Nanotecnologia potencializa a ação tripanocida do nerolidol em camundongos infectados com Trypanosoma evansi: envolvimento da barreira hematoencefálica

Abstract

In spite of significant advances in the studies against Trypanosoma evansi, the effective elimination of protozoan from the central nervous system (CNS) remains a difficult task. The incapacity of trypanocidal drugs (synthetics or naturals) to cross the blood-brain barrier (BBB) makes the brain the main refuge area for T. evansi. In this sense, the incorporation of nanoparticles into a delivery system for natural products has been considered a new approach to potentiates the therapeutic effects, principally linked with the capacity to across the BBB. Thus, the aim of this study was to evaluate whether the nanotechnology is capable to potentiates the nerolidol trypanocidal effect, a natural compound with trypanocidal activity, as well as to investigate whether nanoencapsulated nerolidol is capable to across the BBB and to eliminate the T. evansi from CNS. The in vitro test was performed in three different concentrations (0.5, 1.0 and 2.0 %) of free nerolidol (FN) and nerolidol-loaded in nanospheres (NN), as well as a control using diminazene aceturate (DA 0.5 %), drug available commercially for the treatment of disease. Based in the in vitro test, was possible to observe that both treatments were capable to eliminate the protozoan in a concentration-dependent manner. For the in vivo study, thirty mice were divided into five groups (A-E) with six animals each: the group A was composed by uninfected and untreated animals (negative control), while the groups B to E were inoculated via intraperitoneally with 60 μL containing 2.0 x 105 trypanosomes. The group B was composed by infected and untreated animals (positive control), while the groups C and D were treated with FN and NN, respectively, during 10 days (5 days before inoculation and 5 days after inoculation) by oral route at dose of 1.0 mL kg-1. The group E was treated 1 h after inoculation with a single dose of DA via intramuscularly at dose of 3.5 mg kg-1. Based on in vivo results, was possible to observe that FN was able to increase the longevity when compared to positive control, but without curative effectiveness. To other hand, the NN treatment showed 66 % of curative effectiveness, while the DA showed 33 %. From this, a second experiment was performed following the same experimental conditions above cited. On day 5 post-infection, the animals were euthanized to collect serum and cerebral tissue. Using high performance liquid chromatography, was possible to quantify the seric concentrations of FN, NN and DA. To other hand, was not possible to detect FN and DA in the cerebral tissue, only in the NN treatment. Also, all animals treated with NN were negative to presence of parasite in the brain using polymerase chain reaction technique. Based on these evidences, was possible to conclude that the passage on NN through the BBB allows the elimination of T. evansi from CNS, an important factor involved in therapeutic failures and disease recurrence.