Georges Combaut

A novel acyclic diterpene from the brown alga bifurcaria bifurcata

Abstract A novel epoxy-diterpene identified as 7,8-epoxy-1-hydroxy-13-keto-3,7,11,15-tetramethylhexadeca-2 E ,5 E ,10 E ,-14-tetraene was isolated from Bifurcaria bifurcata , a brown alga belonging to the family Cystoseiraceae, in which eleganolone, epoxy-eleganolone and eleganediol have previously been isolated.

Phenols bromes d'une algue rouge, Halopytis incurvus: Acides carboxyliques

Abstract Extracts of Halopytis incurvus yielded, after methylation, the esters of 3,5-dibromo-4-methoxy-phenylacetic acid and 2-methoxy-3-(3′,5′-dibromo-4′-methoxyphenyl)acrylic acid.

Cystodamine, a new cytotoxic fused polyaromatic alkaloid from the Mediterranean ascidian Cystodytes delle chiajei

Abstract a fused pentacyclic aromatic alkaloid - cystodamine - was isolated from a Mediterranean ascidian Cystodytes delle chiajei (Polycitoridae). The structure, determinated by extensive 2D-NMR means, is the first example of a marine product displaying a 1 H- 14 N coupling during 1 H NMR analysis.

Monoterpenes et sesquiterpenes oxygenes de Cupressus dupreziana

Resume Twelve oxygenated mono- and sesquiterpenes have been isolated from the heartwood extractives of Cupressus dupreziana. Six of them are new compounds with p-menthane, alaskane and 1,7-diepicedrane skeletons. Structures were determined by spectral methods. The chemotaxonomic significance of these findings are discussed.

Seasonal chemical evolution of the alga Cystoseira elegans

Abstract Among the Mediterranean algae belonging to the family Cystoseiraceae analysed for diterpenic compounds, only Cystoseira elegans contains eleganolone, epoxy-eleganolone and elegandiol, as does the Atlantic alga Bifurcaria bifurcata . Surprisingly, for the seasonal Cystoseira elegans , these compounds are present only at the beginning of growth of the alga during Spring and they disappear in the Summer yielding important seasonal variation data for diterpenoids, and also for sterols, alginic acid,mannitol and cellulose.

The complete spectral assignment of didemnin H a new constituent of the tunicate Trididemnum cyanophorum

Abstract Complete 1H and 13C spectral assignments by 2D NMR means are presented for a new cyclodepsipeptide namely didemnin H, isolated from Trididemnum cyanophorum (Didemnidae).

Tyr5didemnin B and [D-Pro4]didemnin B; Two new natural didemnins with a modified macrocycle

Abstract The structures of the two natural didemnins with a modified macrocycle, [Tyr5]didemnin B [2] and [D-Pro4]didemnin B [3], isolated from the Aplousobranch ascidian Trididemnum cyanophorum (Didemnidae) are described. Structures were determined by FABMS and NMR spectroscopy, absolute configurations by Marfey analysis of the acid hydrolisatcs. Conformational informations arc given and cytotoxic activities against human lymphoblastic leukemia cell lines evaluated.

Sterols of the red alga Rissoella verruculosa

Abstract The Mediterranean red alga Rissoella verruculosa contains desmosterol in the esterified form whereas this sterol is not present in the free state.

Phenols bromes des algues rouges: Cyclotribromoveratrylene, nouveau derive obtenu au cours de l'extraction de Halopytis pinastroïdes

Abstract Cyclotribromoveratrylene has been isolated from an ethanolic extract of fresh Halopytis pinastroides , after treatment with diazomethane. This new

Composes halogenes d'une algue rouge, Falkenbergia rufolanosa tetrasporophyte d' Asparagopsis armata

Abstract Water extraction of fresh Falkenbergia rufolanosa followed by water-ether partition, yielded halomethanes, polyhalo ethyl and methyl acetates and especially polyhalo acetones. It is the first example of polyhalo compounds extracted from a tetrasporophyte in the Bonnemaisoniaceae.