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Saxitoxin (STX) is a neurotoxin produced by dinoflagellates in diverse species, such as Alexandrium spp., and it causes paralytic shellfish poisoning (PSP) in humans after the ingestion of contaminated shellfish. Recent studies have suggested that the immune functions of bivalves could be affected by harmful algae and/or by their toxins. Herein, hemocytes are the main effector cells of the immune cellular response. In this study, we evaluated the response of hemocytes from the mussel Mytilus chilensis to STX exposure in a primary culture. Cell cultures were characterized according to size and complexity, while reactive oxygen species (ROS) production was evaluated using a dichlorofluorescein diacetate (DCFH-DA) assay. Finally, phagocytic activity was measured using both flow cytometry and fluorescence microscopy assays. Additionally, gene transcription of candidate genes was evaluated by qPCR assays. The results evidenced that exposures to different concentrations of STX (1–100 nM) for 24 h did not affect cell viability, as determined by an MTT assay. However, when hemocytes were exposed for 4 or 16 h to STX (1–100 nM), there was a modulation of phagocytic activity and ROS production. Moreover, hemocytes exposed to 100 nM of STX for 4 or 16 h showed a significant increase in transcript levels of genes encoding for antioxidant enzymes (SOD, CAT), mitochondrial enzymes (COI, COIII, CYTB, ATP6, ND1) and ion channels (K+, Ca2+). Meanwhile, C-type lectin and toll-like receptor genes revealed a bi-phase transcriptional response after 16 and 24–48 h of exposure to STX. These results suggest that STX can negatively affect the immunocompetence of M. chilensis hemocytes, which were capable of responding to STX exposure in vitro by increasing the mRNA levels of antioxidant enzymes.

From the fruiting body of ectomycorrhizal fungi Cortinarius xiphidipus, sterols were identified from the crude extract and the cytotoxic effect of ergosta-4, 6, 8(14), 22-tetraen-3-one (ergone) was evaluated. Ten sterols including ergosta-3,5,7,9(11),22-pentaene, (22E)-ergosta-5,7,9(11),22-tetraen-3b-ol, (3β,22E)-ergosta-5,7,22-trien-3-ol, (22E)-ergosta-7,22-dien-3-ol, neoergosterol, (3β)-ergosta-5,8-dien-3-ol, (3β)-ergosta-7-en-3-ol, stigmasterol, stigmasterol 22,23-dihydro and (22E)-ergosta-4,6,8(14),22-tetraen-3-one were identified from the crude extract. The cytotoxic activity of the sterol fraction containing ergosta-4, 6, 8(14), 22-tetraen-3-one was assessed on four tumour cell lines (Neuro-2a, Saos-2, MCF7 and LNCaP-C42). The cytotoxic activity against the four tumour cell lines tested, being Neuro-2a and Saos-2 the most sensitive, with a half-maximal inhibitory concentration (IC) of 20.8 ± 2.2 and 27.8 ± 1.0 μg/mL, respectively. This is the first report of this Antarctic fungi collected in the Magallanes and Chilean Antarctica Region. This work represents a potential source for the development of anticancer drugs.

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4Agri-Food Laboratories-Concepción, SGS Chile Ltda. Américo Vespucio 820, Parque Industrial Las Arucas, Talcahuano, ChileResumen.-En la última década se ha incrementado el interés por la búsqueda de moléculas con potencial biomédico y amigable para el ambiente. Desde esta perspectiva, la búsqueda de principios bioactivos de origen marino ha permitido valorar la diversidad biológica presente en los ecosistemas acuáticos. En el Phylum Equinodermata, se destaca la familia Holothuridae, por su capacidad de sintetizar moléculas como saponinas y otros metabolitos secundarios de alto interés farmacológico debido a su capacidad hemolítica, antitumoral, anti-inflamatoria, antimicrobiana, citostática y antineoplásica. El interés del presente trabajo se centró en la caracterización de un extracto purificado obtenido desde Athyonidium chilensis (Holothuria) mediante técnicas cromatográficas y de espectrometría de masas, con la posterior evaluación de su potencial bioactivo sobre modelos in vitro. Como resultado de estos análisis, se identificaron 2 saponinas. La primera con un peso molecular de 1522 Da y altamente conjugada con monosacáridos. La segunda con un peso molecular de 764 Da fue identificada como holoturinósido D. Respecto a los resultados de la actividad biológica del extracto purificado, éste mostró actividad antibacteriana, antifúngica y citotóxica frente a una línea celular de neuroblastoma. Los resultados de este estudio se convierten en la primera caracterización de moléculas con actividad biológica desde Athyonidium chilensis. Palabras clave: Holothuria, holoturinósido D, saponinaAbstract.-In the last decade, the interest for searching molecules with biomedical potential as well as innocuous for the environment has been increased. Under this perspective, the search for bioactive principles of marine origin has allowed to value the biological diversity present in aquatic systems. In phylum Echinodermata, the family Holothuridae is distinguished by its capacity of synthesizing molecules such as saponins and other secondary metabolites of high pharmacological interest because of their interesting haemolytic, antitumor, anti-inflammatory, antimicrobial, cytostatic and antineoplastic capacity. The aim of the present study was focused on the characterization of a purified extract obtained from Athyonidium chilensis (Holothuria) by chromatographic and mass spectrometric techniques and the later assessment of its bioactive potential on in vitro models. As a result of these analyses 2 saponins were identified. The first with a molecular weight of 1522 Da and highly conjugated with monosaccharides. The second with a molecular weight of 764 Da was identified as holothurinoside D. The biological activity of the purified extract showed antibacterial, antifungal and cytotoxic activity on a neuroblastoma cell line. Outcomes of this study correspond to the first characterization of molecules with biological activity from Athyonidium chilensis.