Extraction, caractérisation, modifications chimiques des biomolécules et applications

Abstract

Nature is an inexhaustible source of bioactive molecules which can be chemically modified in order to enhance their biological properties or to develop new applications. In this context, the hemi-synthesis of nitrogenous and / or oxygenated or even sulfur bioactive molecules from essential oils chemotypes ketones and aldehydes from four Algerian plants (Ruta montana L., Artemisia judaica L., Cuminum cyminum L. and Ammodaucus leucotrichus) is the main objective of this work. The identification of the essential oils extracted by hydrodistillation and analayzed by GC / MS revealed the predominance of linear aliphatic ketones, mainly 2-undecanone (67%) in the essential oil of Ruta montana L.; on the other hand, the xanthotoxin has been isolated from its apolar extract. Piperitone has been revealed as the major constituent of the essential oil of Artemisia judaica with a content of (86.48%); cuminum cymunum and Ammodaucus leucotrichus are mainly consisted of aldehydes, represented in: 2-caren-10-al (25.91%), cuminaldehyde (21.60%) and perilaldehydes (48.01%) respectively. In the second part, the hemi-synthesis of a natural linear alkyl sulfonate-sodium surfactant, subsequently used to stabilize Oil / Water emulsions by the reaction of the sodium bisulfite on 2-undecanone (SHUS) was carried out; in the same way a mixed surfactant system made up of alkyl chains of different lengths (MSHAS) was synthesized from the essential oil of Ruta montana L.; the synergistic effect of the latter gave it better performance and efficiency than the SHUS. The obtained surfactants showed a good adsorption at the air / water interface, which caused a decrease in surface tension between the two phases to 39.6 and 47.4 mN.Cm-1 with CMCs of 0.8 and 1 mM for MSHAS and SHUS respectively. The thionation of the Artemisia judaica L. essential oil using P2S5 has led to the conversion of piperitone to its derivatives piperithione and pipérito-ene-thiol; the study of thione-thiol tautomerism carried out by UV-vis, FTIR and GC/MS showed the predominance of the thione form in solid phase and the thiol in solutions. The carbonyl derivatives have shown different aspects of reactivity against the attack of hyrazine monohydrate. Aldehydes constituting the essential oils of cumin and hairy cumin were easily converted into symmetrical aldazines under stirring at room temperature; on the other hand, and due to the stability of ketones, 2-undecanone was converted to undecanazine after 5h of heating in the presence of acetic acid; piperotone was reduce to pmenthene according to the Wolf-Kishner reaction after 24 hours of reflux heating, and only xanthotoxin hydrazone was recovered after 9h of xanthotoxin heating. Antimicrobial tests were carried out in order to evaluate the effect of substitution on microbiological activity. According to the obtained results, a considerable improvement in the antimicrobial activity of essential oils and furocoumarins ws observed using their sulfur and nitrogenous analogues against all tested germs, these results were confirmed by the determination of their minimum inhibitory concentrations.