Glycolipids from sponges, III. Glycosyl ceramides from the marine spongeAgelas conifera

Secondary metabolites from marine sponges of the genus Agelas: a comprehensive update insight on structural diversity and bioactivity

As one of the most common marine sponges in tropical and subtropical oceans, the sponges of the genus Agelas, have emerged as unique and yet under-investigated pools for discovery of natural products with fabulous molecular diversity and myriad interesting biological activities. The present review highlights the chemical structure and biological activity of 355 compounds that have been isolated and characterized from the members of Agelas sponges, over the period of about five decades (from 1971 to November 2021). For a better understanding, these numerous compounds are firstly classified and presented according to their carbon skeleton as well as their biosynthetic origins. Relevant summaries focusing on the source organism and the associated bioactivity of these compounds belonging to different chemical classes are also provided. This review highlights sponges of the genus Agelas as exciting source for discovery of intriguing natural compounds.

The marine sponges of the genus Agelas, are unique and yet under-investigated pools for discovery of natural products with fabulous molecular diversity and myriad interesting biological activities.

Bioactive Secondary Metabolites from the Marine Sponge Genus Agelas

The marine sponge genus Agelas comprises a rich reservoir of species and natural products with diverse chemical structures and biological properties with potential application in new drug development. This review for the first time summarized secondary metabolites from Agelas sponges discovered in the past 47 years together with their bioactive effects.

Anti-inflammatory Cerebrosides from Cultivated Cordyceps militaris

Cordyceps militaris (bei-chong-chaw, northern worm grass) is a precious and edible entomopathogenic fungus, which is widely used in traditional Chinese medicine (TCM) as a general booster for the nervous system, metabolism, and immunity. Saccharides, nucleosides, mannitol, and sterols were isolated from this fungus. The biological activity of C. militaris was attributed to the saccharide and nucleoside contents. In this study, the aqueous methanolic fraction of C. militaris fruiting bodies exhibited a significant anti-inflammatory activity. Bioactivity-guided fractionation of the active fraction led to the isolation of eight compounds, including one new and two known cerebrosides (ceramide derivatives), two nucleosides, and three sterols. Cordycerebroside A (1), the new cerebroside, along with soyacerebroside I (2) and glucocerebroside (3) inhibited the accumulation of pro-inflammatory iNOS protein and reduced the expression of COX-2 protein in LPS-stimulated RAW264.7 macrophages. This is the first study on the isolation of cerebrosides with anti-inflammatory activity from this TCM.

Flavusides A and B, antibacterial cerebrosides from the marine-derived fungus Aspergillus flavus

Flavusides A (1) and B (2), two new antibacterial cerebroside derivatives, and the previously described phomaligol A (3), kojic acid (4), methyl kojic acid (5), and dimethyl kojic acid (6) have been isolated from the extract of a marine isolate of the fungus Aspergillus flavus. The structure and absolute stereochemistry of two cerebrosides were assigned on the basis of NMR and Tandem FAB-MS/MS experiments. Compounds 1, 2, and 3 exhibited a mild antibacterial activity against Staphylococcus aureus, methicillin-resistant S. aureus, and multidrug-resistant S. aureus. The minimum inhibitory concentration (MIC) values for each strain are as follows: compounds 1 and 2 showed 15.6 μg/ml for S. aureus and 31.2 μg/ml for methicillin-resistant S. aureus and multidrug-resistant S. aureus, and compound 3 exhibited 31.2 μg/ml for S. aureus and methicillin-resistant S. aureus and 62.5 μg/ml for multidrug-resistant S. aureus.

New cerebrosides from a marine sponge Haliclona (Reniera) sp

A chemical investigation of the MeOH extract of a marine sponge Haliclona (Reniera) sp., collected off the coast of Ulleung Island, Korea, led to the isolation of thirteen new cerebrosides (1--3, 5--14), along with a known analogue (4). Their structures were elucidated on the basis of 1D and 2D NMR spectroscopy, MS spectrometry, and chemical method. The major new features of these glucocerebrosides are C15 and C19 acyl chains, long (C24-C28) acyl chains, or the S-configuration of the acyl chains. It is noteworthy that both R- and S-configurations of the acyl chains were observed in the same specimen.

Concise synthesis of clarhamnoside, a novel glycosphingolipid isolated from the marine sponge Agela clathrodes

The first total synthesis of a novel alpha-galactoglycosphingolipid clarhamnoside has been achieved through a straightforward strategy. A thiogalactosyl donor with a benzylidene group at C-4 and C-6 and nonparticipating p-methoxybenzyl group at C-2 was successfully employed in the stereocontrolled syntheses of alpha-GalGSLs. The N-Phth-protected trifluoroacetimidate donor for terminal disaccharide was successfully applied in constructing the [GalNAc beta-(1-->6)-Gal] glycosidic linkage.

Renierosides, cerebrosides from a marine sponge Haliclona (Reniera) sp

Guided by the brine shrimp lethality assay, eight new cerebrosides (1-8) have been isolated from an extract of the marine sponge Haliclona (Reniera) sp. A novel feature of these cerebrosides was the presence of unprecedented amide-linked long-chain fatty acid moieties. The planar structures of the cerebrosides (1-8) were established by 1D and 2D NMR spectroscopic techniques, mass spectrometric analyses, and chemical degradation methods. The isolated compounds did not display cytotoxicity to a panel of five human solid tumor cell lines.

Astonishing diversity of natural surfactants: 4. Fatty acid amide glycosides, their analogs and derivatives

FA amide glycosides are of great interest, especially for the medicinal and pharmaceutical industries. These biologically active natural surfactants are good prospects for future chemical preparation of compounds useful as antibiotics, anticancer agents, or for industry. More than 200 unusual and interesting natural surfactants, including their chemical structures and biological activities, are described in this review article.

Glycosphingolipid structural analysis and glycosphingolipidomics

Sphingosines, or sphingoids, are a family of naturally occurring long-chain hydrocarbon derivatives sharing a common 1,3-dihydroxy-2-amino-backbone motif. The majority of sphingolipids, as their derivatives are collectively known, can be found in cell membranes in the form of amphiphilic conjugates, each composed of a polar head group attached to an N-acylated sphingoid, or ceramide. Glycosphingolipids (GSLs), which are the glycosides of either ceramide or myo-inositol-(1-O)-phosphoryl-(O-1)-ceramide, are a structurally and functionally diverse sphingolipid subclass; GSLs are ubiquitously distributed among all eukaryotic species and are found in some bacteria. Since GSLs are secondary metabolites, direct and comprehensive analysis (metabolomics) must be considered an essential complement to genomic and proteomic approaches for establishing the structural repertoire within an organism and deducing its possible functional roles. The glycosphingolipidome clearly comprises an important and extensive subset of both the glycome and the lipidome, but the complexities of GSL structure, biosynthesis, and function form the outlines of a considerable analytical problem, especially since their structural diversity confers by extension an enormous variability with respect to physicochemical properties. This chapter covers selected developments and applications of techniques in mass spectrometric (MS) that have contributed to GSL structural analysis and glycosphingolipidomics since 1990. Sections are included on basic characteristics of ionization and fragmentation of permethylated GSLs and of lithium-adducted nonderivatized GSLs under positive-ion electrospray ionization mass spectrometry (ESI-MS) and collision-induced mass spectrometry (CID-MS) conditions; on the analysis of sulfatides, mainly using negative-ion techniques; and on selected applications of ESI-MS and matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) to emerging GSL structural, functional, and analytical issues. The latter section includes a particular focus on evolving techniques for analysis of gangliosides, GSLs containing sialic acid, as well as on characterizations of GSLs from selected nonmammalian eukaryotes, such as dipterans, nematodes, cestodes, and fungi. Additional sections focus on the issue of whether it is better to leave GSLs intact or remove the ceramide; on development and uses of thin-layer chromatography (TLC) blotting and TLC-MS techniques; and on emerging issues of high-throughput analysis, including the use of flow injection, liquid chromatography mass spectrometry (LC-MS), and capillary electrophoresis mass spectrometry (CE-MS).

Plant sphingolipids: structural diversity, biosynthesis, first genes and functions

In mammals and Saccharomyces cerevisiae, sphingolipids have been a subject of intensive research triggered by the interest in their structural diversity and in mammalian pathophysiology as well as in the availability of yeast mutants and suppressor strains. More recently, sphingolipids have attracted additional interest, because they are emerging as an important class of messenger molecules linked to many different cellular functions. In plants, sphingolipids show structural features differing from those found in animals and fungi, and much less is known about their biosynthesis and function. This review focuses on the sphingolipid modifications found in plants and on recent advances in the functional characterization of genes gaining new insight into plant sphingolipid biosynthesis. Recent studies indicate that plant sphingolipids may be also involved in signal transduction, membrane stability, host-pathogen interactions and stress responses.

A glucosylceramide with a novel ceramide and three novel ceramides from the basidiomycete Cortinarius umidicola

A glucosylceramide with novel ceramide and three novel ceramide homologs were isolated from the basidiomycete Cortinarius umidicola and structurally characterized. The ceramide portion of the glucocerebroside consists of a rare (4E,8E)-9-methyl-4,8-sphingadienine sphingoid base. In contrast, the three ceramide homologs, while having the same sphingoid base, contain as FA residues 2-hydroxydocosanoic acid, 2-hydroxytricosanoic acid, and 2-hydroxytetracosanoic acid.

Characterization of cerebrosides from the thermally dimorphic mycopathogen Histoplasma capsulatum: expression of 2-hydroxy fatty N-acyl (E)-Delta(3)-unsaturation correlates with the yeast-mycelium phase transition

Cerebroside (monohexosylceramide) components were identified in neutral lipids extracted from both the yeast and mycelial forms of the thermally dimorphic mycopathogen Histoplasma capsulatum. The components were purified from both forms and their structures elucidated by 1- and 2-dimensional nuclear magnetic resonance (NMR) spectroscopy, electrospray ionization mass spectrometry (ESI-MS), and low energy tandem collision-induced dissociation mass spectrometry (ESI-MS/CID-MS). Both components were characterized as beta-glucopyranosylceramides (GlcCers) containing (4E,8E)-9-methyl-4,8-sphingadienine as the long-chain base, attached to 18-carbon 2-hydroxy fatty N-acyl components. However, while the fatty acid of the yeast form GlcCer was virtually all N-2'-hydroxyoctadecanoate, the mycelium form GlcCer was characterized by almost exclusive expression of N-2'-hydroxy-(E)-delta(3)-octadecenoate. These results suggest that the yeast-mycelium transition is accompanied by up-regulation of an as yet uncharacterized ceramide or cerebroside 2-hydroxy fatty N-acyl (E)-delta(3)-desaturase activity. They also constitute further evidence for the existence of two distinct pathways for ceramide biosynthesis in fungi, since glycosylinositol phosphorylceramides (GIPCs), the other major class of fungal glycosphingolipids, are found with ceramides consisting of 4-hydroxysphinganine (phytosphingosine) and longer chain 2-hydroxy fatty acids. In addition to identification of the major glucocerebroside components, minor components (< 5%) detectable by molecular weight differences in the ESI-MS profiles were also characterized by tandem ESI-MS/CID-MS analysis. These minor components were identified as variants differing in fatty acyl chain length, or the absence of the sphingoid 9-methyl group or (E)-delta(8)-unsaturation, and are hypothesized to be either biosynthetic intermediates or the result of imperfect chemical transformation by the enzymes responsible for these features. Possible implications of these findings with respect to chemotaxonomy, compartmentalization of fungal glycosphingolipid biosynthetic pathways, and regulation of morphological transitions in H.capsulatum and other dimorphic fungi are discussed.

Comparative analysis of ceramide structural modification found in fungal cerebrosides by electrospray tandem mass spectrometry with low energy collision-induced dissociation of Li+ adduct ions

Fungal cerebrosides (monohexosylceramides, or CMHs) exhibit a number of ceramide structural modifications not found in mammalian glycosphingolipids, which present additional challenges for their complete characterization. The use of Li+ cationization, in conjunction with electrospray ionization mass spectrometry and low energy collision-induced dissociation tandem mass spectrometry (ESI-MS/CID-MS), was found to be particularly effective for detailed structural analysis of complex fungal CMHs, especially minor components present in mixtures at extremely low abundance. A substantial increase in both sensitivity and fragmentation was observed on collision-induced dissociation of [M + Li]+ versus [M + Na]+ of the same CMH components analyzed under similar conditions. The effects of particular modifications on fragmentation were first systematically evaluated by analysis of a wide variety of standard CMHs expressing progressively more functionalized ceramides. These included bovine brain galactocerebrosides with non-hydroxy and 2-hydroxy fatty N-acylation; a plant glucocerebroside having (E/Z)-delta8 in addition to (E)-delta4 unsaturation of the sphingoid base; and a pair of fungal cerebrosides known to be further modified by a branching 9-methyl group on the sphingoid moiety, and to have a 2-hydroxy fatty N-acyl moiety either fully saturated or (E)-delta3 unsaturated. The method was then applied to characterization of both major and minor components in CMH fractions from a non-pathogenic mycelial fungus, Aspergillus niger; and from pathogenic strains of Candida albicans (yeast form); three Cryptococcus spp. (all yeast forms); and Paracoccidioides brasiliensis (both yeast and mycelium forms). The major components of all species examined differed primarily (and widely) in the level of 2-hydroxy fatty N-acyl delta3 unsaturation, but among the minor components a significant degree of additional structural diversity was observed, based on differences in sphingoid or N-acyl chain length, as well as on the presence or absence of the sphingoid delta8 unsaturation or 9-methyl group. Some variants were isobaric, and were not uniformly present in all species, affirming the need for MS/CID-MS analysis for full characterization of all components in a fungal CMH fraction. The diversity in ceramide distribution observed may reflect significant species-specific differences among fungi with respect to cerebroside biosynthesis and function.

Glycolipids from sponges. VII. Simplexides, novel immunosuppressive glycolipids from the Caribbean sponge Plakortis simplex

The new glycolipids simplexides (1) have been isolated from the marine sponge Plakortis simplex, and their structure determined by spectroscopic data and microgram-scale chemical degradation. Simplexides are composed of long-chain secondary alcohols glycosylated by a disaccharide chain, and represent a new structural kind of glycolipids. Simplexides strongly inhibit proliferation of activated T-cells by a non-cytotoxic mechanism and can be regarded as simple model molecules for designing immunosuppressive drugs.

Immunostimulatory activities of monoglycosylated alpha-D-pyranosylceramides

We compared the immunostimulatory effects of chemically synthesized alpha-galactosylceramides (alpha-GalCers), alpha-glucosylceramides (alpha-GluCers), 6"-monoglycosylated alpha-GalCer and 6"- or 4"-monoglycosylated alpha-GluCer and made the following observations: (1) the length of the fatty acid side chain in the ceramide portions greatly affects the immunostimulatory effects of alpha-GalCers and alpha-GluCers; (2) the configuration of the 4"-hydroxyl group of the inner pyranose moiety plays an important role in the immunostimulatory effects of monoglycosylated alpha-D-pyranosylceramides; (3) the free 4"-hydroxyl group of the inner pyranose of monoglycosylated alpha-D-pyranosylceramides plays a more important role in their immunostimulatory effects than the free 6"-hydroxyl group.

Living and Leaving Life on One's Own Terms: Certain Legal Rights of Older Adults and Persons with Disabilities

While attention has been focused on granting equal rights based on race, religion, and gender, the rights of older and disabled persons have been overlooked for many years. Existing laws were of limited scope or were not enforced. However, with the adoption of the Americans with Disabilities Act of 1990, and the recognition and adoption by various states of living wills and related protections, the legal rights of older and disabled persons in attempting to live as normal a life as possible and to deal with serious or terminal illnesses have been greatly expanded. This article provides an overview of existing law in these areas.