Bioactivity guided isolation and characterization of the phytoconstituents from the Tridax procumbens

Abstract

Tridax procumbens L., Asteraceae, has been extensively used in Ayurvedic system of medicine for various ailments. Previous studies on the extracts of T. procumbens revealed remarkable immunomodulatory activity of TPEIF (T. procumbens ethanol insoluble fraction) extract. The dried methanol extract of T. procumbens was dissolved in distilled water, and then fractioned by re-extracting with chloroform, ethyl acetate and n-butanol subsequently. Immunomodulatory activities of these fractions were determined in vivo. The amounts of total phenolic compounds were also determined. Ethyl acetate and n-butanol fractions showed the significant immunomodulary activity. However, the ethyl acetate fraction exhibited the highest total phenolic content. Therefore, ethyl acetate fraction was subjected to further separation by chromatographic methods. Two phytochemicals SA-3 and SA-4 were obtained by repeated purification in sufficient amount to screen them for the immunomodulatory activity by the in vivo models i.e. neutrophil adhesion and delayed type hypersensitivity. In addition, the n-butanol fraction was subjected to silica gel column chromatography (CC); SA-6 was isolated from it. Mice were treated with two doses of SA-3, SA-4 and SA-6 (2 and 4 mg/kg) for fifteen days. Immune responses to T-dependent antigen SRBCs were observed using parameters like DTH and Neutrophil adhesion. Overall, SA-4 and SA-6 showed dose relative immunostimulatory effect on in vivo immune functions in mice. From these results, it can be suggested that these compounds may be used as potential immunostimulators. The structures of isolated phytochemicals were determined by UV, IR, NMR, and MS spectroscopic methods.