Litoamentenes A-K, eleven undescribed cembranoids with cytotoxicity from the South China Sea soft coral Litophyton amentaceum.

Eleven undescribed cembrane-type diterpenoids, named litoamentenes A-K (1-11), were isolated from the soft coral Litophyton amentaceum collected from the South China Sea. Their structures were elucidated by extensive analysis of spectroscopic data, comparison with the literature data, single crystal X-ray diffraction, quantum chemical calculations and TDDFT-ECD calculations. This is the first systematic investigation of L. amentaceum. In particular, compounds 1-3 are cembrane-type norditerpenoids that lack isopropyl side chains. Compound 6 is a cembrane-type norditerpenoid without a methyl group at C-4, the first natural product identified with this carbon skeleton. Compounds 6, 9 and 10 showed modest cytotoxicity against several human cancer cell lines with IC50 values ranging from 3.99 to 14.56 µM.

Sarcocinerenolides A, an open-loop decarbonizing cembranolide, and sarcocinerenolides B-I, eight polyoxygenated cembranolides with anti-thrombotic activity from the South China Sea soft coral Sarcophyton cinereum.

A previously undescribed open-loop decarbonizing cembranolide, sarcocinerenolide A, and eight undescribed cembranolides, sarcocinerenolides B-I, characterized by poly-membered oxygen ring fragments were isolated from the soft coral Sarcophyton cinereum collected from the South China Sea. The structures and absolute configurations of these previously undescribed compounds were precisely determined by analysis of NMR data, DP4+ and ECD spectra. The bioactivities of the compounds were evaluated using zebrafish models and sarcocinerenolides C and H exhibited anti-thrombotic activity.

Lemneolemnanes A-D, Four Uncommon Sesquiterpenoids from the Soft Coral Lemnalia sp.

Four undescribed sesquiterpenoids, lemneolemnanes A-D (1-4), have been isolated from the marine soft coral Lemnalia sp. The absolute configurations of the stereogenic carbons of 1-4 were determined by single-crystal X-ray crystallographic analysis. Compounds 1 and 2 are epimers at C-3 and have an unusual skeleton with a formyl group on C-6. Compound 3 possesses an uncommonly rearranged carbon skeleton, while 4 has a 6/5/5 tricyclic system. Compound 1 showed significant anti-Alzheimer's disease (AD) activity in a humanized Caenorhabditis elegans AD pathological model.

New Diterpenes and Diterpene Glycosides with Antibacterial Activity from Soft Coral Lemnalia bournei.

Five new biflorane-type diterpenoids, biofloranates E-I (1-5), and two new bicyclic diterpene glycosides, lemnaboursides H-I (6-7), along with the known lemnabourside, were isolated from the South China Sea soft coral Lemnalia bournei. Their chemical structures and stereochemistry were determined based on extensive spectroscopic methods, including time-dependent density functional theory (TDDFT) ECD calculations, as well as a comparison of them with the reported values. The antibacterial activities of the isolated compounds were evaluated against five pathogenic bacteria, and all of these diterpenes and diterpene glycosides showed antibacterial activities against Staphylococcus aureus and Bacillus subtilis, with MICs ranging from 4 to 64 µg/mL. In addition, these compounds did not exhibit noticeable cytotoxicities on A549, Hela, and HepG2 cancer cell lines, at 20 µM.

Exploring the chemical diversity of sesquiterpenes from the rarely studied south China sea soft coral Sinularia tumulosa assisted by molecular networking strategy.

Molecular networking strategy-based prioritization of the isolation of the rarely studied soft coral Sinularia tumulosa yielded 14 sesquiterpenes. These isolated constituents consisted of nine different types of carbon frameworks, namely asteriscane, humulane, capillosane, seco-asteriscane, guaiane, dumortane, cadinane, farnesane, and benzofarnesane. Among them, situmulosaols A-C (1, 3 and 4) were previously undescribed ones, whose structures with absolute configurations were established by the combination of extensive spectral data analyses, quantum mechanical-nuclear magnetic resonance and time-dependent density functional theory electronic circular dichroism calculations, the Snatzke's method, and the modified Mosher's method. Notably, situmulosaol C (4) was the second member of capillosane-type sesquiterpenes. The plausible biogenetic relationships of these skeletally different sesquiterpenes were proposed. All sesquiterpenoids were evaluated for their antibacterial, cytotoxic and anti-inflammatory effects. The bioassay results showed compound 14 exhibited significant antibacterial activities against a variety of fish and human pathogenic bacteria with MIC90 values ranging from 3.6 to 33.8 µg/mL. Moreover, moderate cytotoxic effects against HEL cells for components 13 and 14 and moderate inhibitory effect on lipopolysaccharide-induced inflammatory responses in RAW264.7 cells for substance 13 were also observed.

A Brain-Protective Sterol from Soft Coral Inhibits Lipopolysaccharide-Induced Matrix Metalloproteinase-9-Mediated Astrocytic Migration.

Matrix metalloproteinases (MMPs), which are proteolytic enzymes, promote blood-brain barrier (BBB) disruption, leading to neuronal damage and neuroinflammation. Among them, MMP-9 upregulation serves as an inflammatory biomarker in the central nervous system (CNS). Currently, the development of marine organism-derived bioactive compounds or metabolites as anti-inflammatory drugs has received considerable attention. The 9,11-secosteroid, 3ß,11-dihydroxy-9,11-secogorgost-5-en-9-one (4p3f), is a novel sterol compound extracted from the soft coral Sinularia leptoclado with potential anti-inflammatory activity. However, the effect of and potential for brain protection of 4p3f on brain astrocytes remain unclear. Herein, we used rat brain astrocytes (RBAs) to investigate the effects and signaling mechanisms of 4p3f on lipopolysaccharide (LPS)-induced MMP-9 expression via zymographic, quantitative reverse transcription-polymerase chain reaction (qRT-PCR), Western blot, immunofluorescence staining, promoter-reporter, and cell migration analyses. We first found that 4p3f blocked LPS-induced MMP-9 expression in RBAs. Next, we demonstrated that LPS induced MMP-9 expression via the activation of ERK1/2, p38 MAPK, and JNK1/2, which is linked to the STAT3-mediated NF-κB signaling pathway. Finally, 4p3f effectively inhibited LPS-induced upregulation of MMP-9-triggered RBA cell migration. These data suggest that a novel sterol from soft coral, 4p3f, may have anti-inflammatory and brain-protective effects by attenuating these signaling pathways of MMP-9-mediated events in brain astrocytes. Accordingly, the soft coral-derived sterol 4p3f may emerge as a potential candidate for drug development or as a natural compound with neuroprotective properties.

Nine New Antibacterial Diterpenes and Steroids from the South China Sea Soft Coral Lobophytum catalai Tixier-Durivault.

Five new cembrane-type diterpenes, lobocalines A-E (1-5), and four new steroids, lobocaloids A-D (9-12), along with six known related compounds (6-8 and 13-15) were isolated from the Yalong Bay soft coral Lobophytum catalai Tixier-Durivault. The structures of the new compounds were elucidated by extensive spectroscopic analysis, NMR calculation with DP4+ analysis, time-dependent density functional theory-electronic circular dichroism (TDDFT-ECD) calculations, X-ray diffraction analyses and comparison with the reported spectroscopic data of known compounds. Further, with the aid of X-ray diffraction analysis, the structure of lobocrasol B (15) was firmly revised as 15a. In in vitro bioassays, compound 2 showed moderate antibacterial activities against fish pathogenic bacteria Streptococcus parauberis KSP28 and Phoyobacterium damselae FP2244 with minimum inhibitory concentration (MIC) values of 8.7 and 17.3 µg/mL, respectively. All the steroids exhibited antibacterial activities against the S. parauberis KSP28 with MIC values ranging from 12.3 to 53.6 µg/mL. Compounds 2, 7 and 14 have remarkable inhibitory effects on the hemolysin production of Staphylococcus aureus, while compounds 8-12 have medium inhibitory effects on the pyocyanin production in Pseudomonas aeruginosa.

Four uncommon cycloamphilectane-type diterpenoids with antibacterial activity from the South China Sea soft coral Sinularia brassica.

The chemical investigation on the soft coral Sinularia brassica collected off Xuwen Country, Guangdong Province, China, has resulted in the isolation and characterization of three uncommon cycloamphilectane-type diterpenoids, namely sinucycloamtin A-C (1-3), along with two known analogues (5 and 6). In addition, compounds 2 and 3 were hydrolyzed and their hydrolytic derivative sinucycloamtin D (4) was obtained. The structures of these previously undescribed compounds were established on the basis of extensive spectroscopic analysis, X-ray diffraction analysis, chemical conversion, as well as the comparison with the literature reported data. Compounds 1-3 represented the first examples of benzene-containing cycloamphilectane-type diterpenoids isolated from soft coral of genus Sinularia. In the in vitro bioassays, all the isolated and derived diterpenoids exhibited significant antibacterial activities against the fish pathogenic bacteria Phoyobacterium damselae FP2244 and Streptococcus parauberis SPOF3K with MIC90 values ranging from 3.7 to 9.1 µM.

A new capnosane-type diterpenoid from the South China sea soft coral Lobophytum pauciflorum.

A new rare capnosane-type diterpenoid (1) along with two known compounds sarcophyolides D (2) and arbolide C (3), were isolated from the soft coral Lobophytum pauciflorum collected at Xisha Islands in the South China Sea. The structure of 1 was established based on comprehensive spectroscopic data, literature comparison, and quantum chemical calculations. Compound 1 exhibited moderate anti-inflammatory activities in the zebrafish model at a concentration of 20 µM.

Six Undescribed Capnosane-Type Macrocyclic Diterpenoids from South China Sea Soft Coral Sarcophyton crassocaule: Structural Determination and Biological Evaluation.

Six undescribed capnosane-type macrocyclic diterpenes sarcocrassolins A-F (1-6) and one related known analog pavidolide D (7) were isolated from Sarcophyton crassocaule, a soft coral collected off the Nansha Islands, in the South China Sea. Their complete structures, relative configurations and absolute configurations were established through comprehensive spectroscopic analysis, quantum mechanical nuclear magnetic resonance (QM-NMR) and single-crystal X-ray diffraction. Sarcocrassolins D (4) and E (5) showed inhibitory activity against lipopolysaccharide (LPS)-stimulated inflammatory responses in RAW264.7 cells with IC50 values of 76.8 ± 8.0 µM and 93.0 ± 3.8 µM, respectively.

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-3ß,8ß-diol (3) and (22E,24R)-7ß-acetoxy-24-methyl-cholesta-5,22-dien-3ß,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.

Genus Litophyton: A Hidden Treasure Trove of Structurally Unique and Diversely Bioactive Secondary Metabolites.

Marine soft corals are prolific sources of various natural products that have served as a wealthy reservoir of diverse chemical scaffolds with potential as new drug leads. The genus Litophyton contains almost 100 species but only a small proportion of them has been chemically investigated, which calls for more attentions from global researchers. In the current work, 175 secondary metabolites have been discussed, drawing from published data spanning almost five decades, up to July 2023. The studied species of the genus Litophyton resided in various tropical and temperate regions and encompassed a broad range of biologically active natural products including terpenes, steroids, nitrogen-containing metabolites, lipids, and other metabolites. A wide spectrum of pharmacological effects of these compounds had been evaluated, such as cytotoxic, antiviral, antibacterial, antifungal, anti-malarial, antifeedant, anti-inflammatory, molluscicidal, PTP1B inhibitory, insect growth inhibitory, and neuroprotective activities. This review aims to offer an up-to-date survey of the literature and provide a comprehensive understanding of the chemical structures, taxonomical distributions, and biological activities of the reported metabolites from the title genus whenever available.

The complete mitochondrial genome of soft coral, Eleutherobia rubra (Brundin, 1896) (Cnidaria; Anthozoa; Malacalcyonacea; Alcyoniidae).

The mitogenome of a soft coral, Eleutherobia rubra (Brundin, 1896), was completely sequenced for the first time. The total mitogenome length of E. rubra is 18,724 bp with 14 protein-coding genes, two ribosomal RNA genes, one transfer RNA gene (tRNA-Met), and one non-coding region (NCR). The gene order is also consistent with other Alcyoniidae species. The base composition is 30.1% A, 16.7% C, 19.5% G, and 33.7% T, with a G-C content of 36.2%. This is the first record of the complete mitogenome sequence of the genus Eleutherobia.

Sarcoeleganolides H-K, new anti-thrombotic cembranes from soft coral Sarcophyton elegans.

Chemical investigation of soft coral the Sarcophyton elegans collected from the South China Sea led to the identification of four new cembranes, namely sarcoeleganolides H-K (1-4). Their structures and absolute configurations were established by 1D and 2D NMR spectroscopy, quantum chemical calculations of NMR chemical shifts and electronic circular dichroism (ECD) data analysis. Moreover, compound 2 exhibited moderate anti-thrombotic activity in zebrafish.

New Cytotoxic Monoalkyl Glycerol Ether from the Red Sea Soft Coral Nephthea mollis.

A new monoalkyl glycerol ether, 3-(n-henicosyloxy)propane-1,2-diol (1), was isolated from the CH2 Cl2 /MeOH crude extract of the Red Sea soft coral Nephthea mollis. Additionally, three known related analogs were identified: chimyl alcohol (2), batyl alcohol (3), and 3-(icosyloxy)propane-1,2-diol (4). The chemical structure of 3-(n-henicosyloxy)propane-1,2-diol was determined using advanced spectroscopic analyses, including 1D, 2D Nuclear Magnetic Resonance (NMR), Electron Ionization mass spectra (EI-MS), and High-Resolution Electron Spray Ionization mass spectra (HR-ESI-MS) analyses. Furthermore, the identification of chimyl alcohol, batyl alcohol and 3-(icosyloxy)propane-1,2-diol was achieved by studying their EI mass fragmentation analyses and comparing their mass data with those previously reported in the literature. The cytotoxic activity of the Nephthea mollis crude extract and 3-(n-henicosyloxy)propane-1,2-diol was evaluated against five human cancer cell lines: HepG2 (hepatocellular carcinoma), MCF-7 (breast carcinoma), NCI-1299 (lung carcinoma), HeLa (cervical cancer cell), and HT-29 (colon adenocarcinoma). Moreover, 3-(n-henicosyloxy)propane-1,2-diol revealed moderate cytotoxicity against the HeLa cell lines with an IC50 value of 24.1 µM, while showing inactivity against the remaining cell lines (IC50 >100 µM).

Lobosteroids A-F: Six New Highly Oxidized Steroids from the Chinese Soft Coral Lobophytum sp.

To explore the steroidal constituents of the soft coral Lobophytum sp. at the coast of Xuwen County, Guangdong Province, China, a chemical investigation of the above-mentioned soft coral was carried out. After repeated column chromatography over silica gel, Sephadex LH-20, and reversed-phase HPLC, six new steroids, namely lobosteroids A-F (1-6), along with four known compounds 7-10, were obtained. Their structures were determined by extensive spectroscopic analysis and comparison with the spectral data reported in the literature. Among them, the absolute configuration of 1 was determined by X-ray diffraction analysis using Cu Kα radiation. These steroids were characterized by either the presence of an α,ß-α',ß'-unsaturated carbonyl, or an α,ß-unsaturated carbonyl moiety in ring A, or the existence of a 5α,8α-epidioxy system in ring B, as well as diverse oxidation of side chains. The antibacterial bioassays showed that all isolated steroids exhibited significant inhibitory activities against the fish pathogenic bacteria Streptococcus parauberis FP KSP28, Phoyobacterium damselae FP2244, and Streptococcus parauberis SPOF3K, with IC90 values ranging from 0.1 to 11.0 µM. Meanwhile, compounds 2 and 6-10 displayed potent inhibitory effects against the vancomycin-resistant Enterococcus faecium bacterium G7 with IC90 values ranging from 4.4 to 18.3 µM. Therefore, ten highly oxidized steroids with strong antibacterial activities were isolated from the Chinese soft coral Lobophytum sp., which could be developed as new chemotypes of antibacterial drug leads.

Identification of potential antiviral compounds from Egyptian Red Sea soft corals against Middle East respiratory syndrome coronavirus.

The ongoing threat of Middle East respiratory syndrome coronavirus (MERS-CoV) underscores the importance of developing effective antiviral treatments. Current research was conducted to identify potential antiviral compounds from soft corals: Sinularia leptoclados, Sarcophyton ehrenbergi, Nephthea sp., Sarcophyton glaucum and Sarcophyton regulare. The antiviral activities of soft corals extracts were evaluated against MERS-CoV. Gas chromatography-mass spectrometry (GC-MS) was used to identify bioactive compounds. The molecular docking was performed to examine the identified compounds for their binding potentials towards three pathogenic factors of MERS-CoV: main protease, spike and non-structural protein 16/10 complex. The methanolic extract of soft coral Sarcophyton regulare exhibited the most promising activity with 50% inhibitory concentration (IC50) of 4.29 µg/ml and selective index (SI) of 112.2. Among the identified compounds in the active fraction, the molecular docking showed that two fatty acid esters: hexadecanoic acid, 2-hydroxy-1-(hydroxymethyl) ethyl ester and octadecanoic acid, 2-hydroxy-1 (hydroxymethyl) ethyl ester had promising docking scores.

Anti-Inflammatory Steroids from the South China Sea Soft Coral Lobophytum sarcophytoides.

Three new steroids, along with two known related analogs, were isolated from the Xisha Island soft coral Lobophytum sarcophytoides. The structures and absolute configurations of the new compounds were elucidated by extensive spectroscopic data analyses, time dependent density functional theory electronic circular dichroism calculation, and comparison with the spectral data previously reported in the literature. In in vitro bioassay, four compounds showed interesting suppressive effects on lipopolysaccharide (LPS) induced inflammation in BV-2 microglial cells at 10 µM level.

New Antibacterial Diterpenoids from the South China Sea Soft Coral Klyxum molle.

Fifteen new diterpenoids, namely xishaklyanes A-O (1-15), along with three known related ones (16-18), were isolated from the soft coral Klyxum molle collected from Xisha Islands, South China Sea. The stereochemistry of the new compounds was elucidated by a combination of detailed spectroscopic analyses, chemical derivatization, quantum chemical calculations, and comparison with the reported data. The absolute configuration of compound 18 was established by the modified Mosher's method for the first time. In bioassay, some of these compounds exhibited considerable antibacterial activities on fish pathogenic bacteria, and compound 4 showed the most effective activity with MIC of 0.225 µg/mL against Lactococcus garvieae.

Bioactive secondary metabolites isolated from the soft coral derived Penicillium sp. SCSIO 41038.

Chemical investigation of the Penicillium sp. SCSIO 41038 led to the isolation and characterization of one new cyclopiazonic acid-type alkaloid, speradine I (1), and one new phloroglucinol derivative, speradine J (8), along with 13 known compounds. Their structures were determined on the basis of extensive spectroscopic analysis, and by a comparison with data from the literature. All the compounds were evaluated for their antitumor (22Rv1 and PC-3) and enzyme inhibitory activity against acetylcholinesterase (AChE) in vitro.