A phase III randomized controlled trial of plitidepsin, a marine derived compound, in hospitalized adults with moderate COVID-19.

BACKGROUND: Plitidepsin has shown potent preclinical activity against SARS-CoV-2 and was generally well tolerated in a Phase I trial of hospitalized patients with COVID-19. NEPTUNO, a Phase III, multicenter, randomized, controlled trial, was designed to evaluate the efficacy and safety of plitidepsin in the management of moderate COVID-19 in hospitalized adult patients. METHODS: Included patients had documented SARS-CoV-2 infection, required oxygen therapy, and had adequate organ function. The planned sample size was 609 patients. Patients were randomized 1:1:1 to at least 3 days of dexamethasone plus either plitidepsin (1.5 mg/day or 2.5 mg/day, for 3 days) or standard of care (control). The primary endpoint was the time to sustained withdrawal of supplemental oxygen. Secondary endpoints included time to sustained hospital discharge, clinical status, duration of oxygen support, percentage of patients requiring admission to the intensive care unit, and safety. FINDINGS: After randomizing 205 patients, NEPTUNO was discontinued due to a notable drop in COVID-19-related hospitalizations. Available data suggest a 2-day improvement in the median time to sustained oxygen therapy discontinuation (5 vs 7 days) favoring both plitidepsin arms (hazard ratio [HR] 1.37, 95% confidence interval [CI] 0.96-1.96, p=0.08 for plitidepsin 1.5 mg vs control; HR 1.06, 95% CI 0.73-1.53, p=0.78 for plitidepsin 2.5 mg vs control). Plitidepsin was generally well tolerated. INTERPRETATION: Despite the trial limitations, these results suggest that plitidepsin may have a positive benefit-risk ratio in the management of patients requiring oxygen therapy. Further studies with plitidepsin, including those in immunosuppressed patients, are warranted. FUNDING: This trial has been funded by Pharmamar, S.A. (Madrid, Spain).

Marine Compounds and Age-Related Diseases: The Path from Pre-Clinical Research to Approved Drugs for the Treatment of Cardiovascular Diseases and Diabetes.

Ageing represents a main risk factor for several pathologies. Among them, cardiovascular diseases (CVD) and type 2 diabetes mellitus (T2DM) are predominant in the elderly population and often require prolonged use of multiple drugs due to their chronic nature and the high proportion of co-morbidities. Hence, research is constantly looking for novel, effective molecules to treat CVD and T2DM with minimal side effects. Marine active compounds, holding a great diversity of chemical structures and biological properties, represent interesting therapeutic candidates to treat these age-related diseases. This review summarizes the current state of research on marine compounds for the treatment of CVD and T2DM, from pre-clinical studies to clinical investigations and approved drugs, highlighting the potential of marine compounds in the development of new therapies, together with the limitations in translating pre-clinical results into human application.

Zosterabisphenone B, a new diarylheptanoid heterodimer from the seagrass Zostera marina, induces apoptosis cell death in colon cancer cells and reduces tumour growth in mice.

Colorectal cancer (CRC) is one of the most common malignant tumours worldwide. Diarylheptanoids, secondary metabolites isolated from Zostera marina, are of interest in natural products research due to their biological activities. Zosterabisphenone B (ZBP B) has recently been shown to inhibit the viability of CRC cells. The aim of this study was to investigate the therapeutic potential of ZBP B for targeting human CRC cells. Cell viability was determined using the MTT assay. Flow cytometry and Western blot analyses were used to assess apoptosis and autophagy. A CRC xenograft model was used to evaluate the in vivo effect of ZBP B. No cytotoxic effect on HCEC cells was observed in the in vitro experiments. ZBP B caused morphological changes in HCT116 colon cancer cells due to an increase in early and late apoptotic cell populations. Mechanistically, ZBP B led to an increase in cleaved caspase-3, caspase-8, caspase-9, PARP and BID proteins and a decrease in Bcl-2 and c-Myc proteins. In the xenograft model of CRC, ZBP B led to a reduction in tumour growth. These results indicate that ZBP B exerts a selective cytotoxic effect on CRC cells by affecting apoptotic signalling pathways and reducing tumour growth in mice. Taken together, our results suggest that ZBP B could be a lead compound for the synthesis and development of CRC drugs.

Immune-modulating and anti-inflammatory marine compounds against cancer.

The recent advances in cancer immunotherapy confirm the crucial role of the immune system in cancer progression and treatment. Chronic inflammation and reduced immune surveillance are both features of the tumor microenvironment. Strategies aimed at reverting pro-tumor inflammation and stimulating the antitumor immune components are being actively searched, and the anticancer effects of many candidate drugs have been linked to their ability to modulate the immune system. Marine organisms constitute a rich reservoir of new bioactive molecules; some of them have already been exploited for pharmaceutical use, whereas many others are undergoing clinical or preclinical investigations for the treatment of different diseases, including cancer. In this review, we will discuss the immune-modulatory properties of marine compounds for their potential use in cancer prevention and treatment and as possible tools in the context of cancer immunotherapy.

Unveiling the potential of marine compounds as quorum sensing inhibitors targeting Pseudomonas aeruginosa's LasI: A computational study using molecular docking and molecular dynamics.

Antimicrobial resistance (AMR) poses a significant threat to global public health, with multidrug-resistant Pseudomonas aeruginosa being a leading cause of mortality, accounting for 18%-61% of deaths annually. The quorum sensing (QS) systems of P. aeruginosa, particularly the LasI-LasR system, play a crucial role in promoting biofilm formation and expression of virulent genes, which contribute to the development of AMR. This study focuses on LasI, the mediator of biofilm formation for identifying its inhibitors from a marine compound database comprising of 32 000 compounds using molecular docking and molecular simulation techniques. The virtual screening and docking experiments demonstrated that the top 10 compounds exhibited favorable docking scores of <-7.19 kcal/mol compared to the reported inhibitor 3,5,7-Trihydroxyflavone with a docking score of -3.098 kcal/mol. Additionally, molecular mechanics/Poisson-Boltzmann generalized born surface area (MM-GBSA) analyses were conducted to assess these compounds' suitability for further investigation. Out of 10 compounds, five compounds demonstrated high MM-GBSA binding energy (<-35.33 kcal/mol) and were taken up for molecular dynamics simulations to evaluate the stability of the protein-ligand complex over a 100 ns period. Based on root mean square deviation, root mean square fluctuation, radius of gyration, and hydrogen bond interactions analysis, three marine compounds, namely MC-2 (CMNPD13419) and MC-3 (CMNPD1068), exhibited consistent stability throughout the simulation. Therefore, these compounds show potential as promising LasI inhibitors and warrant further validation through in vitro and in vivo experiments. By exploring the inhibitory effects of these marine compounds on P. aeruginosa's QS system, this research aims to contribute to the development of novel strategies to combat AMR.

Ircinia ramosa Sponge Extract (iSP) Induces Apoptosis in Human Melanoma Cells and Inhibits Melanoma Cell Migration and Invasiveness.

Marine compounds represent a varied source of new drugs with potential anticancer effects. Among these, sponges, including those belonging to the Irciniidae family, have been demonstrated to exert cytotoxic effects on different human cancer cells. Here, we investigated, for the first time, the therapeutic effect of an extract (referred as iSP) from the sponge, Ircinia ramosa (Porifera, Dictyoceratida, and Irciniidae), on A375 human melanoma cells. We found that iSP impaired A375 melanoma cells proliferation, induced cell death through caspase-dependent apoptosis and arrested cells in the G1 phase of the cell cycle, as demonstrated via both flow cytometry and qPCR analysis. The proapoptotic effect of iSP is associated with increased ROS production and mitochondrial modulation, as observed by using DCF-DHA and mitochondrial probes. In addition, we performed wound healing, invasion and clonogenic assays and found that iSP was able to restrain A375 migration, invasion and clonogenicity. Importantly, we observed that an iSP treatment modulated the expression of the EMT-associated epithelial markers, E-CAD and N-CAD, unveiling the mechanism underlying the effect of iSP in modulating A375 migration and invasion. Collectively, this study provides the first evidence to support the role of Ircinia ramosa sponge extracts as a potential therapeutic resource for the treatment of human melanoma.

Anticancer effects of marine compounds blocking the nuclear factor kappa B signaling pathway.

The abnormal expression of nuclear factor kappa B (NF-κB) target genes is closely related to the occurrence, metastasis, and invasion of tumor cells and is an inhibitor of their apoptosis. In recent years, the unique biodiversity in the marine environment has aroused great interest. Many studies indicate that some marine compounds exert anticancer effects on most common human tumors by modulating the NF-κB signaling pathway. In this study, 26 marine compounds that reduce cancer cell survival by suppressing the NF-κB signaling pathway were reviewed. They were derived from a wide range of sources, including sponges, fungi, algae and their derivatives or metabolites. These marine compounds exert antitumor effects through the canonical, noncanonical and atypical NF-κB signaling pathways; however, most of their anticancer targets and mechanisms remain unclear, and more research is needed in the future. Our article provides comprehensive information for researchers investigating the bioactivities of marine compounds and developing marine-derived anticancer drugs.

Marine Compounds, Mitochondria, and Malignancy: A Therapeutic Nexus.

The marine environment is important yet generally underexplored. It contains new sources of functional constituents that can affect various pathways in food processing, storage, and fortification. Bioactive secondary metabolites produced by marine microorganisms may have significant potential applications for humans. Various components isolated from disparate marine microorganisms, including fungi, microalgae, bacteria, and myxomycetes, showed considerable biological effects, such as anticancer, antioxidant, antiviral, antibacterial, and neuroprotective activities. Growing studies are revealing that potential anticancer effects of marine agents could be achieved through the modulation of several organelles. Mitochondria are known organelles that influence growth, differentiation, and death of cells via influencing the biosynthetic, bioenergetic, and various signaling pathways related to oxidative stress and cellular metabolism. Consequently, mitochondria play an essential role in tumorigenesis and cancer treatments by adapting to alterations in environmental and cellular conditions. The growing interest in marine-derived anticancer agents, combined with the development and progression of novel technology in the extraction and cultures of marine life, led to revelations of new compounds with meaningful pharmacological applications. This is the first critical review on marine-derived anticancer agents that have the potential for targeting mitochondrial function during tumorigenesis. This study aims to provide promising strategies in cancer prevention and treatment.

Marine-Derived Compounds Targeting Topoisomerase II in Cancer Cells: A Review.

Cancer affects more than 19 million people and is the second leading cause of death in the world. One of the principal strategies used in cancer therapy is the inhibition of topoisomerase II, involved in the survival of cells. Side effects and adverse reactions limit the use of topoisomerase II inhibitors; hence, research is focused on discovering novel compounds that can inhibit topoisomerase II and have a safer toxicological profile. Marine organisms are a source of secondary metabolites with different pharmacological properties including anticancer activity. The objective of this review is to present and discuss the pharmacological potential of marine-derived compounds whose antitumor activity is mediated by topoisomerase II inhibition. Several compounds derived from sponges, fungi, bacteria, ascidians, and other marine sources have been demonstrated to inhibit topoisomerase II. However, some studies only report docking interactions, whereas others do not fully explain the mechanisms of topoisomerase II inhibition. Further in vitro and in vivo studies are needed, as well as a careful toxicological profile evaluation with a focus on cancer cell selectivity.

A Molecular Modeling Investigation of the Therapeutic Potential of Marine Compounds as DPP-4 Inhibitors.

Type 2 diabetes mellitus (T2DM) is a chronic metabolic disorder characterized by elevated levels of blood glucose due to insulin resistance or insulin-secretion defects. The development of diabetes is mainly attributed to the interaction of several complex pathogenic, genetic, environmental and metabolic processes. Dipeptidyl peptidase-4 (DPP-4) is a serine protease that cleaves X-proline dipeptides from the N-terminus of several polypeptides, including natural hypoglycemic incretin hormones. Inhibition of this enzyme restores and maintains glucose homeostasis, making it an attractive drug target for the management of T2DM. Natural products are important sources of bioactive agents for anti-T2DM drug discovery. Marine ecosystems are a rich source of bioactive products and have inspired the development of drugs for various human disorders, including diabetes. Here, structure-based virtual screening and molecular docking were performed to identify antidiabetic compounds from the Comprehensive Marine Natural Products Database (CMNPD). The binding characteristics of two shortlisted compounds, CMNPD13046 and CMNPD17868, were assessed using molecular dynamics simulations. Thus, this study provides insights into the potential antidiabetic activity and the underlying molecular mechanism of two compounds of marine origin. These compounds could be investigated further for the development of potent DPP-4 inhibitors.

Marine Migrastatics: A Comprehensive 2022 Update.

Metastasis is responsible for the bad prognosis in cancer patients. Advances in research on metastasis prevention focus attention on the molecular mechanisms underlying cancer cell motility and invasion to improve therapies for long-term survival in cancer patients. The so-called "migrastatics" could help block cancer cell invasion and lead to the rapid development of antimetastatic therapies, improving conventional cancer therapies. In the relentless search for migrastatics, the marine environment represents an important source of natural compounds due to its enormous biodiversity. Thus, this review is a selection of scientific research that has pointed out in a broad spectrum of in vitro and in vivo models the anti-cancer power of marine-derived products against cancer cell migration and invasion over the past five years. Overall, this review might provide a useful up-to-date guide about marine-derived compounds with potential interest for pharmaceutical and scientific research on antimetastatic drug endpoints.

Exploring Oceans for Curative Compounds: Potential New Antimicrobial and Anti-Virulence Molecules against Pseudomonas aeruginosa.

Although several antibiotics are already widely used against a large number of pathogens, the discovery of new antimicrobial compounds with new mechanisms of action is critical today in order to overcome the spreading of antimicrobial resistance among pathogen bacteria. In this regard, marine organisms represent a potential source of a wide diversity of unique secondary metabolites produced as an adaptation strategy to survive in competitive and hostile environments. Among the multidrug-resistant Gram-negative bacteria, Pseudomonas aeruginosa is undoubtedly one of the most important species due to its high intrinsic resistance to different classes of antibiotics on the market and its ability to cause serious therapeutic problems. In the present review, we first discuss the general mechanisms involved in the antibiotic resistance of P. aeruginosa. Subsequently, we list the marine molecules identified up until now showing activity against P. aeruginosa, dividing them according to whether they act as antimicrobial or anti-virulence compounds.

The Inhibitors of CDK4/6 from a Library of Marine Compound Database: A Pharmacophore, ADMET, Molecular Docking and Molecular Dynamics Study.

BACKGROUND: CDK4/6 (Cyclin-dependent kinases 4/6) are the key promoters of cell cycle transition from G1 phase to S phase. Thus, selective inhibition of CDK4/6 is a promising cancer treatment. METHODS: A total of 52,765 marine natural products were screened for CDK4/6. To screen out better natural compounds, pharmacophore models were first generated, then the absorption, distribution, metabolism, elimination, and toxicity (ADMET) were tested, followed by molecular docking. Finally, molecular dynamics simulation was carried out to verify the binding characteristics of the selected compounds. RESULTS: Eighty-seven marine small molecules were screened based on the pharmacophore model. Then, compounds 41369 and 50843 were selected according to the ADMET and molecular docking score for further kinetic simulation evaluation. Finally, through molecular dynamics analysis, it was confirmed that compound 50843 maintained a stable conformation with the target protein, so it has the opportunity to become an inhibitor of CDK4/6. CONCLUSION: Through structure-based pharmacophore modeling, ADMET, the molecular docking method and molecular dynamics (MD) simulation, marine natural compound 50843 was proposed as a promising marine inhibitor of CDK4/6.

Biochemical Characterization of Cassiopea andromeda (Forsskål, 1775), Another Red Sea Jellyfish in the Western Mediterranean Sea.

Increasing frequency of native jellyfish proliferations and massive appearance of non-indigenous jellyfish species recently concur to impact Mediterranean coastal ecosystems and human activities at sea. Nonetheless, jellyfish biomass may represent an exploitable novel resource to coastal communities, with reference to its potential use in the pharmaceutical, nutritional, and nutraceutical Blue Growth sectors. The zooxanthellate jellyfish Cassiopea andromeda, Forsskål, 1775 (Cnidaria, Rhizostomeae) entered the Levant Sea through the Suez Canal and spread towards the Western Mediterranean to reach Malta, Tunisia, and recently also the Italian coasts. Here we report on the biochemical characterization and antioxidant activity of C. andromeda specimens with a discussion on their relative biological activities. The biochemical characterization of the aqueous (PBS) and hydroalcoholic (80% ethanol) soluble components of C. andromeda were performed for whole jellyfish, as well as separately for umbrella and oral arms. The insoluble components were hydrolyzed by sequential enzymatic digestion with pepsin and collagenase. The composition and antioxidant activity of the insoluble and enzymatically digestible fractions were not affected by the pre-extraction types, resulting into collagen- and non-collagen-derived peptides with antioxidant activity. Both soluble compounds and hydrolyzed fractions were characterized for the content of proteins, phenolic compounds, and lipids. The presence of compounds coming from the endosymbiont zooxanthellae was also detected. The notable yield and the considerable antioxidant activity detected make this species worthy of further study for its potential biotechnological sustainable exploitation.

Synthesis and Cytotoxicity Evaluation of Spirocyclic Bromotyrosine Clavatadine C Analogs.

Marine-originated spirocyclic bromotyrosines are considered as promising scaffolds for new anticancer drugs. In a continuation of our research to develop potent and more selective anticancer compounds, we synthesized a library of 32 spirocyclic clavatadine analogs by replacing the agmatine, i.e., 4-(aminobutyl)guanidine, side chain with different substituents. These compounds were tested for cytotoxicity against skin cancer using the human melanoma cell line (A-375) and normal human skin fibroblast cell line (Hs27). The highest cytotoxicity against the A-375 cell line was observed for dichloro compound 18 (CC50 0.4 ± 0.3 µM, selectivity index (SI) 2). The variation of selectivity ranged from SI 0.4 to reach 2.4 for the pyridin-2-yl derivative 29 and hydrazide analog of 2-picoline 37. The structure-activity relationships of the compounds in respect to cytotoxicity and selectivity toward cancer cell lines are discussed.

Different Macrophage Type Triggering as Target of the Action of Biologically Active Substances from Marine Invertebrates.

Macrophages play a fundamental role in the immune system. Depending on the microenvironment stimuli, macrophages can acquire distinct phenotypes characterized with different sets of the markers of their functional activities. Polarization of macrophages towards M1 type (classical activation) is involved in inflammation and the related progression of diseases, while, in contrast, alternatively activated M2 macrophages are associated with the anti-inflammatory mechanisms. Reprogramming macrophages to switch their phenotypes could provide a new therapeutic strategy, and targeting the M1/M2 macrophage balance is a promising current trend in pharmacology. Marine invertebrates are a vast source of the variety of structurally diverse compounds with potent pharmacological activities. For years, a large number of studies concerning the immunomodulatory properties of the marine substances have been run with using some intracellular markers of immune stimulation or suppression irrespective of the possible application of marine compounds in reprogramming of macrophage activation, and only few reports clearly demonstrated the macrophage-polarizing activities of some marine compounds during the last decade. In this review, the data on the immunomodulating effects of the extracts and pure compounds of a variety of chemical structure from species of different classes of marine invertebrates are described with focus on their potential in shifting M1/M2 macrophage balance towards M1 or M2 phenotype.

Impact of Prevalence Ratios of Chondroitin Sulfate (CS)- 4 and -6 Isomers Derived from Marine Sources in Cell Proliferation and Chondrogenic Differentiation Processes.

Osteoarthritis is the most prevalent rheumatic disease. During disease progression, differences have been described in the prevalence of chondroitin sulfate (CS) isomers. Marine derived-CS present a higher proportion of the 6S isomer, offering therapeutic potential. Accordingly, we evaluated the effect of exogenous supplementation of CS, derived from the small spotted catshark (Scyliorhinus canicula), blue shark (Prionace glauca), thornback skate (Raja clavata) and bovine CS (reference), on the proliferation of osteochondral cell lines (MG-63 and T/C-28a2) and the chondrogenic differentiation of mesenchymal stromal cells (MSCs). MG-G3 proliferation was comparable between R. clavata (CS-6 intermediate ratio) and bovine CS (CS-4 enrichment), for concentrations below 0.5 mg/mL, defined as a toxicity threshold. T/C-28a2 proliferation was significantly improved by intermediate ratios of CS-6 and -4 isomers (S. canicula and R. clavata). A dose-dependent response was observed for S. canicula (200 µg/mL vs 50 and 10 µg/mL) and bovine CS (200 and 100 µg/mL vs 10 µg/mL). CS sulfation patterns discretely affected MSCs chondrogenesis; even though S. canicula and R. clavata CS up-regulated chondrogenic markers expression (aggrecan and collagen type II) these were not statistically significant. We demonstrate that intermediate values of CS-4 and -6 isomers improve cell proliferation and offer potential for chondrogenic promotion, although more studies are needed to elucidate its mechanism of action.

Amentadione from the Alga Cystoseira usneoides as a Novel Osteoarthritis Protective Agent in an Ex Vivo Co-Culture OA Model.

Osteoarthritis (OA) remains a prevalent chronic disease without effective prevention and treatment. Amentadione (YP), a meroditerpenoid purified from the alga Cystoseira usneoides, has demonstrated anti-inflammatory activity. Here, we investigated the YP anti-osteoarthritic potential, by using a novel OA preclinical drug development pipeline designed to evaluate the anti-inflammatory and anti-mineralizing activities of potential OA-protective compounds. The workflow was based on in vitro primary cell cultures followed by human cartilage explants assays and a new OA co-culture model, combining cartilage explants with synoviocytes under interleukin-1ß (IL-1ß) or hydroxyapatite (HAP) stimulation. A combination of gene expression analysis and measurement of inflammatory mediators showed that the proposed model mimicked early disease stages, while YP counteracted inflammatory responses by downregulation of COX-2 and IL-6, improved cartilage homeostasis by downregulation of MMP3 and the chondrocytes hypertrophic differentiation factors Col10 and Runx2. Importantly, YP downregulated NF-κB gene expression and decreased phosphorylated IkBα/total IkBα ratio in chondrocytes. These results indicate the co-culture as a relevant pre-clinical OA model, and strongly suggest YP as a cartilage protective factor by inhibiting inflammatory, mineralizing, catabolic and differentiation processes during OA development, through inhibition of NF-κB signaling pathways, with high therapeutic potential.

Diatom-Derived Polyunsaturated Aldehydes Activate Similar Cell Death Genes in Two Different Systems: Sea Urchin Embryos and Human Cells.

Programmed cell death, such as apoptosis and autophagy, are key processes that are activated early on during development, leading to remodelling in embryos and homeostasis in adult organisms. Genomic conservation of death factors has been largely investigated in the animal and plant kingdoms. In this study, we analysed, for the first time, the expression profile of 11 genes involved in apoptosis (extrinsic and intrinsic pathways) and autophagy in sea urchin Paracentrotus lividus embryos exposed to antiproliferative polyunsaturated aldehydes (PUAs), and we compared these results with those obtained on the human cell line A549 treated with the same molecules. We found that sea urchins and human cells activated, at the gene level, a similar cell death response to these compounds. Despite the evolutionary distance between sea urchins and humans, we observed that the activation of apoptotic and autophagic genes in response to cytotoxic compounds is a conserved process. These results give first insight on death mechanisms of P. lividus death mechanisms, also providing additional information for the use of this marine organism as a useful in vitro model for the study of cell death signalling pathways activated in response to chemical compounds.

Plakinamine P, A Steroidal Alkaloid with Bactericidal Activity against Mycobacterium tuberculosis.

Tuberculosis is the leading cause of death due to infectious disease worldwide. There is an urgent need for more effective compounds against this pathogen to control the disease. Investigation of the anti-mycobacterial activity of a deep-water sponge of the genus Plakina revealed the presence of a new steroidal alkaloid of the plakinamine class, which we have given the common name plakinamine P. Its structure is most similar to plakinamine L, which also has an acyclic side chain. Careful dissection of the nuclear magnetic resonance data, collected in multiple solvents, suggests that the dimethyl amino group at the 3 position is in an equatorial rather than axial position unlike previously reported plakinamines. Plakinamine P was bactericidal against M. tuberculosis, and exhibited moderate activity against other mycobacterial pathogens, such as M. abscessus and M. avium. Furthermore, it had low toxicity against J774 macrophages, yielding a selectivity index (SI, or IC50/MIC) of 8.4. In conclusion, this work provides a promising scaffold to the tuberculosis drug discovery pipeline. Future work to determine the molecular target of this compound may reveal a pathway essential for M. tuberculosis survival during infection.