Encapsulação de moléculas com atividade antileishmania e antimalárica em ciclodextrinas: preparo, caracterização físico-química e avaliação biológica

Abstract

This work includes a study of supramolecular systems stabilized by non-covalent interactions, formed between the substances used in the treatment of neglected diseases such leishmaniasis and malaria, with β-cyclodextrin (βCD). We investigated the association of antileishmanial pentamidine isethionate (PNT), the antimalarial artesunate (AS) and potential antimalarial 1,7-chloroquinolinyl-thiosemicarbazide (CQT) with βCD. The compounds involving PNT were obtained by lyophilization, while compounds involving AS and CQT were obtained by spray drying. The compounds were characterized by standard solid state methods such as vibrational spectroscopy in the infrared regiond (IR), thermal analysis (TG/DTA) and scanning electron microscopy (SEM). In solution, we used mass spectrometry with electrospray ionization (ESI-MS), nuclear magnetic resonance (1H and ROESY) and isothermal titration calorimetry (ITC) (only the system involving PNT). Furthermore, the compounds have biological activity investigated. Combining thermodynamic and structural techniques such as ITC, ESI-MS and NMR, the inclusion process and the thermodynamic parameters were identified. The experimental data obtained by ESI-MS and ITC suggest the simultaneous formation of different supramolecular complexes in solution. Also, NMR data suggest a deep inclusion of PNT in βCD cavity. The biological tests performed in vivo showed the oral activity of inclusion compound studied (βCD:PNT)1:1, compared to free drug which is inactive. These results are promising with regard to the investigation of alternative therapeutic alternatives for leishmaniasis treatment. For the system formed between AS e βCD the characterizations indicated the formation of a supramolecular system involving two species. DOSY experiments indicated the same diffusion coefficient for the drug and the macromolecule, showing the formation of inclusion compound (βCD:AS)1:1. It was verified that (βCD:CQT) inclusion compound was not formed. Thus the compound (αCD:CQT)1:1 was prepared, which was properly characterized. The ROESY results indicated interactions between the aromatic hydrogens, H5, H6 and H8 with H-3 and H-5 located in the cavity of host molecule, showing the formation of inclusion compound with αCD. The biological tests for antimalarials AS and CQT were performed in vivo. Acute toxicity of the inclusion compound (βCD:AS)1:1 showed no toxicity to mice after 5 days of administration. Additionally, tests were conducted to evaluate the cytotoxic activity of AS, (βCD:AS)1:1 and CQT. The results indicated that the molecules showed no toxicity in vitro in renal and hepatic cells. The in vivo activity of CQT was tested against P. Berghei, noting the potential antimalarial was active in the fifth and seventh days, reducing approximately 66% parasitemia.