Polystachyasaponin with Adjuvant Activity from Entada polystachya

A new complex triterpenoid saponin, polystachyasaponin, was isolated from leaves of Entada polystachya (L.) DC. (Leguminosae) by using chromatographic methods. Its structure was established as 15,16-dihydroxy-3-[[O-β -D-xylopyranosyl-(1→2)-O-α-L-arabinopyranosyl-(1→6)-2(acetylamino)-2-deoxy-β -D-glucopyranosyl]oxy]-(3β ,15α ,16α)-olean-12-en-28-oic acid O-D-apioβ -D-furanosyl-(1→3)-O-β -D-xylopyranosyl-(1→2)-O-[β -D-glucopyranosyl-(1→4)]-6-O-[(2E,6R)6-hydroxy-2,6-dimethyl-1-oxo-2,7-octadienyl]-β -D-glucopyranosyl ester. Structural elucidation was performed using detailed analyses of 1H and 13C NMR spectra including 2D NMR spectroscopic techniques and chemical conversions. The hemolytic activity of the saponin was evaluated using in vitro assays, and its adjuvant potential on the cellular immune response against ovalbumin antigen was investigated using in vivo assays.