Original Article DEVELOPMENT OF NANOEMULSION CONTAINING PELARGONIUM GRAVEOLENS OIL: CHARACTERIZATION AND STABILITY STUDY JANICE LUEHRING GIONGO 1,2* , RODRIGO DE ALMEIDA VAUCHER 3,4 , ALINE FERREIRA OURIQUE 4 , MIRIAM CARINE RIBEIRO STEFFLER 4 , CLARISSA PICCININ FRIZZO 5 , BRUNO HENNEMMAN 5 ,ROBERTO CHRIST VIANNA SANTOS 4,6 , LEONARDO QUINTANA S. LOPES 4 , VIRGINIA CIELO RECH 4 , VIVIAN SHINOBU KISHIMOTO NISHIHIRA 4 , RECH RENATA PLATCHECK RAFFIN 4 , PATRICIA GOMES 4 , MARTIN STEPPE 2 1 Laboratory of Pharmaceutical Technology, University of High Uruguay Regional Integrated (URI), Santiago, Rio Grande do Sul, Brazil, 2 Post Graduate Program in Pharmaceutical Sciences, School of Pharmacy, Federal University of Rio Grande do Sul (UFRGS), Porto Alegre, Rio Grande do Sul, Brazil, 3 Post Graduate Program in Biochemistry and Bioprospecting, Center of Chemistry, Pharmaceutical and Food Science, Federal University of Pelotas (UFPel), Pelotas, the Rio Grande do Sul, Brazil, 4 Laboratory of Nanotechnology, Post Graduate Program in Nanosciences, Franciscan University Center, Santa Maria, Rio Grande do Sul, Brazil, 5 Chemistry of Heterocyclic Core (NUQUIMHE), Department of Chemistry, Federal University of Santa Maria (UFSM), Santa Maria, Rio Grande do Sul, Brazil, 6 Microbiology and Parasitology Department, Health Sciences Center, Federal University of Santa Maria (UFSM), Santa Maria, Rio Grande do Sul, Brazil Email: janicegiongo@hotmail.com Received: 08 Sep 2016 Revised and Accepted: 21 0ct 2016 ABSTRACT Objective: To develop, characterize and evaluate the stability of nanoemulsions containing geranium oil (NEG) at different temperatures (4 °C, 25 °C and 45 °C) for 90 d. Methods: The quantification of oil in the nanostructure was performed by gas chromatography–mass spectrometry (GC-MS). The NEG was prepared in Ultra-Turrex and characterized by determining the particle size, polydispersity indices and pH. The thermo gravimetric analysis (TGA), differential scanning calorimetry (DSC) and transmission electron microscopy (TEM) to evaluate the thermal stability of the compounds, the thermal events and morphological analyses of NEG, respectively. Results: The results allow us to suggest that the use the ultra-turrax method is a strategy good to NEG preparation. The stability of the NEG was strongly influenced by storage temperature, with droplet size increasing rapidly at higher temperatures (45 °C), which was attributed to coalescence near the phase inversion temperature. The NEG submitted the low temperatures (4±2 °C) remained with the same particle size value (164 nm). However, the citronellol and geraniol showed a significant reduction throughout the test even in these conditions of temperature. Thermo gram of NEG shows the crystallization peak at the cooling cycle in-20.1 °C and a melting was observed at 1.5 °C. TEM images indicated that NEG was spherical and nanometric. Conclusion: The proposed Ultra-Turrax method is simple which prevents volatilization of GO for the production of NEG. The formulations presented good physicochemical characteristics and stability for 90 d was only achieved in 4 °C. Keywords: Geranium oil, Ultra-Turrax, Nanoemulsion, Citronellol, Geraniol © 2016 The Authors. Published by Innovare Academic Sciences Pvt Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4. 0/) DOI: http://dx.doi.org/10.22159/ijpps.2016v8i12.15108 INTRODUCTION Nanoemulsions are emulsified systems with droplets that are between 20 and 200 nm in size [1]. Due to their characteristic size appear transparent or translucent to the naked eye [2]. Depending on the preparation method, different droplet size distributions might be achieved, explaining why the route of preparation can have an influence on the emulsion stability [3]. The preparation of emulsions with droplet sizes in the submicrometer range may be performed mechanically, which involves high-energy input that is generally achieved by high-shear stirring, high-pressure homogenizers, or ultrasound generators [1]. In contrast, nanoemulsions produced with low energy methods depend on the spontaneous formation of emulsions based on the phase behavior of certain surfactant, oil, and water systems [4]. There is interest in using lower energy techniques in the emulsion formation process due to economic benefits and increasing amounts of research have been conducted to investigate the utility of different low-energy approaches [5, 6]. Self-emulsifying systems offer a strategy for dealing with the low bioavailability of compounds (drugs and oils) that are not easily dissolved in water [7, 8]. The oil from Pelargonium graveolens, also known as a geranium oil (GO) or mauve is extracted from the tree Pelargonium odorantissimum originating from South Africa. The Pelargonium (Geraniaceae) genus is represented by many essential oil producing species inter alia: P. graveolens, P. odoranissimum, P. zonale and P. roseum. Geranium oil is obtained from leaves, flowers, and stalks by steam or hydrodistillation. The GO is composed of various chemical constituents such as linalool, citronellol, geraniol, and their esters [9, 10]. Further, the GO is non-toxic, non-irritant, generally non- sensitizing, and it is not known to cause any other side effects. Studies show that GO has therapeutic properties as antidepressant, antiseptic and healing. It is used to diverse dermatological problems such as oily or congested skin, eczema, and dermatitis [11]. However, few studies have explored the incorporation of GO in nanostructures [12, 13]. One of the main objectives of the current study was to investigate the formation of nanoemulsions by low energy isothermal methods using a well-defined model system: oil, non-ionic surfactant, and water. In addition, there is no study in the literature about the optimizing of nanoemulsion preparation in terms of droplet size, emulsion stability, and emulsification efficiency (EE). The produced formulations were analyzed and characterized in terms of physical properties such as particle size, zeta potential, morphology, entrapment efficiency and long-term stability. International Journal of Pharmacy and Pharmaceutical Sciences ISSN- 0975-1491 Vol 8, Issue 12, 2016