Composition chimique et propriétés antibactériennes des huiles essentielles d’Ocimum basilicum et d’Hyptis suaveolens (L.) Poit récoltés dans la région de Dakar au Sénégal

Les huiles essentielles des feuilles d’Ocimum basilicumet d’Hyptis suaveolens, récoltées dans la région de Dakar au Sénégal ont été extraites par entraînement à la vapeur et analysées en CPG et CPG-SM. Les monoterpènes oxygénés dont l’estragol (38,78 %), le linalol (19,45 %) et le méthyl-eugénol (9,98 %) sont majoritaires dans l’huile essentielle d’O. basilicum. Ils sont suivis d’un sesquiterpène hydrocarboné: le bergamotène (8,48 %). Par contre, l’huile essentielle de H. suaveolensest essentiellement constituée de composés hydrocarbonés: le β-caryophyllène (16,63 %), le sabinène (11,30 %), le terpinolène (8,58 %), le limonène (8,45 %) et le bergamotène (5,26 %). Les propriétés antimicrobiennes des huiles essentielles de ces plantes ont été testées in vitro sur cinq souches bactériennes (Staphylococcus aureus, Bacillus sp.,Salmonella sp., Escherichia coli, Streptococcus sp.). Une activité inhibitrice des huiles sur les souches étudiées a été observée. Toutefois, celle d’O.basilicums’est révélée plus active, particulièrement contre Bacillus sp., Salmonella sp., et Escherichia coli.Mots-clés: Ocimum basilicum, Hyptis suaveolens, huiles essentielles, composition chimique, propriétés antimicrobiennes. Chemical composition and antimicrobial properties of the essential oils of Ocimum basilicum andHyptis suaveolensharvested from Dakar region in SenegalEssential oils of leaves from Ocimum basilicum and Hyptis suaveolens collected in the region of Dakar in Senegal have been extracted by steam distillation and analyzed by GC and GC-MS. The oxygenated monoterpenes which estragol (38.78%), linalool (19.45%) and methyl-eugenol (9.98%) constitute the major portion of the essential oils of O. basilicum followed by bergamotene (8.48%) which is a sesquiterpene hydrocarbon. Principal compounds of H.suaveolens essential oilsare: β-caryophyllene (16.63%), sabinene (11.30%), terpinolene (8.58%), limonene (8.45%) and bergamotene (5.26%).The antimicrobial properties of essential oils of these plants were tested in vitro against five bacterial strains (Staphylococcus aureus, Bacillussp, Salmonella sp., Escherichia coli, Streptococcus sp.). The inhibitory activity of the oils on the strains studied was observed. However, the essential oil of O. basilicum was more active, especially against Bacillus sp., Salmonella sp. and Escherichia coli.Keywords: Ocimum basilicum, Hyptis suaveolens, essential oils, chemical composition, antimicrobial properties

Identification of a delta5-like fatty acyl desaturase from the cephalopod Octopus vulgaris (Cuvier 1797) involved in the biosynthesis of essential fatty acids

Long-chain polyunsaturated fatty acids (LC-PUFA) have been identified as essential compounds for common octopus (Octopus vulgaris), but precise dietary requirements have not been determined due in part to the inherent difficulties of performing feeding trials on paralarvae. Our objective is to establish the essential fatty acid (EFA) requirements for paralarval stages of the common octopus through characterisation of the enzymes of endogenous LC-PUFA biosynthetic pathways. In this study we isolated a cDNA with high homology to fatty acyl desaturases (Fad). Functional characterisation in recombinant yeast showed the octopus Fad exhibited ∆5 desaturation activity towards saturated and polyunsaturated fatty acyl substrates. Thus, it efficiently converted the yeast’s endogenous 16:0 and 18:0 to 16:1n-11 and 18:1n-13, respectively, and desaturated exogenously added PUFA substrates, 20:4n-3 and 20:3n-6, to 20:5n-3 (EPA) and 20:4n-6 (ARA), respectively. Although the ∆5 Fad enables common octopus to produce EPA and ARA, the low availability of its adequate substrates 20:4n-3 and 20:3n-6, either in the diet or by limited endogenous synthesis from C18 PUFA, might indicate that EPA and ARA are indeed EFA for this species. Interestingly, the octopus ∆5 Fad can also participate in the biosynthesis of non-methylene interrupted FA, PUFA that are generally uncommon in vertebrates but that have been found previously in marine invertebrates including molluscs, and now also confirmed to be present in specific tissues of common octopus

Molecular Phylogeny Restores the Supra-Generic Subdivision of Homoscleromorph Sponges (Porifera, Homoscleromorpha)

Homoscleromorpha is the fourth major sponge lineage, recently recognized to be distinct from the Demospongiae. It contains <100 described species of exclusively marine sponges that have been traditionally subdivided into 7 genera based on morphological characters. Because some of the morphological features of the homoscleromorphs are shared with eumetazoans and are absent in other sponges, the phylogenetic position of the group has been investigated in several recent studies. However, the phylogenetic relationships within the group remain unexplored by modern methods.Here we describe the first molecular phylogeny of Homoscleromorpha based on nuclear (18S and 28S rDNA) and complete mitochondrial DNA sequence data that focuses on inter-generic relationships. Our results revealed two robust clades within this group, one containing the spiculate species (genera Plakina, Plakortis, Plakinastrella and Corticium) and the other containing aspiculate species (genera Oscarella and Pseudocorticium), thus rejecting a close relationship between Pseudocorticium and Corticium. Among the spiculate species, we found affinities between the Plakortis and Plakinastrella genera, and between the Plakina and Corticium. The validity of these clades is furthermore supported by specific morphological characters, notably the type of spicules. Furthermore, the monophyly of the Corticium genus is supported while the monophyly of Plakina is not.As the result of our study we propose to restore the pre-1995 subdivision of Homoscleromorpha into two families: Plakinidae Schulze, 1880 for spiculate species and Oscarellidae Lendenfeld, 1887 for aspiculate species that had been rejected after the description of the genus Pseudocorticium. We also note that the two families of homoscleromorphs exhibit evolutionary stable, but have drastically distinct mitochondrial genome organizations that differ in gene content and gene order

New eunicellin type diterpenoids from the gorgonian coral Eunicella labiata

Two new eunicellin type diterpenes, labiatin D (1) and labiatin E (2) have been isolated hem the organic extract of the Senegalese gorgonian Eunicella labiata. The structure elucidation of the new secondary metabolites was based on the interpretation of their spectral data. The cytotoxicity evaluation for the new metabolites is reported