Three Togolese aromatic plants' essential oils diurnal variations and their insecticidal activities against the dengue vector Aedesaegypti.

The present reported work deals with the ability of Togolese plants' essential oils (EOs) to act as repellents for Aedes aegypti mosquitoes in order to use them as personal protective requirements or actions against mosquito bites and therefore to drastically reduce the risk of contracting dengue or yellow fever. EOs studied here were extracted from dry leaves of Ageratum conyzoides L., Eucalyptus citriodora Hook, and Lantana camara Linn, three plants that were collected at different daytimes (7 a.m., 1 p.m., and 7 p.m.) at various locations in Togo. Using a Clevenger-type device, EOs were obtained by the hydrodistillation method (Clevenger, 1928). The physical parameters of the EOs such as density, refractive index, rotatory power, and organoleptic properties were determined. Then, the characterization of EOs using gas chromatography equipped with a flame ionization detector (GC/FID) and gas chromatography coupled to mass spectrometry (GC/MS) was conducted. Chemical analyses showed the presence of several main compounds from EO samples of the three plants. The major compounds were characterized and identified as: (i) precocene I (67.7, 70.6, and 66.9%) and ß-caryophyllene (17.4, 12.1, and 16.5%) for the EO of A. conyzoïdes; (ii) citronellal (63.3, 67.2, and 75.4%) and citronellol (24.5, 21.4, and 14.3%) for E. citriodora and (iii) ß-caryophyllene (15.3, 11.7, and 12.4%), sabinene (28.4, 35, and 33.3%) and eucalyptol (11.5, 14.1, and 15.6%) for L. camara at 7 a.m., 1 p.m., and 7 p.m., respectively. The yield and the chemical composition of the oils vary according to harvesting time and sunlight. The insecticidal activity of EOs was evaluated following the CDC bottle method on Aedes aegypti females. All the EOs tested on the female adults of Aedes aegypti showed significant insecticidal activity. The EO of A. conyzoïdes at 1 p.m. and 7 p.m. resulted in 100% mortality after 8 min of exposure time at the lowest concentration (0.0025%). At the same concentration for the EO of E. citriodora, the mortality rates were 83%, 38.8%, and 30.80% at 7 a.m., 1 p.m., and 7 p.m., respectively for an exposure time of 8 min. The EO extracted from the leaves of L. camara harvested at 7 a.m. was effective after an exposure time of 15 min for a concentration of 0.02%. For the same concentration, the mortality rates of the EO of L. camara harvested at 1 p.m. and 7 p.m., after 8 min were 62.9% and 52%, respectively. From these interesting results reported for the first time in Togo, EOs from leaves of three Togolese plants harvested at different times of the day appear to be a valuable alternative for mosquito vector control in Togo or abroad countries in which dengue and yellow fever constitute a terrible scourge.

Fragrance in dermocosmetic emulsions: From microstructure to skin application.

Fragrance is added to almost all dermocosmetic emulsions, as it has been found to be a key driver in consumer choice and contributes to the perception of product performance. Fragrance is a complex mixture of odorant chemicals at different concentrations. When incorporated into a formulation, the individual fragrance chemicals partition between the emulsion phases depending on their physicochemical properties, which can impact the structure, stability, texture and odour of the final product. On the other hand, it is well known in the food industry how the composition and structure of food emulsion matrices influence the release of aroma chemicals. Fragranced dermocosmetic emulsions have been studied to a lesser extent but it is interesting to apply findings from the food domain since emulsion structure, composition and aroma compounds share common features. This review aims to give an overview of the literature dealing with the interactions between fragrance and dermocosmetic emulsions. The effects of fragrance on emulsion microstructure, stability and texture are highlighted and discussed. The effects of composition and structure of emulsion on the release of fragrance molecules are also presented. Finally, the interactions between skin and fragranced emulsions are addressed.

Des parfums sont ajoutés dans la plupart des émulsions dermocosmétiques. L'odeur d'un produit est en effet un facteur déterminant lors du choix par les consommateurs, et elle peut même contribuer à la perception de ses performances. Le parfum est un mélange complexe de substances chimiques odorantes à différentes concentrations. Lorsqu'elles sont incorporées dans une formule, les molécules odorantes se répartissent entre les phases de l'émulsion en fonction de leurs propriétés physicochimiques, ce qui peut avoir un impact sur la structure, la stabilité, la texture et l'odeur du produit fini. D'autre part, il est bien connu dans l'industrie alimentaire que la composition et la structure des matrices alimentaires influencent la libération des molécules aromatiques. Les émulsions dermocosmétiques parfumées ont été moins étudiées dans la littérature, mais les résultats obtenus dans le domaine alimentaire peuvent être utiles pour comprendre les phénomènes mis en jeu dans ces systèmes. En effet, la structure et la composition des deux types d'émulsions, et la nature des composés aromatiques et odorants présentent de nombreuses caractéristiques communes. Cette revue vise à donner une analyse de la littérature traitant des interactions entre les parfums et les émulsions dermocosmétiques. Dans un premier temps, les effets des parfums sur la microstructure, la stabilité et la texture des émulsions sont présentés et discutés. Puis, les effets de la composition et de la structure de l'émulsion sur la libération des molécules parfumantes sont abordés. Enfin, les interactions entre la peau et les émulsions parfumées sont renseignées.

Triumfetta cordifolia Gum as a Promising Bio-Ingredient to Stabilize Emulsions with Potentials in Cosmetics.

The cosmetics industry is searching for efficient and sustainable substances capable of stabilizing emulsions or colloidal dispersions that are thermodynamically unstable because of their high surface energy. Therefore, surfactants are commonly used to stabilize the water/oil interface. However, the presence of a surfactant is not always sufficient to obtain stable emulsions on the one hand, and conventional surfactants are often subject to such controversies as their petroleum origin and environmental concerns on the other hand. As a consequence, among other challenges, it is obvious that research related to new-natural, biodegradable, biocompatible, available, competitive-surfactants are nowadays more intensive. This study aims to valorize a natural gum from Triumfetta cordifolia (T. cordifolia) as a sustainable emulsifier and stabilizer for oil-in-water (O/W) emulsions, and to evaluate how the nature of the fatty phase could affect this potential. To this end, O/W emulsions were prepared at room temperature using three different oils varying in composition, using a rotor-stator mixer. Resulting mixtures were characterized using optical microscopy, laser granulometry, rheology, pH and stability monitoring over time. The results demonstrated good potential for the gum as an emulsifying agent. T. cordifolia gum appears efficient even at very low concentrations (0.2% w/w) for the preparation and stabilization of the different O/W emulsions. The best results were observed for cocoglyceride oil due to its stronger effect of lowering interfacial tension (IFT) thus acting as a co-emulsifier. Therefore, overall results showed that T. cordifolia gum is undoubtedly a highly promising new bio-sourced and environmentally friendly emulsifier/stabilizer for many applications including cosmetics.

Understanding of the residual odour of fatty esters used as emollient in cosmetic products.

OBJECTIVE: Fatty esters are known for their versatility, but in addition to their performance as emollients, emulsifiers, solubilizers, or dispersing agents, they have to meet more and more criteria to be used in cosmetic products. Thus, their olfactory characteristics are expected to be as neutral as possible. However, despite a step of deodorization during the synthesis of fatty esters, a residual odour is currently still perceived at the end of the process. METHODS: In this study, a specific analytical methodology combining sensory with chemical analyses was implemented to characterize the residual odour of two fatty esters and to determine its origin. Ethyl oleate and isononyl isononanoate were selected and underwent a sensory analysis to evaluate their odour intensity and odour profile. Volatile compounds released by these esters were assessed by GC-MS after solid-phase microextraction and among them, odouractive compounds were brought into light using gas chromatography coupled with mass spectrometry and olfactometry analyses. RESULTS: On the isononyl isononanoate chromatogram, only peaks corresponding to the different isomeric ester forms were evidenced while around 70 volatile compounds were detected in the ethyl oleate headspace, including esters, aldehydes, hydrocarbons, and ketones. Isononyl alcohol used as raw material in the synthesis was proven to be responsible for isononyl isononanoate final odour. As for ethyl oleate, of the 23 odour-active compounds perceived, 14 have been identified; they are mainly esters and saturated as well as unsaturated aldehydes. CONCLUSION: A novel measurement approach was presented to analyse trace odours of fatty esters and the results will be useful to control their deodorization by targeting appropriate strategies with the aim to either avoid the formation or remove the identified odorant compounds. This study may be further expanded by investigating the impact of deodorization on odour-active compounds for a complete understanding of their contribution to the fatty ester global odour.

OBJECTIF: Les esters gras sont connus pour leur polyvalence, mais en plus de leurs performances en tant qu'émollients, émulsifiants, solubilisants ou agents dispersants, ils doivent répondre à de plus en plus de critères pour être utilisés dans les produits cosmétiques. Ainsi, une odeur la plus neutre possible est recherchée par les formulateurs. Cependant, malgré une étape de désodorisation lors de la synthèse, une faible odeur résiduelle est souvent encore perçue à la fin du processus. METHODES: Dans cette étude, une méthodologie analytique spécifique combinant des analyses sensorielles et chimiques a été mise en œuvre pour caractériser l'odeur résiduelle de deux esters gras et déterminer son origine. L'oléate d'éthyle et l'isononanoate d'isononyle ont été sélectionnés et une analyse sensorielle a été menée pour évaluer l'intensité et le profil descriptif de leur odeur. Les composés volatils libérés par ces deux esters ont été identifiés par GC-MS après microextraction en phase solide (SPME) et parmi eux, les composés odorants ont été mis en évidence à l'aide de la chromatographie en phase gazeuse couplée à des analyses de spectrométrie de masse et d'olfactométrie (GC-MS-O). RESULTATS: Sur le chromatogramme de l'isononanoate d'isononyle, seuls des pics correspondant aux différentes formes isomériques de l'ester ont été mis en évidence tandis qu'environ 70 composés volatils ont été détectés dans l'espace de tête de l'oléate d'éthyle, parmi lesquels des esters, des aldéhydes, des hydrocarbures et des cétones. Il a été montré que l'alcool isononylique utilisé comme matière première dans la synthèse était responsable de l'odeur finale de l'isononanoate d'isononyle. Pour l'oléate d'éthyle, sur les 23 composés odorants perçus, 14 ont été identifiés ; il s'agit principalement d'esters et d'aldéhydes saturés ou insaturés. CONCLUSION: Ce travail présente une approche efficace pour analyser les traces d'odeur des esters gras. Les résultats obtenus permettront de contrôler la désodorisation de ces ingrédients cosmétiques en ciblant des stratégies appropriées dans le but d'éliminer spécifiquement les composés odorants identifiés. Cette étude pourra être élargie en étudiant l'impact de la désodorisation sur les composés odorants pour une meilleure compréhension de leur contribution à l'odeur globale des esters gras.