Glycolipids from sponges. Part 17. Clathrosides and isoclathrosides, unique glycolipids from the Caribbean sponge Agelas clathrodes

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.

Marine Pyrrole Alkaloids

Nitrogen heterocycles are essential parts of the chemical machinery of life and often reveal intriguing structures. They are not only widespread in terrestrial habitats but can also frequently be found as natural products in the marine environment. This review highlights the important class of marine pyrrole alkaloids, well-known for their diverse biological activities. A broad overview of the marine pyrrole alkaloids with a focus on their isolation, biological activities, chemical synthesis, and derivatization covering the decade from 2010 to 2020 is provided. With relevant structural subclasses categorized, this review shall provide a clear and timely synopsis of this area.

A Fast Detection Strategy for Cyanobacterial blooms and associated cyanotoxins (FDSCC) reveals the occurrence of lyngbyatoxin A in campania (South Italy)

Fast Detection Strategy for Cyanobacterial blooms and associated Cyanotoxins (FDSCC) is a multidisciplinary strategy that allows early detection, in 24 man-hours, of cyanobacteria and related cyanotoxins in water and bivalve samples. This approach combines the advantages of remote/proximal sensing with those of analytical/bioinformatics analyses, namely, LC-HRMS-based molecular networking. The detection of Lyngbyatoxin A, a lipophilic cyanotoxin, in all analyzed water samples and in bivalves, commonly used as food, was the proof of the reliability of the new method.

Chemistry and Biology of Bioactive Glycolipids of Marine Origin

Glycolipids represent a broad class of natural products structurally featured by a glycosidic fragment linked to a lipidic molecule. Despite the large structural variety of these glycoconjugates, they can be classified into three main groups, i.e., glycosphingolipids, glycoglycerolipids, and atypical glycolipids. In the particular case of glycolipids derived from marine sources, an impressive variety in their structural features and biological properties is observed, thus making them prime targets for chemical synthesis. In the present review, we explore the chemistry and biology of this class of compounds.

Isolation of Smenopyrone, a Bis-γ-Pyrone Polypropionate from the Caribbean Sponge Smenospongia aurea

The organic extract of the Caribbean sponge Smenospongia aurea has been shown to contain an array of novel chlorinated secondary metabolites derived from a mixed PKS-NRPS biogenetic route such as the smenamides. In this paper, we report the presence of a biogenetically different compound known as smenopyrone, which is a polypropionate containing two γ-pyrone rings. The structure of smenopyrone including its relative and absolute stereochemistry was determined by spectroscopic analysis (NMR, MS, ECD) and supported by a comparison with model compounds from research studies. Pyrone polypropionates are unprecedented in marine sponges but are commonly found in marine mollusks where their biosynthesis by symbiotic bacteria has been hypothesized and at least in one case demonstrated. Since pyrones have recently been recognized as bacterial signaling molecules, we speculate that smenopyrone could mediate inter-kingdom chemical communication between S. aurea and its symbiotic bacteria.

Smenamide A Analogues. Synthesis and Biological Activity on Multiple Myeloma Cells

Smenamides are an intriguing class of peptide/polyketide molecules of marine origin showing antiproliferative activity against lung cancer Calu-1 cells at nanomolar concentrations through a clear pro-apoptotic mechanism. To probe the role of the activity-determining structural features, the 16-epi-analogue of smenamide A and eight simplified analogues in the 16-epi series were prepared using a flexible synthetic route. The synthetic analogues were tested on multiple myeloma (MM) cell lines showing that the configuration at C-16 slightly affects the activity, since the 16-epi-derivative is still active at nanomolar concentrations. Interestingly, it was found that the truncated compound 8, mainly composed of the pyrrolinone terminus, was not active, while compound 13, essentially lacking the pyrrolinone moiety, was 1000-fold less active than the intact substance and was the most active among all the synthesized compounds.

Dandelion Root Extract Induces Intracellular Ca2+ Increases in HEK293 Cells

Dandelion (Taraxacum officinale Weber ex F.H.Wigg.) has been used for centuries as an ethnomedical remedy. Nonetheless, the extensive use of different kinds of dandelion extracts and preparations is based on empirical findings. Some of the tissue-specific effects reported for diverse dandelion extracts may result from their action on intracellular signaling cascades. Therefore, the aim of this study was to evaluate the effects of an ethanolic dandelion root extract (DRE) on Ca²⁺ signaling in human embryonic kidney (HEK) 293 cells. The cytotoxicity of increasing doses of crude DRE was determined by the Calcein viability assay. Fura-2 and the fluorescence resonance energy transfer (FRET)-based probe ERD1 were used to measure cytoplasmic and intraluminal endoplasmic reticulum (ER) Ca²⁺ levels, respectively. Furthermore, a green fluorescent protein (GFP)-based probe was used to monitor phospholipase C (PLC) activation (pleckstrin homology [PH]–PLCδ–GFP). DRE (10–400 µg/mL) exposure, in the presence of external Ca²⁺, dose-dependently increased intracellular Ca²⁺ levels. The DRE-induced Ca²⁺ increase was significantly reduced in the absence of extracellular Ca²⁺. In addition, DRE caused a significant Ca²⁺ release from the ER of intact cells and a concomitant translocation of PH–PLCδ–GFP. In conclusion, DRE directly activates both the release of Ca²⁺ from internal stores and a significant Ca²⁺ influx at the plasma membrane. The resulting high Ca²⁺ levels within the cell seem to directly stimulate PLC activity.

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.

Evaluating the Effects of an Organic Extract from the Mediterranean Sponge Geodia cydonium on Human Breast Cancer Cell Lines

Marine sponges are an excellent source of bioactive secondary metabolites for pharmacological applications. In the present study, we evaluated the chemistry, cytotoxicity and metabolomics of an organic extract from the Mediterranean marine sponge Geodia cydonium, collected in coastal waters of the Gulf of Naples. We identified an active fraction able to block proliferation of breast cancer cell lines MCF-7, MDA-MB231, and MDA-MB468 and to induce cellular apoptosis, whereas it was inactive on normal breast cells (MCF-10A). Metabolomic studies showed that this active fraction was able to interfere with amino acid metabolism, as well as to modulate glycolysis and glycosphingolipid metabolic pathways. In addition, the evaluation of the cytokinome profile on the polar fractions of three treated breast cancer cell lines (compared to untreated cells) demonstrated that this fraction induced a slight anti-inflammatory effect. Finally, the chemical entities present in this fraction were analyzed by liquid chromatography high resolution mass spectrometry combined with molecular networking.

A new species of Agelas from the Zanzibar Archipelago, western Indian Ocean (Porifera, Demospongiae)

A new sponge species (Demospongiae: Agelasida: Agelasidae) is described from the eastern coast of Unguja Island in the Zanzibar Archipelago. Agelassansibaricasp. n. is compared to all other Agelas species described so far. The new species differs from its congeners mainly in its three categories of verticillate spicules (acanthostyles, acanthostrongyles, and acanthoxeas) and their sizes. Acanthostrongyles, well represented in the spicular complement, are an exclusive trait of the new species widening the morphological range of the genus. Summarizing on spicular complement and spicular morphotraits of 36 species belonging to the genus Agelas: i) 32 species show only acanthostyles from Indo-Pacific (n = 14), Atlantic (n = 17), and Mediterranean (n = 1); ii) three Indo-Pacific species show acanthostyles and acanthoxeas; iii) one species Agelassansibaricasp. n. from the western Indian Ocean is characterised by the unique trait of three categories of verticillate spicules (acanthostyles, acanthostrongyles and acanthoxeas). A key for the Indo-Pacific species is supplied together with short descriptions, illustrations, and geographic range; literature on chemical bioprospecting of the genus Agelas is also provided.

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

Literature data about glycosides from sponges (Porifera, Demospongiae) are reviewed. Structural diversity, biological activities, taxonomic distribution and biological functions of these natural products are discussed.

Structural Variations to the 9-N-Methyladeninium Diterpenoid Hybrid Commonly Isolated from Agelas Sponges

Four novel 9-N-methyladeninium diterpenoids, agelasine M (3), 2-oxo-agelasine B (4), gelasine A (5), and gelasine B (6) accompanied by the known-agelasine B (1) and F (2) were isolated from the marine sponge Agelas sp. collected in Papua New Guinea. Compounds 3–6 represent higher unsaturated 9-N-methyladeninium bicyclic diterpenoid derivatives including 5 and 6 as unusual norditerpenoid-agelasines. Their structures were elucidated through detailed physical data analyses and comparison with literature properties. All pure compounds were evaluated for inhibitory activity against Trypanosoma brucei as well as for cytotoxicity against Jurkat cells.

Marine natural products

This review covers the literature published in 2006 for marine natural products, with 758 citations (534 for the period January to December 2006) referring to compounds isolated from marine microorganisms and phytoplankton, green algae, brown algae, red algae, sponges, cnidaria, bryozoans, molluscs, tunicates and echinoderms. The emphasis is on new compounds (779 for 2006), together with their 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.