An antiplasmodial new (bis)indole alkaloid from the hard coral Tubastraea sp

Marine Natural Products as Novel Treatments for Parasitic Diseases

Parasitic diseases including malaria, leishmaniasis, and trypanosomiasis have received significant attention due to their severe health implications, especially in developing countries. Marine natural products from a vast and diverse range of marine organisms such as sponges, corals, molluscs, and algae have been found to produce unique bioactive compounds that exhibit promising potent properties, including antiparasitic, anti-Plasmodial, anti-Leishmanial, and anti-Trypanosomal activities, providing hope for the development of effective treatments. Furthermore, various techniques and methodologies have been used to investigate the mechanisms of these antiparasitic compounds. Continued efforts in the discovery and development of marine natural products hold significant promise for the future of novel treatments against parasitic diseases.

An Overview of Aplysinopsins: Synthesis and Biological Activities

Marine products are among the most promising sources of biologically active molecules. Aplysinopsins, tryptophan-derived marine natural products, were isolated from different natural marine sources including sponges, stony corals (hard corals) especially genus scleractinian, as well as sea anemone, in addition to one nudibranch. Aplysinopsins were reported to be isolated from different marine organisms related to various geographic areas such as Pacific, Indonesia, Caribbean, and Mediterranean regions. This review gives an up-to-date overview of marine alkaloid aplysinopsins: their various sources, their synthesis, and the fact that many aplysinopsin derivatives are biologically active compounds.

Expanding the 'aplysinospin cascade' through DNA-templated [2+2] photocycloaddition

Inspired by the unique ability of nucleic acids to template chemical transformations that are otherwise impossible in solution, we embarked on the generalisation of our DNA-templated [2+2] photo-induced homo- and heterodimerization of aplysinopsins. Our process ensures a straightforward access to cyclobutane containing natural products and analogues thereof. Most importantly, this conceptual biomimetic achievement presents interesting arguments to build a biosynthetic scenario.

Trends of antimalarial marine natural products: progresses, challenges and opportunities

This review provides an overview of the antimalarial marine natural products, focusing on their chemistry, malaria-related targets and mechanisms, and highlighting their potential for drug development.

Cnidarians as a potential source of antiparasitic drugs

New antiparasitic drugs are urgently required for treating parasitic infections. The marine environment has proven to be a valuable source of compounds with therapeutic properties against many diseases, including parasitic diseases. Cnidarian venoms are known for their toxicological properties and are candidates for developing medications. In this review, the antiparasitic properties of cnidarian toxins, discovered over the last two decades, were examined. A total of 61 cnidarian compounds from 18 different genera of cnidaria were studied for their antiparasitic activities. The assessed genera belonged mainly to three geographical areas: South America, North America, and Southeast Asia. The in vitro activities of crude extracts and compounds against a range of parasites including Plasmodium falciparum, Trypanosoma brucei gambiense, T. cruzi, T. congolense, Leishmania donovani, L. chagasi, L. braziliensis, and Giardia duodenalis are reviewed. The challenges involved in developing these compounds into effective drugs are discussed.

Biological activities of marine invertebrates extracts from the northeast brazilian coast

This paper reports the in vitro antiproliferative effects, antiprotozoal, anti-herpes and antimicrobial activities of 32 organic extracts of 14 marine sponges and 14 corals collected in northeast Brazilian coast. The ethanolic extracts of the sponges Amphimedon compressa and Tedania ignis, and the acetone extract of Dysidea sp. showed relevant results concerning the antiproliferative effects against A549, HCT-8, and PC-3 cell lines by sulforhodamine B assay, but also low specificity. Concerning the antiprotozoal screening, the ethanolic extract of Amphimedon compressa and the acetone and ethanolic extracts of Dysidea sp. were the most active against Leishmania amazonensis and Trypanosoma cruzi expressing β-galactosidase in THP-1 cells. In the preliminary anti-HSV-1 (KOS strain) screening, the ethanolic extracts of the sponges Amphimedon compressa, Haliclona sp. and Chondrosia collectrix inhibited viral replication by more than 50%. The most promising anti-herpes results were observed for the ethanolic extract of Haliclona sp. showing high selective indices against HSV-1, KOS and 29R strains (SI> 50 and >79, respectively), and HSV-2, 333 strain (IS>108). The results of the antibacterial screening indicated that only the ethanolic extract of Amphimedon compressa exhibited a weak activity against Enterococcus faecalis, Pseudomonas aeruginosa and Escherichia coli by the disk diffusion method. In view of these results, the extracts of Amphimedon compressa, Tedania ignis and Dysidea sp. were selected for further studies aiming the isolation and identification of the bioactive compounds with antiproliferative and/or antiprotozoal activities. The relevant anti-herpes activity of the ethanolic extract of Haliclona sp. also deserves special attention, and will be further investigated.

Anti-inflammatory potential of invasive sun corals (Scleractinia: Tubastraea spp.) from Brazil: alternative use for management?

OBJECTIVES

The objective was to analyse the anti-inflammatory potential of the invasive coral species Tubastraea coccinea and Tubastraea tagusensis.

METHODS

Methanolic extracts, fractions and synthesized compounds were evaluated for their anti-inflammatory ability, and their composition was elucidated through chemical analysis.

KEY FINDINGS

The genus Tubastraea (Order Scleractinia, Family Dendrophylliidae) (known as sun corals) presents compounds with pharmacological value. The introduction of these azooxanthellate hard corals into Brazil, initially in Rio de Janeiro state, occurred through their fouling of oil and gas platforms from the Campos oil Basin. The two invasive species have successfully expanded along the Brazilian coast and threaten endemic species and biodiversity. The HPLC-MS and GC-MS data suggest the presence of aplysinopsin analogues (alkaloids). Anti-inflammatory activity was observed in all samples tested in in-vivo assays, especially in T. coccinea. The ethyl acetate fraction from this sample was more effective in in-vitro assays for anti-inflammatory activity. Depending on the concentration, this fraction showed cytotoxic responses.

CONCLUSIONS

These species have potential pharmacological use, and considering their invasive nature, this study presents a potential alternative use, which may enhance the management of this biological invasion.

Mutagenic, genotoxic and cytotoxic studies of invasive corals Tubastraea coccinea and Tubastraea tagusensis

The high diversity of species in the marine environment gives rise to compounds with unique structural patterns not found as natural products in other systems and with great potential for pharmacological, cosmetic and nutritional use. The genus Tubastraea (Class Anthozoa, Order Scleractinia, Family Dendrophylliidae) is characterized as a hard coral without the presence of zooxanthellae. In species of this genus alkaloids derived from the compound aplysinopsin with pharmacological activity are known. In Brazil T. coccinea and T. tagusensis are characterized as non-indigenous and invasive and are currently found along the Brazilian coast, from Santa Catarina to Bahia states. This study aims to analyze the mutagenic, cytotoxic and genotoxic potential of methanolic and ethanolic extracts from T. coccinea and T. tagusensis collected in Ilha Grande Bay, Rio de Janeiro state, Brazil. Bacterial reverse mutation assay on the standard strains TA97, TA98, TA100, TA102 and TA104, in vitro micronucleus formation test and colorimetric assays for cytotoxic signals on the cell lines HepG2 and RAW264.7 were used. We also synthesized an oxoaplysinopsin derivate alkaloid (APL01) for comparative purposes. No mutagenic (250; 312.5; 375; 437.5 and 500 μg/plate) or genotoxic (0.05; 0.5; 5.0; 50 and 500 μg/mL) effects were observed in any sample tested for all measured concentrations. Cytotoxic responses were observed for eukaryotic cells in all tested samples at 500 and 5000 μg/mL concentrations. Cytotoxicity found in the WST-1 assay was independent of the metabolism of substances present in samples compositions. The cytotoxicity observed in the LDH release assay depended on metabolism.

Medicinal Purposes: Bioactive Metabolites from Marine-derived Organisms

The environment of marine occupies about 95% biosphere of the world and it can be a critical source of bioactive compounds for humans to be explored. Special environment such as high salt, high pressure, low temperature, low nutrition and no light, etc. has made the production of bioactive substances different from terrestrial organisms. Natural ingredients secreted by marine-derived bacteria, fungi, actinomycetes, Cyanobacteria and other organisms have been separated as active pharmacophore. A number of evidences have demonstrated that bioactive ingredients isolated from marine organisms can be other means to discover novel medicines, since enormous natural compounds from marine environment were specified to be anticancer, antibacterial, antifungal, antitumor, cytotoxic, cytostatic, anti-inflammatory, antiviral agents, etc. Although considerable progress is being made within the field of chemical synthesis and engineering biosynthesis of bioactive compounds, marine environment still remains the richest and the most diverse sources for new drugs. This paper reviewed the natural compounds discovered recently from metabolites of marine organisms, which possess distinct chemical structures that may form the basis for the synthesis of new drugs to combat resistant pathogens of human life. With developing sciences and technologies, marine-derived bioactive compounds are still being found, showing the hope of solving the problems of human survival and sustainable development of resources and environment.

Cnidarian peptide neurotoxins: a new source of various ion channel modulators or blockers against central nervous systems disease

Cnidaria provide the largest source of bioactive peptides for new drug development. The venoms contain enzymes, potent pore-forming toxins and neurotoxins. The neurotoxins can immobilize predators rapidly when discharged via modifying sodium-channel-gating or blocking the potassium channel during the repolarization stage. Most cnidarian neurotoxins remain conserved under the strong influence of negative selection. Neuroactive peptides targeting the central nervous system through affinity with ion channels could provide insight leading to drug treatment of neurological diseases, which arise from ion channel dysfunctions. Although marine resources offer thousands of possible peptides, only one peptide derived from Cnidaria: ShK-186, also named dalazatide, has reached the pharmaceutical market. This review focuses on neuroprotective agents derived from cnidarian neurotoxic peptides.

Emergence of diversity and stereochemical outcomes in the biosynthetic pathways of cyclobutane-centered marine alkaloid dimers

A deep-sea dive into the ecology and chemistry of surprising cyclobutanes from marine invertebrates.

Marine Indole Alkaloids

Marine indole alkaloids comprise a large and steadily growing group of secondary metabolites. Their diverse biological activities make many compounds of this class attractive starting points for pharmaceutical development. Several marine-derived indoles were found to possess cytotoxic, antineoplastic, antibacterial and antimicrobial activities, in addition to the action on human enzymes and receptors. The newly isolated indole alkaloids of marine origin since the last comprehensive review in 2003 are reported, and biological aspects will be discussed.

Marine Bi-, Bis-, and Trisindole Alkaloids

This chapter, covering the chemistry literature up until June 2013 and comprising 142 references, records the chemical structures of 130 bi-, bis-, and trisindole alkaloids isolated from a plethora of marine phyla including bacteria, algae, bryozoans, sponges, mollusks, hard corals, and ascidians. While the vast majority of bisindoles have been isolated from marine sponges, biindoles are more commonly found in red algae species than sponges. Trisindoles are far less common than bisindoles in the marine environment and have been limited to two species of sponge and a single species of marine microbe. Antimicrobial activity and cytotoxicity dominate the bioactivities explored for selected members of this family of alkaloids. Synthetic approaches to 28 natural products are presented in 33 schemes, and in the absence of any in vivo biosynthetic studies, the putative biosyntheses of eight bisindole metabolites are presented.

Cnidarians as a source of new marine bioactive compounds--an overview of the last decade and future steps for bioprospecting

Marine invertebrates are rich sources of bioactive compounds and their biotechnological potential attracts scientific and economic interest worldwide. Although sponges are the foremost providers of marine bioactive compounds, cnidarians are also being studied with promising results. This diverse group of marine invertebrates includes over 11,000 species, 7500 of them belonging to the class Anthozoa. We present an overview of some of the most promising marine bioactive compounds from a therapeutic point of view isolated from cnidarians in the first decade of the 21st century. Anthozoan orders Alcyonacea and Gorgonacea exhibit by far the highest number of species yielding promising compounds. Antitumor activity has been the major area of interest in the screening of cnidarian compounds, the most promising ones being terpenoids (monoterpenoids, diterpenoids, sesquiterpenoids). We also discuss the future of bioprospecting for new marine bioactive compounds produced by cnidarians.

The structural diversity and promise of antiparasitic marine invertebrate-derived small molecules

This review focuses on six important parasitic diseases that adversely affect the health and lives of over one billion people worldwide. In light of the global human impact of these neglected tropical diseases (NTDs), several initiatives and campaigns have been mounted to eradicate these infections once and for all. Currently available therapeutics summarized herein are either ineffective and/or have severe and deleterious side effects. Resistant strains continue to emerge and there is an overall unmet and urgent need for new antiparasitic drugs. Marine-derived small molecules (MDSMs) from invertebrates comprise an extremely diverse and promising source of compounds from a wide variety of structural classes. New discoveries of marine natural product privileged structures and compound classes that are being made via natural product library screening using whole cell in vitro assays are highlighted. It is striking to note that for the first time in history the entire genomes of all six parasites have been sequenced and additional transcriptome and proteomic analyses are available. Furthermore, open and shared, publicly available databases of the genome sequences, compounds, screening assays, and druggable molecular targets are being used by the worldwide research community. A combined assessment of all of the above factors, especially of current discoveries in marine natural products, implies a brighter future with more effective, affordable, and benign antiparasitic therapeutics.