Desenvolvimento e caracterização de microemulsões antimicrobianas e anti-inflamatórias contendo óleo de copaíba (Copaifera multijuga)

Abstract

Copaiba oil, extracted from the Copaiba plant, a common tree to Latin America and West Africa. It is found over 20 species in Brazil, throughout Southeast, Midwest and Amazon regions. Among the various pharmacological activities studied for this oil, antimicrobial and anti-inflammatory stand out. It is taken topically or orally, but indiscriminately, often without any quality control. The extensive use of this oil has attracted increasing interest in pharmaceutical research to develop pharmaceutical forms containing them. This way, it is interesting the development of topically administered microemulsions (ME) O/W, in order to improve the skin permeability of this oil, as well as its therapeutic effect. Thus, the aim of this study was to develop and characterize ME containing copaiba oil and evaluate its antimicrobial and anti-inflammatory activity. It was initially determined the hydrophilelipophile

balance (HLB) of the Copaifera multijuga oil (11-12) and it was subsequently defined the HLB of the mixture of surfactant/cosurfactant, guiding the choice of the pseudoternary phase diagrams (2:1 and 4:1). In ME regions of diagrams were selected seven formulations and chosen two (ME-F2 and ME-F6) for characterizing study. Regarding pH, all formulations were within the range of pH of the skin. All samples, after centrifugated, remained unchanged. The electrical conductivity and differential scanning calorimetry (DSC) techniques suggested a system of O/W. The transmission electron microscopy revealed spherical droplets of uniform size less than 200nm and homogeneous distribution. The polarized light microscopy showed dark fields that characterize isotropic systems of the type ME O/W. The size of the droplets was confirmed by dynamic light scattering (DLS) on which it was observed a phenomenon of destabilization by Ostwald ripening, increasing the diameter of the droplets when the system is diluted. All the ME showed negative zeta potential, low viscosity and Newtonian behavior. The ME-F2 and ME-F6 showed activity for the bacterial strain Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli and for the fungi Cryptococcus neoforman. Regarding the anti-inflammatory activity the ME-F6 showed acute activity higher than the positive control (diclofenac diethylamine emulgel). As for MEF2,

it presented a lag time up to the third hour, but less intense than the control one. Therefore, the systems developed become promising agents in antimicrobial therapy and particularly for acute inflammation, which can be an alternative to use oral nonsteroidal antiinflammatory,

thereby reducing side effects. However, it is necessary further studies for quality control of copaiba oil since there are many variables in relation to the composition and consequently the pharmacological activity. Thus, the use of this oil should be standardized as well as carried out studies of skin irritability and toxicity of the formulations.