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.

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.

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.

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 GI values in the range of 3.7-5.6μM. Antimicrobial evaluation showed that three polyaromatic compounds were active against Staphylococcus aureus (MIC values from 8.3μM to 50μM), whereas a (decyloxy)benzene substitution exhibited moderate activity against Candida albicans (MIC values 36μM). 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.

Las acilhidrazonas se han estudiado desde 1850, son compuestos importantes para el diseño de fármacos por su amplia actividad biológica, entre ellas. Los compuestos fueron sintetizados mediante una reacción de adición nucleofílica al grupo carbonilo; se obtuvieron seis derivados empleando la 2,4-dinitrofenilhidracina (2,4-DNPH) y las cetonas: fluorenona, benzofenona y benzofenonas sustituidas; en todos los casos se han alcanzado buenos rendimientos, el mejor porcentaje corresponde al compuesto (7), con un 67% y el más bajo al compuesto (10) con un rendimiento de 29%. En el desarrollo de la síntesis se aplicaron los principios número dos y cinco de química verde. Además, la metodología de obtención usada fue una modificación del procedimiento descrito en la literatura. Las benzofenonas sustituidas fueron obtenidas mediante la oxidación de los respectivos alcoholes para la obtención de las benzofenonas y fluoenona; en este método se emplea hipoclorito de sodio como agente de oxidación y bromuro de tetrabutil amonio como medio de transferencia de fase en medio acuoso. Las moléculas se caracterizaron por resonancia magnética nuclear de protón (RMN-1H) y espectroscopia de infrarroja de reflectancia total atenuada (IR-ATR) entre otras técnicas espectroscópicas. La evaluación de la actividad biológica se realizó mediante el método Kirby-Bauer, empleado para determinar la sensibilidad de un organismo frente a antibióticos o antifúngicos. Los resultados muestran que las hidrazonas sustituidas (9) y (10) presentaron una actividad inhibitoria mayor frente Candida albicans y Aspergillus niger en comparación con cicloheximida al 1%, pero considerablemente son menos efectivo que ketoconazol compuestos utilizados como control.