[Seasonal and geographical variation range of antifungal activity of sponge extracts from the Moroccan Atlantic coasts]. / Variation saisonnière et géographique de l'activité antifongique des extraits de deux éponges marines récoltées sur le littoral atlantique d'El Jadida, Maroc.

Currently, marine organisms have a very important source of new molecules in pharmacology and thus in the development of new bioactive products. The organic and aqueous extracts of two marine sponges, Cinachyrella tarentine collected during two different seasons, winter and summer, and Cliona viridis collected in two different zones on the coast of El Jadida (Morocco) were tested for their antifungal activity using the diffusion method. The C. tarentine sponge collected in January (winter) has a very important activity compared to that collected in August (summer). While the sponge C. viridis collected from Jorf Lasfar port (shallower and polluted area) has a very important activity compared to that collected from the coast of El Jadida (depth and unpolluted area).

Detection of griseofulvin in a marine strain of Penicillium waksmanii by ion trap mass spectrometry.

A marine strain of Penicillium waksmanii Zaleski was isolated from a sample of seawater from shellfish-farming area in the Loire estuary (France). The in vitro marine culture showed an important antifungal activity. Bioassay-guided fractionation was used to purify the crude extract. Dereplication by electrospray-ion trap/mass spectrometry (ESI-IT/MS) afforded the identification of the antifungal compound, after a semi-purification consisting of two stages. A comparison of the ionic composition between the active and the non-active fractions allowed the detection of a monocharged ion at m/z 353 containing a chlorine atom, which could be attributed to the antifungal griseofulvin [C17H17ClO6+H]+. Multi-stage fragmentation (MSn) confirmed the identity of the m/z 353 ion of the antifungal fraction as griseofulvin. It is the first description of griseofulvin production by a strain of P. waksmanii and the first chemical study of a strain of this species isolated from marine temperate cold water.

[Marine resources and drugs: fishing for molecules]. / Ressources marines et médicaments: la pêche aux molécules.

Biodiversity on the Earth is mainly made up of the huge number of existing marine organisms. Marine animals and plants elaborate a great panel of chemicals, many of them exhibiting strong biological activities. So, the seas enable human kingdom to obtain a large number of active products of medicinal interest. This paper deal with the various steps since the collection of the marine samples up to the marketing of the new molecules. Recent drugs from the seas and the main scientific or industrial partners concerned are also introduced.

Cardiovascular effects of lepadiformine, an alkaloid isolated from the ascidians Clavelina lepadiformis (Müller) and C. moluccensis (Sluiter).

The effects of lepadiformine, a natural marine alkaloid isolated from the ascidians Clavelina lepadiformis (Müller) and C. moluccensis (Sluiter), were studied in vivo by arterial blood pressure (aBP) recordings and electrocardiograms (ECG) in anaesthetised rats and in situ by peripheral vascular pressure recordings on perfused rabbit ear. Transmembrane resting (RP) and action (AP) potentials were also recorded by intracellular microelectrodes on electrically stimulated left ventricular papillary muscle and spontaneously beating atrium isolated from rat and frog hearts, respectively. Intravenous injection of lepadiformine (6mg/kg) produced marked bradycardia and a lengthening of ECG intervals as well as a transient decrease of aBP, which rapidly returned to normal. The decrease of aBP may have been related to a vasoconstrictor effect observed in the perfused ear experiment. Lepadiformine did not alter RP, but significantly lengthened the repolarising phase of AP in rat papillary muscle and frog atrium. Lepadiformine also mimicked the effect of Ba(2+) (0.2mM) on the rat AP repolarising phase. Moreover, the lengthening of the AP in frog atrium induced by lepadiformine still developed after the delayed outward K(+) current (I(K)) was blocked by tetraethylammonium (10mM). These observations suggest that lepadiformine-induced lengthening of AP duration was not due to a decrease of I(K), but may reasonably be attributed to a reduction of the inward rectifying K(+) current (I(K1)). This blockade of I(K1) could account for the cardiovascular effects of lepadiformine in vivo and in vitro and suggests that lepadiformine has antiarrhythmic properties.

Toxicity of French strains of the dinoflagellate Prorocentrum minimum experimental and natural contaminations of mussels.

Mediterranean strains of Prorocentrum minimum do not appear to have the same toxic component as Japanese strains since they showed no cytotoxicity for hepatocytes in culture. However, their toxic components, which appear to block calcium channels, were detectable by the immobilisation test on Diptera larvae. A bio-accumulation experiment in the laboratory showed that the toxins could accumulate in nearly equivalent amounts in the hepatopancreas and meat of cultured mussels. The same toxicity was found in natural samples collected in a period of bloom of P. minimum. These results suggest that P. minimum could be responsible for shellfish toxicity in the natural environment and thus present a risk for human health.

Antiproliferative effects of a product isolated from the gorgonian Rumphella aggregata.

A fraction isolated from the gorgonian Rumphella aggregata (Plexauridae) was studied vitro on asynchronous cells of a human non-small-cell-bronchopulmonary-carcinoma line (NSCLC-N6). Cell growth appeared to be inhibited in the Gl phase of the cell cycle, and kinetic studies in pretreated cells showed that this growth arrest was irreversible. These events seem to show a terminal maturation induced by this new product.

Antifungal metabolites from the marine sponge Pachastrissa sp.: new bengamide and bengazole derivatives.

This paper reports the studies of components of an undescribed sponge in the genus Pachastrissa sp., collected along the Djibouti coast. The extract showed activity against Candida albicans. Six new bengazoles (1-6) and a new bengamide, named bengamide L (16), in addition to the known bengazoles (7-11), bengamides A (12), B (13), E (14), and F (15), and a lactone (17) are described in this paper. All structures were determined on the basis of spectroscopic studies.

Subtractive hybridization and differential screening identified two genes differentially expressed after induction of in vitro (atypical) terminal differentiation in the NSCLC-N6 cell line by a marine substance (bistramide K).

Non-small-cell lung carcinoma is generally refractory to chemotherapy. The difficulties that arise in the treatment of this type of tumor make it necessary to develop new therapeutic strategies. Previous work done in our laboratory showed that a marine substance named bistramide K induced in vitro (atypical) terminal differentiation of NSCLC-N6 cell line. This activity is linked to a growth arrest of NSCLC-N6 cell line and an irreversible block at the G1 phase of the cell cycle (G1DT). In order to identify the genes that could be expressed after the treatment by the drug, we constructed a subtractive cDNA library with enriched mRNA extracted from BK-treated NSCLC-N6. After differential hybridization and DNA sequencing, we identified two sequences. The sequence identified for the clone 8 showed strong homology to the sequence of the ribosomal protein L35A. The sequence identified for the clone 4 did not show any homology with known sequences in official gene data banks.

Terminal differentiation in a non-small-cell bronchopulmonary carcinoma correlates with increased expression of p53.

We studied the pharmacomodulating effects of a marine substance, bistramide D, which is capable of inducing terminal differentiation on the expression of the c-erb-B1, ras, src, myc and p53 genes in the NSCLC-N6 cell line established from a non-small cell lung carcinoma. Analysis (subsequent to treatment) demonstrated that among the genes for which it was possible to detect expression, namely c-erb-B1, c-myc and p53, only the expression of the p53 gene varied significantly. The increase of the expression rate of the p53 gene underlines its prominent role in the control of cell proliferation and differentiation.

Bistramides A, B, C, D, and K: a new class of bioactive cyclic polyethers from Lissoclinum bistratum.

The isolation and characterization is described of four novel cyclic polyethers, bistramides B [2], C [3], D [4], and K [5], which are closely related to the previously reported bistramide A [1] from the New Caledonian urochordata Lissoclinum bistratum. The structures of these metabolites were defined by spectroscopic methods. The four compounds exhibited in vitro cytotoxicity toward six tumor cell lines, including the human non-small cell lung carcinoma (NSCLC-N6) line. Cytofluorimetric analysis with bistramide K showed a complete block of NSCLC-N6 cells in the G1 phase. Bistramide D and particularly bistramide K are less toxic than bistramides A, B, and C and are thereby effective in vivo against NSCLC-N6.

Influence of Bistramide A on the twitch tension in rat atrial heart muscle.

Bistramide A, a new toxin isolated from the Urochordate Lissoclinum bistratum Sluiter, was applied to rat auricular heart muscle bundles. At a stimulation frequency of 0.2 Hz, the toxin induces a dose-dependent reduction of the stimulated twitch tension force; it decreases Vmax and shortens the duration of the plateau and the slow repolarizing phase of the action potential. In the control solution, switching from a stimulation frequency of 0.2 Hz to 1 Hz decreases the force with which a positive potentiation develops either at a maintained high frequency or after switching from 1 Hz to 0.2 Hz. Bistramide A reduces both the force evoked at 1 Hz and the potentiation. The data suggest that Bistramide A blocks Na+ conductance; inhibits Ca++ channels in a time- and frequency-dependent manner; reduces Na(+)-Ca++ exchange activity; but does not modify the ability of the sarcoplasmic reticulum to be refilled although the rate of Ca++ accumulation is decreased.

Chemotherapeutic inhibition of erb-B2 oncogene expression on a non-small-cell cancer line (NSCLC-N6) by marine substances.

The inhibitory effect of natural substances of marine origin on the erb-B2 oncogene of a human NSCLC-N6 line was demonstrated in vitro by simultaneous study of the expression of the gene and its product, using respectively an erb-B2 specific probe and an anti-c-erb-B2 polyclonal antibody. Preliminary results indicate inhibition ranging from 17-77% of oncogene expression and from 77-90% of product expression. The fact that substances of this type, with different chemical structures, have the common ability to induce terminal differentiation in an experimental model after irreversible blockade in G1 phase suggests a relationship between the inhibition of certain oncogenes and terminal differentiation.

Comparative study of the antitumor activity of bistramides A, D and K against a non-small cell broncho-pulmonary carcinoma.

Bistramides A, D and K are substances extracted from the marine ascidian Lissoclinum bistratum Sluiter that are capable of inducing in vitro terminal differentiation (G1DT) of cells from a non-small cell broncho-pulmonary carcinoma (NSCLCN6), but present different in vitro toxicities. This study shows that only the least toxic bistramides D and K possess an antitumor activity. These two substances could be administered as a continuous treatment which would induce terminal differentiation of stem cells at their entry into the cell cycle, thereby causing their destruction.

The polyether Bistramide A affects the calcium sensitivity of the contractile proteins in frog atrial heart muscle.

The effects of Bistramide A, a new toxin isolated from the Urochordate Lissoclinum bistratum Sluiter have been studied on the mechanical activity of frog heart atrial muscle preparations. The peak tension of isolated trabeculae was sensitive to nanomolar concentrations of Bistramide A. Lineweaver-Burk relationships suggest that Bistramide A competes with Ca for a common site. In voltage-clamped trabeculae, the toxin inhibited both the cadmium-sensitive Ca current and the phasic component of the tension with a dissociation constant of 3.3 microM and a stoichiometry of 2. Bistramide A decreased the isometric tension of skinned fibres in a dose-dependent manner with a dissociation constant of 400 nM and a stoichiometry of 2. The toxin reduced the maximum Ca activated force and decreased the sensitivity of the contractile proteins to Ca. The data suggest that Bistramide A decreases the Ca-sensitivity of contractile proteins prior to blocking the Ca current.

Bistramide A-induced irreversible arrest of cell proliferation in a non-small-cell bronchopulmonary carcinoma is similar to induction of terminal maturation.

Bistramide A, a new toxin isolated from a New Caledonian Urochordata, shows an antiproliferative effect on a non-small-cell lung carcinoma line in vitro and G1-blockade. In this work, the growth arrest induced by bistramide A was shown to be irreversible as assessed by growth kinetics of pretreated cells. Furthermore, the drug caused an underexpression of the nuclear antigen Ki67. These events are similar to a G1-differentiation cell cycle step blockage and a terminal maturation induction.

Effects in vitro of two marine substances, chlorolissoclimide and dichlorolissoclimide, on a non-small-cell bronchopulmonary carcinoma line (NSCLC-N6).

The antiproliferative activity of two nitrogenous labdane cytotoxic substances from Lissoclinum voeltzkowi Michaelson (Urochordata), dichlorolissoclimide (P2) and chlorolissoclimide (P1), was studied in vitro on a continuous human non-small-cell bronchopulmonary carcinoma line (NSCLC-N6) at the cell cycle level. This antiproliferative effect resulted from a blockade of G1 phase cells. Mortality occurred, regardless of the degree of cell ploidy, with cell transition to an out-of-cycle situation characteristic of a G1D terminal maturation state.

Effects of bistramide A on a non-small-cell bronchial carcinoma line.

The antiproliferative effects of bistramide A, a nitrogenous dilactam polyether from Lissoclinum bistratum Sluiter (Urochordata), were studied at the level of the cell cycle in asynchronous cells of the NSCLCN6-L16 line. Bistramide A has a dual mechanism that induces blockade in the G1 phase (compatible with differentiation properties reported elsewhere) and causes polyploidy that is suggestive of inaptitude for cytokinesis. These effects confirm the results of cytomorphology studies in electron microscopy.