Essential oils are volatile products of plant origin and promising sources of bioactive substances. Rosmarinus officinalis essential oil, for example, is used in aromatherapy as a potent stimulant of the scalp, aiding in the treatment of dandruff and hair growth (1). However its physic-chemical instability may compromise biological properties. An alternative that allows increasing the stability of the essential oils consists of the encapsulation in several types of release systems, thus protecting them from the deterioration and volatilization through techniques involving nanotechnology (2). Among the known nanostructured systems, microemulsions are of great interest for the development of more stable, more effective formulations with a differentiated cosmetic sensory. Thus, the present work aimed to develop different microemulsion systems containing Rosmarinus officinalis essential oil and to overcome the limitations of the use of essential oils as active in cosmetic formulations. Rosmarinus officinalis essential oil was commercially acquired and characterized by Gas Chromatography coupled to the Mass Spectrometer (GC-MS) (3). The microemulsions containing Rosmarinus officinalis essential oil were developed by the titration method described by Falcão (4). The formulations were characterized for particle size distribution by dynamic light scattering (DLS) and Zeta potential using Zetsizer ZN90 (Malvern) (5) and identification of isotropic behavior by polarized light microscopy. Qualitative analysis of Rosmarinus officinalis essential oil by GC-MS led to the elucidation of 22 substances. The major constituents identified were eucalyptol (36.6%), limonene (23.5%), camphor (28.2%) and α-pinene (2.9%) corresponding to 91.2% of the total oil. The best formulation showed a mean particle diameter of 89nm, Zeta potential close to neutrality and isotropic behavior, remaining stable at intervals of 1, 7, 15 and 30 days at 25ºC (room temperature) and 40ºC. This nanosystem will be tested for cosmetic use.

References:
(1) ALI, B., AL-WABER, N.A., SHAMS, S., AHAMAD, A., KHAN, S.A., ANWAR, F. Essential oils used in aromatherapy: A systemic review. Asian Pac J Trop Biomed 5(8): 601–611, 2015
(2) DAUDT, R. M., EMANUELLI, J., KÜLKAMP-GUERREIRO, I.C., POHLMANN, A.R., GUTERRES, S.S.. A nanotecnologia como estratégia para o desenvolvimento de cosméticos. Ciência e Cultura vol 65 nº3. São Paulo, 2013
(3) ADAMS, R.P. Identification of essential oils componets by gás chromatography/quadrupole mass spectroscopy, 4 ed.: Allured Publishing Corporation, 2007, 804 p.
(4) FALCÃO, D. Q. Estudo da composição química de Calceolaria chelidonioides Humb. Bonpl. & Kunth.: da etnofarmacologia à elaboração de formulações galênicas tópicas contra Herpes simplex. Rio de Janeiro, 2007. Tese (Doutorado) – UFRJ/NPPN/Programa de Pós Graduação em Química de Produtos Naturais, 2007.
(5) FERNANDES C.P., MASCARENHAS, M.P., ZIBETTI, F.M., LIMA, B.G., OLIVEIRA, R.P.R.F., ROCHA, L., FALCÃO, D.Q. HLB value, an important parameter for the development of essential oil phytopharmaceuticals. Brazilian Journal of Pharmacognosy, v.23, n.1, p.108-114, 2013.