Anti-Inflammatory Halogenated Monoterpenes from the Red Alga Portieria hornemannii.

The chemical investigation of a red alga Portieria hornemannii enabled the identification of three new halogenated monoterpenes (1-3) along with two previously identified metabolites (4 and 5). Their structures were determined by spectroscopic analysis and also by utilizing single-crystal diffraction analysis and quantum chemical calculation, as well as by comparison with literature data. Further corrections for dichloro and dibromo carbons using the sorted training set (STS) method were established in this study to significantly improve the accuracy in GIAO 13C NMR calculation of compounds 1-3. To discover the potential bioactive metabolites from P. hornemannii, the anti-inflammatory activities of all compounds were examined. Compounds 1 and 3-5 showed significant anti-inflammatory activity to inhibit the production of pro-inflammatory cytokines in the LPS-stimulated mature dendritic cells.

An amperometric method for the determination of cystine in urine samples and pharmaceutical tablets using screen-printed silver electrodes.

Elevated urinary cystine levels are closely associated with the development of cystine stone. Therefore, the ability to rapidly and efficiently determine urinary cystine levels is crucial for physicians to manage patients with cystinuria or those undergoing cystine medication. In this study, an amperometric method employing a commercial screen-printed silver electrode was successfully established. The resulting calibration curve indicated a detection limit of 0.65 mg/dL. Satisfactory recoveries ranging from 89% to 109% were obtained for urine samples. The method was also effective for the quality control analysis of cystine in pharmaceutical tablets. The recovery of cystine from pharmaceutical tablets ranged from 98% to 101% using the developed method. This method enables the rapid and accurate determination of cystine in both urine samples and pharmaceutical tablets and provides valuable information for clinical diagnosis and pharmaceutical quality control.

Dihydroaustrasulfone alcohol induces apoptosis in nasopharyngeal cancer cells by inducing reactive oxygen species-dependent inactivation of the PI3K/AKT pathway.

Dihydroaustrasulfone alcohol (DA), the synthetic precursor of a natural compound (austrasulfone) isolated from the coral species Cladiella australis, has shown cytotoxic effects against cancer cells. However, it is unknown whether DA has antitumor effects on nasopharyngeal carcinoma (NPC). In this study, we determined the antitumor effects of DA and investigated its mechanism of action on human NPC cells. The MTT assay was used to determine the cytotoxic effect of DA. Subsequently, apoptosis and reactive oxygen species (ROS) analyses were performed by using flow cytometry. Apoptotic and PI3K/AKT pathway-related protein expression was determined using Western blotting. We found that DA significantly reduced the viability of NPC-39 cells and determined that apoptosis was involved in DA-induced cell death. The activity of caspase-9, caspase-8, caspase-3, and PARP induced by DA suggested caspase-mediated apoptosis in DA-treated NPC-39 cells. Apoptosis-associated proteins (DR4, DR5, FAS) in extrinsic pathways were also elevated by DA. The enhanced expression of proapoptotic Bax and decreased expression of antiapoptotic BCL-2 suggested that DA mediated mitochondrial apoptosis. DA reduced the expression of pPI3K and p-AKT in NPC-39 cells. DA also reduced apoptosis after introducing an active AKT cDNA, indicating that DA could block the PI3K/AKT pathway from being activated. DA increased intracellular ROS, but N-acetylcysteine (NAC), a ROS scavenger, reduced DA-induced cytotoxicity. NAC also reversed the chances in pPI3K/AKT expression and reduced DA-induced apoptosis. These findings suggest that ROS-mediates DA-induced apoptosis and PI3K/AKT signaling inactivation in human NPC cells.

Isosarcophytoxide Derivatives with a 2,5-Dihydrofuran Moiety from the Soft Coral Sarcophyton cinereum.

The present chemical investigation on the organic extract of the soft coral Sarcophyton cinereum has contributed to the isolation of four new cembranoids: 16ß- and 16α-hydroperoxyisosarcophytoxides (1 and 2), 16ß- and 16α-methoxyisosarcophytoxides (3 and 4), and a known cembranoid, lobocrasol (5). The structures of all isolates were elucidated by detailed spectroscopic analysis. Their structures were characterized by a 2,5-dihydrofuran moiety, of which the relative configuration was determined by DU8-based calculation for long-range coupling constants (4JH,H). The cytotoxicity and immunosuppressive activities of all isolates were evaluated in this study.

Computationally Assisted Structural Elucidation of Cembranoids from the Soft Coral Sarcophyton tortuosum.

A persistent study on soft coral Sarcophyton tortuosum resulted in the characterization of two new cembranolides, tortuolides A and B (1 and 2), and a new related diterpene, epi-sarcophytonolide Q. Their structures were determined not only by extensive spectroscopic analysis but also by DFT calculations of ECD and NMR data, the latter of which was combined with statistical analysis methods, e.g., DP4+ and J-DP4 approaches. Anti-inflammatory and cytotoxicity activities were evaluated in this study.

Cembranolides and Related Constituents from the Soft Coral Sarcophyton cinereum.

In an attempt to explore the bioactive metabolites of the soft coral Sarcophyton cinereum, three new cembranolides, cinerenolides A-C (1-3), and 16 known compounds were isolated and identified from the EtOAc extract. The structures of the new cembranolides were elucidated on the basis of spectroscopic analysis, and the NOE analysis of cinerenolide A (1) was performed with the assistance of the calculated lowest-energy molecular model. The relative configuration of cinerenolide C (3) was determined by the quantum chemical NMR calculation, followed by applying DP4+ analysis. In addition, the cytotoxic assays disclosed that some compounds exhibited moderate to potent activities in the proliferation of P388, DLD-1, HuCCT-1, and CCD966SK cell lines.

5-epi-Sinuleptolide from Soft Corals of the Genus Sinularia Exerts Cytotoxic Effects on Pancreatic Cancer Cell Lines via the Inhibition of JAK2/STAT3, AKT, and ERK Activity.

Pancreatic ductal adenocarcinoma is one of the most lethal malignancies: more than half of patients are diagnosed with a metastatic disease, which is associated with a five-year survival rate of only 3%. 5-epi-Sinuleptolide, a norditerpene isolated from Sinularia sp., has been demonstrated to possess cytotoxic activity against cancer cells. However, the cytotoxicity against pancreatic cancer cells and the related mechanisms are unknown. The aim of this study was to evaluate the anti-pancreatic cancer potential of 5-epi-sinuleptolide and to elucidate the underlying mechanisms. The inhibitory effects of 5-epi-sinuleptolide treatment on the proliferation of pancreatic cancer cells were determined and the results showed that 5-epi-sinuleptolide treatment inhibited cell proliferation, induced apoptosis and G2/M cell cycle arrest, and suppressed the invasion of pancreatic cancer cells. The results of western blotting further revealed that 5-epi-sinuleptolide could inhibit JAK2/STAT3, AKT, and ERK phosphorylation, which may account for the diverse cytotoxic effects of 5-epi-sinuleptolide. Taken together, our present investigation unveils a new therapeutic and anti-metastatic potential of 5-epi-sinuleptolide for pancreatic cancer treatment.

Cherbonolides M and N from a Formosan Soft Coral Sarcophyton cherbonnieri.

Two new isosarcophine derivatives, cherbonolides M (1) and N (2), were further isolated from a Formosan soft coral Sarcophyton cherbonnieri. The planar structure and relative configuration of both compounds were established by the detailed analysis of the IR, MS, and 1D and 2D NMR data. Further, the absolute configuration of both compounds was determined by the comparison of CD spectra with that of isosarcophine (3). Notably, cherbonolide N (2) possesses the unique cembranoidal scaffold of tetrahydrooxepane with the 12,17-ether linkage fusing with a γ-lactone. In addition, the assay for cytotoxicity of both new compounds revealed that they showed to be noncytotoxic toward the proliferation of A549, DLD-1, and HuCCT-1 cell lines. Moreover, the anti-inflammatory activities of both metabolites were carried out by measuring the N-formyl-methionyl-leucyl-phenylalanine/cytochalasin B (fMLF/CB)-induced generation of superoxide anion and elastase release in the primary human neutrophils. Cherbonolide N (2) was found to reduce the generation of superoxide anion (20.6 ± 6.8%) and the elastase release (30.1 ± 3.3%) in the fMLF/CB-induced human neutrophils at a concentration of 30 µM.

An Anti-Inflammatory 2,4-Cyclized-3,4-Secospongian Diterpenoid and Furanoterpene-Related Metabolites of a Marine Sponge Spongia sp. from the Red Sea.

Chemical investigation of a Red Sea Spongia sp. led to the isolation of four new compounds, i.e., 17-dehydroxysponalactone (1), a carboxylic acid, spongiafuranic acid A (2), one hydroxamic acid, spongiafuranohydroxamic acid A (3), and a furanyl trinorsesterpenoid 16-epi-irciformonin G (4), along with three known metabolites (-)-sponalisolide B (5), 18-nor- 3,17-dihydroxy-spongia-3,13(16),14-trien-2-one (6), and cholesta-7-ene-3ß,5α-diol-6-one (7). The biosynthetic pathway for the molecular skeleton of 1 and related compounds was postulated for the first time. Anti-inflammatory activity of these metabolites to inhibit superoxide anion generation and elastase release in N-formyl-methionyl-leucyl phenylalanine/cytochalasin B (fMLF/CB)-induced human neutrophil cells and cytotoxicity of these compounds toward three cancer cell lines and one human dermal fibroblast cell line were assayed. Compound 1 was found to significantly reduce the superoxide anion generation and elastase release at a concentration of 10 µM, and compound 5 was also found to display strong inhibitory activity against superoxide anion generation at the same concentration. Due to the noncytotoxic activity and the potent inhibitory effect toward the superoxide anion generation and elastase release, 1 and 5 can be considered to be promising anti-inflammatory agents.

New Hydroquinone Monoterpenoid and Cembranoid-Related Metabolites from the Soft Coral Sarcophyton tenuispiculatum.

Chemical investigation of the marine soft coral Sarcophyton tenuispiculatum resulted in the isolation of a 1,4-dihydrobenzoquinone, sarcotenuhydroquinone (1), three new cembranoids, sarcotenusenes A‒C (2‒4), and ten previously reported metabolites 5-14. The chemical structures of all isolated metabolites were determined by detailed spectroscopic analyses. In biological assays, anti-inflammatory, cytotoxic, and peroxisome proliferator-activated receptor γ (PPAR-γ) transcription factor assays of all compounds were performed. None of the isolated compounds were found to exhibit activity in the PPAR-γ transcription factor assay. The anti-inflammatory assays showed that (+)-7α,8ß-dihydroxydeepoxysarcophine (13) inhibited the production of IL-1ß to 56 ± 1% at a concentration of 30 µM in lipopolysaccharide (LPS)-stimulated J774A.1 macrophage cells. In addition, 1 and 2 were found to exhibit cytotoxicity towards a panel of cancer cell lines.

Anti-Inflammatory Cembranoids from a Formosa Soft Coral Sarcophyton cherbonnieri.

The present investigation on chemical constituents of the soft coral Sarcophyton cherbonnieri resulted in the isolation of seven new cembranoids, cherbonolides F-L (1-7). The chemical structures of 1-7 were determined by spectroscopic methods, including infrared, one- and two-dimensional (1D and 2D) NMR (COSY, HSQC, HMBC, and NOESY), MS experiments, and a chemical reduction of hydroperoxide by triphenylphosphine. The anti-inflammatory activities of 1-7 against neutrophil proinflammatory responses were evaluated by measuring their inhibitory ability toward N-formyl-methionyl-leucyl-phenylalanine/cytochalasin B (fMLF/CB)-induced superoxide anion generation and elastase release in primary human neutrophils. The results showed that all isolates exhibited moderate activities, while cherbonolide G (2) and cherbonolide H (3) displayed a more active effect than others on the inhibition of elastase release (48.2% ± 6.2%) and superoxide anion generation (44.5% ± 4.6%) at 30 µM, respectively.

New Biscembranoids Sardigitolides A-D and Known Cembranoid-Related Compounds from Sarcophyton digitatum: Isolation, Structure Elucidation, and Bioactivities.

Chemical examination from the cultured soft coral Sarcophyton digitatum resulted in the isolation and structural identification of four new biscembranoidal metabolites, sardigitolides A-D (1-4), along with three previously isolated biscembranoids, sarcophytolide L (5), glaucumolide A (6), glaucumolide B (7), and two known cembranoids (8 and 9). The chemical structures of all isolates were elucidated on the basis of 1D and 2D NMR spectroscopic analyses. Additionally, in order to discover bioactivity of marine natural products, 1-8 were examined in terms of their inhibitory potential against the upregulation of inflammatory factor production in lipopolysaccharide (LPS)-stimulated murine macrophage J774A.1 cells and their cytotoxicities against a limited panel of cancer cells. The anti-inflammatory results showed that at a concentration of 10 µg/mL, 6 and 8 inhibited the production of IL-1ß to 68 ± 1 and 56 ± 1%, respectively, in LPS-stimulated murine macrophages J774A.1. Furthermore, sardigitolide B (2) displayed cytotoxicities toward MCF-7 and MDA-MB-231 cancer cell lines with the IC50 values of 9.6 ± 3.0 and 14.8 ± 4.0 µg/mL, respectively.

Isolation of Lobane and Prenyleudesmane Diterpenoids from the Soft Coral Lobophytum varium.

Further chemical investigation of the EtOAc extract of the soft coral Lobophytum varium resulted in the discovery of eleven new diterpenoids lobovarols F-P (1-11) of lobane- and prenyleudesmane-types, along with two known metabolites (12 and 13). The structures of the new metabolites were established by spectroscopic analyses, including 2D NMR experiments. The absolute configuration of 1 was determined using Mosher's method. The complete assignment of 1H and 13C NMR spectroscopic data of 12 and 13 and the identification of pyran-derived moieties in the prenyleudesmanes were reported for the first time. Anti-inflammatory activities of the isolated compounds in suppressing elastase release and superoxide anion generation in human neutrophils were disclosed for 1, 2, 4, 12, and 13. A stereospecific biosynthesis for lobanes and prenyleudesmanes from the related prenylgermacranes could explain the coexistence of lobanes and prenylgermacranes in L. varium.

Bioactive Capnosanes and Cembranes from the Soft Coral Klyxum flaccidum.

Two new capnosane-based diterpenoids, flaccidenol A (1) and 7-epi-pavidolide D (2), two new cembranoids, flaccidodioxide (3) and flaccidodiol (4), and three known compounds 5 to 7 were characterized from the marine soft coral Klyxum flaccidum, collected off the coast of the island of Pratas. The structures of the new compounds were determined by extensive spectroscopic analyses, including 1D and 2D nuclear magnetic resonance (NMR) spectroscopy, and spectroscopic data comparison with related structures. The rare capnosane diterpenoids were isolated herein from the genus Klyxum for the first time. The cytotoxicity of compounds 1 to 7 against the proliferation of a limited panel of cancer cell lines was assayed. The isolated diterpenoids also exhibited anti-inflammatory activity through suppression of superoxide anion generation and elastase release in the N-formyl-methionyl-leucyl-phenylalanine/cytochalasin B (fMLF/CB)-stimulated human neutrophils. Furthermore, 1 and 7 also exhibited cytotoxicity toward the tested cancer cells, and 7 could effectively inhibit elastase release. It is worth noting that the biological activities of 7 are reported for the first time in this paper.

Cembranoid-Related Metabolites and Biological Activities from the Soft Coral Sinularia flexibilis.

Five new cembranoid-related diterpenoids, namely, flexibilisins D and E (1 and 2), secoflexibilisolides A and B (3 and 4), and flexibilisolide H (5), along with nine known compounds (6⁻14), were isolated from the soft coral Sinularia flexibilis. Their structures were established by extensive spectral analysis. Compound 3 possesses an unusual skeleton that could be biogenetically derived from cembranoids. The cytotoxicity and anti-inflammatory activities of the isolates were investigated, and the results showed that dehydrosinulariolide (7) and 11-epi-sinulariolide acetate (8) exhibited cytotoxicity toward a limited panel of cancer cell lines and 14-deoxycrassin (9) displayed anti-inflammatory activity by inhibition of superoxide anion generation and elastase release in N-formyl-methionyl-leucyl-phenylalanine/cytochalasin B (fMLF/CB)-induced human neutrophils.

New Cembranoids and a Biscembranoid Peroxide from the Soft Coral Sarcophyton cherbonnieri.

Six new cembranoids, cherbonolides A-E (1⁻5) and bischerbolide peroxide (6), along with one known cembranoid, isosarcophine (7), were isolated from the Formosan soft coral Sarcophyton cherbonnieri. The structures of these compounds were elucidated by detailed spectroscopic analysis and chemical methods. Compound 6 was discovered to be the first example of a molecular skeleton formed from two cembranoids connected by a peroxide group. Compounds 1⁻7 were shown to have the ability of inhibiting the production of superoxide anions and elastase release in N-formyl-methionyl-leucyl-phenyl-alanine/cytochalasin B (fMLF/CB)-induced human neutrophils.

A Sterol from Soft Coral Induces Apoptosis and Autophagy in MCF-7 Breast Cancer Cells.

The peroxisome proliferator-activated receptor γ (PPARγ) is a nuclear receptor that plays a key role in regulating cellular metabolism, and is a therapeutic target for cancer therapy. To search for potential PPARγ activators, a compound library comprising 11 marine compounds was examined. Among them, a sterol, 3ß,11-dihydroxy-9,11-secogorgost-5-en-9-one (compound 1), showed the highest PPARγ activity with an IC50 value of 8.3 µM for inhibiting human breast adenocarcinoma cell (MCF-7) growth. Western blotting experiments showed that compound 1 induces caspase activation and PARP cleavage. In addition, compound 1 modulated the expression of various PPARγ-regulated downstream biomarkers including cyclin D1, cyclin-dependent kinase (CDK)6, B-cell lymphoma 2 (Bcl-2), p38, and extracellular-signal-regulated kinase (ERK). Moreover, compound 1 increased reactive oxygen species (ROS) generation, upregulated the phosphorylation and expression of H2AX, and induced autophagy. Interestingly, pre-treatment with the autophagy inhibitor 3-methyladenine rescued cells from compound 1-induced growth inhibition, which indicates that the cytotoxic effect of compound 1 is, in part, attributable to its ability to induce autophagy. In conclusion, these findings suggest the translational potential of compound 1 in breast cancer therapy.

Correction: Huang, H.W.; et al. Sinularin Selectively Kills Breast Cancer Cells Showing G2/M Arrest, Apoptosis, and Oxidative DNA Damage. Molecules 2018, 23, 849.

The authors wish to make the following correction to their paper [1].[...].

Lobohedleolide suppresses hepatitis C virus replication via JNK/c-Jun-C/EBP-mediated down-regulation of cyclooxygenase-2 expression.

Hepatitis C virus (HCV) chronically infects 2-3% people of the global population, which leads to liver cirrhosis and hepatocellular carcinoma. Drug resistance remains a serious problem that limits the effectiveness of US Food and Drug Administration (FDA)-approved direct-acting antiviral (DAA) drugs against HCV proteins. The objective of our study was to discover new antivirals from natural products to supplement current therapeutics. We demonstrated that lobohedleolide, isolated from the Formosan soft coral Lobophytum crassum, significantly reduced HCV replication in replicon cells and JFH-1 infection system, with EC50 values of 10 ± 0.56 and 22 ± 0.75 µM, respectively, at non-toxic concentrations. We further observed that the inhibitory effect of lobohedleolide on HCV replication is due to suppression of HCV-induced cyclooxygenase-2 (COX-2) expression. Based on deletion-mutant analysis of the COX-2 promoter, we identified CCAAT/enhancer-binding protein (C/EBP) as a key transcription factor for the down-regulation of COX-2 by lobohedleolide, through which lobohedleolide decreased the phosphorylation of c-Jun NH2-terminal protein kinase and c-Jun to suppress HCV-induced C/EBP expression. The combination treatment of lobohedleolide with clinically used HCV drugs synergistically reduced HCV RNA replication, indicating that lobohedleolide exhibited a high biomedical potential to be used as a supplementary therapeutic agent to control HCV infection.

Isolation and Structure Elucidation of Cembranoids from a Dongsha Atoll Soft Coral Sarcophyton stellatum.

Six new polyoxygenated cembrane-based diterpenoids, stellatumolides A⁻C (1⁻3), stellatumonins A and B (4 and 5), and stellatumonone (6), were isolated together with ten known related compounds (7⁻16) from the ethyl acetate (EtOAc) extract of soft coral Sarcophyton stellatum. The structures of the new compounds were established by extensive spectroscopic analyses, including 1D and 2D nuclear magnetic resonance (NMR) spectroscopy and data comparison with related structures. Compounds 8 and 14 were isolated from a natural source for the first time. The isolated metabolites were shown to be not cytotoxic against a limited panel of cancer cells. Compound 9 showed anti-inflammatory activity by reducing the expression of proinflammatory cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) proteins in lipopolysaccharide (LPS)-stimulated mouse leukaemic monocyte macrophage (RAW 264.7) cells.