Alcaloides do gênero crotalaria: isolamento, elucidação estrutural, síntese de derivados e potencial biológico.
Crotalaria is widespread in tropical areas mainly in Argentina and Brazil. Two species of Crotalaria: Crotalaria retusa and Crotalaria pallida could be found in Rio Grande do Norte, Brazil. The aim of this study is to obtain extracts containing alkaloids as well as the isolation and structural ch...
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| Formato: | Dissertação |
| Idioma: | por |
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| Acesso em linha: | https://repositorio.ufrn.br/jspui/handle/123456789/26062 |
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| Resumo: | Crotalaria is widespread in tropical areas mainly in Argentina and Brazil. Two species
of Crotalaria: Crotalaria retusa and Crotalaria pallida could be found in Rio Grande
do Norte, Brazil. The aim of this study is to obtain extracts containing alkaloids as
well as the isolation and structural characterization of these metabolites. In addition,
the potential of the pyrrolizidine alkaloids obtained was evaluated regarding biological
properties and synthesis of derivatives. The extracts were prepared by exhaustive
maceration with ethanol 96%. The crude extract was subjected to an acid-base
extraction to obtain alkaloids-enriched fractions. Additional purification procedures
afforded monocrotaline from C. retusa and pallidine from C. pallida. Monocrotaline
was submitted to synthesis of two derivatives: retronecine and azide-retronecine. The
activity against T. vaginalis was evaluated and the results indicated inhibition on
parasite growth of 80% at 1 mg/mL neither cytotoxicity against vaginal epithelial cells
nor hemolytic activity. On the other hand, retronecine showed no anti-T. vaginalis
activity while azide-retronecine was more active than monocrotaline by killing 85% of
the parasites at 1 mg/mL. Pallidine is an uncommon pyrrolizidine alkaloid that has
important structural features. Furthermore, pallidine was evaluated against antibiofilm
activity and demonstrated the ability to inhibit more than 50% of Staphylococcus
epidermidis biofilm formation at 1mg/mL, without providing biocidal activity. It is an
outstanding start point to develop new antibiofilm strategies. Finally, the pyrrolizidine
alkaloids are suggested as promising prototypes for new drugs as well as our results
suggests that the edaphoclimatic conditions of Rio Grande do Norte could affect the
biosynthesis of these alkaloids and facilitate the occurrence of new chemical
skeletons. |
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