Evaluation of the antiviral activity of natural sulfated polyhydroxysteroids and their synthetic derivatives and analogs

Chemical compositions and experimental and computational modeling activity of sea cucumber Holothuria parva ethanolic extract against herpes simplex virus type 1

Sea cucumber has antiviral activities against various viruses including herpes simplex virus type 1 (HSV-1). The purpose of the current study was to determine the chemical profile and inhibitory effects of tegument ethanolic extract of Holothuria parva on HSV-1 infection and to elucidate the mechanism of antiviral action of this marine invertebrate. Cytotoxic activity of the extract on Vero cell line was determined using the methyl thiazolyl tetrazolium (MTT) method. The different components in H. parva were determined by GC-MS analysis. To assess the antiviral activity of the extract, MTT and 50% tissue culture infective dose (TCID50) were applied. Finally, computational molecular docking was performed to screen the potential binding ability of extract contents with HSV-1 surface glycoproteins and host cell surface receptors. Using MTT assay, the non-cytotoxic concentration of the extract was measured 46.5 μg/mL. Octadecanoic acid 2-hydroxy-1-(hydroxymethyl) ethyl ester and 2',6'-acetoxylidide were two major constituents in the H. parva extract. Pre-treatment of HSV-1 with the ethanolic extract of H. parva led to a 2.1 log10 TCID50 reduction in virus titers when compared to the control group (P = 0.002). The log10 TCID50 reductions relative to the control group for co-penetration and post-penetration assays were 1.5 (P = 0.009) and 0.7 (P = 0.09), respectively. The tegument ethanolic extract of H. parva has significant antiviral properties against HSV-1. Docking analysis demonstrated that compounds of the extract [lidocaine and 2-hydroxy-1-(hydroxymethyl) ethyl ester octadecanoic acid] may cover similarly both virus and host cells binding domains leading to interference in virus attachment to cell receptors.

Sulfated and Sulfur-Containing Steroids and Their Pharmacological Profile

The review focuses on sulfated steroids that have been isolated from seaweeds, marine sponges, soft corals, ascidians, starfish, and other marine invertebrates. Sulfur-containing steroids and triterpenoids are sourced from sedentary marine coelenterates, plants, marine sediments, crude oil, and other geological deposits. The review presents the pharmacological profile of sulfated steroids, sulfur-containing steroids, and triterpenoids, which is based on data obtained using the PASS program. In addition, several semi-synthetic and synthetic epithio steroids, which represent a rare group of bioactive lipids that have not yet been found in nature, but possess a high level of antitumor activity, were included in this review for the comparative pharmacological characterization of this class of compounds. About 140 steroids and triterpenoids are presented in this review, which demonstrate a wide range of biological activities. Therefore, out of 71 sulfated steroids, thirteen show strong antitumor activity with a confidence level of more than 90%, out of 50 sulfur-containing steroids, only four show strong antitumor activity with a confidence level of more than 93%, and out of eighteen epithio steroids, thirteen steroids show strong antitumor activity with a confidence level of 91% to 97.4%.

Current progress on identification of virus pathogens and the antiviral effectors in echinoderms

Echinoderms are important marine organisms that live in a wide range from the intertidal zone to the abyssal zone. Members of this phylum are prone to dramatic population fluctuations that may trigger dramatic shifts in ecosystem structure. Despite the extremely complex nature of the marine environment, the immune systems of echinoderms induce a complex innate immune response to prokaryotic and eukaryotic pathogens. Previous studies showed that many echinoderm disease outbreaks were associated with specific bacteria, whereas recent scientific investigations using newly developed technologies revealed the amazing diversity of viruses in seawater. Viruses are potential pathogens of several infectious diseases of marine echinoderms. We reviewed the discovery of viruses in echinoderms and discussed the relationship between viruses and diseases for the first time. We further summarized the research progress of the potential immune-related genes and signal pathways induced by viruses and poly (I:C). Additionally, numbers of studies showed that active substances extracted from echinoderms, or the compounds synthesized from these substances, have significant antihuman virus ability. This result suggests that the active substances derived from echinoderms provide potential antiviral protection for the organism, which may provide future research directions for the antiviral immunity of echinoderms. Thus, this review also collected information on the antiviral activities of biologically active substances from echinoderms, which may pave the way for new trends in antiviral immunity for echinoderms and antiviral drugs in humans.

Marine Terpenoids from Polar Latitudes and Their Potential Applications in Biotechnology

Polar marine biota have adapted to thrive under one of the ocean’s most inhospitable scenarios, where extremes of temperature, light photoperiod and ice disturbance, along with ecological interactions, have selected species with a unique suite of secondary metabolites. Organisms of Arctic and Antarctic oceans are prolific sources of natural products, exhibiting wide structural diversity and remarkable bioactivities for human applications. Chemical skeletons belonging to terpene families are the most commonly found compounds, whereas cytotoxic antimicrobial properties, the capacity to prevent infections, are the most widely reported activities from these environments. This review firstly summarizes the regulations on access and benefit sharing requirements for research in polar environments. Then it provides an overview of the natural product arsenal from Antarctic and Arctic marine organisms that displays promising uses for fighting human disease. Microbes, such as bacteria and fungi, and macroorganisms, such as sponges, macroalgae, ascidians, corals, bryozoans, echinoderms and mollusks, are the main focus of this review. The biological origin, the structure of terpenes and terpenoids, derivatives and their biotechnological potential are described. This survey aims to highlight the chemical diversity of marine polar life and the versatility of this group of biomolecules, in an effort to encourage further research in drug discovery.

Ten-Year Research Update Review: Antiviral Activities from Marine Organisms

Oceans cover more than 70 percent of the surface of our planet and are characterized by huge taxonomic and chemical diversity of marine organisms. Several studies have shown that marine organisms produce a variety of compounds, derived from primary or secondary metabolism, which may have antiviral activities. In particular, certain marine metabolites are active towards a plethora of viruses. Multiple mechanisms of action have been found, as well as different targets. This review gives an overview of the marine-derived compounds discovered in the last 10 years. Even if marine organisms produce a wide variety of different compounds, there is only one compound available on the market, Ara-A, and only another one is in phase I clinical trials, named Griffithsin. The recent pandemic emergency caused by SARS-CoV-2, also known as COVID-19, highlights the need to further invest in this field, in order to shed light on marine compound potentiality and discover new drugs from the sea.

SULFATION PATHWAYS: Sources and biological activities of marine sulfated steroids

Marine environment is rich in structurally unique molecules and can be an inspiring source of novel drugs. Currently, six marine-derived drugs are in the market with FDA approval and several more are in the clinical pipeline. Structurally diverse and complex secondary metabolites have been isolated from the marine world and these include sulfated steroids. Biological activities of nearly 150 marine sulfated steroids reported from 1978 to 2017 are compiled and described, namely antimicrobial, antitumor, cardiovascular and antifouling activities. Structure-activity relationship for each activity is discussed.

Synthesis of sulfated brassinosteroids

A number of water soluble sulfates of 24-epibrassinolide including the 2α,3α-disulfate and all possible monosulfates were synthesized. The target compounds were isolated in crystalline form as the corresponding sodium salts. Pyridine-sulfur trioxide complex was used as sulfating agent followed by transformation of the resulting pyridinium salts into the sodium sulfates by treatment with NaOH. The control of the regioselectivity was achieved by an appropriate use of acetyl and benzyl protecting groups.

Polyhydroxylated sulfated steroids derived from 5α-cholestanes as antiviral agents against herpes simplex virus

Twelve polyhydroxylated sulfated steroids synthesized from a 5α-cholestane skeleton with different substitutions in C-2, C-3 and C-6 were evaluated for cytotoxicity and antiviral activity against herpes simplex virus (HSV) by a virus plaque reduction assay. Four compounds elicited a selective inhibitory effect against HSV. The disodium salt of 2β,3α-dihydroxy-6E-hydroximine-5α-cholestane-2,3-disulfate, named compound 7, was the most effective inhibitor of HSV-1, HSV-2 and pseudorabies virus (PrV) strains, including acyclovir-resistant variants, in human and monkey cell lines. Preliminary mechanistic studies demonstrated that compound 7 did not affect the initial steps of virus entry but inhibited a subsequent event in the infection process of HSV.

Synthesis and cytotoxic evaluation of four new 6E-hydroximinosteroids

Four new 6E-hydroximinosteroids (1, 2a, 3 and 4) have been synthesized from the corresponding ketones, 2β,3β-dihydroxy-5α-cholestan-6-one (5), 2α,3α-dihydroxy-5α-cholestan-6-one (6), 2β,3α-dihydroxy-5α-cholestan-6-one (7) and 2β,3α-dihydroxy-5α-cholestan-6-one-disulfate (8). The cytotoxic activity of the steroidal oximes was evaluated against two prostate carcinoma cell lines (PC-3 and LNCaP) and compared with that of five polyhydroxylated sulfated analogs (8-12). Oxime 3 and trisulfated analog 11 were the most active compounds with IC50 values of 10.8μM (PC-3) and 7.9μM (LNCaP), respectively.

Emerging sulfated flavonoids and other polyphenols as drugs: nature as an inspiration

Nature uses sulfation of endogenous and exogenous molecules mainly to avoid potential toxicity. The growing importance of natural sulfated molecules, as modulators of a number of physiological and pathological processes, has inspired the synthesis of non-natural sulfated scaffolds. Until the 1990s, the synthesis of sulfated small molecules was almost restricted to derivatives of flavonoids and aimed mainly at structure elucidation and plant biosynthesis studies. Currently, the synthesis of this type of compounds concerns structurally diverse scaffolds and is aimed at the development of potential drugs and/or exploitation of the biological effects of sulfated metabolites. Some important hit compounds are emerging from sulfated flavonoids and other polyphenols mainly as anticoagulant and antiviral agents. When compared with polymeric macromolecules such as heparins, sulfated small molecules could be of value in therapeutics due to their hydrophobic nature that can contribute to improve the bioavailability. This review highlights the synthetic approaches that were applied to obtain monosulfated or polysulfated phenolic small molecules and compiles the diverse biological activities already reported for this type of derivatives. Toxicity and pharmacokinetic parameters of this emerging class of derivatives will also be considered, emphasizing their value for therapeutic applications.

Antiviral activity of natural products extracted from marine organisms

Many epidemics have broken out over the centuries. Hundreds and thousands of humans have died over a disease. Available treatments for infectious diseases have always been limited. Some infections are more deadly than the others, especially viral pathogens. These pathogens have continuously resisted all kinds of medical treatment, due to a need for new treatments to be developed. Drugs are present in nature and are also synthesized in vitro and they help in combating diseases and restoring health. Synthesizing drugs is a hard and time consuming task, which requires a lot of man power and financial aid. However, the natural compounds are just lying around on the earth, may it be land or water. Over a thousand novel compounds isolated from marine organisms are used as antiviral agents. Others are being pharmacologically tested. Today, over forty antiviral compounds are present in the pharmacological market. Some of these compounds are undergoing clinical and preclinical stages. Marine compounds are paving the way for a new trend in modern medicine.

Synthesis and acetylcholinesterase inhibitory activity of 2β,3α-disulfoxy-5α-cholestan-6-one

Disodium 2β,3α-dihydroxy-5α-cholestan-6-one disulfate (8) has been synthesized using cholesterol (1) as starting material. Sulfation was performed using trimethylamine-sulfur trioxide complex in dimethylformamide as the sulfating agent. The acetylcholinesterase inhibitory activity of compound 8 was evaluated and compared to that of disodium 2β,3α-dihydroxy-5α-cholestane disulfate (10) and diols 7 and 9. Compounds 8 and 10 were active with IC(50) values of 14.59 and 59.65 μM, respectively. Diols 7 and 9 showed no inhibitory activity (IC(50)>500 μM).

Discovery of sulfated sterols from marine invertebrates as a new class of marine natural antagonists of farnesoid-X-receptor

We report the biochemical characterization of sulfated polyhydroxysterols isolated from marine invertebrates as potent antagonists of farnesoid-X-receptor (FXR), a ligand-regulated transcription factor involved in the regulation of lipid and glucose homeostasis in mammals. Molecular characterization of a library of sulfated polyhydroxysteroids resulted in the identification of a first FXR antagonist. In contrast to partial antagonists, this compound was endowed with an antagonistic activity on the expression of a subset of FXR-regulated genes in liver cells and abrogated the release of nuclear coreceptor from the promoter of these genes. The putative binding mode to FXR, obtained through docking calculations, suggested the crucial role played by the bent shape of the molecule as well as the presence of one hydroxyl group in its side chain. This compound is a major tool to explore the effect of FXR inhibition in pharmacological settings.

Expeditious and convenient synthesis of pregnanes and its glycosides as potential anti-dyslipidemic and anti-oxidant agents

A series of new pregnane derivatives and its glycosides were synthesized in order to find new 'leads' against some important targets. The 3beta-hydroxy-16alpha-(2-hydroxy ethoxy) pregn-5-en-20-one (5) was synthesized from 3beta-hydroxy-5,16-pregnadiene-20-one (2) by adopting general modified procedure using BF(3):Et(2)O as a catalyst. Reduction of 5, with sodium borohydride yielded 3beta,20beta-dihydroxy-16alpha-(2-hydroxy ethoxy) pregn-5-en (7) as the major isolable product. O-alkylation of the C-20-oxime-pregnadiene (9) with 1,5-dibromopentane yielded 20-(O-5-bromopentyl)-oximino-3beta-hydroxy-pregn-5,16-diene (11). Synthesis of C-16 substituted pregnane glycosides (20) and (21) were accomplished with the imidate method using BF(3):Et(2)O. The synthesis of 4-chlorobenzoate (3) and 2-chlorobenzoate (4), derivatives of 2 were also accomplished. These compounds were evaluated for their anti-dyslipidemic and anti-oxidant activity and amongst them compounds 3 and 7 showed more lipid lowering and anti-oxidant activity.

Antiviral mode of action of a synthetic brassinosteroid against Junin virus replication

The antiviral mode of action of the synthetic brassinosteroid (22S,23S)-3beta-bromo-5alpha,22,23-trihydroxystigmastan-6-one (6b) against Junin virus replication in Vero cells was investigated. Time-related experiments showed that 6b mainly affects an early event of virus growth cycle. Neither adsorption nor internalization of viral particles was the target of the inhibitory action. The analysis of the effect of 6b on viral RNA synthesis demonstrated that the presence of the compound adversely affects virus RNA replication by preventing the synthesis of full length antigenomic RNA. Although 6b was most effective the earlier it was added to the cells after infection with JV, a high level of inhibition of JV yield and fusion activity of newly synthesized viral glycoproteins was still detected when the compound was present during the last hours of infection. Therefore, we cannot rule out an inhibitory action of 6b on later events of JV replicative cycle.

Antiherpetic mode of action of (22S,23S)-3β-bromo-5α,22,23-trihydroxystigmastan-6-one in vitro

The replication of herpes simplex virus (HSV) type 1 in Vero cells is inhibited in the presence of (22S,23S)-3beta-bromo-5alpha,22,23-trihydroxystigmastan-6-one (6b), a synthetic brassinosteroid derivative. Attempts to disclose the mode of action of 6b indicate that a late step of virus multiplication is affected. In the presence of 6b, HSV late protein synthesis was severely diminished and this inhibitory effect of 6b on HSV antigen expression was confirmed by immunofluorescence assays.

Synthesis and antiviral activity of sulfated and acetylated derivatives of 2beta,3alpha-dihydroxy-5alpha-cholestane

Five new steroid sulfates, sodium 2beta,3alpha-dihydroxy-5alpha-cholestane 3-sulfate (6), sodium 2beta,3alpha-dihydroxy-5alpha-cholestane 2-sulfate (7), disodium 2beta,3alpha-dihydroxy-5alpha-cholestane disulfate (8), sodium 3alpha-acetoxy-2beta-hydroxy-5alpha-cholestane 2-sulfate (12), and sodium 2beta-acetoxy-3alpha-hydroxy-5alpha-cholestane 3-sulfate (13), have been synthesized starting from 3beta-hydroxy-5alpha-cholestane (1). The synthetic steroids were completely characterized by one-dimensional and two-dimensional NMR and FABMS spectra. Sulfation was performed using triethylamine-sulfur trioxide complex in dimethylformamide as the sulfating agent. The sulfated steroids were comparatively evaluated for their inhibitory effect on the replication of herpes simplex virus type 2 (HSV-2). Compounds 7 and 8 were the most effective in their inhibitory action against HSV-2. The disulfated steroid 8 also proved to be active against DEN-2 and JV.

Marine pharmacology in 1999: compounds with antibacterial, anticoagulant, antifungal, anthelmintic, anti-inflammatory, antiplatelet, antiprotozoal and antiviral activities affecting the cardiovascular, endocrine, immune and nervous systems, and other miscellaneous mechanisms of action

This review, a sequel to the 1998 review, classifies 63 peer-reviewed articles on the basis of the reported preclinical pharmacological properties of marine chemicals derived from a diverse group of marine animals, algae, fungi and bacteria. In all, 21 marine chemicals demonstrated anthelmintic, antibacterial, anticoagulant, antifungal, antimalarial, antiplatelet, antituberculosis or antiviral activities. An additional 23 compounds had significant effects on the cardiovascular, sympathomimetic or the nervous system, as well as possessed anti-inflammatory, immunosuppressant or fibrinolytic effects. Finally, 22 marine compounds were reported to act on a variety of molecular targets, and thus could potentially contribute to several pharmacological classes. Thus, during 1999 pharmacological research with marine chemicals continued to contribute potentially novel chemical leads in the ongoing global search for therapeutic agents for the treatment of multiple disease categories.

Cytotoxic and antifungal triterpene glycosides from the Patagonian sea cucumber Hemoiedema spectabilis

Two new sulfated triterpene glycosides, hemoiedemosides A (1) and B (2), have been isolated from the Patagonian sea cucumber Hemoiedema spectabilis. Their structures have been established by a combination of spectroscopic analysis (NMR and FABMS) and chemical transformations. Both glycosides present the same aglycon and differ in the degree of sulfation of the tetrasaccharide chain. Hemoiedemoside B (2) is a new example of a small number of trisulfated triterpene glycosides from sea cucumbers belonging to the family Cucumariidae. Glycosides 1 and 2 exhibit considerable antifungal activity against the phytopathogenic fungus Cladosporium cucumerinum, while the semisynthetic desulfated derivative 1a is less active.

Two new cytotoxic and virucidal trisulfated triterpene glycosides from the Antarctic sea cucumber Staurocucumis liouvillei

Two new trisulfated triterpene glycosides, liouvillosides A (1) and B (2), have been isolated from the Antarctic sea cucumber Staurocucumis liouvillei. Their structures have been elucidated by spectroscopic analysis (NMR and FABMS) and chemical transformations. Liouvillosides A (1) and B (2) are two new examples of a small number of trisulfated triterpene glycosides from sea cucumbers belonging to the family Cucumariidae. Both glycosides were found to be virucidal against herpes simplex virus type 1 (HSV-1) at concentrations below 10 microg/mL.