L'indice de réfraction et la densité des échantillons d'huile essentielle de Lippia multiflora (feuilles et fleurs), Cymbopogon citratus, Cymbopogon nardus, Cymbopogon giganteus de Côte-d'Ivoire sont déterminés. La viscosité de ces échantillons a été étudiée. Ces huiles ne sont pas newtoniennes. Seule l'huile essentielle de C. citratus est thixotrope. Pour citer cet article :

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A theoretical study of the reactivity of quinoline-4-one derivatives is undertaken in order to understand the involved mechanisms. The calculations were carried out in gas phase and in N, N-Dimethylformamide (DMF) solution. The Density Functional Theory (DFT) with B3LYP functional associated to 6-311G (d) and 6-311+G (d) bases is used to perform these calculations. The results of the thermodynamic parameters showed that there is an equilibrium relation between the different tautomers. This equilibrium can be used to explain the failure to obtain tetrahydroquinoline from 5,8-dimethoxy-quinolin-4-one. Reactivity analysis from Frontier Molecular Orbitals theory and Fukui function calculations revealed that ketone forms are less reactive than enol ones. The methoxyl substituent decreases the acidity of the nitrogen and oxygen atoms of quinolin-4-one while the bromine increases the acidity of the same sites. These results foresee that nitrogen deprotonation in the case of the brominated compound is easier than in the case of methoxylated ones.

The chemical composition of the essential oils obtained from the dried leaves of five species of the genus Eucalyptus (E. camaldulensis, E. deglupta, E. grandis, E. torelliana, E. urophylla) growing in Côte d'Ivoire, was analyzed by means of GC and GC/MS. The density and the refractive index were measured. The major components of all these oils are: α-pinene, β-pinene, α-phellandrene, limonene, γ-terpinene, p-cymene and β-caryophyllene. The particularity of these oils is their monoterpene hydrocarbons major components.

The hydrogen-bonding properties of galanthamine have been investigated experimentally from a thorough analysis of crystallographic data retrieved from the Protein Data Bank and Cambridge Structural Database databases and theoretically through ab initio [MP2/6-311++G(2d,p)] and density functional theory [MPWB1K/6-31++G(d,p)] calculations. The main hydrogen-bond acceptor (HBA) interaction sites of the molecule are the O atoms and their spatial proximity allows multi-centered hydrogen-bond (HB) motifs. The hydrogen-bond donor (HBD) sites of the molecule are the NH(+) and OH groups as well as several CH donors. Among them, the preferred ones are those directly linked to the ammonium nitrogen, followed by aromatic CH and finally the methyl group of the methoxy substituent. All these observations are in fairly good agreement with the computed positions of the molecular electrostatic potential (MEP) minima and maxima of various galanthamine species. The galanthamine HBD and HBA properties, investigated through the MEP analysis, appear sensitive to the degree of neutralization of the ammonium NH(+) positive charge.