Optimization of extraction method and evaluation of antileishmanial activity of oil and nanoemulsions of Pterodon pubescens benth. fruit extracts

Abstract

Currently, leishmaniasis is difficult to manage owing to the limited choice and high toxicity of available drugs, and emergence of drug-resistant protozoa. Medicinal plants, which produce various bioactive molecules, can help counter this global shortage. In this study, we prepared Pterodon pubescens fruit extracts, which show antileishmanial activity, and developed a nanoemulsion of the optimized extract to improve its performance. The extracts were prepared using conventional methods and a supercritical fluid method and were tested for activity against Leishmania amazonensis promastigotes and amastigotes. The two most effective extracts were formulated as nanoemulsions. Although both extracts showed cytotoxicity, the supercritical extracts were more effective against L. amazonensis promastigotes and amastigotes than conventional extracts were. This was attributed to the high content of the geranylgeraniol derivative in the supercritical extracts. The nanoemulsions showed a better selectivity index and significantly improved activity against parasites (IC50: 2.7 μg/mL for nanoemulsion of hexane extract; IC50: 1.9 μg/mL for nanoemulsion of supercritical extract) compared to the Miltefosine standard (0.7 μg/mL). This could be due to the smaller droplets of the supercritical extracts, allowing better penetration. In conclusion, the extracts showed promise in in vitro tests, and could be used as a leishmaniasis treatment.