(+)-Spectaline, a Piperidine Alkaloid from <i>Senna spectabilis</i> DC. Effective in Reducing the <i>In Vitro</i> Infection of <i>Leishmania major</i>

Abstract

Senna spectabilis is known to have antimicrobial, laxative, antiulcerogenic, analgesic, and anti-inflammatory properties in folk medicine. Piperidine alkaloids extracted from various parts of this plant have been shown to have anticonvulsant (iso-6-spectaline), antinociceptive [(-)-spectaline] and lipid peroxidation [(+)-3-O-feruloylcassine, (-)-spectaline and (-)-3-O-acetylspectaline] activities. In our study, the ethyl acetate extract from S. spectabilis exhibited antileishmanial activity via intracellular promastigote assay or leishmanicidal assay and was further fractionated by using bioassay-guided isolation approach. The antiprotozoal principle was isolated from the ethyl acetate portion through solvent fractionation and a few series of chromatographic processes. The isolated active compound 1 was identified as (+)-spectaline on the basis of its spectral analysis (MS, 1D &amp; 2D NMR) with EC50 value of 0.063 ± 0.005 µM for antileishmanial activity and selectivity index of 3.76.