Extracts from Cladiella australis, Clavularia viridis and Klyxum simplex (Soft Corals) are Capable of Inhibiting the Growth of Human Oral Squamous Cell Carcinoma Cells

Many biomedical products have already been obtained from marine organisms. In order to search more therapeutic drugs against cancer, this study demonstrates the cytotoxicity effects of Cladiella australis, Clavularia viridis and Klyxum simplex extracts on human oral squamous cell carcinoma (SCC4, SCC9 and SCC25) cells using cell adhesion and cell viability assay. The morphological alterations in SCCs cells after treatment with three extracts, such as typical nuclear condensation, nuclear fragmentation and apoptotic bodies of cells were demonstrated by Hoechst stain. Flow cytometry indicated that three extracts sensitized SCC25 cells in the G₀/G₁ and S-G₂/M phases with a concomitant significantly increased sub-G₁ fraction, indicating cell death by apoptosis. This apoptosis process was accompanied by activation of caspase-3 expression after SCC25 cells were treated with three extracts. Thereby, it is possible that extracts of C. australis, C. viridis and K. simplex cause apoptosis of SCCs and warrant further research investigating the possible anti-oral cancer compounds in these soft corals.     

Three New Resveratrol Derivatives from the Mangrove Endophytic Fungus Alternaria sp.

Three new resveratrol derivatives, namely, resveratrodehydes A–C (1–3), were isolated from the mangrove endophytic fungus Alternaria sp. R6. The structures of these compounds were elucidated by analysis of their MS, 1D and 2D NMR spectroscopic data. All compounds showed broad-spectrum inhibitory activities against three human cancer cell lines including human breast MDA-MB-435, human liver HepG2, and human colon HCT-116 by MTT assay (IC₅₀ < 50 μM). Among them, compounds 1 and 2 both exhibited marked cytotoxic activities against MDA-MB-435 and HCT-116 cell lines (IC₅₀ < 10 μM). Additionally, compounds 1 and 3 showed moderate antioxidant activity by DPPH radical scavenging assay.     

New Dimeric Members of the Phomoxanthone Family: Phomolactonexanthones A,B and Deacetylphomoxanthone C Isolated from the Fungus Phomopsis sp.

Three new phomoxanthone compounds, phomolactonexanthones A (1), B (2) and deacetylphomoxanthone C (3), along with five known phomoxanthones, including dicerandrol A (4), dicerandrol B (5), dicerandrol (6), deacetylphomoxanthone B (7) and penexanthone A (8), were isolated in the metabolites of the fungus Phomopsis sp. HNY29-2B, which was isolated from the mangrove plants. The structures of compounds 1–3 were established on the basis of spectroscopic analysis. All compounds were evaluated against four human cancer cell lines including human breast MDA-MB-435, human colon HCT-116, human lung Calu-3 and human liver Huh7 by MTT assay. The compounds 4, 5, 7 and 8 showed cyctotoxic activities against tested cancer cell lines (IC₅₀ < 10 μM).     

Cytotoxic and antimicrobial activity of pseudopterosins and seco-pseudopterosins isolated from the octocoral Pseudopterogorgia elisabethae of San Andrés and Providencia Islands (Southwest Caribbean Sea)

To expand the potential of pseudopterosins and seco-pseudopterosins isolated from the octocoral Pseudopterogorgia elisabethae of San Andrés and Providencia islands (southwest Caribbean Sea), we report the anti-microbial profile against four pathogenic microorganisms (Staphylococcus aureus, Enterococcus faecalis, Pseudomonas aeruginosa and Candida albicans) and report a more complete cytotoxic profile against five human cells lines (HeLa, PC-3, HCT116, MCF-7 and BJ) for the compounds PsG, PsP, PsQ, PsS, PsT, PsU, 3-O-acetyl-PsU, seco-PsJ, seco-PsK and IMNGD. For the cytotoxic profiles, all compounds evaluated showed moderate and non-selective activity against both tumor and normal cell lines, where PsQ and PsG were the most active compounds (GI₅₀ values between 5.8 μM to 12.0 μM). With respect to their anti-microbial activity the compounds showed good and selective activity against the Gram-positive bacteria, while they did not show activity against the Gram-negative bacterium or yeast. PsU, PsQ, PsS, seco-PsK and PsG were the most active compounds (IC₅₀ 2.9–4.5 μM) against S. aureus and PsG, PsU and seco-PsK showed good activity (IC₅₀ 3.1–3.8 μM) against E. faecalis, comparable to the reference drug vancomycin (4.2 μM).     

Klymollins T–X,Bioactive Eunicellin-Based Diterpenoids from the Soft Coral Klyxum molle

Five new eunicellin-based diterpenoids, klymollins T–X (1–5), along with two known compounds (6 and 7) have been isolated from the soft coral Klyxum molle. The structures of these new metabolites were elucidated by extensive spectroscopic analysis and by comparison with related known compounds. Compound 5 was found to exert significant in vitro anti-inflammatory activity against LPS-stimulated RAW264.7 macrophage cells. Furthermore, compounds 4 and 7 were shown to exhibit cytotoxicity against a limited panel of human cancer cell lines.     

Polyoxygenated Steroids from the Octocoral Leptogorgia punicea and in Vitro Evaluation of Their Cytotoxic Activity

Five new polyoxygenated marine steroids—punicinols A–E (1–5)—were isolated from the gorgonian Leptogorgia punicea and characterized by spectroscopic methods (IR, MS, ¹H, ¹³C and 2-D NMR). The five compounds induced in vitro cytotoxic effects against lung cancer A549 cells, while punicinols A and B were the most active, with IC₅₀ values of 9.7 μM and 9.6 μM, respectively. The synergistic effects of these compounds with paclitaxel, as well as their effects on cell cycle distribution and their performance in the clonogenic assay, were also evaluated. Both compounds demonstrated significant synergistic effects with paclitaxel.     

Phenolic Polyketides from the Co-Cultivation of Marine-Derived Penicillium sp. WC-29-5 and Streptomyces fradiae 007

Penicillium sp. WC-29-5 was co-cultured with Streptomyces fradiae 007 to produce five natural products (1–3, 4a and 4b) that were isolated and characterized by spectroscopic analysis. Interestingly, these compounds were found to be different from those produced in discrete fungal and bacterial controls. Among these compounds, the absolute configurations of compounds 4a and 4b were determined for the first time by X-ray single crystal diffraction experiments and electronic circular dichroism (ECD) calculations. An evaluation of the cytotoxic activities of these compounds revealed that 4b was moderately cytotoxic towards HL-60 and H1975 tumor cells with IC₅₀ values of 3.73 and 5.73 µM, respectively, whereas compound 4a was only moderately cytotoxic towards H1975 cells with an IC₅₀ value of 3.97 µM.     

Sphingosines Derived from Marine Sponge as Potential Multi-Target Drug Related to Disorders in Cancer Development

Haliclona tubifera, marine sponge species abundant in Brazilian coastline, presents only a few papers published in the literature. Recently, we have reported the isolation of two modified C18 sphingoid bases: (2R,3R,6R,7Z)-2-aminooctadec-7-ene-1,3,6-triol and and (2R,3R,6R)-2-aminooctadec-1,3,6-triol. In order to continue our research, in this work aimed at the biological investigation of fractions that led to the isolation of these compounds. We evaluated the cytotoxic effect of marine sponge H. tubifera fractions in glioma (U87) and neuroblastoma (SH-SY5Y) human cell lines. In addition, considering the link between cancer, imbalance of reactive oxygen species and coagulation disorders, we also investigated the in vitro effects on blood coagulation and their redox properties. We showed that the ethyl acetate (EtOAc) fraction, rich in sphingoid bases, had important cytotoxic effects in both cancer cell lines with an IC₅₀ < 15 μg/mL and also can inhibit the production of peroxyl radicals. Interestingly, this fraction increased the recalcification time of human blood, showing anticoagulant properties. The present study indicates the sphingosines fraction as a promising source of chemical prototypes, especially multifunctional drugs in cancer therapy.     

Cytotoxic and Apoptosis-Inducing Activity of Triterpene Glycosides from Holothuria scabra and Cucumaria frondosa against HepG2 Cells

The cytotoxic effects of thirteen triterpene glycosides from Holothuria scabra Jaeger and Cucumaria frondosa Gunnerus (Holothuroidea) against four human cell lines were detected and their cytotoxicity-structure relationships were established. The apoptosis-inducing activity of a more potent glycoside echinoside A (1) in HepG2 cells was further investigated by determining its effect on the morphology, mitochondrial transmembrane potential (Δψ_m) and mRNA expression levels of the apoptosis-related genes. The results showed that the number of glycosyl residues in sugar chains and the side chain of aglycone could affect their cytotoxicity towards tumor cells and selective cytotoxicity. 1 significantly inhibited cell viability and induced apoptosis in HepG2 cells. 1 also markedly decreased the Δψ_m and Bcl-2/Bax mRNA express ratio, and up-regulated the mRNA expression levels of Caspase-3, Caspase-8 and Caspase-9 in HepG2 cells. Therefore, 1 induced apoptosis in HepG2 cells through both intrinsic and extrinsic pathway. These findings could potentially promote the usage of these glycosides as leading compounds for developing new antitumor drugs.     

Apoptogenic Metabolites in Fractions of the Benthic Diatom Cocconeis scutellum parva

Benthic diatoms of the genus Cocconeis contain a specific apoptogenic activity. It triggers a fast destruction of the androgenic gland in the early post-larval life of the marine shrimp Hippolyte inermis, leading to the generation of small females. Previous in vitro investigations demonstrated that crude extracts of these diatoms specifically activate a dose-dependent apoptotic process in human cancer cells (BT20 breast carcinoma) but not in human normal lymphocytes. Here, a bioassay-guided fractionation has been performed to detect the apoptogenic compound(s). Various HPLC separation systems were needed to isolate the active fractions, since the apoptogenic metabolite is highly active, present in low amounts and is masked by abundant but non-active cellular compounds. The activity is due to at least two compounds characterized by different polarities, a hydrophilic and a lipophilic fraction. We purified the lipophilic fraction, which led to the characterization of an active sub-fraction containing a highly lipophilic compound, whose molecular structure has not yet been identified, but is under investigation. The results point to the possible medical uses of the active compound. Once the molecular structure has been identified, the study and modulation of apoptotic processes in various types of cells will be possible.     

Pseudaboydins A and B: Novel Isobenzofuranone Derivatives from Marine Fungus Pseudallescheria boydii Associated with Starfish Acanthaster planci

Two novel isobenzofuranone derivatives, pseudaboydins A (1) and B (2), along with five known compounds, including (R)-2-(2-hydroxypropan-2-yl)-2,3-dihydro-5-hydroxybenzofuran (3), (R)-2-(2-hydroxypropan-2-yl)-2,3-dihydro-5-methoxybenzofuran (4), 3,3′-dihydroxy-5,5′-dimethyldiphenyl ether (5), 3-(3-methoxy-5-methylphenoxy)-5-methylphenol (6) and (−)-regiolone (7), were isolated from the culture broth of the marine fungus, Pseudallescheria boydii, associated with the starfish, Acanthaster planci. Their structures were elucidated primarily based on NMR and MS data. The absolute configurations of 1–4 were determined by CD spectroscopy and single-crystal X-ray diffraction studies. The cytotoxic and antibacterial activities of 1–4 were evaluated. Pseudaboydin A (1) showed moderate cytotoxic activity against human nasopharyngeal carcinoma cell line HONE1, human nasopharyngeal carcinoma cell line SUNE1 and human glandular lung cancer cell line GLC82 with IC₅₀ values of 37.1, 46.5 and 87.2 μM, respectively.     

Cespitulones A and B,Cytotoxic Diterpenoids of a New Structure Class from the Soft Coral Cespitularia taeniata

Two novel diterpenoids, cespitulones A (1) and B (2), were isolated from extracts of the soft coral Cespitularia taeniata. Both compounds possess an unprecedented bicyclo [10.3.1] ring system with C-C bond connections between C-10 and C-20, and between C-20 and C-11. Their structures were elucidated on the basis of extensive spectroscopic analyses. Compound 1 exhibited significant cytotoxicity against human medulloblastoma and colon adenocarcinoma cancer cells.     

Antitumor and Antimicrobial Potential of Bromoditerpenes Isolated from the Red Alga,Sphaerococcus coronopifolius

Cancer and infectious diseases continue to be a major public health problem, and new drugs are necessary. As marine organisms are well known to provide a wide range of original compounds, the aim of this study was to investigate the bioactivity of the main constituents of the cosmopolitan red alga, Sphaerococcus coronopifolius. The structure of several bromoditerpenes was determined by extensive spectroscopic analysis and comparison with literature data. Five molecules were isolated and characterized which include a new brominated diterpene belonging to the rare dactylomelane family and named sphaerodactylomelol (1), along with four already known sphaerane bromoditerpenes (2–5). Antitumor activity was assessed by cytotoxicity and anti-proliferative assays on an in vitro model of human hepatocellular carcinoma (HepG-2 cells). Antimicrobial activity was evaluated against four pathogenic microorganisms: Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Candida albicans. Compound 4 exhibited the highest antimicrobial activity against S. aureus (IC₅₀ 6.35 µM) and compound 5 the highest anti-proliferative activity on HepG-2 cells (IC₅₀ 42.9 µM). The new diterpene, sphaerodactylomelol (1), induced inhibition of cell proliferation (IC₅₀ 280 µM) and cytotoxicity (IC₅₀ 720 µM) on HepG-2 cells and showed antimicrobial activity against S. aureus (IC₅₀ 96.3 µM).     

Methylthio-Aspochalasins from a Marine-Derived Fungus Aspergillus sp.

Two novel aspochalasins, 20-β-methylthio-aspochalsin Q (named as aspochalasin V), (1) and aspochalasin W (2), were isolated from culture broth of Aspergillus sp., which was found in the gut of a marine isopod Ligia oceanica. The structures were determined on the basis of NMR and mass spectral data analysis. This is the first report about methylthio-substituted aspochalasin derivatives. Cytotoxicity against the prostate cancer PC3 cell line and HCT116 cell line was assayed using the MTT method. Apochalasin V showed moderate activity at IC₅₀ values of 30.4 and 39.2 μM, respectively.     

Cladieunicellins M–Q,New Eunicellins from Cladiella sp.

Five new 7α-hydroxyeunicellin-based diterpenoids, designated as cladieunicellins M–Q (1–5), were isolated from a Formosan octocoral Cladiella sp. The structures of 1–5 were elucidated on the basis of spectroscopic methods and by comparison of the data with those of the related metabolites. Cytotoxicity of metabolites 1–5 against the human leukemia Molt 4 and HL 60 is also described. Among them, compounds 1, 3 and 5 exhibited moderate cytotoxicity toward Molt 4 cells with IC₅₀ values 16.43, 14.17 and 15.55 μM, respectively. Preliminary SAR (structure activity relationship) information was obtained from these compounds and their analogues.     

Bioactive Secondary Metabolites from the Red Sea Marine Verongid Sponge Suberea Species

In a continuation of our efforts to identify bioactive compounds from Red Sea Verongid sponges, the organic extract of the sponge Suberea species afforded seven compounds including two new dibrominated alkaloids, subereamollines C and D (1 and 2), together with the known compounds aerothionin (3), homoaerothionin (4), aeroplysinin-1 (5), aeroplysinin-2 (6) and a revised subereaphenol C (7) as ethyl 2-(2,4-dibromo-3,6-dihydroxyphenyl)acetate. The structures of the isolated compounds were assigned by different spectral data including optical rotations, 1D (¹H and ¹³C) and 2D (COSY, multiplicity-edited HSQC, and HMBC) NMR and high-resolution mass spectroscopy. Aerothionin (3) and subereaphenol C (7) displayed potent cytotoxic activity against HeLa cell line with IC₅₀ values of 29 and 13.3 µM, respectively. In addition, aeroplysinin-2 (6) showed potent antimigratory activity against the human breast cancer cell line MDA-MB-231 with IC₅₀ of 18 µM. Subereamollines C and D are new congeners of the previously reported compounds subereamollines A and B with methyl ester functionalities on the side chain. These findings provide further insight into the biosynthetic capabilities of members of the genus Suberea and the chemical diversity as well as the biological activity of these compounds.     

6-Bromohypaphorine from Marine Nudibranch Mollusk Hermissenda crassicornis is an Agonist of Human α7 Nicotinic Acetylcholine Receptor

6-Bromohypaphorine (6-BHP) has been isolated from the marine sponges Pachymatisma johnstoni, Aplysina sp., and the tunicate Aplidium conicum, but data on its biological activity were not available. For the nudibranch mollusk Hermissenda crassicornis no endogenous compounds were known, and here we describe the isolation of 6-BHP from this mollusk and its effects on different nicotinic acetylcholine receptors (nAChR). Two-electrode voltage-clamp experiments on the chimeric α7 nAChR (built of chicken α7 ligand-binding and glycine receptor transmembrane domains) or on rat α4β2 nAChR expressed in Xenopus oocytes revealed no action of 6-BHP. However, in radioligand analysis, 6-BHP competed with radioiodinated α-bungarotoxin for binding to human α7 nAChR expressed in GH₄C₁ cells (IC₅₀ 23 ± 1 μM), but showed no competition on muscle-type nAChR from Torpedo californica. In Ca²⁺-imaging experiments on the human α7 nAChR expressed in the Neuro2a cells, 6-BHP in the presence of PNU120596 behaved as an agonist (EC₅₀ ~80 μM). To the best of our knowledge, 6-BHP is the first low-molecular weight compound from marine source which is an agonist of the nAChR subtype. This may have physiological importance because H. crassicornis, with its simple and tractable nervous system, is a convenient model system for studying the learning and memory processes.     

Identification and Bioactivity of Compounds from the Fungus Penicillium sp. CYE-87 Isolated from a Marine Tunicate

In the course of our continuous interest in identifying bioactive compounds from marine microbes, we have investigated a tunicate-derived fungus, Penicillium sp. CYE-87. A new compound with the 1,4-diazepane skeleton, terretrione D (2), together with the known compounds, methyl-2-([2-(1H-indol-3-yl)ethyl]carbamoyl)acetate (1), tryptamine (3), indole-3-carbaldehyde (4), 3,6-diisobutylpyrazin-2(1H)-one (5) and terretrione C (6), were isolated from Penicillium sp. CYE-87. The structures of the isolated compounds were established by spectral analysis, including 1D (¹H, ¹³C) and 2D (COSY, multiplicity edited-HSQC and HMBC) NMR and HRESIMS, as well as comparison of their NMR data with those in the literature. The compounds were evaluated for their antimigratory activity against the human breast cancer cell line (MDA-MB-231) and their antiproliferation activity against HeLa cells. Compounds 2 and 6 showed significant antimigratory activity against MDA-MB-231, as well as antifungal activity against C. albicans.