Search

The sterol 3β,5α,6β,7α-tetrahydroxyergosta-8(14),22-diene was obtained from bio-guided fractioning of the chloroform extract of 50 L of liquid culture of Acremonium persicinum. This fungal strain was selected because of its anti-proliferative activity against solid human tumour cell lines (GI50 ≤ 50 μg/mL) in a bio-prospective study of fungi isolated from plant material, sediment and water samples obtained from alkaline lakes Alchichica and Atexcac in Puebla, Mexico. This compound showed GI50 (μM) values of: 16, 24, 18, 15 and 12 against tumour cell lines A-549, HBL-100, HeLa, T-47D and WiDr respectively. GI50 effects against tumour lines T-47D and WiDr were found to be greater than the clinically used drugs Etoposide and Cisplatin. Because of this, the results obtained support the pharmacological importance of the microorganisms that develop in these ecosystems and strengthen the non-invasive bio-prospection studies that our work group has developed in recent years.

Background: The study of plant-associated microorganisms is very important in the discovery and development of bioactive compounds. Pseudomonas is a diverse genus of Gammaproteobacteria comprising more than 60 species capable of establishing themselves in many habitats, which include leaves and stems of many plants. There are reports of metabolites with diverse biological activity obtained from bacteria of this genus, and some of the metabolites have shown cytotoxic activity against cancer cell lines.Because of the high incidence of cancer, research in recent years has focused on obtaining new sources of active compounds that exhibit interesting pharmacodynamic and pharmacokinetic properties that lead to the development of new therapeutic agents. Results: A bacterial strain was isolated from tumors located in the stem of Pinus patula, and it was identified as Pseudomonas cedrina. Extracts from biomass and broth of P. cedrina were obtained with chloroform:methanol (1:1). Only biomass extracts exhibited antiproliferative activity against human tumor cell lines of cervix (HeLa), lung (A-549), and breast (HBL-100). In addition, a biomass extract from P. cedrina was fractioned by silica gel column chromatography and two diketopiperazines were isolated: cyclo-(l-Prolyl-l-Valine) and cyclo-(l-Leucyl-l-Proline). Conclusions: This is the first report on the association of P. cedrina with the stems of P. patula in Mexico and the antiproliferative activity of extracts from this species of bacteria against human solid tumor cell lines.How to cite: Sánchez-Tafolla L, Padrón JM, Mendoza G, et al. Antiproliferative activity of biomass extract from Pseudomonas cedrina. Electron J Biotechnol 2019;40. https://doi.org/10.1016/j.ejbt.2019.03.010. Keywords: Antiproliferative activity, Bioactive compounds, Cancer, Diketopiperazines, Mexico, Pinus patula, Plant-associated bacteria, Plant-associated microorganisms, Pseudomonas cedrina, Therapeutic agents

Marine dinoflagellate microalgae belonging to the genus Amphidinium are a key source of an interesting group of polyketide metabolites with potent bioactivities, wide-ranging functional diversity and stereochemical complexity, but low natural availabilities. The feasibility of a microalgae dinoflagellate-based sustainable bioprocess for producing amphidinols (APDNs) by photoautotrophic culture of Amphidinium carterae in a pilot-scale LED-illuminated bubble column photobioreactor (PBR) was therefore investigated. A fed-batch culture mode with pulse feeding strategy provided a growth pattern strongly limited by the availability of phosphate content in the culture medium that stimulated the production of cellular APDNs. Since A. carterae was found to be much more shear-sensitive than other shear-tolerant non-dinoflagellate microalgae, the culture height and air flow rate were established to ensure the absence of damaging levels of hydrodynamic stress. The biomass capacity yielded by the PBR at the end of the culture (0.540 g d.w. L−1 equivalent to 1.70 × 106 cell mL−1) corresponded to that estimated stoichiometrically from the experimentally determined biomass P-molar formula (C329 O126 H732 N69 S3 P1) and the total phosphorus and nitrogen balances. The downstream processing section was initially conceived to recover APDNs excreted by cells into the supernatant. A dry APDN-enriched extract concentration of 49 mg per liter of supernatant was obtained. This purification process led to partitioning of the extract into several fractions and sub-fractions thereof. Only two sub-fractions were studied, yielding thereof highly pure (>95% pure) luteophanol D and lingshuiol A, and a new, roughly purified (>80% pure) APDN, namely amphidinol 20. The percentages of luteophanol D, lingshuiol A and amphidinol 20 by dry weight of the APDN-enriched extract obtained were 1%, 0.39% and 0.31%, respectively, thus representing a concentration in the culture supernatant of 490, 191 and 152 μg L−1, respectively.

Consumption of Brassica (Cruciferae) vegetables is associated with a reduced risk of cancer, but identification of the active components and insights into the underlying molecular events are scarce. Here we found that an extract of Lepidium latifolium, a cruciferous plant native to southern Europe, Mediterranean countries and Asia, showed in vitro cytotoxic activity, inducing caspase-dependent apoptosis, in a variety of human tumor cells, and the plant juice showed in vivo antitumor activity in a HT-29 human colon cancer xenograft mouse model. The epithionitrile 1-cyano-2,3-epithiopropane (CETP) was identified as the major active cancer cell-killing principle of L. latifolium. Synthetic and plant-derived CETP displayed similar proapoptotic activities as assessed by biochemical and morphological analyses. Analysis of the antiproliferative capacity of CETP on a wide number of cancer cell lines from the NCI-60 cell line panel followed by COMPARE analysis, showed an activity profile different from known anticancer agents. Flow cytometry and biochemical analyses revealed that CETP-induced apoptosis involved mitochondria, as assessed by loss of mitochondrial transmembrane potential and generation of reactive oxygen species, while overexpression of Bcl-X and Bcl-2 prevented CETP-induced apoptosis. Inhibition of reactive oxygen species by glutathione and N-acetyl cysteine reduced the apoptotic response induced by CETP. FADD dominant negative form, blocking Fas/CD95 signaling, and a specific caspase-8 inhibitor also inhibited CETP-induced killing. Taken together, our data suggest that the cancer cell-killing action of CETP, involving both intrinsic and extrinsic apoptotic signaling pathways, underlies the antitumor activity of L. latifolium plant, which could be of potential interest in cancer treatment., This work was supported by grants from the Spanish Ministry of Economy and Competitiveness (SAF2011-30518; SAF2014-59716-R; CTQ2014-55888-C03-01-R), Instituto de Salud Carlos III (RD12/0036/0065 from Red Temática de Investigación Cooperativa en Cáncer, cofunded by the EU's European Regional Development Fund—FEDER), and the European Community's Seventh Framework Programme FP7-2007-2013 (HEALTH-F2-2011-256986, PANACREAS).

The study of marine natural products for their bioactive potential has gained strength in recent years. Oceans harbor a vast variety of organisms that offer a biological and chemical diversity with metabolic abilities unrivalled in terrestrial systems, which makes them an attractive target for bioprospecting as an almost untapped resource of biotechnological applications. Among them, there is no doubt that microalgae could become genuine “cell factories” for the biological synthesis of bioactive substances. Thus, in the course of inter-laboratory collaboration sponsored by the European Union (7th FP) into the MAREX Project focused on the discovery of novel bioactive compounds of marine origin for the European industry, a bioprospecting study on 33 microalgae strains was carried out. The strains were cultured at laboratory scale. Two extracts were prepared for each one (biomass and cell free culture medium) and, thus, screened to provide information on the antimicrobial, the anti-proliferative, and the apoptotic potential of the studied extracts. The outcome of this study provides additional scientific data for the selection of Alexandrium tamarensis WE, Gambierdiscus australes, Prorocentrum arenarium, Prorocentrum hoffmannianum, and Prorocentrum reticulatum (Pr-3) for further investigation and offers support for the continued research of new potential drugs for human therapeutics from cultured microalgae., This work was supported by the grants EU FP7-KBBE-3-245137 (MAREX), CTQ2014-55888-C03-01 (the Spanish MINECO) and by the Academy of Finland (PT, grant no. 277001). The authors thank Dr. Santiago Fraga (Oceanographic Centre of Vigo, IEO, Spain) for the generous gift of microalgae strains and Pirjo Käpylä for the valuable technical assistance in the high throughput anticancer assays carried out at VTT.

The red seaweed Laurencia viridis is a rich source of oxygenated secondary metabolites that were derived from squalene. We report here the structures of three novel compounds, (+)-longilene peroxide (1), longilene (2), and (+)-prelongilene (3) that were isolated from this alga, in addition to other substances, 4 and 5, resulting from their acid-mediated degradation. The effect of compounds 1 and 3 against Ser-Thr protein phosphatase type 2A (PP2A) was evaluated, showing that (+)-longilene peroxide (1) inhibited PP2A (IC 11.3 µM). In order to explain the interaction between PP2A and compounds 1 and 3, molecular docking simulations onto the PP2A enzyme-binding region were used., This work was supported by grant CTQ2014-55888-C03-01-R (Ministry of Economy and Competitiveness of Spain, MINECO). Authors are grateful to M. C. Gil-Rodríguez (Departamento de Biología Vegetal, ULL) for the taxonomic classification of the alga.

Various species of the genus Ganoderma have been used for centuries according to oriental tradition as a source of medicines and nutrients. A chemical study of the fruiting bodies and mycelial culture of G. oerstedii was carried out with the idea of isolating and characterizing active natural components present to make use of their potential pharmaceutical application in Mexico. The fruiting bodies and mycelial culture of G. oesrtedii were lyophylized and extracted one after the other with hexane, chloroform, and methanol. Following this process, each substance was extracted separately by using column chromatography. From fruiting bodies eight metabolites, five sterols (ergosta-7,22-dien-3β-ol, ergosterol peroxide, ergosterol, cerevisterol, and ergosta-7,22-dien-3-one) as well as three terpene compounds (ganodermanondiol, ganoderic acid Sz, and ganoderitriol M) were obtained from fruiting bodies. From the mycelial culture three metabolites, two sterols (ergosterol and cerevisterol), and a new terpene compound (ganoderic acetate from the acid) were obtained. These structures were established based on a spectroscopic analysis mainly using nuclear magnetic resonance and a comparison with data already established.

Red algae of Laurencia continue to provide wide structural diversity and complexity of halogenated C acetogenin medium-ring ethers. Here, we described the isolation of three new C acetogenins (3–5), and one truncated derivative (6) from Laurencia viridis collected on the Canary Islands. These compounds are interesting variations on the pinnatifidenyne structure that included the first examples of ethynyl oxirane derivatives (3–4). The structures were elucidated by extensive study of NMR (Nuclear Magnetic Resonance) data, J-based configuration analysis and DFT (Density Functional Theory) calculations. Their antiproliferative activity against six human solid tumor cell lines was evaluated., This work was supported by grant CTQ2014-55888-C03-01-R (Ministry of Economy and Competitiveness of Spain, MINECO). A.M.-A. and C.R.d.V. acknowledge MINECO for a Ph.D. scholarship and O.M.-F. thanks ULL for a grant.

8 pages, 1 table, 3 figures, Three strains of the toxic benthic dinoflagellate Prorocentrum hoffmannianum were isolated in the Canary Islands (north-east Atlantic Ocean, Spain). The identity of the strains was determined by phylogenetic analyses of partial LSU rDNA (D1-D2 regions) but their morphology based on SEM images corresponded to P. maculosum. Their toxin profiles were analyzed by liquid chromatography and high resolution mass spectrometry analysis (LC–HRMS) on cell extracts and culture media. Okadaic acid and three analogs were detected in all strains. Rather, in culture media the detected compounds were variable among strains, two of them being okadaic acid analogs not found on cell extracts. As a result, the taxonomy of the species was revised and P. maculosum is proposed as a junior synonym of P. hoffmannianum whose description is emended., This work was funded by projects CICAN, CCVIEO and CTQ2014-55888-C3-01-R

Five-membered rings are of particular interest, due to their presence in some of the most common molecules in chemistry and biology. Despite their apparent simplicity, the structural resolution of these rings is complex, due to their inherent conformational flexibility. Here, we describe an application of a recently reported simple and efficient NMR protocol based on the measurement of spin-spin coupling constants to achieve the challenging relative configurations of five new halogenated C15 tetrahydrofuranyl-acetogenins, marilzafurollenes A–D (1–4) and 12-acetoxy-marilzafurenyne (5), isolated from the red alga, Laurencia marilzae. Although DFT chemical shift calculations were used to connect remote stereocenters, the NMR-based approach seems advantageous over computational techniques in this context, as the presence of halogens may interfere with reliable calculations.

The structural determination of small organic molecules is mainly undertaken by using NMR techniques, although it is increasingly supplemented by using computational methods. NMR parameters, such as chemical shifts and coupling constants, are extremely sensitive indicators of local molecular conformation and are a source of structural evidence. However, their interpretation is fairly challenging in many circumstances, such as the case of the new polyether squalene derivative nivariol, the structure of which was elucidated by means of NMR spectroscopy and DFT calculations. The potential flexibility of this molecule and the high number of quaternary carbon atoms that it contains make its configurational assignment very difficult. Moreover, the relative configuration of four separated stereoclusters was established and subsequently connected by using NOE and J ‐based analysis, as well as by a comparison of its experimental 13C NMR chemical shifts with the corresponding population‐weighted values, as calculated by using DFT methods. Limitations of these used approaches became apparent but were overcome by combining the two methods.

A set of crown ethyl acyl derivatives based on 18-crown-6 moiety was synthesized and evaluated for biological activity. In vitro antiproliferative profiling demonstrated significant activities against HBL-100, HeLa, SW1573 and WiDr human cell lines. The most active compound exhibited GI50 values in the range of 3.7–5.6 μM. Antimicrobial evaluation showed that three polyaromatic compounds were active against Staphylococcus aureus (MIC90 values from 8.3 μM to 50 μM), whereas a (decyloxy)benzene substitution exhibited moderate activity against Candida albicans (MIC90 values 36 μM). According to SAR evaluation, the size of the crown ether and the acyl side chain had a significant effect on the bioactivity. Aromatic moieties close to the acyl group led to improved bioactivity as exemplified by some of the tested compounds. These results provide further evidence on the potential of crown ethyl structure as a scaffold for developing new biological probes and lead candidates for drug development.

The red seaweed Laurencia viridis is a rich source of secondary metabolites derived from squalene. New polyethers, such as iubol (2), 22-hydroxy-15(28)-dehydrovenustatriol (3), 1,2-dehydropseudodehydrothyrsiferol (4), and secodehydrothyrsiferol (5) have been isolated and characterized from this alga. The structures were determined through the interpretation of NMR spectroscopic data and the relative configuration was proposed on the basis of NOESY spectrum and biogenetic considerations. All new compounds exhibited significant cytotoxic activity against a panel of cancer cell lines.

Macrosporin, a bioactive metabolite produced by a plant-pathogenic fungus Stemphylium lycopersici , was found to be a non-host selective toxin which plays a part in leaf necrosis, a disease caused by this fungus. Here, we discuss the role of this metabolite in necrotic spots, through the direct inoculation of the midribs of the leaves of a natural host, as well as its ability to generate active oxygen species, through the process of photosensitizing oxygen.

Five‐membered rings are clearly among the most common structural motifs found in chemistry and biology. Nevertheless, the configuration of conformationally mobile five‐membered rings is often difficult to assign from nuclear magnetic resonance (NMR) data. A simple, reliable, and efficient approach for the stereochemical analysis of five‐membered rings based on the measurement of NMR coupling constants is presented. Density functional theory calculations using representative conformations of the full conformational space available to rings with different substitution patterns were used to identify differences between the accessible coupling constant values for cis and trans relative orientations of the substituents. The calculations were assessed experimentally using NMR data obtained from a number of models. This approach can be easily used to analyze different five‐membered rings, such as oxolanes, cyclopentanes, furanosides and pyrrolidines, and their relative configuration can be determined without the need for making further conformational considerations.

Eight new halogenated C(15) acetogenins, 1-8, were isolated from the organic extract of the red alga Laurencia marilzae. The structure elucidation and the assignments of the relative configurations were established by extensive use of spectroscopic studies, particularly 1D and 2D NMR data, while the absolute configurations of compounds 1 and 5 were determined by single-crystal X-ray diffraction analysis. Compounds 1, 2, 4, 5, and 7, along with the previously reported related cyclic ether obtusallene IV (9), were evaluated against six human solid tumor cell lines. All compounds were found to be essentially inactive (GI(50)10 μg/mL).

27 páginas, 4 tablas, 4 figuras, Diarrhetic Shellfish Poisoning (DSP) is a specific type of food poisoning, characterized by severe gastrointestinal illness due to the ingestion of filter feeding bivalves contaminated with a specific suite of toxins. It is known that the problem is worldwide and three chemically different groups of toxins have been historically associated with DSP syndrome: okadaic acid (OA) and dinophysistoxins (DTXs), pectenotoxins (PTXs) and yessotoxins (YTXs). PTXs and YTXs have been considered as DSP toxins because they can be detected with the bioassays used for the toxins of the okadaic acid group, but diarrhegenic effects have only been proven for OA and DTXs. Whereas, some PTXs causes liver necrosis and YTXs damages cardiac muscle after intraperitoneal injection into mice. On the other hand, azaspiracids (AZAs) have never been included in the DSP group, but they cause diarrhoea in humans. This review summarizes the origin, characterization, structure, activity, mechanism of action, clinical symptoms, method for analysis, potential risk, regulation and perspectives of DSP and associated toxins produced by marine dinoflagellates., This work was funded b yGrants AGL2005-07924-C04- 01/02 and CTQ2008-0754-C04-01/04 from the MEC of Spain.

Adriatoxin-B (ATX-B) is the first C13 terminal truncated YTX analogous metabolite that was isolated from large-scale cultures of the dinoflagellate Protoceratium reticulatum. The structure and conformational behavior of ATX-B was elucidated by a combination of NMR spectroscopy experiments and a conformational analysis. The isolation of this metabolite, which possesses a clear structural relationship with adriatoxin, supports the idea that the real source of these cut down substances is in the microalgae and not in the mollusks, via metabolic degradation like it has been assumed until now.

An exclusive club : The first member of an unprecedented class of polyunsaturated and polyhydroxylated macrocycle, belizeanolide (see structure), has been isolated from a marine dinoflagellate. The corresponding open form, belizeanolic acid, was also found. Their structures were determined primarily by analysis of NMR spectroscopic data. Both compounds showed significant antiproliferative activities.

Okadaic acid (1) (OA) and its congeners are mainly responsible for diarrhetic shellfish poisoning (DSP) syndrome. The presence of several OA derivatives have already been confirmed in Prorocentrum and Dinophysis spp. In this paper, we report on the detection and identification of a new DSP toxin, the OA isomer 19-epi-okadaic acid (2) (19-epi-OA), isolated from cultures of Prorocentrum belizeanum, by determining its retention time (RT) and fragmentation pattern using liquid chromatography coupled with mass spectrometry (LC–MS/MS).

The obtusallenes are a significant subset of C15-halogenated acetogenins that incorporate 12-membered cyclic ethers. We have recently reported the isolation from Laurencia marilzae of 12-epoxyobtusallene IV (1) and its related α,β-unsaturated carboxylate ester (2), both of special biogenetic relevance. Here we describe the final step of our study, the isolation of three new analogues (3-5), among these, the first bromopropargylic derivative (3) of this class of macrocyclic C15-acetogenins. The structures were elucidated by analysis of NMR and X-ray data. 12-Epoxyobtusallene IV (1), its new isomer 4, and known obtusallene IV (6) were evaluated for their apoptosis-inducing activities in a human hepatocarcinoma cell line.

Seven new nonadecaketides (1-7), lobophorols A-C, lobophopyranones A and B, and lobophorones A and B, along with the first naturally occurring related metabolites (8-10), were isolated from specimens of Lobophora variegata collected from the Canary Islands. Their structures were determined by extensive spectroscopic methods. In addition, an insight into the biosynthesis of these compounds on the basis of the involvement of type III polyketide synthases is proposed. Lobophorol A (1) showed significant antibacterial activity against Staphylococcus aureus.

The chemical study of the red alga Laurencia viridis has led to the isolation of four new polyether triterpenoids: 28-hydroxysaiyacenol B (2), saiyacenol C (3), 15,16-epoxythyrsiferol A (4), and 15,16-epoxythyrsiferol B (5). The structures of 2 and 3 were established mainly by NMR data analysis and comparison with the well-known metabolite dehydrothyrsiferol (1). However, due to the existence of a nonprotonated carbon within the epoxide functionality, stereochemical assignments in 4 and 5 required an in-depth structural study that included NOESY data, J-based configuration analysis, comparison with synthetic models, and DFT calculations. The biological activities of the new metabolites and other related oxasqualenoids were evaluated for the first time against a panel of relevant biofouling marine organisms, and structure–activity conclusions were obtained.

Dactylomelol 1 , initially isolated from molluscs of the genus Aplysia , was the first example of a monocarbocyclic diterpene skeleton with a C-6–C-11 cyclisation. This paper reports on the identification and structural elucidation of six new diterpenes, compounds 4 – 9 , isolated from specimens of Laurencia sp., together with dactylomelol, all with this particular carbon backbone that we named dactylomelane. This result is the first to confirm a red alga as the biogenetic origin of this class of compounds.

Marine toxins have drawn wide interest because their economical impact and disastrous effect upon the shellfish industry and public health in many parts of the world. One of the most interesting group of substances of marine toxins, from structural and pharmacological points of view are polyether compounds, which generally present a great diversity in size and potent biological activities. The subject of this work was about to biosynthesis of okadaic acid skeleton as leader as DSP toxins. Its biosynthesis attracts considerable attention since the carbon skeleton has been shown to be synthesised via an unusual route. In this paper we report on stable isotope incorporation experiments on DSP toxin in artificial cultures of dinoflagellate. The comparison of the degrees of incorporation in these samples measured by different methods led to contradictory results. This implies that further experimental data is needed in order to propose a logical biogenetic scheme. © 2004 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 4: 1–9; 2004: Published online in Wiley InterScience (www.interscience.wiley.com ) DOI 10.1002/tcr.10072

The red seaweed Laurencia viridis is a rich source of secondary metabolites derived from squalene. Novel polyethers, clavidol 4 , 3-epi-1111-dehydrothyrsiferol 5 , and lactodehydrothyrsiferol 6 , have been isolated and their structures established by spectroscopical methods. The relative stereochemistry proposed for these compounds is based on ROESY and NOEDIFF data. Possible biogenetic pathways are also discussed.

Two new zoantharia-derived metabolites, zoaramine (I) and zoarenone (II), are characterized.

Belizentrin (1), a novel 25-membered polyketide-derived macrocycle, was isolated from cultures of the marine dinoflagellate Prorocentrum belizeanum. This metabolite is the first member of an unprecedented class of polyunsaturated and polyhydroxylated macrolactams. The structure of 1 was primarily determined by NMR and computational methods. Pharmacological assays with cerebellar cells showed that 1 produces important changes in neuronal network integrity at nanomolar concentrations.

Three new norzoanthamine-type alkaloids, named 2-hydroxy-11-ketonorzoan thamide B (1), norzoanthamide B (2) and 15-hydroxynorzoanthamine (3), were isolated from Zoanthus sp. specimens collected at the Canary Islands. Their structures were determined by interpretation of NMR and HR-ESIMS data. Relative configurations of their chiral centers were proposed on the basis of ROESY spectra and by comparison of their spectroscopic data with those of the well-known compound, norzoanthamine.

Four new triterpenoids with a squalene carbon skeleton martiriol 7, pseudodehydrothyrsiferol 8, dioxepandehydrothyrsiferol 9 and 16-epihydroxydehydrothyrsiferol 10 have been isolated from the red alga Laurencia viridis. The structures were determined through the interpretation of their spectral data and the relative stereochemistries were proposed on the basis of ROESY and NOEDIFF data. Their cytotoxic activities were evaluated.

A new monogalactosyl triacylglycerol has been isolated from the artificial cultures of the dinoflagellate Amphidinium sp. Its structure was determined through the interpretation of 2D-NMR spectral data and chemical degradation. The relative steieochemistry is proposed on the basis of ROESY data.

A new alkaloid, epioxyzoanthamine , has been isolated from a marine zoanthid. Its structure and relative stereochemistry were determined through the interpretation of NMR spectral data. This compound as well as norzoanthamine, showed an unusual deuterium exchange at the methylene C-11 after treatment with D2O. A new alkaloid, epioxyzoanthamine , (R1=CH2OH; R2=H) has been isolated from a marine zoanthid. Its structure and relative stereochemistry were determined through the interpretation of NMR spectral data. This compound as well as norzoanthamine, showed an unusual deuterium exchange at the methylene C-11 after treatment with D2O.

Chemical investigation of an Atlantic variety of Zoanthus sp. led to the isolation of two new metabolites, zoaramine and zoarenone. Their structures were deduced by the use of NMR spectroscopy and computational calculation of 1H and 13C chemical shifts. The core of these novel compounds resembles the structure of norzoanthamine alkaloids, and their isolation represents an important step toward a better understanding of the biogenetic origin of this group of antiosteoporotic molecules.

Two new polyether squalene derivatives, thyrsenol A 2 and thyrsenol B 3, have been isolated from the red alga Laurencia viridis. Their structures, which possess an unusual enol-ether moiety, were determined through the interpretation of 2D-NMR spectral data. The relative stereochemistry is proposed on the basis of ROESY and NOEDIFF data. Their cytotoxic activities were evaluated.

Five new triterpenoid polyethers with a squalene carbon skeleton have been isolated from the red alga Laurencia viridis . Their structures were determined through the interpretation of 2D-NMR spectral data. The relative stereochemistry is proposed on the basis of ROESY and NOEDIFF data.

Two new chromenol derivatives, compounds (5) and (6) were isolated from the brown alga Desmarestia menziessi and their structures were elucidated by spectroscopic methods. The already described compounds desmarestial (1), sargadiol I (3), plastoquinone (2) and its hydroquinone form, were also isolated. The results obtained from tests for cytotoxic and anthelmintic activity of all those compounds are reported.

In the present study, we examined the effects of okadaic acid, a selective inhibitor of type I and 2A protein phosphatases, on the mechanical responses evoked by oxytocin, K + - and Na + -modified solutions and ouabain in estrogen-primed rat myometrium. Oxytocin elicited a rapid, phasic contraction followed by rhythmic oscillations. The phasic response was partially resistant to the absence of external Ca 2+ . Okadaic acid (1 μM) and the L-type calcium channel blocker nifedipine (1 μM) abolished the oscillatory component and reduced the initial, phasic response to about 80% of the control response. High K + (60 mM) solution, ouabain (1 mM), K + -free medium and low Na + (25 mM) solution induced extracellular Ca 2+ -dependent biphasic responses composed by an early rapid (KCl, ouabain and K + -free solution) or slower developed (25 mM Na + solution) phasic contraction followed by a sustained increase in tension. Okadaic acid and nifedipine, alone or in combination, abolished or decreased similarly the contractile response evoked by these stimulants. The okadaic acid- and nifedipine-insensitive responses to ouabain, K + -free and low Na + solution were enhanced by increasing the extracellular concentration of Ca 2+ in the medium and were inhibited in a dose-dependent manner by amiloride (0.05-0.5 mM). These data suggest that, in estrogen-primed rat uterus, dephosphorylating mechanisms by OA-sensitive protein phosphatases play an important role in regulating myometrial contractions elicited by Ca 2+ entry through voltage-sensitive Ca 2+ channels.

Marine organisms are an increasingly important source of novel metabolites, some of which have already inspired or become new drugs. In addition, many of these molecules show a high degree of novelty from a structural and/or pharmacological point of view. Structure determination is generally achieved by the use of a variety of spectroscopic methods, among which NMR (nuclear magnetic resonance) plays a major role and determination of the stereochemical relationships within every new molecule is generally the most challenging part in structural determination. In this communication, we have chosen okadaic acid as a model compound to perform a computational chemistry study to predict 1H and 13C NMR chemical shifts. The effect of two different solvents and conformation on the ability of DFT (density functional theory) calculations to predict the correct stereoisomer has been studied

Okadaic acid (OA) has been an invaluable pharmacological tool in the study of cellular signaling. The great affinity of this polyether for its targets together with its high specificity to inhibit certain protein phosphatases enables the differential study of these proteins. Crystallographic structures of protein phosphatases in complex with OA show a 1:1 protein to toxin ratio. Nevertheless, it has been found that OA is able to self-associate under certain conditions although very little is known about the importance of this phenomenon. Here we review the available knowledge on the latter topic and we report on the existence of an unusual self-associated tetrameric form. The structure of these oligomers is proposed based on spectroscopic data and molecular modeling calculations.

Viridiol A (1) and B (2), two new 10–15 cyclophytane-type diterpenes, have been isolated from the red alga Laurencia viridis. The structures were established by spectroscopical methods.

Two new polyether squalene derivatives isodehydrothyrsiferol 2 and 10-epidehydrothyrsiferol 3 have been isolated from the red alga Laurencia viridis. Their structures were determined through the interpretation of 2D NMR spectra and their antitumoral activity was established.

Okadaic acid (OKA) and analogues are frequent contaminants of coastal waters and seafood. Structure analysis of the isolated OKA analogue 19-epi-OKA showed important conformation differences expected to result in lower protein phosphatase (PP) inhibitory potencies than OKA. However, 19-epi-OKA and OKA inhibitory activities versus PP2A were unexpectedly found to be virtually equipotent. To investigate the toxicological relevance of these findings, we tested the effects of 19-epi-OKA on cultured cerebellar cells and compared them with those of OKA and its isomer dinophysistoxin-2. 19-epi-OKA caused degeneration of neurites and neuronal death with much lower potency than its congeners. The concentration of 19-epi-OKA that reduced after 24h the maximum neuronal survival (EC5024) by 50% was ~300nM compared with ~2nM and ~8nM for OKA and dinophysistoxin-2, respectively. Exposure to 19-epi-OKA resulted also in less toxicity for cultured glial cells (EC5024,19-epi-OKA ~ 600nM; EC5024,OKA ~ 20nM). 19-epi-OKA induced apoptotic condensation and fragmentation of chromatin, activation of caspases, and activation of ERK1/2 MAP kinases, features previously reported for OKA and dinophysistoxin-2. Also, differential sensitivity to 19-epi-OKA was observed between neuronal and glial cells, a specific characteristic shared by OKA and dinophysistoxin-2 but not by other toxins. Our results are consistent with 19-epi-OKA being included among the group of toxins of OKA and derivatives and support the suitability of cellular bioassays for the detection of these compounds.

The dinoflagellate Prorocentrum belizeanum is responsible for the production of several toxins involved in the red tide phenomenon known as Diarrhetic Shellfish Poisoning (DSP). In this paper we report on the biosynthetic origin of an okadaic acid water-soluble ester derivative, DTX5c, on the basis of the spectroscopical analysis of 13C enriched samples obtained by addition of labelled sodium [l-13C], [2-13C] acetate to artificial cultures of this dinoflagellate.

Two new cytotoxic oxasqualenoids, saiyacenols A and B, were isolated from the red alga Laurencia viridis and their structures elucidated by spectroscopic methods and chemical correlation with the well-known compound dehydrothyrsiferol. The new compounds share an important part of their structure with thyrsiferol and aplysiols B and C. Isolation of the saiyacenols concludes the controversy about the configuration of aplysiols, correcting the structure of aplysiol B. Our results illustrate the current limitations of NMR J-based methods when approaching quaternary carbons and demand a reappraisal of rational biogenetic proposals in structural elucidation., Financial support was provided by grants MAREX [FP 7; KBBE–3-245137 (EU)], SAF2011-28883-03-01 and SAF2008-02251 (MICINN); RD06/0020/1037 from Red Temática de Investigación Cooperativa en Cáncer, Instituto de Salud Carlos III, co-funded by the Fondo Europeo de Desarrollo Regional of the European Union, and Junta de Castilla y León (CSI052A11-2, and GR15-Experimental Therapeutics and Translational Oncology Program). F.C.P. acknowledges a repatriation fellowship (Consejo Nacional de Ciencia y Tecnología; 168081) and SEGAI-ULL fellowship.

Viridianol 1 , a new rearranged sesquiterpene with a novel carbon skeleton has been isolated from the red seaweed Laurencia viridis . The structure was determined through the interpretation of 2D NMR spectra as a 3,6-cycloprecapnellane carbon skeleton. The relative stereochemistry is proposed on the basis of ROESY and NOEDIFF data.

The effects of okadaic acid, a polyether derivative of a 38-carbon monocarboxylic fatty acid obtained from a culture of the marine dinoflagellate, Prorocentrum lima, were studied on the human isolated bronchus. In low concentrations (0.01 and 0.03 μM), okadaic acid had no significant effect of its own on the human isolated bronchus, but in higher concentrations (0.1–10 μM) it induced a series of contractions and relaxations. The first contraction was of low intensity (5% of maximum response to acetylcholine 3 mM) and occured early. The second contraction had a higher amplitude (30% of maximum response to acetylcholine 3mM) and reached its peak with okadaic acid 0.3 μM. At higher concentrations (1–10 μM), following a relaxation phase, a later rebound contraction occurred between 70 and 120 min and corresponded to 40% of the maximum response to acetylcholine 3 mM. In addition, okadaic acid inhibited or abolished the contractile response evoked by either KCl 60 mM or acetylcholine 3 mM with IC50 of 0.04 and 0.12 μM, respectively. The second contraction evoked by 0.3 μM okadaic acid was partially inhibited in the presence of the Ca2+ channel blocker, nicardipine 1 μM, or after incubation of the human bronchus in a Ca2+-free solution and it was completely abolished in the presence of CdSO4 0.1 mM. The non-specific smooth muscle relaxant, papaverine (1–15 μM), inhibited the second contractile response to okadaic acid 0.3 μM in the way it inhibited the KCl 60 mM- or the acetylcholine 3 mM-induced response. In contrast, caffeine (0.1–10 mM) inhibited or almost completely abolished this okadaic acid 0.3 μM-induced contraction at concentrations at which it failed to modify significantly or induced only a partial inhibition of the contractile responses to KCl 60 mM or acetylcholine 3 mM. Okadaic acid 1 μM did not affect the intracellular levels of phosphoinositides in the human isolated bronchus. To conclude, these results show that okadaic acid induces complex contractile and relaxant effects on the human isolated bronchus. Its contractile effect is independent of the phosphoinositide pathway; it seems to involve, at least partially, entry of Ca2+ into the cell and mobilization of intracellular Ca2+ from a caffeine-dependent pool, but other mechanisms may also be acting.

Siphonarienal 1 , a pentapropionate derivative, was isolated from the marine pulmonate mollusk Siphonaria grisea . Its structure was established on the basis of its spectroscopic data and its absolute configuration was assured by its enantioselective synthesis.

The biosynthetic origin of DTX-1 is establish on the basis of the NMR spectral data of samples obtained by addition of labelled [1- 13 C 1 ], [2- 13 C 1 ] and [1,2- 13 C 2 ] sodium acetate to artificial cultures of the dinoflagellate Prorocentrum lima.

The dinoflagellate Prorocentrum lima is responsible for the production of the toxins involved in the red tide phenomenon known as diarrhetic shellfish poisoning (DSP). In this paper we report on the isolation, structural elucidation and biosynthetic origin of two ester derivatives of okadaic acid on the basis of their spectroscopical data. Its biosynthetic origin was indicated by addition of labelled sodium [1- 13 C 1 ], [2- 13 C 2 ] and [1,2- 13 C 2 ] acetate to artificial cultures of the dinoflagellate.