Michèle Guyot

Grossularine-1 and grossularine-2, cytotoxic α-carbolines from the tunicate: Dendrodoa grossularia

Abstract Several indole derivatives were isolated from the tunicate: Dendrodoa grossularia among which two α-carbolines: grossularine-1 (revised structure) and grossularine-2. The structures were based upon spectral data, including X-ray analysis for grossularine-2. These compounds exhibit marked cytotoxicity toward murine and human tumor cells. They are the first example of naturally occurring α-carbolines.

Araplysillins-I and-II : biologically active dibromotyrosine derivatives from the sponge Psammaplysilla Arabica

Araplysillins-I and-II, two novel dibromotyrosine derivatives, were isolated fromPsammaplysilla arabica and their structure was elucidated by spectroscopic methods. They proved to be inhibitors of Na+/K+ ATPase and to have antimicrobial activity.

Lissoclinotoxin A, an antibiotic 1,2,3-trithiane derivative from the tunicate Lissoclinum perforatum.

Abstract Lissoclinotoxin A, a new antibiotic 1,2,3-trithiane derivative, was isolated from the Tunicate Lissoclinum perforatum . The structure elucidation was based upon spectral data.

Purification and Partial Identification of Novel Antimicrobial Protein from Marine Bacterium Pseudoalteromonas Species Strain X153

A marine bacterium, X153, was isolated from a pebble collected at St. Anne du Portzic (France). By 16S ribosomal DNA gene sequence analysis, X153 strain was identified as a Pseudoalteromonas sp. close to P. piscicida. The crude culture of X153 was highly active against human pathogenic strains involved in dermatologic diseases, and marine bacteria including various ichthyopathogenic Vibrio strains. The active substance occurred both in bacterial cells and in culture supernatant. An antimicrobial protein was purified to homogeneity by a 4-step procedure using size-exclusion and ion-exchange chromatography. The highly purified P-153 protein is anionic, and sodium dodecylsulfate polyacrylamide gel electrophoresis gives an apparent molecular mass of 87 kDa. The X153 bacterium protected bivalve larvae against mortality, following experimental challenges with ichthyopathogenic Vibrio. Pseudoalteromonas sp. X153 may be useful in aquaculture as a probiotic bacterium.

Novel alkaloids of the aaptamine class from an Indonesian marine sponge of the genus Xestospongia

Abstract Four novel alkaloids of the aaptamine class have been isolated in addition to the known aaptamine, isoaaptamine, demethyl(oxy)aaptamine and its dimethylketal from an unidentified species of Indonesian marine sponge of the genus Xestospongia . Their structures were elucidated on the basis of detailed 1D and 2D NMR spectroscopic data. Their antimicrobial activity was tested towards Gram (+) ( S. aureus ), Gram (−) ( E. coli , V. anguillarum ) bacterial strains, a fungus ( C. tropicalis ); their cytotoxic activity was evaluated against KB cells.

Lissoclinotoxins : antibiotic polysulfur derivatives from the tunicate Lissoclinum perforatum. Revised structure of lissoclinotoxin A

Abstract Lissoclinotoxin B, a new pentathiepin derivative, was isolated from the tunicate Lissoclinum perforatum. Structure elucidation of this compound is described based on spectroscopic data, together with a revised structure for lissoclinotoxin A. A synthesis of tetraacetyl isolissoclinotoxin A is described.

Metabolites from the Sponge-Associated Bacterium Pseudomonas Species

Abstract: Quinolones and a phosphatidyl glyceride were isolated from the sponge-associated bacterial strain Pseudomonas sp. Structures were elucidated by spectroscopic analysis and chemical transformations.

Smenospongine: A cytotoxic and antimicrobial aminoquinone isolated from Smenospongia sp.

Abstract Smenospongine a cytotoxic and antimicrobial sesquiterpene-aminoquinone was isolated from Smenospongia sp. Structure elucidation was achieved by spectral analysis.

A short entry into the pyrido[2,3-b]indole ring system. Synthesis of the tetracyclic segment of the marine antitumor agents : grossularines-1 and -2

Abstract A new method for the synthesis of substituted pyrido[2,3- b ] indoles (α-carbolines) ( 14, 27-31 ), featuring Pd-catalyzed cross coupling between pyridine and aniline derivatives and subsequent intramolecular cylization, has been developed. This method provided a highly convergent access to the tetracyclic segment ( 3 ) of the marine antitumor agents: grossularines-1 and -2 ( 1,2 ).

An expeditious synthesis of structural analogs of the marine cytotoxic agents grossularines-1 and -2

Abstract A short access to 2-carbethoxy-3-(5-imidazolyl)indoles (13, 14, 16), featuring Pd-catalyzed cross coupling between 3-iodoindoles (10–12) and imidazolostannane (9) has been developed. These derivatives when subjected to tandem modified Curtius rearrangement-intramolecular electrocyclization led to the pyridones (19–23) which are key intermediates in the synthesis of the analogs (31), (33) and (36) of the naturally occurring cytoxic α-carbolines grossularines-1 and -2 (1,2).