Development of nanoemulsions containing ursolic acid to optimize the treatment of Chagas disease

Author(s)

Erika Cristina Vargas de Oliveira

• Document type: Doctoral Thesis
• Press: Ribeirão Preto.
• Institution: Universidade de São Paulo (USP). Faculdade de Ciências Farmacêuticas de Ribeirão Preto (PCARP/BC)
• Defense date: 2014-11-26

Examining board members

Juliana Maldonado Marchetti; Maria Teresa Junqueira Garcia; Priscyla Daniely Marcato Gaspari; Andresa Aparecida Berretta e Silva

• Advisor: Juliana Maldonado Marchetti

Abstract

Over a hundred years after the discovery of Chagas disease it remains victimizing thousands of people. Previously restricted to Latin America, today is reason for alert in Europe and USA. Caused by the parasite Trypanosoma cruzi, is a silent disease, with severe systemic complications. For more than 40 years, there are only two drugs to treat Chagas disease, however, these do not have an effect on the the chronic phase and have severe side effects. In recent years there has been progress in the development of new drugs with trypanocidal activity and many researches have been conducted in this area whose main target is still natural products. Ursolic acid is a naturally occurring terpene that has already shown to have important trypanocidal action besides antitumor and hepatoprotective, however, the hydrophobicity of this compound is a challenge to produce proper delivery systems. Nanoemulsions find use in the cosmetic industry and medicine due to advantages such as greater solubilizing capacity compared to conventional emulsions enabling the incorporation of sparingly soluble drugs in water in the oily phase besides greater stability conferred by the diminutive size of the droplets and increased availability of the drug. The chromatographic method to quantify ursolic acid was validated and shown to be selective, linear in the range from 1.0 to 50.0 ?g mL-1, with a limit of detection and quantification corresponding to 0.34 and 1.0 ?g mL-1, respectively. The developed nanoemulsion was stable throughout the 90 days of testing, as evidenced by the results obtained from the analysis by turbidimetry and Ostwald ripening index, however, precipitation was observed over time particularly at a concentration of 1 mg/ml. Apparently the phenomenon is related to temperature and the change of this variable to 30°C during emulsification was successful in that it was no longer observed decrease in the amounts of quantified drug. Infrared spectroscopy and mass spectrometry results allowed to verify that the drug does not react with other components of the formulation and do not suffer degradation in the time period under the studied conditions. The in vitro release profile showed that the drug was immediately released from the nanoemulsion which was not observed with the physical mixture. The biological activity assays showed that the system is safe for the tested cell line and shows good trypanocidal activity for amastigotes. (AU)