New 4-methylated and 19-oxygenated steroids from the Formosan soft coral Nephthea erecta

Cytotoxic evaluation of new polyhydroxylated steroids from the Red Sea soft coral Litophyton mollis (Macfadyen, 1936)

An efficient column chromatography of the CH2Cl2/MeOH crude extract from the soft coral Litophyton mollis (Macfadyen, 1936) yielded seven steroids, including five 4α-methylated steroids (1-5) and two 19-oxygenated steroids (6-7). Notably, both compounds 3 and 7 are new, identified as (22E)-4α,24-dimethyl-5α-cholesta-22,24(28)-dien-3β,8β-diol (3) and (22E,24R)-7β-acetoxy-24-methyl-cholesta-5,22-dien-3β,19-diol (7). The chemical structures and relative configurations were elucidated through comprehensive spectroscopic analyses, including 1D and 2D NMR, as well as HRESIMS analysis. The cytotoxicity of metabolites 1-7 was evaluated against three cancer cell lines: MCF-7, HepG2, and NCI-1299. Remarkably, metabolites 6 and 7 exhibited strong cytotoxic activity against MCF-7, with IC50 values of 8.6 and 8.4 μM, respectively, while also showing moderate effects against NCI-1299, with IC50 values of 15.7 and 15.1 μM, respectively. Additionally, steroids 4 and 5 displayed weak cytotoxicity against all three cell lines, with IC50 values in the ranges of 34.7-37.5 and 30.8-46.3 μM, respectively.

Molecular Network Guided Cataloging of the Secondary Metabolome of Selected Egyptian Red Sea Soft Corals

Soft corals are recognized as an abundant source of diverse secondary metabolites with unique chemical features and physiologic capabilities. However, the discovery of these metabolites is usually hindered by the traditional protocol which requires a large quantity of living tissue for isolation and spectroscopic investigations. In order to overcome this problem, untargeted metabolomics protocols have been developed. The latter have been applied here to study the chemodiversity of common Egyptian soft coral species, using only minute amounts of coral biomass. Spectral similarity networks, based on high-resolution tandem mass spectrometry data, were employed to explore and highlight the metabolic biodiversity of nine Egyptian soft coral species. Species-specific metabolites were highlighted for future prioritization of soft coral species for MS-guided chemical investigation. Overall, 79 metabolites were tentatively assigned, encompassing diterpenes, sesquiterpenes, and sterols. Simultaneously, the methodology assisted in shedding light on newly-overlooked chemical diversity with potential undescribed scaffolds. For instance, glycosylated fatty acids, nitrogenated aromatic compounds, and polyketides were proposed in Sinularia leptoclados, while alkaloidal terpenes and N-acyl amino acids were proposed in both Sarcophyton roseum and Sarcophyton acutum.

Structural diversity of bioactive steroid compounds isolated from soft corals in the period 2015-2020

Marine soft corals are known as a good source of biologically active compounds, among which a large number of steroid compounds are identified. Structures and activities of these compounds have been used in drug discovery and development. From 2015 to 2020, 179 new steroid compounds were isolated from soft corals and structurally characterized. In this review, we report the structural classification and bioactivities of these compounds. The largest group of steroids from soft corals are hydroxysteroids, while the most common biological activity is anticancer. Besides, anticancer hydroxysteroids from soft corals exhibit anti-inflammatory and antibacterial activity. Unlike anticancer and antibacterial activity that can be observed in a number of steroid classes, antioxidant activity and antileishmanial effect were observed only in 19-oxygenated steroids, antiviral activity in pregnane-type steroids and spirosteroids, immunosuppressive activity in epoxy- and epidioxysteroids, and antibacterial activity in two steroid classes, hydroxysteroids and ketosteroids. This systematically analyzed link between the structure and activity of natural marine steroids is a good starting point for future drug design.

Natural Products from Octocorals of the Genus Dendronephthya (Family Nephtheidae)

In this review, 170 natural substances, including steroid, diterpenoid, sesquiterpenoid, peptide, prostaglandin, base, chlorolipid, bicyclolactone, amide, piperazine, polyketide, glycerol, benzoic acid, glycyrrhetyl amino acid, hexitol, pentanoic acid, aminoethyl ester, octadecanone, alkaloid, and a 53-kD allergenic component from octocorals belonging to genus Dendronephthya, were listed. Some of these compounds displayed potential bioactivities.

Bioactive Steroids from the Red Sea Soft Coral Sinularia polydactyla

Six new (1, 2, 6, 8, 13, and 20) and twenty previously isolated (3-5, 7, 9-12, 14-19, and 21-26) steroids featuring thirteen different carbocycle motifs were isolated from the organic extract of the soft coral Sinularia polydactyla collected from the Hurghada reef in the Red Sea. The structures and the relative configurations of the isolated natural products have been determined based on extensive analysis of their NMR and MS data. The cytotoxic, anti-inflammatory, anti-angiogenic, and neuroprotective activity of compounds 3-7, 9-12, 14-20, and 22-26, as well as their effect on androgen receptor-regulated transcription was evaluated in vitro in human tumor and non-cancerous cells. Steroids 22 and 23 showed significant cytotoxicity in the low micromolar range against the HeLa and MCF7 cancer cell lines, while migration of endothelial cells was inhibited by compounds 11, 12, 22, and 23 at 20 µM. The results of the androgen receptor (AR) reporter assay showed that compound 11 exhibited the strongest inhibition of AR at 10 µM, while it is noteworthy that steroids 10, 16, and 20 displayed increased inhibition of AR with decreasing concentrations. Additionally, compounds 11 and 23 showed neuroprotective activity on neuron-like SH-SY5Y cells.

Chemical Diversity of Soft Coral Steroids and Their Pharmacological Activities

The review is devoted to the chemical diversity of steroids produced by soft corals and their determined and potential activities. There are about 200 steroids that belong to different types of steroids such as secosteroids, spirosteroids, epoxy- and peroxy-steroids, steroid glycosides, halogenated steroids, polyoxygenated steroids and steroids containing sulfur or nitrogen heteroatoms. Of greatest interest is the pharmacological activity of these steroids. More than 40 steroids exhibit antitumor and related activity with a confidence level of over 90 percent. A group of 32 steroids shows anti-hypercholesterolemic activity with over 90 percent confidence. Ten steroids exhibit anti-inflammatory activity and 20 steroids can be classified as respiratory analeptic drugs. Several steroids exhibit rather rare and very specific activities. Steroids exhibit anti-osteoporotic properties and can be used to treat osteoporosis, as well as have strong anti-eczemic and anti-psoriatic properties and antispasmodic properties. Thus, this review is probably the first and exclusive to present the known as well as the potential pharmacological activities of 200 marine steroids.

A Steroid-Type Antioxidant Targeting the Keap1/Nrf2/ARE Signaling Pathway from the Soft Coral Dendronephthya gigantea

Four new steroids, named 7-dehydroerectasteroid F (1), 11α-acetoxyarmatinol A (2), 22,23-didehydroarmatinol A (3), and 3-O-acetylhyrtiosterol (4), together with 11 previously described analogues, were isolated from a South China Sea collection of the soft coral Dendronephthya gigantea. The structures of the new steroids were elucidated by comprehensive spectroscopic analysis and by comparison with previously reported data. Compound 1 showed potent protection against H₂O₂-induced oxidative damage in neuron-like PC12 cells by promoting nuclear translocation of Nrf2 and enhancing the expression of HO-1. 1 represents the first steroid-type antioxidant from marine organisms.

4α-Methylergosta-22(E),24(28)-dien-3β-ol, a New Marine Sterol from the Octocoral Nephthea Columnaris

A new marine sterol, 4α-methylergosta-22( E),24(28)-dien-3β-ol (1), was isolated from the octocoral Nephthea columnaris. The structure of 1 was elucidated on the basis of spectroscopic and mass spectrometric methods.

New steroids from the soft coral Nephthea chabrolii

A new cytotoxic 19-oxygenated steroid, nebrosteroid Q (1) and two new cytotoxic 19-norergosterols, nebrosteroids R and S (2 and 3) were isolated from the soft coral Nephthea chabrolii collected at San-Hsian-Tai. The structures of nebrosteroids Q–S (1–3) were elucidated by spectral analysis, and their cytotoxicity against selected cancer cells as well as antiviral activity against human cytomegalovirus (HCMV) were measured in vitro.

New 19-oxygenated steroids from the soft coral Nephthea chabrolii

In order to search for novel bioactive substances from marine organisms, we investigated the acetone extract of the soft coral Nephthea chabrolii collected at San-Hsian-Tai, Taitong County, Taiwan. From this extract three new 19-oxygenated steroids, nebrosteroids N–P (1–3) were isolated. The structures of these compounds were elucidated by extensive spectroscopic analyses.

Antiprotozoal steroidal saponins from the marine sponge Pandaros acanthifolium

The chemical composition of the Caribbean sponge Pandaros acanthifolium was reinvestigated and led to the isolation of 12 new steroidal glycosides, namely, pandarosides E-J (1-6) and their methyl esters (7-12). Their structures were determined on the basis of extensive spectroscopic analyses, including two-dimensional NMR and HRESIMS data. Like the previously isolated pandarosides A-D (13-16), the new compounds 1-12 share an unusual oxidized D-ring and a cis C/D ring junction. The absolute configurations of the aglycones were assigned by interpretation of CD spectra, whereas the absolute configurations of the monosaccharide units were determined by chiral GC analyses of the acid methanolysates. The majority of the metabolites showed in vitro activity against three or four parasitic protozoa. Particularly active were the compounds 3 (pandaroside G) and its methyl ester (9), which potently inhibited the growth of Trypanosoma brucei rhodesiense (IC(50) values 0.78 and 0.038 microM, respectively) and Leishmania donovani (IC(50)'s 1.3 and 0.051 microM, respectively).

A new norsesquiterpenoid from a Bornean soft coral genus Nephthea

A new germacrane-type norsesquiterpenoid, 1-acetoxy-germacra-5E,10(14)-diene-4-one (1), as well as three known compounds, were isolated from the organic extracts of a Bornean soft coral Nephthea sp. Their structures were elucidated on the basis of spectroscopic data analysis.

A new 4alpha-methylated sterol from a Nephthea sp. (Nephtheidae) Bornean soft coral

A new 4alpha-methyl sterol, 4alpha-methyl-ergosta-6,8(14),22E-triene-3beta-ol (1), was isolated along with cholesterol from a Nephthea sp. Bornean soft coral The structure of compound 1 was elucidated on the basis of spectroscopic analysis and comparison of the data with those of the related compounds.

New 19-oxygenated and 4-methylated steroids from the Formosan soft coral Nephthea chabroli

Chemical investigation of the Formosan soft coral Nephthea chabroli resulted in the isolation of four new 19-oxygenated steroids, nebrosteroids I-L (1-4), together with a new 4alpha-methylated steroid, nebrosteroid M (5). The molecular structures of these isolated metabolites were elucidated on the basis of extensive spectroscopic analysis and by comparison of the data with those of related metabolites. Compounds 1-5 were evaluated for anti-inflammatory activity using RAW 264.7 macrophages.

Marine natural products

This review covers the literature published in 2007 for marine natural products, with 948 citations(627 for the period January to December 2007) referring to compounds isolated from marine microorganisms and phytoplankton, green algae, brown algae, red algae, sponges, cnidarians,bryozoans, molluscs, tunicates, echinoderms and true mangrove plants. The emphasis is on new compounds (961 for 2007), 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.1 Introduction, 2 Reviews, 3 Marine microorganisms and phytoplankton, 4 Green algae, 5 Brown algae, 6 Red algae, 7 Sponges, 8 Cnidarians, 9 Bryozoans, 10 Molluscs, 11 Tunicates (ascidians),12 Echinoderms, 13 Miscellaneous, 14 Conclusion, 15 References.

New anti-inflammatory 4-methylated steroids from the Formosan soft coral Nephthea chabroli

Eight new 4-methylated steroids, nebrosteroids A-H (1-8) were isolated from the acetone solubles of the Formosan soft coral Nephthea chabroli. The structures were elucidated by extensive NMR spectroscopic analysis and their anti-inflammatory activity was measured in vitro.