Glycosides from marine sponges (Porifera, Demospongiae): structures, taxonomical distribution, biological activities and biological roles

Integration of HPTLC with ATR-FTIR, HRMS and bioquantification for evaluation of antibacterial and antioxidant compounds in marine sponges

Marine sponges are an abundant source of unique bioactive compounds, offering immense potential for the development of innovative medicines. This study presents an analytical approach for the identification of bioactive compounds in marine sponge extracts. The approach capitalizes high-performance thin-layer chromatography (HPTLC) - Effect-Directed Analysis (EDA) with high-resolution mass spectrometry (MS) and Fourier-transform infrared (FTIR) spectroscopy, enabling identification of bioactive compounds. HPTLC-EDA was done to evaluate radical scavenging and antimicrobial activities against five pathogenic bacterial strains: Escherichia coli, Klebsiella pneumoniae, Bacillus spizizenii, Staphylococcus aureus, and methicillin-resistant Staphylococcus aureus (MRSA). The bioquantification of streptomycin and gallic acid was conducted using image analysis of HPTLC chromatograms, with subsequent analysis via antimicrobial assays against the aforementioned bacterial strains and DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging assays. The developed HPTLC chromatograms, utilizing toluene:ethyl acetate:acetic acid (60:37.5:2.5, V/V/V) as a mobile phase for the first time, enabled the optimal separation of bioactive compounds from complex marine sponge extracts. Avarol from Dysidea avara was identified as the compound with the highest potential using FTIR and HRMS techniques. The study highlights a high-throughput, cost-effective approach for screening bioactive metabolites from marine sponges using HPTLC-bioassay. This approach accelerates therapeutic discovery and offers a sustainable, eco-friendly alternative to traditional methods.

Bioactive Terpenes from Marine Sponges and Their Associated Organisms

In recent years, marine natural products have continued to serve as a pivotal resource for novel drug discovery. Globally, the number of studies focusing on Porifera has been on the rise, underscoring their considerable importance and research value. Marine sponges are prolific producers of a vast array of bioactive compounds, including terpenes, alkaloids, peptides, and numerous secondary metabolites. Over the past fifteen years, a substantial number of sponge-derived terpenes have been identified, exhibiting extensive structural diversity and notable biological activities. These terpenes have been isolated from marine sponges or their associated symbiotic microorganisms, with several demonstrating multifaceted biological activities, such as anti-inflammatory, antibacterial, cytotoxic, anticancer, and antioxidant properties. In this review, we summarize 997 novel terpene metabolites, detailing their structures, sources, and activities, from January 2009 to December 2024. The structural features and structure-activity relationship (SAR) of different types of terpenes are broadly analyzed and summarized. This systematic and comprehensive review will contribute to the summary of and speculation on the taxonomy, activity profiles, and SAR of terpenes and the development of sponge-derived terpenes as potential lead drugs.

Recent Advances in Natural Products Derived from Marine Echinoderms and Endophytic Microbes: Chemical Insights and Therapeutic Potential

Echinoderms, a diverse group of marine invertebrates including starfish, sea urchins, and sea cucumbers, have been recognized as prolific sources of structurally diverse natural products. In the past five years, remarkable progress has been made in the isolation, structural elucidation, and pharmacological assessment of these bioactive compounds. These metabolites, including polysaccharides, triterpenoids, steroids, and peptides, demonstrate potent bioactivities such as anticancer, anti-inflammatory, antiviral, and antimicrobial effects, providing valuable insights and scaffolds for drug discovery. This review highlights the structural diversity and biological activities of natural products derived from echinoderms over the last five years, with a particular focus on their structure-activity relationships and therapeutic potential. It also outlines the prospects and challenges for future research, aiming to stimulate further exploration in marine drug discovery.

Stichoposide C and Rhizochalin as Potential Aquaglyceroporin Modulators

Aquaporins (AQPs) are a family of integral membrane proteins that selectively transport water and glycerol across the cell membrane. Because AQPs are involved in a wide range of physiological functions and pathophysiological conditions, AQP-based therapeutics may have the broad potential for clinical utility, including for disorders of water and energy balance. However, AQP modulators have not yet been developed as suitable candidates for clinical applications. In this study, to identify potential modulators of AQPs, we screened 31 natural products by measuring the water and glycerol permeability of mouse erythrocyte membranes using a stopped-flow light scattering method. None of the tested natural compounds substantially affected the osmotic water permeability. However, several compounds considerably affected the glycerol permeability. Stichoposide C increased the glycerol permeability of mouse erythrocyte membranes, whereas rhizochalin decreased it at nanomolar concentrations. Immunohistochemistry revealed that AQP7 was the main aquaglyceroporin in mouse erythrocyte membranes. We further verified the effects of stichoposide C and rhizochalin on aquaglyceroporins using human AQP3-expressing keratinocyte cells. Stichoposide C, but not stichoposide D, increased AQP3-mediated transepithelial glycerol transport, whereas the peracetyl aglycon of rhizochalin was the most potent inhibitor of glycerol transport among the tested rhizochalin derivatives. Collectively, stichoposide C and the peracetyl aglycon of rhizochalin might function as modulators of AQP3 and AQP7, and suggests the possibility of these natural products as potential drug candidates for aquaglyceroporin modulators.

Two new sarasinosides from marine sponge Petrosia nigricans

Two new sarasinosides designated as 5,8-epoxysarasinoside (1) and 8,9-epoxysarasinoside (2) and four known sarasinosides were isolated from marine sponge Petrosia nigricans, collected off the coast of Lipata, Surigao City, Philippines (9°49' North, 125°27' East). The structures were determined through extensive 2D NMR spectroscopy and HRMS. Both compounds exhibited low cytotoxicity against the HCT116 (colon) and A549 (lung) cancer cell lines.

Additional Sarasinosides from the Marine Sponge Melophlus sarasinorum Collected from the Bismarck Sea

In our continuing efforts to describe the biological and chemical diversity of sponges from Kimbe Bay, Papua New Guinea, the known 30-norlanostane saponin sarasinoside C1 (1) was identified along with six new analogues named sarasinosides C4, C5, C6, C7, C8, and C9 (2-7) from the sponge Melophlus sarasinorum. The structures of the new compounds were elucidated by analysis of 1D and 2D NMR and HRMS data, as well as comparison with literature data. All new compounds are characterized by the same tetraose moiety, β-d-Xylp-(1→6)-β-d-GlcNAcp-(1→2)-[β-d-GalNAcp-(1→4)]-β-d-Xylp, as described previously for sarasinoside C1, but differed in their aglycone moieties. When comparing NMR data of sarasinoside C8 with those of known analogues, a misassignment was identified in the configuration of the C-8/C-9 diol for the previously described sarasinoside R (8), and it has been corrected here using a combination of ROESY analysis and molecular modeling.

Triterpene and Steroid Glycosides from Marine Sponges (Porifera, Demospongiae): Structures, Taxonomical Distribution, Biological Activities

The article is a comprehensive review concerning tetracyclic triterpene and steroid glycosides from sponges (Porifera, Demospongiae). The extensive oxidative transformations of the aglycone and the use of various monosaccharide residues, with up to six possible, are responsible for the significant structural diversity observed in sponge saponins. The saponins are specific for different genera and species but their taxonomic distribution seems to be mosaic in different orders of Demospongiae. Many of the glycosides are membranolytics and possess cytotoxic activity that may be a cause of their anti-predatory activities. All these data reveal the independent origin and parallel evolution of the glycosides in different taxa of the sponges. The information concerning chemical structures, biological activities, biological role, and taxonomic distribution of the sponge glycosides is discussed.

Characterization of seahorse (Hippocampus comes L.) extracts originating from culture and nature in Pesawaran, Lampung, Indonesia

Objective

Indonesia is an archipelagic country with a mega biodiversity, among others, in the marine area. Seahorses (Hippocampus spp.) are a marine fish known to have biocompounds used in traditional medicine "Jamu," such as Hippocampus comes L. (HCL). The present study aims to analyze and compare the chemical contents of cultured seahorse (CS) and natural seahorse (NS) extracts.

Materials and Methods

The CS and NS were identified morphometrically. After freeze-drying, the seahorses were ground into powder with a grinder. The seahorse powder was extracted with ethanol and a water solvent. The extract contained biocompounds, proximate, amino acids, and steroids with high-performance liquid chromatography.

Results

The study found unique characteristics of HCL. The highest yield was obtained in NS using a water solvent (18.6%). The biocompounds in seahorses consist of alkaloids and triterpenoids. The highest proximate of water content (11.03%) and ash content (42.50%) was found in NS. In addition, other compounds were also detected in CS, such as fat (7.48%) and protein (47.67%). Both of HCL's different sources had all essential and nonessential amino acids in which the highest concentration were in NS, i.e., L-arginine (56,537.22 mg/kg), L-lysine (17,794.17), glycine (113,649.80 mg/kg), L-proline (47,056.15), and L-alanine (43,451.81). The analysis of the steroid compound of the extract suggested the presence of steroid glycosides.

Conclusion

The highest yield of the seahorse extract with a water solvent is about 18.6% and protein content of 47.67% in CS. The crude extract has alkaloids, triterpenoids, and glycine (113,649.80 mg/kg) in NS with water, suggesting the presence of steroid glycosides.

Chemical Diversity and Bioactivity of Marine Sponges of the Genus Oceanapia: A Review

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The marine sponges of the genus Oceanapia sp. is comprised of more than 50 species and are distributed in the seas around the tropical and subtropical regions. They are mainly found in the northern Indian oceans, Japan, and the south pacific coast. They are highly colored and known to be a rich source of various secondary metabolites, particularly, alkaloids. Several other secondary metabolites were also reported from this genus which include terpenes, sphingolipids, ceramides, cerebrosides, acetylenic acids, and thiocyanatins, etc. Many of these compounds isolated from this genus exhibited various biological properties including anticancer, antimicrobial, anti-HIV, ichthyotoxicity and nematocidal activities. Although several secondary metabolites have been reported from this genus, a dedicated review of the chemicals and biological activities of this genus is so far lacking. Keeping this in mind this review describes the various chemical entities isolated from the sponges of the genus Oceanapia detailing their chemical structures along with their reported biological properties.

A Soft Spot for Chemistry-Current Taxonomic and Evolutionary Implications of Sponge Secondary Metabolite Distribution

Marine sponges are the most prolific marine sources for discovery of novel bioactive compounds. Sponge secondary metabolites are sought-after for their potential in pharmaceutical applications, and in the past, they were also used as taxonomic markers alongside the difficult and homoplasy-prone sponge morphology for species delineation (chemotaxonomy). The understanding of phylogenetic distribution and distinctiveness of metabolites to sponge lineages is pivotal to reveal pathways and evolution of compound production in sponges. This benefits the discovery rate and yield of bioprospecting for novel marine natural products by identifying lineages with high potential of being new sources of valuable sponge compounds. In this review, we summarize the current biochemical data on sponges and compare the metabolite distribution against a sponge phylogeny. We assess compound specificity to lineages, potential convergences, and suitability as diagnostic phylogenetic markers. Our study finds compound distribution corroborating current (molecular) phylogenetic hypotheses, which include yet unaccepted polyphyly of several demosponge orders and families. Likewise, several compounds and compound groups display a high degree of lineage specificity, which suggests homologous biosynthetic pathways among their taxa, which identifies yet unstudied species of this lineage as promising bioprospecting targets.

Mechanisms driving genome reduction of a novel Roseobacter lineage

Members of the marine Roseobacter group are key players in the global carbon and sulfur cycles. While over 300 species have been described, only 2% possess reduced genomes (mostly 3-3.5 Mbp) compared to an average roseobacter (>4 Mbp). These taxonomic minorities are phylogenetically diverse but form a Pelagic Roseobacter Cluster (PRC) at the genome content level. Here, we cultivated eight isolates constituting a novel Roseobacter lineage which we named 'CHUG'. Metagenomic and metatranscriptomic read recruitment analyses showed that CHUG members are globally distributed and active in marine pelagic environments. CHUG members possess some of the smallest genomes (~2.6 Mb) among all known roseobacters, but they do not exhibit canonical features of typical bacterioplankton lineages theorized to have undergone genome streamlining processes, like higher coding density, fewer paralogues and rarer pseudogenes. While CHUG members form a genome content cluster with traditional PRC members, they show important differences. Unlike other PRC members, neither the relative abundances of CHUG members nor their relative gene expression levels are correlated with chlorophyll a concentration across the global samples. CHUG members cannot utilize most phytoplankton-derived metabolites or synthesize vitamin B₁₂, a key metabolite mediating the roseobacter-phytoplankton interactions. This combination of features is evidence for the hypothesis that CHUG members may have evolved a free-living lifestyle decoupled from phytoplankton. This ecological transition was accompanied by the loss of signature genes involved in roseobacter-phytoplankton symbiosis, suggesting that relaxation of purifying selection owing to lifestyle shift is likely an important driver of genome reduction in CHUG.

Structure Elucidation of Calyxoside B, a Bipolar Sphingolipid from a Marine Sponge Cladocroce sp. through the Use of Beckmann Rearrangement

Marine sponges are an excellent source of biologically active secondary metabolites. We focus on deep-sea sponges for our discovery study. A marine sponge Cladocroce sp. exhibited cytotoxic activity in the bioactivity screening. From this sponge a previously unreported cytotoxic glycosphingolipid, calyxoside B, was isolated and the structure of this compound was elucidated by analyses of MS and NMR spectra and chemical derivatization. We converted the ketone in the middle of a long aliphatic chain into an oxime to which was applied Beckmann rearrangement to afford two positional isomers of amides. The products were subjected to acidic hydrolysis followed by LC-MS analysis, permitting us to assign unequivocally the position of the ketone. Calyxoside B shows cytotoxicity against HeLa cells with an IC50 value of 31 µM and also weakly stimulated the production of cytokines in mice.

Identification of α-Amylase and α-Glucosidase Inhibitors and Ligularoside A, a New Triterpenoid Saponin from Passiflora ligularis Juss (Sweet Granadilla) Leaves, by a Nuclear Magnetic Resonance-Based Metabolomic Study

The leaves of Passiflora ligularis Juss (known as sweet granadilla for its edible fruits) are a crop byproduct that is discarded. With the aim of contributing to give value-added products from these crop by-side products to farmers of Colombian Andes, we carried out a ¹H-NMR-metabolomics analysis of polar extracts from leaves collected in three locations and stored in two conditions in order to identify glucosyl-hydrolase inhibitors. Variations in the metabolic profile and the bioactivity among samples were analyzed by orthogonal partial least square discriminant analysis. Thus, ¹H-NMR signals related to polyphenolic compounds, saponins, and amino acids were correlated with higher inhibitory activities. Moreover, a targeted NMR and HPLC-MS/MS analysis allowed the identification of 14 polyphenolic compounds and the structural characterization of a new triterpenoid saponin, ligularoside A. The measurements of IC₅₀ values for α-amylase and α-glycosidase inhibitors allowed the identification of quercetin-3-O-β-glucoside, kaempferol-3-O-β-glucoside, and ligularoside A as the most active compounds. These results suggest that P. ligularis leaves are a source of glucosyl-hydrolase inhibitors and lay the foundation for exploring additional applications.

In Vitro and In Vivo Effects of Holotoxin A1 From the Sea Cucumber Apostichopus japonicus During Ionizing Radiation

Radiation therapy is one of the most important approaches to cancer therapy, but radiotoxicity to normal tissue is a serious limitation of this treatment. Compounds which are able to either sensitize cancer cells or protect normal cells to radiation are of great interest. The cytotoxicity of holotoxin A1 and the effects of radiation against DLD-1 and HT-29 cells were measured by MTS (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium) assay. The effect of the combination of holotoxin A1 with X-ray on colony formation of cancer cells was determined by the soft agar assay. The effect of holotoxin A1 on the recovery of peripheral blood leukocyte number, mass, and cellularity of the lymphoid organs of irradiated mice, as well as on growth of murine Ehrlich solid carcinoma was studied. Holotoxin A1 enhanced the sensitivity of colorectal carcinoma cells to radiation in vitro. Injection of holotoxin A1 to mice led to an increase in the spleen endogenous colony number and peripheral blood leukocyte number, as well as the weight and cellularity of the lymphoid organs of the irradiated mice. Holotoxin A1 in combination with X-ray radiation effectively inhibited the growth of Ehrlich solid carcinoma in vivo. Holotoxin A1 is suggested to be a promising agent for improving the efficiency of radiotherapy.

Antimicrobial lead compounds from marine plants

Marine environment is a home to a very wide diversity of flora and fauna, which includes an array of genetically diverse coastline and under seawater plant species, animal species, microbial species, their habitats, ecosystems, and supporting ecological processes. The Earth is home to an estimated 10 million species, of which a large chunk belongs to marine environment. Marine plants are a store house of a variety of antimicrobial compounds like classes of marine flavonoids—flavones and flavonols, terpenoids, alkaloids, peptides, carbohydrates, fatty acids, polyketides, polysaccharides, phenolic compounds, and steroids. Lot of research today is directed toward marine species, which have proved to be a potent source of structurally widely diverse and yet highly bioactive secondary metabolites. Varied species of phylum Porifera, algae including diatoms, Chlorophyta, Euglenophyta, Dinoflagellata, Chrysophyta, cyanobacteria, Rhodophyta, and Phaeophyta, bacteria, fungi, and weeds have been exploited by mankind for their inherent indigenous biological antimicrobial compounds, produced under the extreme stressful underwater conditions of temperature, atmospheric pressure, light, and nutrition. The present study aims at presenting a brief review of bioactive marine compounds possessing antimicrobial potency.

Chemical synthesis of marine saponins

Covering: 1989-2017 Saponins are characteristic metabolites of starfish and sea cucumbers, and occasionally are also found in sponges, soft coral, and small fish. These steroid or triterpenoid glycosides often show remarkable biological and pharmacological activities, such as antifungal, antifouling, shark repellent, antitumor and anti-inflammatory activities. Over one thousand marine saponins have been characterized; the majority of them can be categorized into three major structural types, i.e., asterosaponins, polyhydroxysteroid glycosides, and holostane glycosides. Thus far, only 12 marine saponins have been synthesized; those representing the major types were successfully synthesized recently. The syntheses involve preparation of the aglycones from the terrestrial steroid or triterpene materials, installation of the carbohydrate units, and manipulation of the protecting groups. Herein, we provide a comprehensive review on these syntheses.

Vaccine Adjuvants Derived from Marine Organisms

Vaccine adjuvants help to enhance the immunogenicity of weak antigens. The adjuvant effect of certain substances was noted long ago (the 40s of the last century), and since then a large number of adjuvants belonging to different groups of chemicals have been studied. This review presents research data on the nonspecific action of substances originated from marine organisms, their derivatives and complexes, united by the name 'adjuvants'. There are covered the mechanisms of their action, safety, as well as the practical use of adjuvants derived from marine hydrobionts in medical immunology and veterinary medicine to create modern vaccines that should be non-toxic and efficient. The present review is intended to briefly describe some important achievements in the use of marine resources to solve this important problem.

Transcriptome Analysis of Clinopodium chinense (Benth.) O. Kuntze and Identification of Genes Involved in Triterpenoid Saponin Biosynthesis

Clinopodium chinense (Benth.) O. Kuntze (C. chinense) is an important herb in traditional Chinese medicine. Triterpenoid saponins are a major class of active compounds in C. chinense with broad pharmacological activities and hemostatic, antitumor, and anti-hyperglycemic effects. To identify genes involved in triterpenoid saponin biosynthesis, transcriptomic analyses of leaves, stems, and roots from C. chinense were performed. A total of 135,968 unigenes were obtained by assembling the leaf, stem, and root transcripts, of which 102,154 were annotated in public databases. Differentially expressed genes were determined based on expression profile analysis and analyzed for differential expression of unique genes related to triterpenoid saponin biosynthesis. Multiple unigenes encoding crucial enzymes or transcription factors involved in triterpenoid saponin synthesis were identified and analyzed. The expression levels of unigenes encoding enzymes were experimentally validated using quantitative real-time PCR. This study greatly broadens the public transcriptome database for this species and provides a valuable resource for identifying candidate genes involved in the biosynthesis of triterpenoid saponins and other secondary metabolites.

Enhancement of photosynthesis in Synechococcus bacillaris by sponge-derived Ageladine A

This study is a proof of concept that the sponge derived pyrrole-imidazole alkaloid Ageladine A acts as an additional light harvesting molecule for photosynthesis of symbionts of marine sponges. The absorbance of Ageladine A is in the UV range and fluoresces blue, matching the blue absorbance of chlorophyll a. A joint modeling and experimental approach demonstrates that Ageladine A increases photosynthetic O₂ production of Synechococcus bacillaris WH5701 (CCMP1333), when the cells are exposed to UV light, which is marginally used for photosynthesis. Due to the presence of Ageladine A, production of O₂ increased 2.54 and 3.1-fold, in the experiments and the model, respectively.

Approaches for the isolation and identification of hydrophilic, light-sensitive, volatile and minor natural products

Water-soluble, volatile, minor and photosensitive natural products are yet poorly known, and this review discusses the literature reporting the isolation strategies for some of these metabolites.

Marine Carbohydrate-Based Compounds with Medicinal Properties

The oceans harbor a great diversity of organisms, and have been recognized as an important source of new compounds with nutritional and therapeutic potential. Among these compounds, carbohydrate-based compounds are of particular interest because they exhibit numerous biological functions associated with their chemical diversity. This gives rise to new substances for the development of bioactive products. Many are the known applications of substances with glycosidic domains obtained from marine species. This review covers the structural properties and the current findings on the antioxidant, anti-inflammatory, anticoagulant, antitumor and antimicrobial activities of medium and high molecular-weight carbohydrates or glycosylated compounds extracted from various marine organisms.

Marine Pharmacology in 2012-2013: 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 peer-reviewed marine pharmacology literature from 2012 to 2013 was systematically reviewed, consistent with the 1998–2011 reviews of this series. Marine pharmacology research from 2012 to 2013, conducted by scientists from 42 countries in addition to the United States, reported findings on the preclinical pharmacology of 257 marine compounds. The preclinical pharmacology of compounds isolated from marine organisms revealed antibacterial, antifungal, antiprotozoal, antituberculosis, antiviral and anthelmitic pharmacological activities for 113 marine natural products. In addition, 75 marine compounds were reported to have antidiabetic and anti-inflammatory activities and affect the immune and nervous system. Finally, 69 marine compounds were shown to display miscellaneous mechanisms of action which could contribute to novel pharmacological classes. Thus, in 2012–2013, the preclinical marine natural product pharmacology pipeline provided novel pharmacology and lead compounds to the clinical marine pharmaceutical pipeline, and contributed significantly to potentially novel therapeutic approaches to several global disease categories.

A new sarasinoside congener, sarasinoside M2, from a marine sponge collected in the Solomon Islands

A new sarasinoside congener (sarasinoside M2) and known sarasinoside B1 were obtained from a marine sponge. Sarasinoside M2 was suggested to have the same aglycon as sarasinoside M although the internal glucose in its sugar moiety is replaced by xylose. Sarasinosides B1 and M2 showed moderate cytotoxicity (approximate IC50 5–18 μM) toward Neuro-2a and HepG2 cell lines.

Marine Sponges as a Drug Treasure

Marine sponges have been considered as a drug treasure house with respect to great potential regarding their secondary metabolites. Most of the studies have been conducted on sponge's derived compounds to examine its pharmacological properties. Such compounds proved to have antibacterial, antiviral, antifungal, antimalarial, antitumor, immunosuppressive, and cardiovascular activity. Although, the mode of action of many compounds by which they interfere with human pathogenesis have not been clear till now, in this review not only the capability of the medicinal substances have been examined in vitro and in vivo against serious pathogenic microbes but, the mode of actions of medicinal compounds were explained with diagrammatic illustrations. This knowledge is one of the basic components to be known especially for transforming medicinal molecules to medicines. Sponges produce a different kind of chemical substances with numerous carbon skeletons, which have been found to be the main component interfering with human pathogenesis at different sites. The fact that different diseases have the capability to fight at different sites inside the body can increase the chances to produce targeted medicines.

Cytotoxic Glycosylated Fatty Acid Amides from a Stelletta sp. Marine Sponge

We have discovered new glycosylated fatty acid amides, stellettosides, from a Stelletta sp. marine sponge. They were detected through LC-MS analysis of the extract combined with the cytotoxicity assay of the prefractionated sample. Their planar structures were determined by analyses of the NMR and tandem FABMS data. Stellettosides A1 and A2 (1 and 2) as well as stellettosides B1-B4 (3-6) were obtained as inseparable mixtures. Careful analysis of the NMR and tandem FABMS data of each mixture, along with comparison of the tandem FABMS data with that of a synthetic model compound, permitted us to assign the structure of the constituents in the mixture. The absolute configuration of the monosaccharide unit was determined by LC-MS after chiral derivatization. The relative configurations of the vicinal oxygenated methines in the fatty acid chains were assigned by the (1)H NMR data of the isopropylidene derivative. The mixture of stellettosides B1-B4 (3-6) exhibit moderate cytotoxic activity against HeLa cells with an IC50 value of 9 μM, whereas the mixture of stellettosides A1 and A2 (1 and 2) was not active at a concentration of 10 μM.

The antimicrobial activity of heterotrophic bacteria isolated from the marine sponge Erylus deficiens (Astrophorida, Geodiidae)

Interest in the study of marine sponges and their associated microbiome has increased both for ecological reasons and for their great biotechnological potential. In this work, heterotrophic bacteria associated with three specimens of the marine sponge Erylus deficiens, were isolated in pure culture, phylogenetically identified and screened for antimicrobial activity. The isolation of bacteria after an enrichment treatment in heterotrophic medium revealed diversity in bacterial composition with only Pseudoalteromonas being shared by two specimens. Of the 83 selected isolates, 58% belong to Proteobacteria, 23% to Actinobacteria and 19% to Firmicutes. Diffusion agar assays for bioactivity screening against four bacterial strains and one yeast, revealed that a high number of the isolated bacteria (68.7%) were active, particularly against Candida albicans and Vibrio anguillarum. Pseudoalteromonas, Microbacterium, and Proteus were the most bioactive genera. After this preliminary screening, the bioactive strains were further evaluated in liquid assays against C. albicans, Bacillus subtilis and Escherichia coli. Filtered culture medium and acetone extracts from three and 5 days-old cultures were assayed. High antifungal activity against C. albicans in both aqueous and acetone extracts as well as absence of activity against B. subtilis were confirmed. Higher levels of activity were obtained with the aqueous extracts when compared to the acetone extracts and differences were also observed between the 3 and 5 day-old extracts. Furthermore, a low number of active strains was observed against E. coli. Potential presence of type-I polyketide synthases (PKS-I) and non-ribosomal peptide synthetases (NRPSs) genes were detected in 17 and 30 isolates, respectively. The high levels of bioactivity and the likely presence of associated genes suggest that Erylus deficiens bacteria are potential sources of novel marine bioactive compounds.

Further study on Penares sp. from Vietnamese waters: minor lanostane and nor-lanostane triterpenes

Eight new oxidized lanostane and nor-lanostane derivatives (1-8) along with the previously known penasterol (9) and 24-ethylcholesta-4,24(28)-dien-3-one (10) were isolated from a sponge Penares sp. collected from the Vietnamese waters. Structures of these minor compounds were elucidated by the detailed NMR spectroscopic and mass-spectrometric analyses and by comparison with earlier reported spectroscopic data. A hypothetic scheme of metabolism of the lanostane derivatives in sponges belonging to Penares and Erylus genera was proposed and discussed.

The effects of marine carbohydrates and glycosylated compounds on human health

Marine organisms have been recognized as a valuable source of bioactive compounds with industrial and nutraceutical potential. Recently, marine-derived carbohydrates, including polysaccharides and low molecular weight glycosylated oligosaccharides, have attracted much attention because of their numerous health benefits. Moreover, several studies have reported that marine carbohydrates exhibit various biological activities, including antioxidant, anti-infection, anticoagulant, anti-inflammatory, and anti-diabetic effects. The present review discusses the potential industrial applications of bioactive marine carbohydrates for health maintenance and disease prevention. Furthermore, the use of marine carbohydrates in food, cosmetics, agriculture, and environmental protection is discussed.

Relationships between chemical structures and functions of triterpene glycosides isolated from sea cucumbers

Many marine triterpene glycosides have in vitro and in vivo activities with very low toxicity, suggesting that they are suitable agents for the prevention and treatment of different diseases, particularly cancer. However, the molecular mechanisms of action of natural marine compounds in cancer, immune, and other various cells are not fully known. This review focuses on the structural characteristics of marine triterpene glycosides and how these affect their biological activities and molecular mechanisms. In particular, the membranotropic and membranolytic activities of frondoside A and cucumariosides from sea cucumbers and their ability to induce cytotoxicity and apoptosis have been discussed, with a focus on structure-activity relationships. In addition, the structural characteristics and antitumor effects of stichoposide C and stichoposide D have been reviewed along with underlying their molecular mechanisms.

Marine natural products

This review covers the literature published in 2012 for marine natural products, with 1035 citations (673 for the period January to December 2012) 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 (1241 for 2012), together with the relevant biological activities, source organisms and country of origin. Biosynthetic studies, first syntheses, and syntheses that lead to the revision of structures or stereochemistries, have been included.

HPLC-ESI-IT-MS/MS analysis and biological activity of triterpene glycosides from the Colombian marine sponge Ectyoplasia ferox

The marine sponge Ectyoplasia ferox produces antipredatory and allelopathic triterpenoid glycosides as part of its chemical defense repertoire against predators, competitors, and fouling organisms. These molecules are responsible for the pharmacological potential found in the glycosides present in this species. In order to observe the glycochemical diversity present in E. ferox, a liquid chromatography coupled to a tandem mass spectrometry approach to analyse a complex polar fraction of this marine sponge was performed. This gave valuable information for about twenty-five compounds three of which have been previously reported and another three which were found to be composed of known aglycones. Furthermore, a group of four urabosides, sharing two uncommon substitutions with carboxyl groups at C-4 on the terpenoid core, were identified by a characteristic fragmentation pattern. The oxidized aglycones present in this group of saponins can promote instability, making the purification process difficult. Cytotoxicity, cell cycle modulation, a cell cloning efficiency assay, as well as its hemolytic activity were evaluated. The cytotoxic activity was about IC₅₀ 40 µg/mL on Jurkat and CHO-k₁ cell lines without exhibiting hemolysis. Discussion on this bioactivity suggests the scanning of other biological models would be worthwhile.

Anti HSV-1 activity of halistanol sulfate and halistanol sulfate C isolated from Brazilian marine sponge Petromica citrina (Demospongiae)

The n-butanol fraction (BF) obtained from the crude extract of the marine sponge Petromica citrina, the halistanol-enriched fraction (TSH fraction), and the isolated compounds halistanol sulfate (1) and halistanol sulfate C (2), were evaluated for their inhibitory effects on the replication of the Herpes Simplex Virus type 1 (HSV-1, KOS strain) by the viral plaque number reduction assay. The TSH fraction was the most effective against HSV-1 replication (SI = 15.33), whereas compounds 1 (SI = 2.46) and 2 (SI = 1.95) were less active. The most active fraction and these compounds were also assayed to determine the viral multiplication step(s) upon which they act as well as their potential synergistic effects. The anti-HSV-1 activity detected was mediated by the inhibition of virus attachment and by the penetration into Vero cells, the virucidal effect on virus particles, and by the impairment in levels of ICP27 and gD proteins of HSV-1. In summary, these results suggest that the anti-HSV-1 activity of TSH fraction detected is possibly related to the synergic effects of compounds 1 and 2.

Inhibition of Tumor Cells Multidrug Resistance by Cucumarioside A2-2, Frondoside A and their Complexes with Cholesterol

In non-cytotoxic concentrations, frondoside A (1) from the sea cucumber Cucumaria okhotensis and cucumarioside A2-2 (2) from C. japonica, as well as their complexes with cholesterol block the activity of membrane transport P-glycoprotein in cells of the ascite form of mouse Ehrlich carcinoma. They prevent in this way an efflux of fluorescent probe Calcein from the cells. Since the blocking of P-glycoprotein activity results in decrease of multidrug resistance, these glycosides and their complexes with cholesterol may be considered as potential inhibitors of multidrug resistance of tumor cells.

A divergent approach to the synthesis of simplexides and congeners via a late-stage olefin cross-metathesis reaction

Simplexides constitute a unique group of immunosuppressive glycolipids that demonstrate antiproliferative activities against activated T-cell lymphocytes via a unique non-cytotoxic inhibition. To investigate the structure-activity relationship of the varied long-chain secondary alcohols on simplexides, we developed an efficient and divergent route to the synthesis of simplexides and congeners, taking advantage of a late-stage olefin cross-metathesis reaction.

Balibalosides, an original family of glucosylated sesterterpenes produced by the Mediterranean sponge Oscarella balibaloi

The chemical investigation of the recently described Mediterranean Homoscleromorpha sponge Oscarella balibaloi revealed an original family of five closely related glucosylated sesterterpenes 1-4, named balibalosides. Their structure elucidation was mainly inferred from NMR and HRMS data analyses. Balibalosides differ by the pattern of acetyl substitutions on the three sugar residues linked to the same aglycone sesterterpenoid core. From a biosynthetic perspective, these compounds may represent intermediates in the pathways leading to more complex sesterterpenes frequently found in Dictyoceratida, a sponge Order belonging to Demospongiae, a clade which is phylogenetically distinct from the Homoscleromorpha. While steroid and triterpenoid saponins were already well known from marine sponges, balibalosides are the first examples of glycosilated sesterterpenes.

Ulososides and urabosides--triterpenoid saponins from the Caribbean marine sponge Ectyoplasia ferox

Three new triterpene glycosides, named ulososide F (1), urabosides A (2) and B (3), together with the previously reported ulososide A (4), were isolated from the Caribbean marine sponge Ectyoplasia ferox. Their structures were elucidated using extensive interpretation of 1D and 2D-NMR data, as well as HRESIMS. The aglycon of all compounds is a rare 30-norlonastane and the sugar residues were identified after acid hydrolysis and GC analyses. Cytotoxicities of the isolated compounds were evaluated against Jurkat and CHO cell lines by a MTT in vitro assay as well as a hemolysis assay. Unexpectedly, all these saponin derivatives showed very low activity in our bioassays.