Chemical and biological studies of soft corals of the nephtheidae family

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.

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).

The Antioxidant and Antitumor Efficiency of Litophyton sp. Extract in DMH-Induced Colon Cancer in Male Rats

One of the most common tumors to cause death worldwide is colon cancer. This study aims to investigate the antitumor potency of Litophyton sp. methanolic extract (LME) against DMH-induced colon cancer in adult male rats. Group (1) normal rats served as the control, group (2) normal rats were ip-injected with LME at a dose of 100 μg/kg/day, group (3) DMH-induced colon cancer animals, and group (4) colon cancer-modeled animals were treated with LME (100 μg/kg/day) for six weeks. The results revealed that injection of LME markedly regenerated the colon cancer pathophysiological disorders; this was monitored from the significant reduction in the values of serum biomarkers (CEA, CA19.9, AFP), cytokines (TNF-α and IL1β), and biochemical measurements (ALAT, ASAT, urea, creatinine, cholesterol, and triglycerides) matched significant increase of apoptotic biomarkers (CD4+); similarly, colon DNA fragmentation, MDA, and NO levels were down-regulated. In contrast, a remarkable upregulation in colon SOD, GPx, GSH, and CAT levels was noted. Moreover, the colon histopathological architecture showed obvious regenerations. Chromatography of LME resulted in the purification of two polyhydroxylated steroids (1 and 2) with potential cytotoxic activities. LME performed therapeutic potential colon tumorigenesis; therefore, LME may have a promising chemo-preventive feature against colon cancer, probably via enhancement of the apoptosis pathway, improvement of the immune response, reduction of inflammation, or/and restoration of the impaired oxidative stress.

Tuaimenal A, a Meroterpene from the Irish Deep-Sea Soft Coral Duva florida, Displays Inhibition of the SARS-CoV-2 3CLpro Enzyme

Cold water benthic environments are a prolific source of structurally diverse molecules with a range of bioactivities against human disease. Specimens of a previously chemically unexplored soft coral, Duva florida, were collected during a deep-sea cruise that sampled marine invertebrates along the Irish continental margin in 2018. Tuaimenal A (1), a cyclized merosesquiterpenoid representing a new carbon scaffold with a highly substituted chromene core, was discovered through exploration of the soft coral secondary metabolome via NMR-guided fractionation. The absolute configuration was determined through vibrational circular dichroism. Functional biochemical assays and in silico docking experiments found tuaimenal A selectively inhibits the viral main protease (3CLpro) of SARS-CoV-2.

Cytotoxicity and chemical profiling of the Red Sea soft corals Litophyton arboreum

The objective of this research was to evaluate the cytotoxic activities of the fractions and isolated compounds of the soft corals Litophyton arboreum against A549, MCF-7 and HepG2 cell lines by MTT assay method, and to chemically investigate the various metabolites of its total extract using LC-HR-ESI-MS metabolomic profiling. The metabolomic profiling revealed the presence of various metabolites, mainly sesquiterpenes and steroids reported for the first time in L. arboreum. Additionally, eight compounds (1-8) have been isolated from the n-hexane-chloroform (1:1) fraction that exhibited noticeable activity towards A549, MCF-7 and HepG2 cell lines. The steroids (5 and 6), and the sesquiterpene (1) exerted noticeable activity against A549 cell line (IC₅₀ 28.5 ± 4.4, 36.9 ± 2.9 and 67.3 ± 9.9 µM/mL, respectively) compared to etoposide as standard cytotoxic agent (IC₅₀ 48.3 ± 7.6 µM/mL). Compound 6 also exhibited cytotoxicity against MCF-7 cell line (IC₅₀ 55.3 ± 4.9 µM/mL).

Litosetoenins A-E, Diterpenoids from the Soft Coral Litophyton setoensis, Backbone-Rearranged through Divergent Cyclization Achieved by Epoxide Reactivity Inversion

Litosetoenins A-E (1-5), five new ring-rearranged serrulatane-type diterpenoids with a common tricyclo[3.0.4]decane core, along with a known diterpenoid glycoside (6), a related known diterpenoid (7), and four known sesquiterpenoids (8-11), were isolated from a Balinese soft coral Litophyton setoensis. Spirolitosetoenin A (5a) and isospirolitosetoenin A (5b), featuring an unprecedented spiro[4,5]decane core, were obtained after treatment of compound 5 with HCl in methanol. The structures of new compounds were elucidated by extensive spectroscopic analysis, quantum mechanical nuclear magnetic resonance approach, and chemical methods. A plausible biosynthetic pathway involving an unusual divergent biogenesis was proposed.

Further new nardosinane-type sesquiterpenoids from the Xisha soft coral Litophyton nigrum

Further chemical investigation of the Xisha soft coral Litophyton nigrum has resulted in the isolation of four new nardosinane-type sesquiterpenoids, namely linardosinenes D-G (1-4). The structures of new compounds were elucidated by extensive analyses of their spectroscopic data and by comparison with the reported data of known related ones. All compounds exhibited weak inhibitory effect against bromodomain-containing protein 4 (BRD4), a promising therapeutic target in various human diseases, at a concentration of 10 μM.

Chemical and biological studies on the soft coral Nephthea sp

Soft corals belonging to the family Nephtheidae have been appreciated as marine sources of diverse metabolites with promising anticancer potential. In view of that, the current work investigates the anti-proliferative potential of the crude extract, different fractions, and green synthesized silver nanoparticles (AgNPs) of the Red Sea soft coral, Nephthea sp. against a panel of tumor cell lines. The metabolic pool of the soft coral under study was also explored via an LC-HR-ESI-MS metabolomics approach, followed by molecular docking analysis of the characterized metabolites against the target proteins, EGFR, VEGFR, and HER2 (erbB2) that are known to be involved in cancer cell proliferation, growth, and survival. Overall, the n-butanol fraction of Nephthea sp. exhibited the highest inhibitory activities against MCF7 (breast cancer) and A549 (lung cancer) cell lines, with interesting IC₅₀ values of 2.30 ± 0.07 and 3.12 ± 0.10 μg ml⁻¹, respectively, whereas the maximum growth inhibition of HL60 (leukemia) cells was recorded by the total extract (IC₅₀ = 2.78 ± 0.09 μg ml⁻¹). More interestingly, the anti-proliferative potential of the total soft coral extract was evidently improved when packaged in the form of biogenic AgNPs, particularly against A549 and MCF7 tumor cells, showing IC₅₀ values of 0.72 ± 0.06 and 9.32 ± 0.57 μg ml⁻¹, respectively. On the other hand, metabolic profiling of Nephthea sp. resulted in the annotation of structurally diverse terpenoids, some of which displayed considerable binding affinities and molecular interactions with the studied target proteins, suggesting their possible contribution to the anti-proliferative properties of Nephthea sp. via inhibition of tyrosine kinases, especially the EGFR type. Taken together, the present findings highlighted the relevance of Nephthea sp. to future anticancer drug discovery and provided a base for further work on the green synthesis of a range of bioactive NPs from marine soft corals.

The cytotoxic potential of the crude extract, different fractions, and green synthesized nanoparticles of the soft coral Nephthea sp. was studied, supported by LC-HR-ESI-MS metabolomics analysis and molecular docking of the dereplicated compounds.

Uncommon nornardosinane, seconeolemnane and related sesquiterpenoids from Xisha soft coral Litophyton nigrum

Three new nardosinane-type sesquiterpenoids linardosinenes A-C (1-3) and four new neolemnane-type sesquiterpenoids lineolemnenes A-D (4-7), together with the related known compound 4-acetoxy-2,8-neolemnadien-5-one (8), were isolated from the Xisha soft coral Litophyton nigrum. The structures of these new compounds were elucidated by comprehensive analyses of spectroscopic data, in association withmodified Mosher's method and ECD calculations for configurational assignments and the absolute configuration of8was determined by X-ray diffraction analysis for the first time. Structurally uncommon nornardosinane and seconeolemnane skeletons for compounds 1 and 7, respectively, are rare carbon frameworks in naturally occurring sesquiterpenoids. The absolute configurations of 1, 7, and 8 were determined by modified Mosher's method, TDDFT ECD approach, and X-ray diffraction analysis, respectively. This is the first chemical study of L. nigrum and the first report of nornardosinane, seconeolemnane and related sesquiterpenoids from the genus Litophyton. The isolates 1-7 were evaluated for their cytotoxicity against THP-1, SNU-398, HT-29, Capan-1 and A549 cell lines and inhibitory activities against PTP1B, BRD4, HDAC1 and HDAC6 protein kinases. The results indicated that compounds 2-5 inhibited proliferation of human cancer cells. However, none of them were potent inhibitors of protein kinases.

Phytosterols Suppress Phagocytosis and Inhibit Inflammatory Mediators via ERK Pathway on LPS-Triggered Inflammatory Responses in RAW264.7 Macrophages and the Correlation with Their Structure

Phytosterols, found in many commonly consumed foods, exhibit a broad range of physiological activities including anti-inflammatory effects. In this study, the anti-inflammatory effects of ergosterol, β-sitosterol, stigmasterol, campesterol, and ergosterol acetate were investigated in lipopolysaccharide (LPS)-induced RAW264.7 macrophages. Results showed that all phytosterol compounds alleviated the inflammatory reaction in LPS-induced macrophage models; cell phagocytosis, nitric oxide (NO) production, release of tumor necrosis factor-α (TNF-α), and expression and activity of pro-inflammatory mediator cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS), and phosphorylated extracellular signal-regulated protein kinase (p-ERK) were all inhibited. The anti-inflammatory activity of β-sitosterol was higher than stigmasterol and campesterol, which suggests that phytosterols without a double bond on C-22 and with ethyl on C-24 were more effective. However, inconsistent results were observed upon comparison of ergosterol and ergosterol acetate (hydroxy or ester group on C-3), which suggest that additional research is still needed to ascertain the contribution of structure to their anti-inflammatory effects.

Recent Updates on Corals from Nephtheidae

Marine natural products display a wide range of biological activities, which play a vital role in the innovation of lead compounds for the drug development. Soft corals have been ranked at the top in regard to the discovery of bioactive metabolites with potential pharmaceutical applications. Many of the isolated cembranoids revealed diverse biological activities, such as anticancer, antidiabetic and anti-osteoporosis. Likewise, sterols from soft corals exhibited interesting biological potential as anti-inflammatory, antituberculosis and anticancer. Consequently, investigating marine soft corals will definitely lead to the discovery of a large number of chemically varied secondary metabolites with countless bioactivities for possible applications in medicine and pharmaceutical industry. This review provides a complete survey of all metabolites isolated from the family Nephtheidae, from 2011 until November 2018, along with their natural sources and biological potential whenever possible.

Screening of NO Inhibitor Release Activity from Soft Coral Extracts Origin Palu Bay, Central Sulawesi, Indonesia

BACKGROUND

As a marine organism, soft corals can be utilized to be various bioactive substances, especially terpenoids and steroids. The soft corals family which produces bioactive generally come from clavulariidae, alcyoniidae, nephtheidae and xeniidae family.

OBJECTIVE

To investigate the bioactivity of Nitric Oxide (NO) inhibitor release from soft coral crude extracts of Sinularia sp. (SCA), Nephthea sp. (SCB), Sarcophyton sp. (SCC), Sarcophyton sp. (SCD), Sinularia sp. (SCE) and Sinularia sp. (SCF).

MATERIALS AND METHODS

Soft coral is collected from Palu Bay (Central Sulawesi). NO inhibitory release activity measured according to the Griess reaction. Soft corals sample macerated with 1:2 (w/v). Then, Soft coral extracts with the best NO Inhibitor activity partitioned with Dichloromethane, Ethyl acetate, and n-butanol. The bioactive of all crude extracts were identified by GC-MS to find compounds with anti-inflammatory potential.

RESULTS

Sarcophyton sp. (SCC) and Sinularia sp. (SCF) are able to inhibit NO concentrations of 0.22 ± 0.04 and 0.20 ± 0.04 µM at 20 mg/mL, respectively. The chemical constituents determined and showed the potential as anti-inflammatory in the crude of Sinularia sp. (SCA) were Octacosane (3.25%). In Nephthea sp., (SCB) were Cyclohexene, 6-ethenyl-6- methyl-1-(1-methylethyl)-3-(1-methylethylidene)-,(S)- (0.55%); Azulene, 1,2,3,4,5,6,7,8- octahydro-1,4-dimethyl-7-(1-methylethylidene)-, (1S-cis)- (0.53%); and 1,7,7-Trimethyl- 2-vinylbicyclo[2.2.1]hept-2-ene (4.72%). In Sarcophyton sp, (SCC) were Eicosane (0.12%); Nonacosane (10.7%); 14(β)-Pregnane (0.87%); Octacosane 6.39%); and Tricosane (1.53%). In Sarcophyton sp. (SCD) were 14(β)-Pregnane (2.69%); and Octadecane (27.43%). In crude of Sinularia sp. (SCE) were Oleic Acid (0.63%); 7,10-Hexadecadienoic acid, methyl ester (0.54%); 14(β)-Pregnane (1.07%); 5,8,11,14-Eicosatetraenoic acid, ethyl ester, (all-Z)- (4.60%); Octacosane (7.75%); and 1,2-Benzisothiazole, 3-(hexahydro-1Hazepin- 1-yl)-, 1,1-dioxide (1.23%). In the crude of Sinularia sp., (SCF) were Oxirane, decyl- (1.38%); Nonacosane (0.57%); Cyclohexanol, 5-methyl-2-(1-methylethenyl)- (0.61%); 14B-Pregnane (0.76%); and Tetratriacontane (1.02%).

CONCLUSION

The extract of Sarcophyton sp. (SCC) and Sinularia sp. (SCF) showed the best NO inhibitory release activity. This study is making soft corals from Central Sulawesi, Indonesia can become a potential organism in the discovery and development of bioactive substances anti-inflammatory.

Soft Coral Dendronephthya puetteri Extract Ameliorates Inflammations by Suppressing Inflammatory Mediators and Oxidative Stress in LPS-Stimulated Zebrafish

Marine-derived extract and/or bioactive compounds have attracted increasing demand due to their unique and potential uses as cures for various inflammation-based diseases. Several studies revealed anti-inflammatory candidates found in soft corals. However, the effects of soft corals on inflammation in an in vivo model remain to be determined. Therefore, the extract of soft coral Dendronephthya puetteri (DPE) was investigated for an in vivo anti-inflammatory effect in a lipopolysaccharide (LPS)-stimulated zebrafish model to determine its potential use as a natural anti-inflammatory agent. We also investigated whether DPE has toxic effects in a zebrafish model. No significant changes were observed in terms of survival, heart beat rate, or developmental abnormalities in the zebrafish embryos exposed to a concentration below 100 µg/mL of DPE. Treating the zebrafish model with LPS-treatment significantly increased the ROS, NO generation, and cell death. However, DPE inhibited this LPS-stimulated ROS, NO generation, and cell death in a dose-dependent manner. In addition, DPE significantly reduced the mRNA expression of both iNOS and COX-2 and markedly suppressed the expression levels of the proinflammatory cytokines, TNF-α and IL-6, in an LPS-stimulated zebrafish model. These findings demonstrate that DPE has profound anti-inflammatory effect in vivo, suggesting that DPE might be a strong natural anti-inflammatory agent.

Terpenoids from Marine Soft Coral of the Genus Lemnalia: Chemistry and Biological Activities

Lemnalia is one of the most widely-distributed marine soft coral in tropical oceans and is known to produce novel terpenoids with a broad spectrum of biological activities. This review provides the first comprehensive overview of terpenoids produced by soft coral Lemnalia since their first discovery in 1974.

Isolation and structure elucidation of natural products of three soft corals and a sponge from the coast of Madagascar

We investigated the three soft corals Sarcophyton stellatum, Capnella fungiformis and Lobophytum crassum and the sponge Pseudoceratina arabica, which have been collected at the coast of Madagascar. In addition to previously known marine natural products, S. stellatum provided the new (+)-enantiomer of the cembranoid (1E,3E,11E)-7,8-epoxycembra-1,3,11,15-tetraene (2). Capnella fungiformis afforded three new natural products, ethyl 5-[(1E,5Z)-2,6-dimethylocta-1,5,7-trienyl]furan-3-carboxylate (6), ethyl 5-[(1E,5E)-2,6-dimethylocta-1,5,7-trienyl]furan-3-carboxylate (7) and the diepoxyguaiane sesquiterpene oxyfungiformin (9a). The extracts of all three soft corals exhibited moderate activities against the malarial parasite Plasmodium falciparum. Extracts of the sponge Pseudoceratina arabica proved to be very active against a series of Gram-positive and Gram-negative bacteria.

Identification of sterols from the soft coral Dendronephthya gigantea and their anti-inflammatory potential

Exploration of anti-inflammatory phytochemicals has received tremendous attention worldwide owing to the rapid increase in inflammatory diseases. Current study reveals the identification of eight 3β-hydroxy-Δ⁵-steroidal congeners from a nonpolar column fraction of the ethanol solubles from the soft coral Dendronephthya gigantea collected from Jeju Island South Korea, using GC-MS/MS analysis. The sterol-rich fraction (DGEH21) showed a significant anti-inflammatory activity as exhibited by the inhibition of NO production (IC₅₀ 4.33±0.50μg/mL) and PGE₂ production in LPS-stimulated RAW 264.7 macrophages. It also suppressed the expression levels of proinflammatory cytokines, TNF-α, IL-1β, and IL-6 in a dose-dependent manner. Furthermore, DGEH21 effectively downregulated the expression levels of iNOS, and COX-2 and reduced NO and ROS production as well as cell death in LPS-stimulated in-vivo zebrafish embryo model. However, DGEH21 at relatively high concentrations indicated cytotoxicity in both RAW cells and zebrafish embryos with RAW cell viability being nearly 80% after treatment with 25μg/mL DGEH21. This study highlights the synergistic anti-inflammatory activity of several steroids found in D. gigantea. Their actions may be useful in the development of anti-inflammatory cosmeceuticals, pharmaceutical agents, and other consumer products.

4α-Methylated steroids with cytotoxic activity from the soft coral Litophyton mollis

Seven new (1-3, 5 and 8-10) and three previously reported (4, 6 and 7) 4α-methylated steroids were isolated from the organic extract of the gorgonian Litophyton mollis. The structures and the relative configurations of the isolated natural products were determined on the basis of extensive analyses of their NMR and MS data. Metabolites 1 and 5-8 exhibited cytotoxic activity against K562 human chronic myelogenous leukemia cells with IC₅₀ values below 10μM, while at the same time displaying low toxicity against healthy PBMCs.

Antitumour effect of sesquiterpene (+)-chabranol on four human cancer cell lines by inducing apoptosis and autophagy

OBJECTIVE

To investigate the effects and mechanisms of sesquiterpene (+)-chabranol on proliferation of a panel of four human tumour cell lines (BGC-823, SGC-7901, SSMC-7721 and HepG2).

METHODS

Cell viability was assessed using a standard methyltetrazolium assay; cell-cycle analysis of BGC-823 cells was performed by flow cytometry. Transmission electron microscopy (TEM) was used to examine the ultrastructure of BGC-823 cells exposed to (+)-chabranol. Apoptosis was investigated by evaluating DNA laddering, using gel electrophoresis.

RESULTS

(+)-Chabranol had a marked time- and concentration-dependent inhibitory effect on BGC-823 cell proliferation. The effect was less marked in SGC-7901, SSMC-7721 and HepG2 cells. Exposure of BGC-823 cells to (+)-chabranol arrested the cell cycle at G(1). Evidence of apoptosis and autophagy was observed by TEM; DNA laddering in BGC-823 cells supported the presence of apoptosis.

CONCLUSIONS

This study suggested that (+)-chabranol has antitumour activity against BGC-823 cells, and may exert its action by inhibition of proliferation and induction of apoptosis and autophagy. With further development, (+)-chabranol may represent a potential novel treatment for poorly differentiated gastric cancer.

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.