Ecdysones from Zoanthus spp. with inhibitory activity against dengue virus 2

Discovery of Zoanthamine Alkaloids from Zoanthus vietnamensis with Antioxidant and Neuroprotective Activities

Two novel alkaloids, zoanides A and B (1 and 2), 12 new zoanthamine-type alkaloids (3-14), together with two known compounds (15 and 16) were obtained from the zoantharian Zoanthus vietnamensis. Their structures and absolute configurations were established by extensive spectroscopic data, DP4+ probability calculation, and X-ray crystallographic analyses. Structurally, compound 1 represents an unusual functionalized skeleton caused by oxidative cleavage; compound 2 possesses an unprecedented 6/6/5/6/7-fused pentacyclic carbon skeleton. Additionally, the plausible biosynthetic pathways of 1 and 2 were proposed. All isolates were evaluated in vitro for neuroprotection. Among them, compounds 2, 3, 8, 9, and 15 exhibited neuroprotection against paclitaxel-induced neurite damage without interfering with the anticancer effects of paclitaxel. Moreover, compounds 2 and 9 demonstrated moderate protective effects against oxaliplatin-induced oxidative stress overload without interfering with the anticancer effects of oxaliplatin.

A comprehensive review of Pfaffia glomerata botany, ethnopharmacology, phytochemistry, biological activities, and biotechnology

ETHNOPHARMACOLOGICAL RELEVANCE

Pfaffia glomerata (Spreng.) Pedersen, Amaranthaceae, is found in South America, mainly in Brazil, where it is considered a species of great medicinal interest owing to its popular use as a tonic, aphrodisiac, anti-inflammatory, and analgesic. These properties can be attributed to the presence of the phytosteroid, 20-Hydroxyecdysone (β-ecdysone), the main compound found in its roots.

AIM OF THE REVIEW

This review aims to provide information about the botanical characteristics, ethnomedicinal uses, the phytochemistry, the biological activities, and the biotechnology of P. glomerata, an important species to local communities and groups researching medicinal plants of South America.

MATERIALS AND METHODS

The information available on P. glomerata was collected from scientific databases (ScienceDirect, PubMed/MEDLINE, SciELO, and Scopus) until June 7, 2023, using the search terms "Pfaffia glomerata", "Pfaffia glomerata (Spreng.) Pedersen", and "Brazilian ginseng". The review includes studies that evaluated the botanical, ethnopharmacological, and phytochemical aspects, biological properties, nutraceutical uses, and the application of biotechnology for improving the biosynthesis of metabolites of interest.

RESULTS

A total of 207 studies were identified, with 81 articles read in full. Seventy-six studies were included for qualitative synthesis. Overall, 40 compounds belonging to different classes are presented in this review, including ecdysteroids, triterpenes, saponins, flavonoids, anthraquinones, tannins, coumarins, alkaloids, and polysaccharides. Among them, flavonoids, anthraquinones, tannins, coumarins, and alkaloids were only putatively identified. β-Ecdysone, triterpenes, saponins, and polysaccharides are the chemical components most frequently identified and isolated from P. glomerata and possibly responsible for ethnopharmacological use and the biological activities of this species, with important in vitro and in vivo activities, such as anti-inflammatory, antidepressant, aphrodisiac, analgesic, gastroprotective, antioxidant, and prebiotic.

CONCLUSIONS

This review summarizes discussions about the P. glomerata species, highlighting its ethnopharmacological, chemical, biotechnological, and nutraceutical importance. New scientific studies on this species are encouraged in the search for new therapeutic molecules with pharmaceutical potential and nutraceutical applications.

Harnessing Natural Resources for Advancements in Dengue Virus Treatment

Dengue fever, caused by the Dengue virus (DENV) and transmitted by Aedes aegypti mosquitoes, has become endemic in over 100 countries. Despite considerable research, there is a lack of specific drugs for clinical use against dengue. Hence, further exploration to identify antidengue compounds is essential. In recent years, natural products have gained attention for their antiviral properties. Plant-based medicines are particularly appealing due to their safety and low toxicity. This review summarizes natural compounds with potential antiviral activity against DENV, highlighting their mechanisms of action. Various compounds, from traditional herbal remedies to novel plant isolates, show promise against dengue, targeting crucial viral proteins like the envelope protein, proteases, and RNA polymerase. Exploring natural sources of antiviral agents against dengue is crucial. These compounds offer hope for effective treatments and mitigating dengue's global impact.

Bombyx mori Ecdysone Receptor B1 May Inhibit BmNPV Infection by Triggering Apoptosis

Bombyx mori nucleopolyhedrovirus (BmNPV) is a serious threat to sericulture. Nevertheless, no effective control strategy is currently available. The innate immunity of silkworm is critical in the antiviral process. Exploring its molecular mechanism provides theoretical support for the prevention and treatment of BmNPV. Insect hormone receptors play an essential role in regulating host immunity. We found a correlation between Bombyx mori ecdysone receptor B1 (BmEcR-B1) and BmNPV infection, whereas the underlying mechanism remains unclear. In this study, the expression patterns and sequence characteristics of BmEcR-B1 and its isoform, BmEcR-A, were initially analyzed. BmEcR-B1 was found to be more critical than BmEcR-A in silkworm development and responses to BmNPV. Moreover, RNAi and an overexpression in BmN cells showed BmEcR-B1 had antiviral effects in the presence of 20-hydroxyecdysone (20E); Otherwise, it had no antiviral activity. Furthermore, BmEcR-B1 was required for 20E-induced apoptosis, which significantly suppressed virus infection. Finally, feeding 20E had no significant negative impacts on larval growth and the cocoon shell, suggesting the regulation of this pathway has practical value in controlling BmNPV in sericulture. The findings of this study provide important theoretical support for understanding the mechanism of the silkworm innate immune system in response to BmNPV infection.

Production, Transmission, Pathogenesis, and Control of Dengue Virus: A Literature-Based Undivided Perspective

Dengue remains one of the most serious and widespread mosquito-borne viral infections in human beings, with serious health problems or even death. About 50 to 100 million people are newly infected annually, with almost 2.5 billion people living at risk and resulting in 20,000 deaths. Dengue virus infection is especially transmitted through bites of Aedes mosquitos, hugely spread in tropical and subtropical environments, mostly found in urban and semiurban areas. Unfortunately, there is no particular therapeutic approach, but prevention, adequate consciousness, detection at earlier stage of viral infection, and appropriate medical care can lower the fatality rates. This review offers a comprehensive view of production, transmission, pathogenesis, and control measures of the dengue virus and its vectors.

Insights on Dengue and Zika NS5 RNA-dependent RNA polymerase (RdRp) inhibitors

Over recent years, many outbreaks caused by (re)emerging RNA viruses have been reported worldwide, including life-threatening Flaviviruses, such as Dengue (DENV) and Zika (ZIKV). Currently, there is only one licensed vaccine against Dengue, Dengvaxia®. However, its administration is not recommended for children under nine years. Still, there are no specific inhibitors available to treat these infectious diseases. Among the flaviviral proteins, NS5 RNA-dependent RNA polymerase (RdRp) is a metalloenzyme essential for viral replication, suggesting that it is a promising macromolecular target since it has no human homolog. Nowadays, several NS5 RdRp inhibitors have been reported, while none inhibitors are currently in clinical development. In this context, this review constitutes a comprehensive work focused on RdRp inhibitors from natural, synthetic, and even repurposing sources. Furthermore, their main aspects associated with the structure-activity relationship (SAR), proposed mechanisms of action, computational studies, and other topics will be discussed in detail.

A Review on the Progress and Prospects of Dengue Drug Discovery Targeting NS5 RNA- Dependent RNA Polymerase

Dengue virus (DENV) infection threatens the health and wellbeing of almost 100 million people in the world. Vectored by mosquitoes, DENV may cause a severe disease in human hosts called Dengue hemorrhagic fever (DHF)/Dengue shock syndrome (DSS), which is not preventable by any known drug. In the absence of a universally-accepted vaccine, a drug capable of inhibiting DENV multiplication is an urgent and unmet clinical need. Here we summarize inhibitory strategies by targeting either host biochemical pathways or virus-encoded proteins. A variety of approaches have been generated to design Directly-acting anti-virals or DAAs targeting different DENV proteins, with diverse success. Among them, DAAs targeting genome replicating viral enzymes have proven effective against many viruses including, Human Immuno-deficiency Virus and Hepatitis C Virus. DAAs may be derived either from existing compound libraries of novel molecules and plant secondary metabolites or devised through Computer-aided Drug design (CADD) methods. Here, we focus on compounds with reported DAA-activity against the DENV RNA-dependent RNA polymerase (RdRp), which replicate the viral RNA genome. The structure-activity relationship (SAR) and toxicity of the natural compounds, including secondary plant metabolites, have been discussed in detail. We have also tabulated novel compounds with known anti-RdRp activity. We concluded with a list of DAAs for which a co-crystal structure with RdRp is reported. Promising hit compounds are often discarded due to poor selectivity or unsuitable pharmacokinetics. We hope this review will provide a useful reference for further studies on the development of an anti-DENV drug.

Marine Pharmacology in 2016-2017: Marine Compounds with Antibacterial, Antidiabetic, Antifungal, Anti-Inflammatory, Antiprotozoal, Antituberculosis and Antiviral Activities; Affecting the Immune and Nervous Systems, and Other Miscellaneous Mechanisms of Action

The review of the 2016-2017 marine pharmacology literature was prepared in a manner similar as the 10 prior reviews of this series. Preclinical marine pharmacology research during 2016-2017 assessed 313 marine compounds with novel pharmacology reported by a growing number of investigators from 54 countries. The peer-reviewed literature reported antibacterial, antifungal, antiprotozoal, antituberculosis, and antiviral activities for 123 marine natural products, 111 marine compounds with antidiabetic and anti-inflammatory activities as well as affecting the immune and nervous system, while in contrast 79 marine compounds displayed miscellaneous mechanisms of action which upon further investigation may contribute to several pharmacological classes. Therefore, in 2016-2017, the preclinical marine natural product pharmacology pipeline generated both novel pharmacology as well as potentially new lead compounds for the growing clinical marine pharmaceutical pipeline, and thus sustained with its contributions the global research for novel and effective therapeutic strategies for multiple disease categories.

Identification of the phytobioactive Polygonum cuspidatum as an antiviral source for restricting dengue virus entry

Dengue virus (DENV) is a mosquito-borne pathogen that is becoming a serious global threat, owing to its rising incidence in inter-tropical regions that yield over 50 million annual infections. There are currently no approved antiviral agents for the management of dengue, and recent shortcomings in its immunization called for immediate action to develop effective drugs with prophylactic ability to better manage its infection. In an attempt to discover novel antiviral sources, we identified the medicinal herb Polygonum cuspidatum (PC) as a bioactive botanical material against DENV infectivity. Specifically, the methanolic extract from PC rhizomes (PCME) potently inhibited DENV infection without causing significant cytotoxicity. Further examination on the viral life cycle demonstrated that PCME particularly targeted the initial stages of DENV infection, while pre- and post-infection treatments had no effect. More importantly, the PCME could efficiently inactivate DENV free virus particles and block the viral attachment and entry/fusion events without apparently influencing viral replication, egress, and cell-to-cell spread. The antiviral effect of PCME was also recapitulated in infection analysis using DENV pseudoparticles displaying viral structural proteins that mediate DENV particle entry. Besides, PCME treatment also inhibited direct DENV entry into several cell types relevant to its infection and reduced viral infectivity of other members of the Flaviviridae family, including the hepatitis C virus (HCV) and Zika virus (ZIKV). Due to its potency against DENV entry, we suggest that the phytobioactive extract from PC is an excellent starting point as an antiviral source material for further development of therapeutic strategies in the prophylactic management of DENV infection.

Marine natural products from zoantharians: bioactivity, biosynthesis, systematics, and ecological roles

The dazzling marine zoantharians represent a reservoir of chemical diversity that remains to be unveiled. These fragile animals have so far been found to harbour the highly bioactive palytoxins or zoanthamines but also the harmless ecdysteroids or zoanthozanthins.

Anti-Lymphangiogenic Alkaloids from the Zoanthid Zoanthus vietnamensis Collected in Taiwan

Eleven new secondary metabolites [kuroshines H-J (1-3), 27-methyl glycinate zoanthenamine (4), 27-hydroxyzoanthenamine (5), 27-methyl glycinate kuroshine A (6), 27-hydroxykuroshine A (7), 3β-hydroxy-28-deoxyzoanthenamine (8), 14α-hydroxy-28-deoxyzoanthenamine (9), 27-hydroxy-28-deoxyzoanthenamine (10), and kuroshine K (11)], along with seven known compounds (12-18), were isolated from the zoantharian Zoanthus vietnamensis. The structures of all isolated components were elucidated by spectroscopic data (IR, MS, NMR, and UV), especially 2D NMR analyses. The relative configurations of 1 and 2 were confirmed by using single-crystal X-ray crystallography. Compounds 1-3 were found to have an unprecedented ether linkage between C-15 and C-28, while the unusual substituent methyl glycinate, attached at C-27 in compounds 4 and 6, was found for the first time in zoanthamine-type alkaloids. The anti-lymphangiogenic activities of 17 isolated compounds were evaluated. Compounds 4, 5, and 10 exerted promising anti-lymphangiogenic functions by reducing cell growth and tube formation of human lymphatic endothelial cells (LECs). In addition, the structure-activity relationships of the isolated alkaloids against lymphangiogenesis of LECs are discussed.

Tomatidine, a novel antiviral compound towards dengue virus

Dengue is the most common arboviral disease worldwide with 96 million symptomatic cases annually. Despite its major impact on global human health and huge economic burden there is no antiviral drug available to treat the disease. The first tetravalent dengue virus vaccine was licensed in 2015 for individuals aged 9 to 45, however, most cases are reported in infants and young children. This, together with the limited efficacy of the vaccine to dengue virus (DENV) serotype 2, stresses the need to continue the search for compounds with antiviral activity to DENV. In this report, we describe tomatidine as a novel compound with potent antiviral properties towards all DENV serotypes and the related Zika virus. The strongest effect was observed for DENV-2 with an EC50 and EC90 value of 0.82 and 1.61 μM, respectively, following infection of Huh7 cells at multiplicity of infection of 1. The selectivity index is 97.7. Time-of-drug-addition experiments revealed that tomatidine inhibits virus particle production when added pre, during and up to 12 h post-infection. Subsequent experiments show that tomatidine predominantly acts at a step after virus-cell binding and membrane fusion but prior to the secretion of progeny virions. Tomatidine was found to control the expression of the cellular protein activating transcription factor 4 (ATF4), yet, this protein is not solely responsible for the observed antiviral effect. Here, we propose tomatidine as a candidate for the treatment of dengue given its potent antiviral activity.

Marine natural products

Covering: 2016. Previous review: Nat. Prod. Rep., 2017, 34, 235-294This review covers the literature published in 2016 for marine natural products (MNPs), with 757 citations (643 for the period January to December 2016) referring to compounds isolated from marine microorganisms and phytoplankton, green, brown and red algae, sponges, cnidarians, bryozoans, molluscs, tunicates, echinoderms, mangroves and other intertidal plants and microorganisms. The emphasis is on new compounds (1277 in 432 papers for 2016), together with the relevant biological activities, source organisms and country of origin. Reviews, biosynthetic studies, first syntheses, and syntheses that led to the revision of structures or stereochemistries, have been included.

Potential Antivirals: Natural Products Targeting Replication Enzymes of Dengue and Chikungunya Viruses

Dengue virus (DENV) and chikungunya virus (CHIKV) are reemergent arboviruses that are transmitted by mosquitoes of the Aedes genus. During the last several decades, these viruses have been responsible for millions of cases of infection and thousands of deaths worldwide. Therefore, several investigations were conducted over the past few years to find antiviral compounds for the treatment of DENV and CHIKV infections. One attractive strategy is the screening of compounds that target enzymes involved in the replication of both DENV and CHIKV. In this review, we describe advances in the evaluation of natural products targeting the enzymes involved in the replication of these viruses.

Anti-Dengue Virus Constituents from Formosan Zoanthid Palythoa mutuki

A new marine ecdysteroid with an α-hydroxy group attaching at C-4 instead of attaching at C-2 and C-3, named palythone A (1), together with eight known compounds (2–9) were obtained from the ethanolic extract of the Formosan zoanthid Palythoa mutuki. The structures of those compounds were mainly determined by NMR spectroscopic data analyses. The absolute configuration of 1 was further confirmed by comparing experimental and calculated circular dichroism (CD) spectra. Anti-dengue virus 2 activity and cytotoxicity of five isolated compounds were evaluated using virus infectious system and [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, inner salt (MTS) assays, respectively. As a result, peridinin (9) exhibited strong antiviral activity (IC₅₀ = 4.50 ± 0.46 μg/mL), which is better than that of the positive control, 2′CMC. It is the first carotene-like substance possessing anti-dengue virus activity. In addition, the structural diversity and bioactivity of the isolates were compared by using a ChemGPS–NP computational analysis. The ChemGPS–NP data suggested natural products with anti-dengue virus activity locate closely in the chemical space.