Síntese e atividade antimalárica de derivados 1,2,3-triazólicos do lupeol

Abstract

This manuscript reports on the isolation of lup-20(29)-en-3-ol (lupeol), a pentacyclic triterpene, from the stem bark of Parahancornia fasciculata (Poir.) Benoist (Apocynaceae) and its use as starting material for the synthesis of triazole hybrids. Lupeol was extracted by exhaustive percolation of P. fasciculata stem bark which was collected in the municipality of Moju, PA. Lupeol is known to present a moderate in vitro antimalarial activity while some synthetic triazole hybrid compounds are reported as good antimalarials what has motivated the present work in the hope that any lupeol triazole derivative might be more active than lupeol. The lupeol triazole hybrids were synthesized by cycloaddtion reactions catalized by Cu (I) (click reaction) between a terminal alkyne and an organic azide. In a first step lupeol was converted to its propagyl ether (TB1) which was submitted to click reactions with different organic azides leading to five new triazole hybrids TB2 - TB6. All the compounds synthesized were characterized by their spectrometric analyses IR, HRMS, 1H and 13C NMR. The in vitro antimalarial activity of the compounds was evaluated against chloroquine resistant Plasmodiumfalciparum (W2 clone) by the lactate dehydrogenase methodology (pLDH). The lupeol propargyl ether was the most active compound causing 81% inhibition of the parasite growth in the concentration of 50 g/mL while the triazole derivatives were less potent than lupeol with inhibition growth ranging from 9% to 26%.