Marine compounds selectively induce apoptosis in female reproductive cancer cells but not in primary-derived human reproductive granulosa cells

Synthesis of Marine-Inspired Multifaceted DNA Damaging Spirooxindoles Combating NSCLC and Associated Bacterial Infection

Targeted therapeutics have gained prominence in combating non-small cell lung carcinoma (NSCLC) and opportunistic bacterial infections like Staphylococcus aureus (S. aureus). This study explores dual-acting marine-inspired spirooxindoles to limit NSCLC and opportunistic bacteria. Pharmacophoric motifs from antitumor and antibacterial marine products were merged into a new series of pyrazole-clubbed spirooxindoles via a stereoselective [3 + 2] cycloaddition reaction. MTT screening identified 4e, 4i, and 4p-4s as potent cytotoxic agents, with 4p showing exceptional activity (IC50 = 0.042 μM) and tumor selectivity (SI = 58.28). 4p exhibited antibacterial efficacy against S. aureus (MIC = 25 μg/mL). DNA damage studies using a terbium(III) chloride biosensor revealed 4p's ability to damage both calf thymus and S. aureus DNA at low concentrations. Docking simulations presumed that 4p binds between DNA strands, while apoptosis studies indicated it induced G1/S phase cell cycle arrest and increased A549 apoptosis by 33.65%. These findings highlight 4p as a promising lead for further studies.

Galaxamide alleviates cisplatin-induced premature ovarian insufficiency via the PI3K signaling pathway in HeLa tumor-bearing mice

BACKGROUND

It is challenging to improve the effects of chemotherapy and reduce its adverse impact on the ovaries. Our previous study suggested that the combination of galaxamide could enhance the antitumor effect of cisplatin (CIS) in HeLa cell xenograft mice. However, their potential effects on ovarian tissues remain unknown.

METHODS

The Hela tumor-bearing female BALB/c mice model was established and randomly divided into three groups: control group (PBS group), CIS group (0.3 mg/kg CIS group) and galaxamide group (0.3 mg/kg CIS + 3 mg/kg galaxamide-treated group). The serum sex hormones levels, ovarian morphology, functional and molecular characterisation were determined and compared with those of the control group.

RESULTS

The hormonal effects indicated premature ovarian insufficiency (POI) associated with CIS-induced tumor-bearing mice. CIS induces the apoptosis in primordial and developing follicles and subsequently increases follicular atresia, eventually leading to follicle loss. After cotreatment, galaxamide significantly increased anti-Mullerian hormone (AMH) and follicle-stimulating hormone receptor (FSHR) expression and prevented the CIS-induced PI3K pathway, which triggers follicle activation, apoptosis or atresia.

CONCLUSION

These findings demonstrate that galaxamide could attenuate CIS-induced follicle loss by acting on the PI3K signaling pathway by stimulating AMH and/or FSHR and thus provides promising therapeutic options for patients with cervical cancer.

Microbial diversity of garden snail mucus

The search for new natural compounds for application in medicine and cosmetics is a trend in biotechnology. One of the sources of such active compounds is the snail mucus. Snail physiology and the biological activity of their fluids (especially the mucus) are still poorly studied. Only a few previous studies explored the relationship between snails and their microbiome. The present study was focused on the biodiversity of the snail mucus used in the creation of cosmetic products, therapeutics, and nutraceuticals. The commonly used cultivation techniques were applied for the determination of the number of major bacterial groups. Fluorescence in situ hybridization for key taxa was performed. The obtained images were subjected to digital image analysis. Sequencing of the 16S rRNA gene was also done. The results showed that the mucus harbors a rich bacterial community (10.78 × 1010  CFU/ml). Among the dominant bacteria, some are known for their ability to metabolize complex polysaccharides or are usually found in soil and plants (Rhizobiaceae, Shewanella, Pedobacter, Acinetobacter, Alcaligenes). The obtained data demonstrated that the snail mucus creates a unique environment for the development of the microbial community that differs from other parts of the animal and which resulted from the combined contribution of the microbiomes derived from the soil, plants, and the snails.

Molluscan Compounds Provide Drug Leads for the Treatment and Prevention of Respiratory Disease

Respiratory diseases place an immense burden on global health and there is a compelling need for the discovery of new compounds for therapeutic development. Here, we identify research priorities by critically reviewing pre-clinical and clinical studies using extracts and compounds derived from molluscs, as well as traditional molluscan medicines, used in the treatment of respiratory diseases. We reviewed 97 biomedical articles demonstrating the anti-inflammatory, antimicrobial, anticancer, and immunomodulatory properties of >320 molluscan extracts/compounds with direct relevance to respiratory disease, in addition to others with promising bioactivities yet to be tested in the respiratory context. Of pertinent interest are compounds demonstrating biofilm inhibition/disruption and antiviral activity, as well as synergism with approved antimicrobial and chemotherapeutic agents. At least 100 traditional medicines, incorporating over 300 different mollusc species, have been used to treat respiratory-related illness in cultures worldwide for thousands of years. These medicines provide useful clues for the discovery of bioactive components that likely underpin their continued use. There is particular incentive for investigations into anti-inflammatory compounds, given the extensive application of molluscan traditional medicines for symptoms of inflammation, and shells, which are the principal molluscan product used in these preparations. Overall, there is a need to target research toward specific respiratory disease-related hypotheses, purify bioactive compounds and elucidate their chemical structures, and develop an evidence base for the integration of quality-controlled traditional medicines.

Almehizia A, Al-Ansary GH. Marine-Inspired Bis-indoles Possessing Antiproliferative Activity against Breast Cancer; Design, Synthesis, and Biological Evaluation

Diverse indoles and bis-indoles extracted from marine sources have been identified as promising anticancer leads. Herein, we designed and synthesized novel bis-indole series 7a-f and 9a-h as Topsentin and Nortopsentin analogs. Our design is based on replacing the heterocyclic spacer in the natural leads by a more flexible hydrazide linker while sparing the two peripheral indole rings. All the synthesized bis-indoles were examined for their antiproliferative action against human breast cancer (MCF-7 and MDA-MB-231) cell lines. The most potent congeners 7e and 9a against MCF-7 cells (IC50 = 0.44 ± 0.01 and 1.28 ± 0.04 μM, respectively) induced apoptosis in MCF-7 cells (23.7-, and 16.8-fold increase in the total apoptosis percentage) as evident by the externalization of plasma membrane phosphatidylserine detected by Annexin V-FITC/PI assay. This evidence was supported by the Bax/Bcl-2 ratio augmentation (18.65- and 11.1-fold compared to control) with a concomitant increase in the level of caspase-3 (11.7- and 9.5-fold) and p53 (15.4- and 11.75-fold). Both compounds arrested the cell cycle mainly in the G2/M phase. Furthermore, 7e and 9a displayed good selectivity toward tumor cells (S.I. = 38.7 and 18.3), upon testing of their cytotoxicity toward non-tumorigenic breast MCF-10A cells. Finally, compounds 7a, 7b, 7d, 7e, and 9a were examined for their plausible CDK2 inhibitory action. The obtained results (% inhibition range: 16%-58%) unveiled incompetence of the target bis-indoles to inhibit CDK2 significantly. Collectively, these results suggested that herein reported bis-indoles are good lead compounds for further optimization and development as potential efficient anti-breast cancer drugs.

Gamma Tocopherol Reduced Chemotherapeutic-Induced ROS in an Ovarian Granulosa Cell Line, But Not in Breast Cancer Cell Lines In Vitro

Doxorubicin and cyclophosphamide are used to treat breast cancer, but they also cause infertility through off-target cytotoxicity towards proliferating granulosa cells that surround eggs. Each chemotherapeutic generates reactive oxygen species (ROS) but the effects of the combination, or the antioxidants alpha (αToc) and gamma tocopherol (γToc) on ROS in breast cancer or ovarian cells are unknown. Human breast cancer (MCF7, T47D) and ovarian cancer (OVCAR, COV434) cells were loaded with DCDFA and exposed (1, 2, 3, 24 h) to the MCF7-derived EC25 values of individual agents, or to combinations of these. ROS were quantified and viable cells enumerated using crystal violet or DAPI. Each chemotherapeutic killed ~25% of MCF7, T47D and OVCAR cells, but 57 ± 2% (doxorubicin) and 66 ± 2% (cyclophosphamide) of the COV434 granulosa cells. The combined chemotherapeutics decreased COV434 cell viability to 34 ± 5% of control whereas doxorubicin + cyclophosphamide + γToc reduced ROS within 3 h (p < 0.01) and reduced cytotoxicity to 54 ± 4% (p < 0.05). αToc was not cytotoxic, whereas γToc killed ~25% of the breast cancer but none of the ovarian cells. Adding γToc to the combined chemotherapeutics did not change ROS or cytotoxicity in MCF7, T47D or OVCAR cells. The protection γToc afforded COV434 granulosa cells against chemotherapy-induced ROS and cytotoxicity suggests potential for fertility preservation.

Isatins Inhibit N5-CAIR Synthetase by a Substrate Depletion Mechanism

The continued rise of antibiotic-resistant infections coupled with the limited pipeline of new antimicrobials highlights the pressing need for the development of new antibacterial agents. One potential pathway for new agents is de novo purine biosynthesis as studies have shown that bacteria and lower eukaryotes synthesize purines differently than humans. Microorganisms utilize two enzymes, N⁵-CAIR synthetase and N⁵-CAIR mutase, to convert 5-aminoimidazole ribonucleotide (AIR) into 4-carboxy-5-aminoimidazole ribonucleotide (CAIR) through the intermediate N⁵-carboxy-5-aminoimidazole ribonucleotide (N⁵-CAIR). In contrast, vertebrates directly convert AIR to CAIR via the enzyme AIR carboxylase. A high-throughput screen against N⁵-CAIR synthetase identified a group of compounds with a 2,3-indolinedione (isatin) core that inhibited the enzyme. While initial studies suggested that isatins inhibited the enzyme by a noncompetitive mechanism, here we show that isatins inhibit N⁵-CAIR synthetase by a substrate depletion mechanism. Unexpectedly, we found that isatin reacts rapidly and reversibly with the substrate AIR. The rate of the reaction is dependent upon the substituents on the phenyl moiety of isatin, with 5- and 7-bromoisatin being faster than 4-bromoisatin. These studies suggest that care should be taken when exploring isatin compounds because the biological activity could be a result of their reactivity.

Bioactive Compounds Isolated from Neglected Predatory Marine Gastropods

A diverse range of predatory marine gastropods produce toxins, yet most of these molecules remain uncharacterized. Conus species have received the most attention from researchers, leading to several conopeptides reaching clinical trials. This review aims to summarize what is known about bioactive compounds isolated from species of neglected marine gastropods, especially in the Turridae, Terebridae, Babyloniidae, Muricidae, Buccinidae, Colubrariidae, Nassariidae, Cassidae, and Ranellidae families. Multiple species have been reported to contain bioactive compounds with potential toxic activity, but most of these compounds have not been characterized or even clearly identified. The bioactive properties and potential applications of echotoxins and related porins from the Ranellidae family are discussed in more detail. Finally, the review concludes with a call for research on understudied species.

Brominated indoles from a marine mollusc inhibit inflammation in a murine model of acute lung injury

New drug leads for the treatment of inflammation are urgently needed. Marine molluscs are widely used as traditional medicines for the treatment of inflammation. Here we report the positive effects of a hypobranchial gland (HBG) extract and the dominant bioactive compound 6-bromoisatin from the Muricidae mollusc Dicathais orbita, for reducing lipopolysaccharide (LPS) induced acute lung inflammation in a mouse model. Both 6-bromoisatin and the HBG extract suppressed the inflammatory response in mice that were pre-treated by oral gavage at 48, 24 and 1 h prior to LPS infusion. The inflammatory antagonists were tested at concentrations of 0.5 mg/g and 0.1 mg/g HBG extract and 0.1 mg/g and 0.05 mg/g 6-bromoisatin in carrier oil and all treatments reduced inflammation as indicated by a significant suppression of inflammatory markers present in bronchoalveolar lavage fluid (BALF), in comparison to LPS induced positive control mice administered the carrier oil alone (p < 0.0001). Tumour necrosis factor-alpha (TNFα) and interleukin-1 beta (IL-1β) levels, in addition to total protein concentration were all significantly reduced in BALF from mice treated with the extract or 6-bromoisatin. Furthermore, all treatment groups showed significant reductions in neutrophil sequestration and preservation of the lung tissue architecture compared to the positive control (p < 0.0001). The combined results from this study and our previous in vitro studies indicate that 6-bromoisatin in the HGB extracts inhibit the activation of inflammatory signalling pathway. The results from this study further confirm that the HBG extract from Muricidae molluscs and 6-bromoisatin are bioavailable and effective in vivo, thus have potential for development as natural therapeutic agents for inflammation.

An Updated Review on Marine Anticancer Compounds: The Use of Virtual Screening for the Discovery of Small-Molecule Cancer Drugs

Marine secondary metabolites are a promising source of unexploited drugs that have a wide structural diversity and have shown a variety of biological activities. These compounds are produced in response to the harsh and competitive conditions that occur in the marine environment. Invertebrates are considered to be among the groups with the richest biodiversity. To date, a significant number of marine natural products (MNPs) have been established as antineoplastic drugs. This review gives an overview of MNPs, both in research or clinical stages, from diverse organisms that were reported as being active or potentially active in cancer treatment in the past seventeen years (from January 2000 until April 2017) and describes their putative mechanisms of action. The structural diversity of MNPs is also highlighted and compared with the small-molecule anticancer drugs in clinical use. In addition, this review examines the use of virtual screening for MNP-based drug discovery and reveals that classical approaches for the selection of drug candidates based on ADMET (absorption, distribution, metabolism, excretion, and toxicity) filtering may miss potential anticancer lead compounds. Finally, we introduce a novel and publically accessible chemical library of MNPs for virtual screening purposes.

Anti-Inflammatory Activity and Structure-Activity Relationships of Brominated Indoles from a Marine Mollusc

Marine molluscs are rich in biologically active natural products that provide new potential sources of anti-inflammatory agents. Here we used bioassay guided fractionation of extracts from the muricid Dicathais orbita to identify brominated indoles with anti-inflammatory activity, based on the inhibition of nitric oxide (NO) and tumour necrosis factor α (TNFα) in lipopolysaccharide (LPS) stimulated RAW264.7 macrophages and prostaglandin E2 (PGE2) in calcium ionophore-stimulated 3T3 ccl-92 fibroblasts. Muricid brominated indoles were then compared to a range of synthetic indoles to determine structure-activity relationships. Both hypobranchial gland and egg extracts inhibited the production of NO significantly with IC₅₀ of 30.8 and 40 μg/mL, respectively. The hypobranchial gland extract also inhibited the production of TNFα and PGE2 with IC₅₀ of 43.03 µg/mL and 34.24 µg/mL, respectively. The purified mono-brominated indole and isatin compounds showed significant inhibitory activity against NO, TNFα, and PGE2, and were more active than dimer indoles and non-brominated isatin. The position of the bromine atom on the isatin benzene ring significantly affected the activity, with 5Br > 6Br > 7Br. The mode of action for the active hypobranchial gland extract, 6-bromoindole, and 6-bromoisatin was further tested by the assessment of the translocation of nuclear factor kappa B (NFκB) in LPS-stimulated RAW264.7 mouse macrophage. The extract (40 µg/mL) significantly inhibited the translocation of NFκB in the LPS-stimulated RAW264.7 macrophages by 48.2%, whereas 40 µg/mL of 6-bromoindole and 6-bromoistain caused a 60.7% and 63.7% reduction in NFκB, respectively. These results identify simple brominated indoles as useful anti-inflammatory drug leads and support the development of extracts from the Australian muricid D. orbita, as a new potential natural remedy for the treatment of inflammation.

Simultaneous Assessment of the Efficacy and Toxicity of Marine Mollusc-Derived Brominated Indoles in an In Vivo Model for Early Stage Colon Cancer

The acute apoptotic response to genotoxic carcinogens animal model has been extensively used to assess the ability of drugs and natural products like dietary components to promote apoptosis in the colon and protect against colorectal cancer (CRC). This work aimed to use this model to identify the main chemopreventative agent in extracts from an Australian mollusc Dicathais orbita, while simultaneously providing information on their potential in vivo toxicity. After 2 weeks of daily oral gavage with bioactive extracts and purified brominated indoles, mice were injected with the chemical carcinogen azoxymethane (AOM; 10 mg/kg) and then killed 6 hours later. Efficacy was evaluated using immunohistochemical and hematoxylin staining, and toxicity was assessed via hematology, blood biochemistry, and liver histopathology. Comparison of saline- and AOM-injected controls revealed that potential toxic side effects can be interpreted from blood biochemistry and hematology using this short-term model, although AOM negatively affected the ability to detect histopathological effects in the liver. Purified 6-bromoisatin was identified as the main cancer preventive agent in the Muricidae extract, significantly enhancing apoptosis and reducing cell proliferation in the colonic crypts at 0.05 mg/g. There was no evidence of liver toxicity associated with 6-bromoisatin, whereas 0.1 mg/g of the brominated indole tyrindoleninone led to elevated aspartate aminotransferase levels and a reduction in red blood cells. As tyrindoleninone is converted to 6-bromoisatin by oxidation, this information will assist in the optimization and quality control of a chemopreventative nutraceutical from Muricidae. In conclusion, preliminary data on in vivo safety can be simultaneously collected when testing the efficacy of new natural products, such as 6-bromoisatin from Muricidae molluscs for early stage prevention of colon cancer.

Evaluation of the Cytotoxic Effect of the Brittle Star (Ophiocoma Erinaceus) Dichloromethane Extract and Doxorubicin on EL4 Cell Line

Leukemia is a blood disease that creates from inhibition of differentiation and increased proliferation rate. The nature has been known as a rich source of medically useful substances. High diversity of bioactive molecules, extracted from marine invertebrates, makes them as ideal candidates for cancer research. The study has been done to investigate cytotoxic effects of dichloromethane brittle star extract and doxorubicin on EL4 cancer cells. Blood cancer EL4 cells were cultured and treated at different concentrations of brittle star (Ophiocoma erinaceus) dichloromethane extract at 24, 48 and 72 h. Cell toxicity was studied using MTT assay. Cell morphology was examined using an invert microscope. Further, apoptosis was examined using Annexin V-FITC, propodium iodide, DAPI, and Acridine orange/propodium iodide staining. Eventually, the apoptosis pathways were analyzed using measurement of Caspase-3 and -9 activity. The statistical analysis was performed using SPSS, ANOVA software, and Tukey's test. P<0.05 was considered to be significant. MTT assay and morphological observations showed that dichloromethane extract can inhibit cell growth in a dose dependent. The results considered 32 µg/mL of the extract as IC50. Also, doxorubicin suppressed EL4 proliferation as IC50=32 µg/mL. All experiments related to apoptosis analysis confirmed that dichloromethane brittle star extract and doxorubicin have a cytotoxic effect on EL4 cells inIC50 concentration. The study showed that dichloromethane brittle star extract is as an adjunct to doxorubicin in treatment of leukemia cells.

Extraction and Quantification of Bioactive Tyrian Purple Precursors: A Comparative and Validation Study from the Hypobranchial Gland of a Muricid Dicathais orbita

Muricidae are marine molluscs known for the production of Tyrian purple and bioactive precursor compounds. A validation study for the extraction and analysis of secondary metabolites found in the hypobranchial gland of the muricid Dicathais orbita is reported, using high performance liquid chromatography–mass spectrometry (HPLC-MS) with diode array detector (DAD). Quantification of the dominant secondary metabolites from D. orbita is described, followed by a comparison of solvent extraction procedures and stability studies. The intra- and inter-day relative standard deviation (RSD) for tyrindoxyl sulphate was 0.46% and 0.17%, respectively. The quantification was linear for standards murexine, 6-bromoisatin, and tyrindoxyl sulphate. The limits of detection were 0.03, 0.004, and 0.07 mg/mL, respectively, and the limits of quantification were 0.09, 0.01, and 0.22 mg/mL, respectively. The results showed that alcoholic solvents were better for extracting choline ester and indoxyl sulphate ultimate precursors, while chloroform was more suitable for the extraction of the intermediate precursors. Multivariate analysis revealed significant differences in extract composition according to the solvent used. Stability testing showed an increase of the oxidative compounds 6-bromoisatin and putative tyrindoxyl S-oxide sulphate in the ethanol extracts while more degradation products were seen in the chloroform extracts after months of cold storage. The validated method was found to be simple, reproducible, precise, and suitable for quantification of the secondary metabolites of muricid molluscs for dye precursor and nutraceutical quality control, as well as applications in marine chemical ecology.

Transcriptome of the Australian Mollusc Dicathais orbita Provides Insights into the Biosynthesis of Indoles and Choline Esters

Dicathais orbita is a mollusc of the Muricidae family and is well known for the production of the expensive dye Tyrian purple and its brominated precursors that have anticancer properties, in addition to choline esters with muscle-relaxing properties. However, the biosynthetic pathways that produce these secondary metabolites in D. orbita are not known. Illumina HiSeq 2000 transcriptome sequencing of hypobranchial glands, prostate glands, albumen glands, capsule glands, and mantle and foot tissues of D. orbita generated over 201 million high quality reads that were de novo assembled into 219,437 contigs. Annotation with reference to the Nr, Swiss-Prot and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases identified candidate-coding regions in 76,152 of these contigs, with transcripts for many enzymes in various metabolic pathways associated with secondary metabolite biosynthesis represented. This study revealed that D. orbita expresses a number of genes associated with indole, sulfur and histidine metabolism pathways that are relevant to Tyrian purple precursor biosynthesis, and many of which were not found in the fully annotated genomes of three other molluscs in the KEGG database. However, there were no matches to known bromoperoxidase enzymes within the D. orbita transcripts. These transcriptome data provide a significant molecular resource for gastropod research in general and Tyrian purple producing Muricidae in particular.

Characterization of Bacterial Communities Associated with the Tyrian Purple Producing Gland in a Marine Gastropod

Dicathais orbita is a marine mollusc recognised for the production of anticancer compounds that are precursors to Tyrian purple. This study aimed to assess the diversity and identity of bacteria associated with the Tyrian purple producing hypobranchial gland, in comparison with foot tissue, using a high-throughput sequencing approach. Taxonomic and phylogenetic analysis of variable region V1-V3 of 16S rRNA bacterial gene amplicons in QIIME and MEGAN were carried out. This analysis revealed a highly diverse bacterial assemblage associated with the hypobranchial gland and foot tissues of D. orbita. The dominant bacterial phylum in the 16S rRNA bacterial profiling data set was Proteobacteria followed by Bacteroidetes, Tenericutes and Spirochaetes. In comparison to the foot, the hypobranchial gland had significantly lower bacterial diversity and a different community composition, based on taxonomic assignment at the genus level. A higher abundance of indole producing Vibrio spp. and the presence of bacteria with brominating capabilities in the hypobranchial gland suggest bacteria have a potential role in biosynthesis of Tyrian purple in D. orbita.

Are the Traditional Medical Uses of Muricidae Molluscs Substantiated by Their Pharmacological Properties and Bioactive Compounds?

Marine molluscs from the family Muricidae hold great potential for development as a source of therapeutically useful compounds. Traditionally known for the production of the ancient dye Tyrian purple, these molluscs also form the basis of some rare traditional medicines that have been used for thousands of years. Whilst these traditional and alternative medicines have not been chemically analysed or tested for efficacy in controlled clinical trials, a significant amount of independent research has documented the biological activity of extracts and compounds from these snails. In particular, Muricidae produce a suite of brominated indoles with anti-inflammatory, anti-cancer and steroidogenic activity, as well as choline esters with muscle-relaxing and pain relieving properties. These compounds could explain some of the traditional uses in wound healing, stomach pain and menstrual problems. However, the principle source of bioactive compounds is from the hypobranchial gland, whilst the shell and operculum are the main source used in most traditional remedies. Thus further research is required to understand this discrepancy and to optimise a quality controlled natural medicine from Muricidae.

Naturally occurring marine brominated indoles are aryl hydrocarbon receptor ligands/agonists

The aryl hydrocarbon receptor (AhR) is a ligand-dependent transcription factor that mediates the toxic and biological effects of structurally diverse chemicals, including the environmental contaminant 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). As part of a larger effort to identify the full spectrum of chemicals that can bind to and activate the AhR, we have examined the ability of several naturally occurring marine-derived brominated indoles and brominated (methylthio)indoles (collectively referred to as brominated indoles) to bind to the AhR and stimulate AhR-dependent gene expression. Incubation of mouse, rat, and guinea pig recombinant cell lines containing a stably transfected AhR-responsive luciferase reporter gene with eight brominated indoles revealed that all compounds stimulated luciferase reporter gene activity, although some species-specific differences were observed. All compounds induced significantly more luciferase activity when incubated with cells for 4 h as compared to 24 h, demonstrating that these compounds are transient activators of the AhR signaling pathway. Three of the brominated indoles induced CYP1A1 mRNA in human HepG2 cells in vitro and Cyp1a mRNA in zebrafish embryos in vivo. The identification of the brominated indoles as direct ligands and activators/agonists of the AhR was confirmed by their ability to compete with [(3)H]TCDD for binding to the AhR and to stimulate AhR transformation and DNA binding in vitro. Taken together, these results indicate that marine-derived brominated indoles are members of a new class of naturally occurring AhR agonists.

Combined Effects of Muricid Extract and 5-Fluorouracil on Intestinal Toxicity in Rats

Chemotherapy drugs, such as 5-fluorouracil (5FU), are the standard approach for cancer and are associated with several peripheral toxicities. We previously demonstrated that Muricidae marine molluscs exhibit chemopreventive properties. This study investigated the combined effect of muricid extract derived from Dicathais orbita, with 5FU, on intestinal toxicity in rats. Groups of rats were orally gavaged water, muricid extract, or sunflower oil, with or without 5FU (150 mg/kg). Metabolic data was collected daily and small intestinal brush border enzyme activity was measured by sucrose breath test (SBT). Blood was collected by cardiac puncture for whole blood analysis. Intestinal biopsies were taken for histopathology. Neutrophil activity was measured by myeloperoxidase activity. No additional toxicity effects were observed in rats receiving the combination of 5FU and muricid extract compared to 5FU alone, as indicated by SBT, histopathology, and myeloperoxidase activity. Intestinal integrity was protected from 5FU-induced damage in the sunflower oil vehicle group, compared to controls, as measured by SBT, villus height, and crypt depth. We concluded that combination of muricid extract and 5FU did not confer any additional intestinal toxicity, further supporting its potential as a chemopreventive food product. In this model system, sunflower oil partially protected against 5FU-induced intestinal toxicity.

Antimicrobial secondary metabolites from marine gastropod egg capsules and egg masses

Marine organisms have attracted special attention in the last three decades for their ability to produce interesting pharmacological active compounds. Even though all marine organisms have the potential to produce antimicrobial secondary metabolites, the gastropod has the vital sources of secondary metabolites particularly their egg capsule which has the promising antimicrobial secondary metabolites. In the present review, we intend to focus on marine secondary metabolites from marine gastropod egg capsule. The following compounds i.e. Kabiramid C, Aplysianin E, Aplysianin A, Thisaplysianin E and Tyrian purple have been documented in egg capsule of various gastropod and most of the antimicrobial secondary metabolites have not been isolated from the egg capsule because of the odious, and complex chemical structure. Stability of the compounds is unknown.

Solvent separating secondary metabolites directly from biosynthetic tissue for surface-assisted laser desorption ionisation mass spectrometry

Marine bioactive metabolites are often heterogeneously expressed in tissues both spatially and over time. Therefore, traditional solvent extraction methods benefit from an understanding of the in situ sites of biosynthesis and storage to deal with heterogeneity and maximize yield. Recently, surface-assisted mass spectrometry (MS) methods namely nanostructure-assisted laser desorption ionisation (NALDI) and desorption ionisation on porous silicon (DIOS) surfaces have been developed to enable the direct detection of low molecular weight metabolites. Since direct tissue NALDI-MS or DIOS-MS produce complex spectra due to the wide variety of other metabolites and fragments present in the low mass range, we report here the use of "on surface" solvent separation directly from mollusc tissue onto nanostructured surfaces for MS analysis, as a mechanism for simplifying data annotation and detecting possible artefacts from compound delocalization during the preparative steps. Water, ethanol, chloroform and hexane selectively extracted a range of choline esters, brominated indoles and lipids from Dicathais orbita hypobranchial tissue imprints. These compounds could be quantified on the nanostructured surfaces by comparison to standard curves generated from the pure compounds. Surface-assisted MS could have broad utility for detecting a broad range of secondary metabolites in complex marine tissue samples.

An in vitro high-throughput assay for screening reproductive and toxic effects of anticancer compounds

An in vitro assay was developed that simultaneously tested the effects of anticancer drug candidates on cytotoxicity, hormone synthesis, and gonadotrophin responsiveness using the choriocarcinoma JAr cell line. JAr culture conditions were optimized and then cells were exposed to a marine mollusc extract in the presence and absence of hCG. The intra- and interassay coefficients of variation of the optimized 1 H thiazolyl blue tetrazolium bromide assay were 11.3% and 10.9%, respectively. hCG (1,000 mIU/mL) increased progesterone (P4) synthesis after 24 H (P<0.05). The mollusc extract significantly decreased cell viability, with the IC50 affected by incubation time, but not hCG. P4 synthesis was inhibited at low concentrations of the anticancer extract, but stimulated at the highest concentration, and complex interactions of P4 were also found with hCG. In conclusion, the optimized assay is useful to characterize the effects of novel drugs on cytotoxicity, basal, and gonadotrophin-stimulated P4 synthesis in vitro, and can be used to inform subsequent in vivo studies.

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.

Marine invertebrate natural products for anti-inflammatory and chronic diseases

The marine environment represents a relatively available source of functional ingredients that can be applied to various aspects of food processing, storage, and fortification. Moreover, numerous marine invertebrates based compounds have biological activities and also interfere with the pathogenesis of diseases. Isolated compounds from marine invertebrates have been shown to pharmacological activities and are helpful for the invention and discovery of bioactive compounds, primarily for deadly diseases like cancer, acquired immunodeficiency syndrome (AIDS), osteoporosis, and so forth. Extensive research within the last decade has revealed that most chronic illnesses such as cancer, neurological diseases, diabetes, and autoimmune diseases exhibit dysregulation of multiple cell signaling pathways that have been linked to inflammation. On the basis of their bioactive properties, this review focuses on the potential use of marine invertebrate derived compounds on anti-inflammatory and some chronic diseases such as cardiovascular disease, osteoporosis, diabetes, HIV, and cancer.

6-bromoisatin found in muricid mollusc extracts inhibits colon cancer cell proliferation and induces apoptosis, preventing early stage tumor formation in a colorectal cancer rodent model

Muricid molluscs are a natural source of brominated isatin with anticancer activity. The aim of this study was to examine the safety and efficacy of synthetic 6-bromoisatin for reducing the risk of early stage colorectal tumor formation. The purity of 6-bromoisatin was confirmed by ¹H NMR spectroscopy, then tested for in vitro and in vivo anticancer activity. A mouse model for colorectal cancer was utilized whereby colonic apoptosis and cell proliferation was measured 6 h after azoxymethane treatment by hematoxylin and immunohistochemical staining. Liver enzymes and other biochemistry parameters were measured in plasma and haematological assessment of the blood was conducted to assess potential toxic side-effects. 6-Bromoisatin inhibited proliferation of HT29 cells at IC₅₀ 223 μM (0.05 mg/mL) and induced apoptosis without increasing caspase 3/7 activity. In vivo 6-bromoisatin (0.05 mg/g) was found to significantly enhance the apoptotic index (p ≤ 0.001) and reduced cell proliferation (p ≤ 0.01) in the distal colon. There were no significant effects on mouse body weight, liver enzymes, biochemical factors or blood cells. However, 6-bromoisatin caused a decrease in the plasma level of potassium, suggesting a diuretic effect. In conclusion this study supports 6-bromoisatin in Muricidae extracts as a promising lead for prevention of colorectal cancer.

Purified brominated indole derivatives from Dicathais orbita induce apoptosis and cell cycle arrest in colorectal cancer cell lines

Dicathais orbita is a large Australian marine gastropod known to produce bioactive compounds with anticancer properties. In this research, we used bioassay guided fractionation from the egg mass extract of D. orbita using flash column chromatography and identified fractions containing tyrindoleninone and 6-bromoisatin as the most active against colon cancer cells HT29 and Caco-2. Liquid chromatography coupled with mass spectrometry (LCMS) and 1H NMR were used to characterize the purity and chemical composition of the isolated compounds. An MTT assay was used to determine effects on cell viability. Necrosis and apoptosis induction using caspase/LDH assay and flow cytometry (PI/Annexin-V) and cell cycle analysis were also investigated. Our results show that semi-purified 6-bromoisatin had the highest anti-cancer activity by inhibiting cell viability (IC50 = ~100 µM) and increasing caspase 3/7 activity in both of the cell lines at low concentration. The fraction containing 6-bromoisatin induced 77.6% apoptosis and arrested 25.7% of the cells in G2/M phase of cell cycle in HT29 cells. Tyrindoleninone was less potent but significantly decreased the viability of HT29 cells at IC50 = 390 µM and induced apoptosis at 195 µM by increasing caspase 3/7 activity in these cells. This research will facilitate the development of these molluscan natural products as novel complementary medicines for colorectal cancer.

Natural product research in the Australian marine invertebrate Dicathais orbita

The predatory marine gastropod Dicathais orbita has been the subject of a significant amount of biological and chemical research over the past five decades. Natural products research on D. orbita includes the isolation and identification of brominated indoles and choline esters as precursors of Tyrian purple, as well as the synthesis of structural analogues, bioactivity testing, biodistributional and biosynthetic studies. Here I also report on how well these compounds conform to Lipinski’s rule of five for druglikeness and their predicted receptor binding and enzyme inhibitor activity. The composition of mycosporine-like amino acids, fatty acids and sterols has also been described in the egg masses of D. orbita. The combination of bioactive compounds produced by D. orbita is of interest for further studies in chemical ecology, as well as for future nutraceutical development. Biological insights into the life history of this species, as well as ongoing research on the gene expression, microbial symbionts and biosynthetic capabilities, should facilitate sustainable production of the bioactive compounds. Knowledge of the phylogeny of D. orbita provides an excellent platform for novel research into the evolution of brominated secondary metabolites in marine molluscs. The range of polarities in the brominated indoles produced by D. orbita has also provided an effective model system used to develop a new method for biodistributional studies. The well characterized suite of chemical reactions that generate Tyrian purple, coupled with an in depth knowledge of the ecology, anatomy and genetics of D. orbita provide a good foundation for ongoing natural products research.

Gastrointestinal and hepatotoxicity assessment of an anticancer extract from muricid molluscs

Marine molluscs from the family Muricidae are under development as a potential medicinal food for the prevention of colon cancer and treatment of gynaecological cancers. Here we report the outcome of the first in vivo toxicity assessment on an anticancer extract from a muricid mollusc containing brominated indole derivatives. Mice received the concentrated lipophilic extract by daily oral gavage over a two-week period. Mortality or clinical toxicity symptoms resulting from the extract were not detected during the trial, and there was no difference in the body weight of treated and control mice at the end of the trial. Histological analysis revealed some evidence for mild, idiosyncratic effects on the gastrointestinal tract and liver, including necrosis, fatty change, and inflammation in a small proportion (<40%) of mice. This is likely to result from first-pass hepatic metabolism of tyrindoxyl sulphate combined with second-pass metabolism of indoles. Overall however, oral administration of muricid extract containing brominated indoles does not result in severe clinical toxicity.

Suppressive subtractive hybridisation transcriptomics provides a novel insight into the functional role of the hypobranchial gland in a marine mollusc

The hypobranchial gland present in gastropods is an organ whose function is not clearly understood. Involved in mucus production, within members of the family Muricidae it is also the source of the ancient dye Tyrian purple and its bioactive precursors. To gain further insights into hypobranchial gland biology, suppressive subtractive hybridisation was performed on hypobranchial gland and mantle tissue from the marine snail Dicathais orbita creating a differentially expressed cDNA library. 437 clones were randomly sequenced, analysed and annotated and 110 sequences had their functions putatively identified. Importantly this approach identified a putative gene involved in Tyrian purple biosynthesis, an arylsulphatase gene. Confirmation of the upregulation of arylsulphatase in the hypobranchial gland compared to the mantle was demonstrated using quantitative real-time PCR. Other genes identified as playing an important role in the hypobranchial gland were those involved in mucus protein synthesis, choline ester regulation, protein and energy production. This study confirms that the hypobranchial gland is involved in the production of mucus secretion and also identifies it as a site of chemical interaction and biosynthesis. This study lays the foundation for a better understanding of the enzymatic production of Tyrian purple precursors within the gland.

Cell survival and apoptosis signaling as therapeutic target for cancer: marine bioactive compounds

Inhibition of apoptosis leads to activation of cell survival factors (e.g., AKT) causes continuous cell proliferation in cancer. Apoptosis, the major form of cellular suicide, is central to various physiological processes and the maintenance of homeostasis in multicellular organisms. A number of discoveries have clarified the molecular mechanism of apoptosis, thus clarifying the link between apoptosis and cell survival factors, which has a therapeutic outcome. Induction of apoptosis and inhibition of cell survival by anticancer agents has been shown to correlate with tumor response. Cellular damage induces growth arrest and tumor suppression by inducing apoptosis, necrosis and senescence; the mechanism of cell death depends on the magnitude of DNA damage following exposure to various anticancer agents. Apoptosis is mainly regulated by cell survival and proliferating signaling molecules. As a new therapeutic strategy, alternative types of cell death might be exploited to control and eradicate cancer cells. This review discusses the signaling of apoptosis and cell survival, as well as the potential contribution of marine bioactive compounds, suggesting that new therapeutic strategies might follow.

Mass spectrometry imaging on porous silicon: investigating the distribution of bioactives in marine mollusc tissues

Desorption/ionization on porous silicon-mass spectrometry (DIOS-MS) is an attractive alternative to conventional matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) for the analysis of low molecular weight compounds. Porous silicon (pSi) chips are also suitable as support for mass spectrometry imaging (MSI). Here, we report an implementation of DIOS-MSI using the biosynthetic organs of a marine mollusc for proof of principle. The tissue section is stamped onto a fluorocarbon-functionalized pSi chip, which extracts and traps small hydrophobic molecules from the tissue under retention of their relative spatial distribution. The section is subsequently removed and the chip is imaged without any remaining tissue. We apply this novel tissue contact printing approach to investigate the distribution of biologically active brominated precursors to Tyrian purple in the hypobranchial gland of the marine mollusc, Dicathais orbita, using DIOS-MSI. The tissue contact printing is also compatible with other types of desorption/ionization surfaces, such as nanoassisted laser desorption/ionization (NALDI) targets.