Antiviral Sulfoquinovosyldiacylglycerols (SQDGs) from the Brazilian brown seaweed Sargassum vulgare

Antiviral Activity of the Marine Haptophyta Diacronema lutheri

There are still several viral infections affecting a considerable number of the world's population, causing thousands of deaths each year. There are no drugs available for most viral infections and for many not even a vaccine. The marine kingdom is characterized by a huge chemical diversity; however, there is currently on the market only one drug derived from the sea with antiviral properties, called Ara-A. In the current study, we used a solid phase extraction method (SPE) to obtain pre-purified fractions from Diacronema lutheri raw extracts. We tested both raw extracts and fractions against enveloped and non-enveloped viruses. Results showed an antiviral activity of fraction C of D. lutheri against the herpes simplex virus type 1 (HSV-1 strain SC16). Liquid chromatography coupled with untargeted high-resolution tandem mass spectrometry (LC-HRMS2) were employed to chart the metabolite distribution in all SPE fractions and pinpoint molecular families unique (or almost unique) to the bioactive fraction. Sulfoquinovosyl di- and monoacylglycerols (SQDGs and SQMGs) and di- and monogalactosyl monoacylglycerols (DGMGs and MGMGs) represent the largest groups of compounds in fraction C and they are likely responsible for the antiviral properties of this fraction.

Unraveling the neutral and polar lipidome of Nordic brown macroalgae: A sustainable source of functional lipids

Brown macroalgae represent a sustainable and abundant source of lipids with acknowledged functional and health benefits. Nonetheless, macroalgae lipidome has been poorly unraveled due to lipids complex structural and chemical diversity. In this study, a comprehensive lipidomic analysis was performed in four macroalgae: Saccharina latissima, Fucus vesiculosus, Fucus serratus and the invasive Sargassum muticum, using HILIC-C30RP-HRMS. Neutral lipids (tri-, di-glycerides) comprised 72-82% of total lipids (TL) with a highly unsaturation profile (27-49% depending on species). The polar lipidome comprised glycolipids, phospholipids, betaine lipids and sphingolipids with varied content among macroalgae. S. latissima displayed the greatest level of glycolipids (23% of TL), by contrast with the dominance of long-chain polyunsaturated betaine lipids (10-18% of TL) in the other species, particularly in S. muticum. Phospholipids and sphingolipids were detected in low abundance (<1.7% of TL). This study elevated the potential of brown macroalgae as an emerging reservoir of bioactive lipids with nutritional relevance.

Antiviral activity of sulphated specialized metabolites from sea urchin Clypeaster humilis: in vitro and in silico studies

Chemical investigations of the sea urchin Clypeaster humilis has led to separation of twelve compounds including one new sulfonic acid derivative (7R) tridec-1-en-7-yl hydrogen sulphate (1), first isolated from natural source, pyridine-3-yl methane sulfonate (2), and first isolated from marine organisms, boldine (12), in addition to nine known compounds (3-11), which were isolated for the first time from the genus Clypeaster. Their structures were elucidated based on spectroscopic analyses (1D and 2D NMR), HR-ESI-MS as well as comparison with the previously reported data. The antiviral activity of the crude extract and sulphated compounds were evaluated using MTT colorimetric assay against Coxsackie B4 virus. The crude extract and compound 1 showed very potent antiviral activity with a percentage of inhibition equal to 89.7 ± 0.53% and 86.1 ± 0.92%, respectively. Results of the molecular docking analysis of the isolated compounds within Coxsackie Virus B4 (COX-B4) X-ray crystal structure and quantum chemical calculation for three sulphated compounds are in a consistent adaptation with the in vitro antiviral results. The pharmacokinetic properties (ADME) of isolated compounds were determined.

Cultivation of Chroococcidiopsis thermalis Using Available In Situ Resources to Sustain Life on Mars

The cultivation of cyanobacteria by exploiting available in situ resources represents a possible way to supply food and oxygen to astronauts during long-term crewed missions on Mars. Here, we evaluated the possibility of cultivating the extremophile cyanobacterium Chroococcidiopsis thermalis CCALA 050 under operating conditions that should occur within a dome hosting a recently patented process to produce nutrients and oxygen on Mars. The medium adopted to cultivate this cyanobacterium, named Martian medium, was obtained using a mixture of regolith leachate and astronauts' urine simulants that would be available in situ resources whose exploitation could reduce the mission payload. The results demonstrated that C. thermalis can grow in such a medium. For producing high biomass, the best medium consisted of specific percentages (40%vol) of Martian medium and a standard medium (60%vol). Biomass produced in such a medium exhibits excellent antioxidant properties and contains significant amounts of pigments. Lipidomic analysis demonstrated that biomass contains strategic lipid classes able to help the astronauts facing the oxidative stress and inflammatory phenomena taking place on Mars. These characteristics suggest that this strain could serve as a valuable nutritional resource for astronauts.

Anti-herpes simplex virus activities and mechanisms of marine derived compounds

Herpes simplex virus (HSV) is the most widely prevalent herpes virus worldwide, and the herpetic encephalitis and genital herpes caused by HSV infection have caused serious harm to human health all over the world. Although many anti-HSV drugs such as nucleoside analogues have been ap-proved for clinical use during the past few decades, important issues, such as drug resistance, toxicity, and high cost of drugs, remain unresolved. Recently, the studies on the anti-HSV activities of marine natural products, such as marine polysaccharides, marine peptides and microbial secondary metabolites are attracting more and more attention all over the world. This review discusses the recent progress in research on the anti-HSV activities of these natural compounds obtained from marine organisms, relating to their structural features and the structure-activity relationships. In addition, the recent findings on the different anti-HSV mechanisms and molecular targets of marine compounds and their potential for therapeutic application will also be summarized in detail.

Glycolipids from Sargassum filipendula, a Natural Alternative for Overcoming ABC Transporter-Mediated MDR in Cancer

Chemotherapy is a widely used strategy to treat cancer, a disease that causes millions of deaths each year. However, its efficacy is reduced by the overexpression of ABC transporters, which are proteins that expel the drugs used in chemotherapy and involved in the multidrug resistance (MDR). Glycolipids have been identified as potential inhibitors of ABC transporters. Algae of the genus Sargassum contain high levels of glycolipids, making them a promising therapeutic alternative against the MDR phenotype. Sargassum filipendula glycolipids were obtained by exhaustive maceration with chloroform/methanol, purified by column and thin layer chromatography, and then characterized by FTIR, NMR, and LC-MS. Cell viability by PI labeling and inhibition of ABC transporters were analyzed by flow cytometry. Assessment of resistance reversal was determined by MTT assay. Ten sulfoquinovosylglycerol-type compounds were found, and six of them are reported for the first time. In particular, moiety 4 (GL-4) showed strong and moderate inhibitory activity against ABCC1 and ABCB1 transporters respectively. Treatment of GL-4 in combination with the antineoplastic drug vincristine sensitized Lucena-1 cell model to drug and reversed the MDR phenotype. This is the first report of glycolipids isolated from S. filipendula capable of inhibiting ABC transporters and thus overcoming acquired drug resistance.

Separation, characterization and anti-inflammatory activities of galactoglycerolipids from Perilla frutescens (L.) Britton

The study was to optimize the separation procedures, characterize the galactoglycerolipids and explore their anti-inflammatory activities. Two monogalactosyldiacylglycerols (MGDGs) and three digalactosyldiacylglycerols (DGDGs) from Perilla frutescens (L.) Britton were obtained through one-step silica gel column chromatography and preparative high-performance liquid chromatography with evaporative light scattering detection (HPLC-ELSD). The presence of additional MGDG (1-O-9Z,12Z,15Z-octadecatrienoyl-2-O-7Z,10Z,13Z-hexadecatrienoyl-3-O-(β-D-galactopyranosyl)-sn-glycerol) and DGDG (1-O-9Z,12Z-octadecadienoyl-2-O-9Z,12Z,15Z-octadecatrienoyl-3-O-(β-D-galactopyranosyl-(1'→6'')-α-D-galactopyranosyl)-sn-glycerol) was concluded for the first time in perilla, by liquid chromatography-mass spectrometry (LC-MS) and nuclear magnetic resonance (NMR). In lipopolysaccharide (LPS)-induced RAW264.7 cells, five galactoglycerolipids exhibited good inhibitory activities against nitric oxide (NO) production and inducible nitric oxide synthase (iNOS) gene expression in a dose-dependent manner, suggesting that fatty acid chain length and unsaturation degree affected their anti-inflammatory activities.

Chemical Defense against Herbivory in the Brown Marine Macroalga Padina gymnospora Could Be Attributed to a New Hydrocarbon Compound

Brown marine macroalga Padina gymnospora (Phaeophyceae, Ochrophyta) produces both secondary metabolites (phlorotannins) and precipitate calcium carbonate (CaCO₃-aragonite) on its surface as potential defensive strategies against herbivory. Here, we have evaluated the effect of natural concentrations of organic extracts (dichloromethane-DI; ethyl acetate-EA and methanol-ME, and three isolated fractions) and mineralized tissues of P. gymnospora as chemical and physical resistance, respectively, against the sea urchin Lytechinus variegatus through experimental laboratory feeding bioassays. Fatty acids (FA), glycolipids (GLY), phlorotannins (PH) and hydrocarbons (HC) were also characterized and/or quantified in extracts and fractions from P. gymnospora using nuclear magnetic resonance (NMR) and gas chromatography (GC) coupled to mass spectrometry (CG/MS) or GC coupled to flame ionization detector (FID) and chemical analysis. Our results showed that chemicals from the EA extract of P. gymnospora were significantly important in reducing consumption by L. variegatus, but the CaCO₃ did not act as a physical protection against consumption by this sea urchin. An enriched fraction containing 76% of the new hydrocarbon 5Z,8Z,11Z,14Z-heneicosatetraene exhibited a significant defensive property, while other chemicals found in minor amounts, such as GLY, PH, saturated and monounsaturated FAs and CaCO₃ did not interfere with the susceptibility of P. gymnospora to L. variegatus consumption. We suggest that the unsaturation of the 5Z,8Z,11Z,14Z-heneicosatetraene from P. gymnospora is probably an important structural characteristic responsible for the defensive property verified against the sea urchin.

Antifungal and Antibacterial Activities of Isolated Marine Compounds

To combat the ineffectiveness of currently available pharmaceutical medications, caused by the emergence of increasingly resistant bacterial and fungal strains, novel antibacterial and antifungal medications are urgently needed. Novel natural compounds with antimicrobial activities can be obtained by exploring underexplored habitats such as the world's oceans. The oceans represent the largest ecosystem on earth, with a high diversity of organisms. Oceans have received some attention in the past few years, and promising compounds with antimicrobial activities were isolated from marine organisms such as bacteria, fungi, algae, sea cucumbers, sea sponges, etc. This review covers 56 antifungal and 40 antibacterial compounds from marine organisms. These compounds are categorized according to their chemical structure groups, including polyketides, alkaloids, ribosomal peptides, and terpenes, and their organismal origin. The review provides the minimum inhibitory concentration MIC values and the bacterial/fungal strains against which these chemical compounds show activity. This study shows strong potential for witnessing the development of new novel antimicrobial drugs from these natural compounds isolated and evaluated for their antimicrobial activities.

Lipidomic Characterization and Antioxidant Activity of Macro- and Microalgae Blend

Macro- and microalgae are currently recognized sources of lipids with great nutritional quality and attractive bioactivities for human health promotion and disease prevention. Due to the lipidomic diversity observed among algae species, giving rise to different nutritional and functional characteristics, the mixture of macro- and microalgae has the potential to present important synergistic effects resulting from the complementarity among algae. The aim of this work was to characterize for the first time the lipidome of a blend of macro- and microalgae and evaluate the antioxidant capacity of its lipid fraction. Fatty acids were profiled by GC-MS, the polar lipidome was identified by high resolution LC-MS, and ABTS^+• and DPPH^• assays were used to assess the antioxidant potential. The most abundant fatty acids were oleic (18:1 n-9), α-linolenic (18:3 n-3), and linoleic (18:2 n-6) acids. The lipid extract presented a beneficial n-6/n-3 ratio (0.98) and low values of atherogenic (0.41) and thrombogenic indices (0.27). The polar lipidome revealed 462 lipid species distributed by glycolipids, phospholipids, and betaine lipids, including some species bearing PUFA and a few with reported bioactivities. The lipid extract also showed antioxidant activity. Overall, the results are promising for the valorization of this blend for food, nutraceutical, and biotechnological applications.

Glyceroglycolipids in marine algae: A review of their pharmacological activity

Glyceroglycolipids are major metabolites of marine algae and have a wide range of applications in medicine, cosmetics, and chemistry research fields. They are located on the cell surface membranes. Together with glycoproteins and glycosaminoglycans, known as the glycocalyx, they play critical roles in multiple cellular functions and signal transduction and have several biological properties such as anti-oxidant and anti-inflammatory properties, anti-viral activity, and anti-tumor immunity. This article focused on the sources and pharmacological effects of glyceroglycolipids, which are naturally present in various marine algae, including planktonic algae and benthic algae, with the aim to highlight the promising potential of glyceroglycolipids in clinical treatment.

Bioactivities of Lipid Extracts and Complex Lipids from Seaweeds: Current Knowledge and Future Prospects

While complex lipids of seaweeds are known to display important phytochemical properties, their full potential is yet to be explored. This review summarizes the findings of a systematic survey of scientific publications spanning over the years 2000 to January 2021 retrieved from Web of Science (WoS) and Scopus databases to map the state of the art and identify knowledge gaps on the relationship between the complex lipids of seaweeds and their reported bioactivities. Eligible publications (270 in total) were classified in five categories according to the type of studies using seaweeds as raw biomass (category 1); studies using organic extracts (category 2); studies using organic extracts with identified complex lipids (category 3); studies of extracts enriched in isolated groups or classes of complex lipids (category 4); and studies of isolated complex lipids molecular species (category 5), organized by seaweed phyla and reported bioactivities. Studies that identified the molecular composition of these bioactive compounds in detail (29 in total) were selected and described according to their bioactivities (antitumor, anti-inflammatory, antimicrobial, and others). Overall, to date, the value for seaweeds in terms of health and wellness effects were found to be mostly based on empirical knowledge. Although lipids from seaweeds are little explored, the published work showed the potential of lipid extracts, fractions, and complex lipids from seaweeds as functional ingredients for the food and feed, cosmeceutical, and pharmaceutical industries. This knowledge will boost the use of the chemical diversity of seaweeds for innovative value-added products and new biotechnological applications.

Viral inhibitors derived from macroalgae, microalgae, and cyanobacteria: A review of antiviral potential throughout pathogenesis

Viruses are abiotic obligate parasites utilizing complex mechanisms to hijack cellular machinery and reproduce, causing multiple harmful effects in the process. Viruses represent a growing global health concern; at the time of writing, COVID-19 has killed at least two million people around the world and devastated global economies. Lingering concern regarding the virus' prevalence yet hampers return to normalcy. While catastrophic in and of itself, COVID-19 further heralds in a new era of human-disease interaction characterized by the emergence of novel viruses from natural sources with heretofore unseen frequency. Due to deforestation, population growth, and climate change, we are encountering more viruses that can infect larger groups of people with greater ease and increasingly severe outcomes. The devastation of COVID-19 and forecasts of future human/disease interactions call for a creative reconsideration of global response to infectious disease. There is an urgent need for accessible, cost-effective antiviral (AV) drugs that can be mass-produced and widely distributed to large populations. Development of AV drugs should be informed by a thorough understanding of viral structure and function as well as human biology. To maximize efficacy, minimize cost, and reduce development of drug-resistance, these drugs would ideally operate through a varied set of mechanisms at multiple stages throughout the course of infection. Due to their abundance and diversity, natural compounds are ideal for such comprehensive therapeutic interventions. Promising sources of such drugs are found throughout nature; especially remarkable are the algae, a polyphyletic grouping of phototrophs that produce diverse bioactive compounds. While not much literature has been published on the subject, studies have shown that these compounds exert antiviral effects at different stages of viral pathogenesis. In this review, we follow the course of viral infection in the human body and evaluate the AV effects of algae-derived compounds at each stage. Specifically, we examine the AV activities of algae-derived compounds at the entry of viruses into the body, transport through the body via the lymph and blood, infection of target cells, and immune response. We discuss what is known about algae-derived compounds that may interfere with the infection pathways of SARS-CoV-2; and review which algae are promising sources for AV agents or AV precursors that, with further investigation, may yield life-saving drugs due to their diversity of mechanisms and exceptional pharmaceutical potential.

Marine algal antagonists targeting 3CL protease and spike glycoprotein of SARS-CoV-2: a computational approach for anti-COVID-19 drug discovery

The COVID-19 pandemic has severely destructed human life worldwide, with no suitable treatment until now. SARS-CoV-2 virus is unprecedented, resistance against number of therapeutics and spreading rapidly with high mortality, which warrants the need to discover new effective drugs to combat this situation. This current study is undertaken to explore the antiviral potential of marine algal compounds to inhibit the viral entry and its multiplication using computational analysis. Among the proven drug discovery targets of SARS-CoV-2, spike glycoprotein and 3-chymotrypsin-like protease are responsible for the virus attachment and viral genome replication in the host cell. In this study, the above-mentioned drug targets were docked with marine algal compounds (sulfated polysaccharides, polysaccharide derivatives and polyphenols) using molecular docking tools (AutoDockTools). The obtained results indicate that κ-carrageenan, laminarin, eckol, trifucol and β-D-galactose are the top-ranking compounds showing better docking scores with SARS-CoV-2 targets, than the current experimental COVID-19 antiviral drugs like dexamethasone, remdesivir, favipiravir and MIV-150. Further, molecular dynamic simulation, ADMET and density functional theory calculations were evaluated to substantiate the findings. To the best of our knowledge, this is the first report on in silico analysis of aforesaid algal metabolites against SARS-CoV-2 targets. This study concludes that these metabolites can be curative for COVID-19 in the hour of need after further validations in in vitro and in vivo testings.Communicated by Ramaswamy H. Sarma.

Potential of algal metabolites for the development of broad-spectrum antiviral therapeutics: Possible implications in COVID-19 therapy

Covid-19 pandemic severely affected human health worldwide. Till October 19, 2020, total confirmed patients of COVID-19 are 39,944,882, whereas 1,111,998 people died across the globe. Till to date, we do not have any specific medicine and/or vaccine to treat COVID-19; however, research is still going on at war footing. So far vaccine development is concerned, here it is noteworthy that till now three major variants (named A, B, and C) of severe acute respiratory syndrome-coronavirus2 (SARS-CoV-2) have been recognized. Increased mutational rate and formation of new viral variants may increase the attrition rate of vaccines and/or candidate chemotherapies. Herbal remedies are chemical cocktails, thus open another avenue for effective antiviral therapeutics development. In fact, India is a large country, which is densely populated, but the overall severity of COVID-19 per million populations is lesser than any other country of the world. One of the major reasons for the aforesaid difference is the use of herbal remedies by the Government of India as a preventive measure for COVID-19. Therefore, the present review focuses on the epidemiology and molecular pathogenesis of COVID-19 and explores algal metabolites for their antiviral properties.

Development of a targeted HPLC-ESI-QqQ-MS/MS method for the quantification of sulfolipids from a cyanobacterium, selected leafy vegetables, and a microalgae species

The use of macro- and microalgae, as well as cyanobacteria, becomes increasingly important for human nutrition, even in Western diets. Health effects, positive as well as negative, are believed to result mainly from minor components in the food. In macro- and microalgae as well as in certain cyanobacteria, one class of such minor compounds is sulfolipids, more precisely sulfoquinovosylmonoacylglycerol (SQMG) and sulfoquinovosyldiacylglycerol (SQDG) derivatives. SQMGs and SQDGs consist of a diacylglycerol esterified with varying fatty acid combinations and a sulfoquinovose moiety. Sulfoquinovose is a sulfonated hexose analogous to D-glucose, but featuring a stable carbon-sulfur bond. With regard to their chemical structure, SQDGs can be distinguished according to their sn1- and sn2-bound fatty acids. Although there is great interest in SQDGs, because of their controversially discussed bioactivities, only a negligible number of comprehensive methods for identification and quantification has been published, so far. Within this work, a sample preparation including a quantitative isolation of SQDGs from selected raw materials, a clean-up with solid-phase extraction (SPE), and a sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for simultaneous identification and quantitation of different, intact SQMGs and SQDGs were developed and validated. The applicability of the method was further demonstrated by comparing a prominent cyanobacterium (Arthrospira sp.) with a microalgae preparation (Chlorella vulgaris), and selected leafy vegetables (spinach, basil).

Antimicrobial Lipids from Plants and Marine Organisms: An Overview of the Current State-of-the-Art and Future Prospects

In the actual post-antibiotic era, novel ways of rethinking antimicrobial research approaches are more urgent than ever. Natural compounds with antimicrobial activity such as fatty acids and monoacylglycerols have been investigated for decades. Additionally, the interest in other lipid classes as antimicrobial agents is rising. This review provides an overview on the research about plant and marine lipids with potential antimicrobial activity, the methods for obtaining and analyzing these compounds, with emphasis on lipidomics, and future perspectives for bioprospection and applications for antimicrobial lipids. Lipid extracts or lipids isolated from higher plants, algae or marine invertebrates are promising molecules to inactivate a wide spectrum of microorganisms. These lipids include a variety of chemical structures. Present and future challenges in the research of antimicrobial lipids from natural origin are related to the investment and optimization of the analytical workflow based on lipidomics tools, complementary to the bioassay-guided fractionation, to identify the active compound(s). Also, further work is needed regarding the study of their mechanism of action, the structure-activity relationship, the synergistic effect with conventional antibiotics, and the eventual development of resistance to lipids, which, as far as is known, is unlikely.

Halophyte plants from sustainable marine aquaponics are a valuable source of omega-3 polar lipids

Marine aquaponics is a promising sustainable approach for the production of profitable crops such as halophytes. However, the effect of this culture approach on the lipid composition of halophytes remains unknown. In this work, we contrasted the polar lipidome of Salicornia ramosissima and Halimione portulacoides when produced in marine aquaponics (effluent from a super-intensive flatfish aquaculture production), with that of conspecifics from donor wild populations. Phospholipids and glycolipids were identified and quantified by LC-MS and MS/MS and their profile statistically analysed. Halophytes produced in aquaponics have higher levels of glycolipids with n-3 fatty acids (DGDG 36:3; SQDG 36:3; MGDG 36:6) compared with the donor wild populations. In the case of H. portulacoides, a significant increase of phospholipids bearing n-3 fatty acids (most in PC and PE) was also recorded. These lipids have potential applications in food, feed and pharmaceutical industries, contributing to the valorization of halophytes produced under sustainable aquaculture practices.

Concise synthesis of sulfoquinovose and sulfoquinovosyl diacylglycerides, and development of a fluorogenic substrate for sulfoquinovosidases

The sulfolipid sulfoquinovosyl diacylglycerol (SQDG) and its headgroup, the sulfosugar sulfoquinovose (SQ), are estimated to harbour up to half of all organosulfur in the biosphere. SQ is liberated from SQDG and related glycosides by the action of sulfoquinovosidases (SQases). We report a 10-step synthesis of SQDG that we apply to the preparation of saturated and unsaturated lipoforms. We also report an expeditious synthesis of SQ and (¹³C₆)SQ, and X-ray crystal structures of sodium and potassium salts of SQ. Finally, we report the synthesis of a fluorogenic SQase substrate, methylumbelliferyl α-d-sulfoquinovoside, and examination of its cleavage kinetics by two recombinant SQases. These compounds will assist in dissecting the role of sulfoglycolysis in the biogeochemical sulfur cycle and understanding the molecular basis of sulfoglycolysis.

Chemical synthesis of diglucosyl diacylglycerols utilizing glycosyl donors with stereodirecting cyclic silyl protective groups

Chemical syntheses of the bacterial diglucosyl diacylglycerols 1-heptadecanoyl-2-pentadecanoyl-3-O-[6-O-(β-d-glucopyranosyl)-β-d-glucopyranosyl]-sn-glycerol and 1-(cis-13-octadecenoyl)-2-palmitoyl-3-O-[2-O-(α-d-glucopyranosyl)-α-d-glucopyranosyl]-sn-glycerol are described. The syntheses feature the stereoselective construction of glycosidic linkages in glycosylation reaction by utilizing glycosyl donors with stereodirecting cyclic silyl protective groups. The 1,1,3,3-tetraisopropyldisiloxane-1,3-diyl (TIPDS) group was used for formation of the β-glycosidic linkage, while the di-tert-butylsilylene (DTBS) group was used for α-linkage formation. The silyl protective groups were chemoselectively cleavable without affecting acyl functionalities on the glycerol moiety and proved effective for the synthesis of diacylglycoglycerolipids.

Lipidomic Signatures Reveal Seasonal Shifts on the Relative Abundance of High-Valued Lipids from the Brown Algae Fucus vesiculosus

Fucus vesiculosus is an edible brown macroalga, with health benefits associated with its consumption and also a source of bioactive molecules. It is acknowledged that the biochemical composition of macroalgae changes when exposed to different environmental conditions occurring on different habitats, such as the water temperature, and light intensity. In the present study, the polar lipidome of Fucus vesiculosus was characterized for the first time using modern high-resolution HILIC-MS, and MS/MS approaches, to evaluate the phenotypic variability in two seasons of the year, e.g., winter and spring. A total of 187 molecular species were identified over eighteen classes of glycolipids, phospholipids and betaine lipids. Principal component analysis (PCA) multivariate statistical analysis and cluster analysis of polar lipid classes, polar lipid species and total fatty acids (FA) datasets, showed clustering according to the seasonal groups. While the lipid profile of Fucus vesiculosus harvested in the winter and spring yielded the same molecular species, the relative abundance of these species was significantly different. In the winter, changes were mainly due to the increased relative abundance of some molecular species of glycolipids and phospholipids, bearing octadeca(poly)enoic (18:3, 18:4) and eicosa(poly)enoic (20:4, 20:5) FA and betaine lipids species with short saturated FA (14:0) and polyunsaturated FA (PUFA). Importantly, glycolipids with n-3 PUFA and sulfolipids, have been reported to have important biological activities and therapeutic value. Overall, Fucus vesiculosus is a promising source of bioactive compounds that can be used as functional food or ingredients for human nutrition, feed, pharma, and cosmetic formulations. In this study, samples harvested in the winter season maximized yields of these bioactive components, when compared with samples harvested in the spring.

Sulfate-based lipids: Analysis of healthy human fluids and cell extracts

Sulfate-based lipids (SL) have been proposed as players in inflammation, immunity and infection. In spite of the many biochemical processes linked to SL, analysis on this class of lipids has only focused on specific SL sub-classes in individual fluids or cells leaving a range of additional SL in other biological samples unaccounted for. This study describes the mass spectrometry screening of SL in lipid extracts of human fluids (saliva, plasma, urine, seminal fluid) and primary human cells (RBC, neutrophils, fibroblasts and skin epidermal) using targeted precursor ion scanning (PIS) approach. The PIS 97 mass spectra reveal a wide diversity of SL including steroid sulfates, sulfoglycolipids and other unidentified SL, as well as metabolites such as taurines, sulfated polyphenols and hypurate conjugates. Semi-quantification of SL revealed that plasma exhibited the highest content of SL whereas seminal fluid and epithelial cells contained the highest sulphur to phosphorous (S/P) ratio. The complexity of biofluids and cells sulfateome presented in this study highlight the importance of expanding the panel of synthetic sulfate-based lipid standards. Also, the heterogenous distribution of SL provides evidence for the interplay of sulfotransferases/sulfatases, opening new avenues for biomarker discovery in oral health, cardiovascular, fertility and dermatology research areas.

Polar lipidome profiling of Salicornia ramosissima and Halimione portulacoides and the relevance of lipidomics for the valorization of halophytes

Some halophytes are currently used as gourmet plant ingredients for human consumption. The polar lipidome of the succulent organs of Salicornia ramosissima (fresh branch tips) and Halimione portulacoides (leaves) were characterized in-depth, with more than two hundred lipid species being identified in both halophytes. The lipid species identified were distributed over five classes of phospholipids, three classes of glycolipids and one class of glycosphingolipids. Despite the existence of some species-specific differences between the polar lipidome, phospholipids and glycolipids show a high content of n-3 fatty acids in both S. ramosissima and H. portulacoides. These results highlights the advantage of employing mass spectrometry based lipidomic platform towards the valorization of halophytes as a source of valuable nutrients and bioactives, fostering potential applications in the fields of healthy and functional food products, and for nutraceutical and pharmaceutical uses.

Glycans with Antiviral Activity from Marine Organisms

There remains today a critical need for new antiviral agents, particularly in view of the alarming increase in drug resistance and associated issues. The marine environment has been a prolific contributor towards the identification of novel therapeutic agents in the recent few decades. Added to this, glycans (or carbohydrate- or sugar-based compounds) have in very recent decades made outstanding contributions to the development of novel therapeutics. This review brings together these significant facets of modern drug discovery by presenting the reported literature on glycans derived from marine organisms that possess antiviral activity.The glycans have been grouped together based on the marine organism they were isolated from, namely, (1) bacteria, (2) chromists, (3) plants and (4) animals. For chromists, glycans are further subsectioned into Ochrophyta (brown algae), Miozoa (according to www.algaebase.org ; also called Myzozoa according to WoRMS, www.marinespecies.org ) (dinoflagellates) and Bacillariophyta (diatoms). For plants, glycans are further subsectioned into Chlorophyta, Rhodophyta and Tracheophyta. Glycans isolated to date are reported as alginates, chitosan, extracellular polysaccharides, fucans (e.g. fucoidans), galactans (e.g. carrageenans), glycolipids, glycosaminoglycans, glycosides, glycosylated haemocyanin, laminarans, mannans, polysaccharides (not defined), rhamnans and xylomannans. Interestingly, many of the glycans displaying antiviral properties are sulfated.Reports indicate that marine-sourced glycans have exhibited antiviral activity against African swine fever virus, cytomegalovirus, dengue virus, Epstein-Barr virus, encephalomyocarditis virus, human immunodeficiency virus, hepatitis C virus, herpes simplex virus, human cytomegalovirus, human papilloma virus, human rhino virus, influenza virus, Japanese encephalitis virus, murine leukaemia virus, murine sarcoma virus, Newcastle disease virus, parainfluenza virus, respiratory syncytial virus, Semliki Forest virus, tobacco mosaic virus, vaccinia virus, varicella zoster virus, viral haemorrhagic septicaemia virus and vesicular stomatitis virus. Selected representative glycan structures are presented in Fig. 20.1.

Unambiguous regiochemical assignment of sulfoquinovosyl mono- and diacylglycerols in parsley and spinach leaves by liquid chromatography/electrospray ionization sequential mass spectrometry assisted by regioselective enzymatic hydrolysis

RATIONALE

Sulfoquinovosylmonoglycerides (SQMG) and sulfoquinovosyldiglycerides (SQDG) in the lipid extracts of parsley (Petroselinum crispum) and spinach (Spinacia oleracea) leaves were investigated. The aim of this work was to assess and establish the chemical characterization of fatty acyl chains in sulfolipids (SQMG and SQDG) and their regiochemistry.

METHODS

A key component of this approach is a combination of hydrolysis reactions catalyzed by Lecitase® Ultra, which is a sn₁ -regioselective hydrolase enzyme, and reversed-phase liquid chromatography with electrospray ionization and sequential mass spectrometry (RPLC/ESI-MS) by collision-induced dissociation (CID)-MSⁿ (n = 2, 3).

RESULTS

The occurrence of SQMG bearing 16:0 or 18:3 acyl chains was established for the first time. A regiochemistry-dependent fragmentation pattern of SQMG was attained whereby the sulfoquinovosyl anion ([C₆ H₁₁ O₈ S]^- at m/z 243.0) provides a diagnostic product ion. Regioselective enzymatic treatment also provided a posteriori confirmation of a widely accepted fragmentation rule for SQDG. The sulfoquinovosyl anion was found to play a role also in the fragmentation pattern of SQDG, whose regiochemical assignment could be ultimately confirmed by MS³ experiments.

CONCLUSIONS

The predominant sulfolipid in leaf extracts of raw parsley (Petroselinum crispum) and spinach (Spinacia oleracea) was identified as SQDG 18:3/16:0, along with SQMG 18:3/0:0 and SQMG 16:0/0:0. The present CID-MS-based method can be considered a successful approach to validate the regiochemical characterization of sulfolipids paving the way for their unambiguous characterization.

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.

Valorization of Lipids from Gracilaria sp. through Lipidomics and Decoding of Antiproliferative and Anti-Inflammatory Activity

The lipidome of the red seaweed Gracilaria sp., cultivated on land-based integrated multitrophic aquaculture (IMTA) system, was assessed for the first time using hydrophilic interaction liquid chromatography-mass spectrometry and tandem mass spectrometry (HILIC-MS and MS/MS). One hundred and forty-seven molecular species were identified in the lipidome of the Gracilaria genus and distributed between the glycolipids classes monogalactosyl diacylglyceride (MGDG), digalactosyl diacylglyceride (DGDG), sulfoquinovosyl monoacylglyceride (SQMG), sulfoquinovosyl diacylglyceride (SQDG), the phospholipids phosphatidylcholine (PC), lyso-PC, phosphatidylglycerol (PG), lyso-PG, phosphatidylinositol (PI), phosphatidylethanolamine (PE), phosphatic acid (PA), inositolphosphoceramide (IPC), and betaine lipids monoacylglyceryl- and diacylglyceryl-N,N,N-trimethyl homoserine (MGTS and DGTS). Antiproliferative and anti-inflammatory effects promoted by lipid extract of Gracilaria sp. were evaluated by monitoring cell viability in human cancer lines and by using murine macrophages, respectively. The lipid extract decreased cell viability of human T-47D breast cancer cells and of 5637 human bladder cancer cells (estimated half-maximal inhibitory concentration (IC50) of 12.2 μg/mL and 12.9 μg/mL, respectively) and inhibited the production of nitric oxide (NO) evoked by the Toll-like receptor 4 agonist lipopolysaccharide (LPS) on the macrophage cell line RAW 264.7 (35% inhibition at a concentration of 100 μg/mL). These findings contribute to increase the ranking in the value-chain of Gracilaria sp. biomass cultivated under controlled conditions on IMTA systems.

Sulfoquinovose in the biosphere: occurrence, metabolism and functions

The sulfonated carbohydrate sulfoquinovose (SQ) is produced in quantities estimated at some 10 billion tonnes annually and is thus a major participant in the global sulfur biocycle. SQ is produced by most photosynthetic organisms and incorporated into the sulfolipid sulfoquinovosyl diacylglycerol (SQDG), as well as within some archaea for incorporation into glycoprotein N-glycans. SQDG is found mainly within the thylakoid membranes of the chloroplast, where it appears to be important for membrane structure and function and for optimal activity of photosynthetic protein complexes. SQDG metabolism within the sulfur cycle involves complex biosynthetic and catabolic processes. SQDG biosynthesis is largely conserved within plants, algae and bacteria. On the other hand, two major sulfoglycolytic pathways have been discovered for SQDG degradation, the sulfo-Embden–Meyerhof–Parnas (sulfo-EMP) and sulfo-Entner–Doudoroff (sulfo-ED) pathways, which mirror the major steps in the glycolytic EMP and ED pathways. Sulfoglycolysis produces C3-sulfonates, which undergo biomineralization to inorganic sulfur species, completing the sulfur cycle. This review discusses the discovery and structural elucidation of SQDG and archaeal N-glycans, the occurrence, distribution, and speciation of SQDG, and metabolic pathways leading to the biosynthesis of SQDG and its catabolism through sulfoglycolytic and biomineralization pathways to inorganic sulfur.

Lipidomic Approaches towards Deciphering Glycolipids from Microalgae as a Reservoir of Bioactive Lipids

In recent years, noteworthy research has been performed around lipids from microalgae. Among lipids, glycolipids (GLs) are quite abundant in microalgae and are considered an important source of fatty acids (FAs). GLs are rich in 16- and 18-carbon saturated and unsaturated fatty acids and often contain polyunsaturated fatty acids (PUFAs) like n-3 α-linolenic (ALA 18:3), eicosapentaenoic (EPA, 20:5) and docosahexaenoic (DHA, 22:6). GLs comprise three major classes: monogalactosyldiacyl glycerolipids (MGDGs), digalactosyl diacylglycerolipids (DGDGs) and sulfoquinovosyl diacylglycerolipids (SQDGs), whose composition in FA directly depends on the growth conditions. Some of these lipids are high value-added compounds with antitumoral, antimicrobial and anti-inflammatory activities and also with important nutritional significance. To fully explore GLs’ bioactive properties it is necessary to fully characterize their structure and to understand the relation between the structure and their biological properties, which can be addressed using modern mass spectrometry (MS)-based lipidomic approaches. This review will focus on the up-to-date FA composition of GLs identified by MS-based lipidomics and their potential as phytochemicals.

Bioprospecting of Marine Macrophytes Using MS-Based Lipidomics as a New Approach

The marine environment supports a remarkable diversity of organisms which are a potential source of natural products with biological activities. These organisms include a wide variety of marine plants (from micro- to macrophytes), which have been used in the food and pharmaceutical industry. However, the biochemistry and biological activities of many of these macrophytes (namely macroalgae and halophytes, including seagrasses) are still far from being fully explored. Most popular bioactive components include polysaccharides, peptides, phenolics and fatty acids (FAs). Polar lipids (glycolipids, phospholipids and betaine lipids) are emerging as novel value-added bioactive phytochemicals, rich in n-3 FA, with high nutritional value and health beneficial effects for the prevention of chronic diseases. Polar lipids account various combinations of polar groups, fatty acyl chains and backbone structures. The polar lipidome of macrophytes is remarkably diverse, and its screening represents a significant analytical challenge. Modern research platforms, particularly mass spectrometry (MS)-based lipidomic approaches, have been recently used to address this challenge and are here reviewed. The application of lipidomics to address lipid composition of marine macrophytes will contribute to the stimulation of further research on this group and foster the exploration of novel applications.

Marine natural products

This review covers the literature published in 2013 for marine natural products (MNPs), with 982 citations (644 for the period January to December 2013) 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 (1163 for 2013), together with the relevant biological activities, source organisms and country of origin. Reviews, biosynthetic studies, first syntheses, and syntheses that lead to the revision of structures or stereochemistries, have been included.

Chemical composition, antioxidant and antibacterial properties of Pteranthus dichotomus from Algerian Sahara

The phytochemical study of ethyl acetate and n-butanol extracts of Pteranthus dichotomus Forssk. led to the isolation and identification of 11 compounds, including three glycolipids 1-3, one lignan 4, three flavonoids 5-7 and four phytosterols 8-11. Structures of the isolated compounds have been elucidated by analysis of 1D and 2D NMR data, and mass spectrometry EI-MS and ESI-MS and by comparison with literature data. Furthermore, the ethyl acetate and n-butanol extracts were examined for their antioxidant and antibacterial activities. The results showed that both extracts (PDAC and PDBU) had a moderate antioxidant activity (IC50 = 375.514 μg/mL and 691.333 μg/mL) respectively.

Anionic glycolipids related to glucuronosyldiacylglycerol inhibit protein kinase Akt

Long chain GlcADG analogues synthesized as PI3P mimics inhibited isolated Akt and proliferation of human ovarian carcinoma IGROV-1 cells.

Glycolipids from seaweeds and their potential biotechnological applications

Marine macroalgae, or seaweeds, are a formidable source of natural compounds with diverse biological activities. In the last five decades it has been estimated that more than 3000 natural compounds were discovered from these organisms. The great majority of the published works have focused on terpenoids. In comparison, glycolipids are a neglected class of macroalgal secondary metabolites therefore remaining as a largely unknown reservoir of molecular diversity. Nevertheless, the interest regarding these compounds has been growing fast in the last decades as activities of ecological or pharmaceutical interest have been highlighted. This paper will review recent work regarding isolation and structural characterization of glycolipids from seaweeds and their prospective biological activities.

Lipids and fatty acids of nudibranch mollusks: potential sources of bioactive compounds

The molecular diversity of chemical compounds found in marine animals offers a good chance for the discovery of novel bioactive compounds of unique structures and diverse biological activities. Nudibranch mollusks, which are not protected by a shell and produce chemicals for various ecological uses, including defense against predators, have attracted great interest for their lipid composition. Lipid analysis of eight nudibranch species revealed dominant phospholipids, sterols and monoalkyldiacylglycerols. Among polar lipids, 1-alkenyl-2-acyl glycerophospholipids (plasmalogens) and ceramide-aminoethyl phosphonates were found in the mollusks. The fatty acid compositions of the nudibranchs differed greatly from those of other marine gastropods and exhibited a wide diversity: very long chain fatty acids known as demospongic acids, a series of non-methylene-interrupted fatty acids, including unusual 21:2∆7,13, and an abundance of various odd and branched fatty acids typical of bacteria. Symbiotic bacteria revealed in some species of nudibranchs participate presumably in the production of some compounds serving as a chemical defense for the mollusks. The unique fatty acid composition of the nudibranchs is determined by food supply, inherent biosynthetic activities and intracellular symbiotic microorganisms. The potential of nudibranchs as a source of biologically active lipids and fatty acids is also discussed.

Total synthesis and structure-activity relationship of glycoglycerolipids from marine organisms

Glycoglycerolipids occur widely in natural products, especially in the marine species. Glycoglycerolipids have been shown to possess a variety of bioactivities. This paper will review the different methodologies and strategies for the synthesis of biological glycoglycerolipids and their analogs for bioactivity assay. In addition, the bioactivities and structure-activity relationship of the glycoglycerolipids are also briefly outlined.

Antifungal and antiviral products of marine organisms

Marine organisms including bacteria, fungi, algae, sponges, echinoderms, mollusks, and cephalochordates produce a variety of products with antifungal activity including bacterial chitinases, lipopeptides, and lactones; fungal (-)-sclerotiorin and peptaibols, purpurides B and C, berkedrimane B and purpuride; algal gambieric acids A and B, phlorotannins; 3,5-dibromo-2-(3,5-dibromo-2-methoxyphenoxy)phenol, spongistatin 1, eurysterols A and B, nortetillapyrone, bromotyrosine alkaloids, bis-indole alkaloid, ageloxime B and (-)-ageloxime D, haliscosamine, hamigeran G, hippolachnin A from sponges; echinoderm triterpene glycosides and alkene sulfates; molluscan kahalalide F and a 1485-Da peptide with a sequence SRSELIVHQR; and cepalochordate chitotriosidase and a 5026.9-Da antifungal peptide. The antiviral compounds from marine organisms include bacterial polysaccharide and furan-2-yl acetate; fungal macrolide, purpurester A, purpurquinone B, isoindolone derivatives, alterporriol Q, tetrahydroaltersolanol C and asperterrestide A, algal diterpenes, xylogalactofucan, alginic acid, glycolipid sulfoquinovosyldiacylglycerol, sulfated polysaccharide p-KG03, meroditerpenoids, methyl ester derivative of vatomaric acid, lectins, polysaccharides, tannins, cnidarian zoanthoxanthin alkaloids, norditerpenoid and capilloquinol; crustacean antilipopolysaccharide factors, molluscan hemocyanin; echinoderm triterpenoid glycosides; tunicate didemnin B, tamandarins A and B and; tilapia hepcidin 1-5 (TH 1-5), seabream SauMx1, SauMx2, and SauMx3, and orange-spotted grouper β-defensin. Although the mechanisms of antifungal and antiviral activities of only some of the aforementioned compounds have been elucidated, the possibility to use those known to have distinctly different mechanisms, good bioavailability, and minimal toxicity in combination therapy remains to be investigated. It is also worthwhile to test the marine antimicrobials for possible synergism with existing drugs. The prospects of employing them in clinical practice are promising in view of the wealth of these compounds from marine organisms. The compounds may also be used in agriculture and the food industry.

Extract of Saccharina japonica induces apoptosis companied by cell cycle arrest and endoplasmic reticulum stress in SK-Hep1 human hepatocellular carcinoma cells

Saccharina japonica is a family member of Phaeophyceae (brown macro-alga) and extensively cultivated in China, Japan and Korea. Here, the potential anti-cancer effect of n-hexane fraction of S. japonica was evaluated in SK-Hep1 human hepatocellular carcinoma cells. The N-hexane fraction reduced cell viability and increased the numbers of apoptotic cells in a both dose- and time-dependent manner. Apoptosis was activated by both caspase-dependent and independent pathways. The caspase-dependent cell death pathway is mediated by cell surface death receptors and activated caspase-8 amplified the apoptotic signal either through direct activation of downstream caspase-3 or pro-apoptotic proteins (Bad, Bax and Bak) subsequently leading to the release of cytochrome c. On the other hand, caspase-independent apoptosis appeared mediated by disruption of mitochondrial membrane potential and translocation of AIF to the nucleus where they induced chromatin condensation and/or large-scale DNA fragmentation. In addition, the n-hexane fraction induced endoplasmic reticulum (ER)-stress and cell cycle arrest. The results suggested that potential anti-cancer effects of n-hexane extract from S. japonica on SK-Hep1 cells.