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| Author(s): |
Marcos Furlanetto
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Conjunto das Químicas (IQ e FCF) (CQ/DBDCQ) |
| Defense date: | 2005-03-17 |
| Examining board members: |
Leoberto Costa Tavares;
Chung Man Chin;
Humberto Gomes Ferraz
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| Advisor: | Leoberto Costa Tavares |
| Abstract | |
Chagas\' Disease reaches whole Latin America exposing 100 million people to infection risk, harming seriously 18 million patients\' life. Thus, the aim of this work was evaluate biological activity of nitro-heterocyclics compounds with similar structure of nifuroxazide, 5-nitro-2-furaldehyde p-hydroxy-benzoylhydrazone, against Trypanosoma cruzi, strain Y, before and after microencapsulation by complex coacervation of gelatin and gum arabic. These compounds, in general, are poorly soluble in concentration used in pharmacological tests, thus the development of a vectorial system will improve pharmacological profile of them. Microencapsulation method was defined based on literature data and preliminary assays and it was used two drying methods: isopropanol-ethanol addition, or spray-drying. Microscopic examination of dried products shown morphological difference between alcohols and spray-dried microcapsules. Microencapsulation percentage average yields were 66.0±12.0% and 24.5±5.3% and coacervate yields were 76.0±3.6% and 61.0±5.1% respectively. After determination of λMAX and standard curves, with DMSO, it was observed no interference of gelatin-acacia complex in UV absorption, making possible reliable dosage of nitro-compounds in microcapsules. ln vitro studies have not shown interference of unloaded microcapsules or DMSO 5% on parasites growth. Solutions used of free nitro-heterocyclics (50 µg/mL) were plenty active against T. cruzi, have shown population reduction of 100% in 48 hours, however, benznidazol (100 µg/mL) in 12th day experiment there were still viable parasitic forms. Dried products by spray-drying had antichagasic behavior similar to pure compounds, with parasitic population reduction of 63±10% in 24 hours (64±13% pure compounds) not being appropriate method for extended release. Dried products by alcohols allowed this liberation type due to integrity of microcapsules, observed by microscope, and in 24 hours there was reduction of only 20±9% of the population, needing 96 hours for total parasites\' elimination. Thus, microencapsulation and drying method useing alcohols resulted in slow liberation rates of nitro compounds indicating the possibility of use this vectorial system in studies with views to improve the antichagasic effect of those compounds. (AU) | |