparasitic, hepatoprotective, antioxidant, antidiabetic, antituberculosis, antiplatelet aggregation, anti-neuraminidase and cholinesterase inhibitory activities. This review will provide a comprehensive understanding between the phytochemical components and its medicinal uses that may serve as a valuable resource for future drug development.

Research progress on antiviral constituents in traditional Chinese medicines and their mechanisms of action

CONTEXT

Viruses have the characteristics of rapid transmission and high mortality. At present, western medicines still lack an ideal antiviral. As natural products, many traditional Chinese medicines (TCM) have certain inhibitory effects on viruses, which has become the hotspot of medical research in recent years.

OBJECTIVE

The antiviral active ingredients and mechanisms of TCM against viral diseases was studied in combination with the pathogenesis of viral diseases and antiviral effects.

MATERIALS AND METHODS

English and Chinese literature from 1999 to 2021 was collected from databases including Web of Science, PubMed, Elsevier, Chinese Pharmacopoeia 2020 (CP), and CNKI (Chinese). Traditional Chinese medicines (TCM), active ingredients, antiviral, mechanism of action, and anti-inflammatory effect were used as the key words.

RESULTS

The antiviral activity of TCM is clarified to put forward a strategy for discovering active compounds against viruses, and provide reference for screening antivirus drugs from TCM. TCM can not only directly kill viruses and inhibit the proliferation of viruses in cells, but also prevent viruses from infecting cells and causing cytophilia. It can also regulate the human immune system, enhance human immunity, and play an indirect antiviral role.

DISCUSSION AND CONCLUSION

Based on the experimental study and antiviral mechanism of TCM, this paper can provide analytical evidence that supports the effectiveness of TCM in treating virus infections, as well as their mechanisms against viruses. It could be helpful to provide reference for the research and development of innovative TCMs with multiple components, multiple targets and low toxicity.

Neuraminidase Inhibitor of Garcinia atroviridis L. Fruits and Leaves Using Partial Purification and Molecular Characterization

Neuraminidase (NA) is an enzyme that prevents virions from aggregating within the host cell and promotes cell-to-cell spread by cleaving glycosidic linkages to sialic acid. The best-known neuraminidase is the viral neuraminidase, which present in the influenza virus. Thus, the development of anti-influenza drugs that inhibit NA has emerged as an important and intriguing approach in the treatment of influenza. Garcinia atroviridis L. (GA) dried fruits (GAF) are used commercially as seasoning and in beverages. The main objective of this study was to identify a new potential neuraminidase inhibitor from GA. A bioassay-guided fractionation method was applied to obtain the bioactive compounds leading to the identification of garcinia acid and naringenin. In an enzyme inhibition study, garcinia acid demonstrated the highest activity when compared to naringenin. Garcinia acid had the highest activity, with an IC₅₀ of 17.34–17.53 µg/mL or 91.22–92.21 µM against Clostridium perfringens-NA, and 56.71–57.85 µg/mL or 298.32–304.31 µM against H1N1-NA. Based on molecular docking results, garcinia acid interacted with the triad arginine residues (Arg118, Arg292, and Arg371) of the viral neuraminidase, implying that this compound has the potential to act as a NA enzyme inhibitor.

Mechanistic Aspects of Medicinal Plants and Secondary Metabolites against Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2)

BACKGROUND AND OBJECTIVE

The Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), a highly pathogenic virus, is responsible for a respiratory disease termed coronavirus disease 2019 (COVID-19). SARS-CoV-2 genome encodes various structural and non-structural proteins, which are necessary for viral entry and replication. Among these proteins, papain-like protease (PLpro), 3C-like protease (3CLpro), RNA-dependent RNA polymerase (RdRp), helicase, a serine protease, and spike protein are potential targets of herbal remedies and phytocompounds for inhibition of viral infection and replication. There is at present no confirmed cure for the COVID-19. Various plants and their components have been introduced against SARS-Co-2. A number of review articles have also been published on them. This article is focusing on the mechanistic aspects of these plants and their derivatives on SARS-CV-2.

METHOD

The material in this review article was prepared from significant scientific databases, including Web of Science, PubMed, Science Direct, Scopus and Google Scholar.

RESULTS

Different medicinal plants and their phytocompounds interact with important structural and non-structural of SARS-CoV-2 proteins. Natural compounds form strong bonds with the active site of SARS-CoV-2 protease and make large conformational changes. These phytochemicals are potential inhibitors of structural and non-structural of SARS-CoV-2 proteins such as Spike protein, PLpro, and 3CLpro. Some important anti-SARS-CoV-2 actions of medicinal plants and their metabolites are inhibition of the virus replication or entry, blocking the angiotensin-converting enzyme 2 (ACE-2) receptor and "Transmembrane protease, serine 2 (TMPRSS2)" regulation of inflammatory mediators, inhibition of endothelial activation, toll-like receptors (TLRs) and activation of the nuclear factor erythroid-derived 2-related factor 2 (Nrf2). Some of these important natural immune boosters that are helpful for prevention and curing various symptoms related to COVID-19 include Allium sativum, Nigella sativa, Glycyrrhiza glabra Zingiber officinalis, Ocimum sanctum, Withania somnifera, Tinospora cordifolia, and Scutellaria baicalensis. Also, Kaempferol, Quercetin, Baicalin, Scutellarin, Glycyrrhizin, Curcumin, Apigenin, Ursolic acid, and Chloroquine are the best candidates for treating the symptoms associated with SARS-CoV-2 infection.

CONCLUSION

Medicinal plants and/or their bioactive compounds with inhibitory effects against SARS-CoV-2 support the human immune system and help in fighting against COVID-19 and rejuvenating the immune system.

Potential roles of medicinal plants for the treatment of viral diseases focusing on COVID-19: A review

The whole world is entangled by the coronavirus disease (COVID‐19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2), people are dying in thousands each day, and without an actual medication, it seems not possible for the bringing this global health crisis to a stop. Natural products have been in constant use since ancient times and are proven by time to be effective. Crude extract or pure compounds isolated from medicinal plants and/or herbs such as Artemisia annua, Agastache rugosa, Astragalus membranaceus, Cassia alata, Ecklonia cava, Gymnema sylvestre, Glycyrrhizae uralensis, Houttuynia cordata, Lindera aggregata, Lycoris radiata, Mollugo cerviana, Polygonum multiflorum, Pyrrosia lingua, Saposhnikoviae divaricate, Tinospora cordifolia etc. have shown promising inhibitory effect against coronavirus. Several molecules, including acacetin, amentoflavone, allicin, blancoxanthone, curcumin, daidzein, diosmin, epigallocatechin‐gallate, emodin, hesperidin, herbacetin, hirsutenone, iguesterin, jubanine G, kaempferol, lycorine, pectolinarin, phloroeckol, silvestrol, tanshinone I, taxifolin, rhoifolin, xanthoangelol E, zingerol etc. isolated from plants could also be potential drug candidates against COVID‐19. Moreover, these could also show promising inhibitory effects against influenza‐parainfluenza viruses, respiratory syncytial virus, severe acute respiratory syndrome (SARS), and Middle East respiratory syndrome coronavirus (MERS‐CoV). Here, we have reported 93 antiviral drug candidates which could be a potential area of research in drug discovery.

Natural Flavonoids as Potential Angiotensin-Converting Enzyme 2 Inhibitors for Anti-SARS-CoV-2

Over the years, coronaviruses (CoV) have posed a severe public health threat, causing an increase in mortality and morbidity rates throughout the world. The recent outbreak of a novel coronavirus, named severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) caused the current Coronavirus Disease 2019 (COVID-19) pandemic that affected more than 215 countries with over 23 million cases and 800,000 deaths as of today. The situation is critical, especially with the absence of specific medicines or vaccines; hence, efforts toward the development of anti-COVID-19 medicines are being intensively undertaken. One of the potential therapeutic targets of anti-COVID-19 drugs is the angiotensin-converting enzyme 2 (ACE2). ACE2 was identified as a key functional receptor for CoV associated with COVID-19. ACE2, which is located on the surface of the host cells, binds effectively to the spike protein of CoV, thus enabling the virus to infect the epithelial cells of the host. Previous studies showed that certain flavonoids exhibit angiotensin-converting enzyme inhibition activity, which plays a crucial role in the regulation of arterial blood pressure. Thus, it is being postulated that these flavonoids might also interact with ACE2. This postulation might be of interest because these compounds also show antiviral activity in vitro. This article summarizes the natural flavonoids with potential efficacy against COVID-19 through ACE2 receptor inhibition.