Brevifoliasaponin with Adjuvant Activity from Calliandra brevifolia
A new complex triterpenoid saponin, brevifoliasaponin, was isolated from leaves of Calliandra brevifolia Benth. (Leguminosae) by using chromatographic methods. Its structure was established as 3-[(O-α-L-arabinopyranosyl-(1 → 2)-O-α-L-arabinopyranosyl-(1 → 6)-2-(acetylamino)- 2-deoxy-β -D-glucopyranosyl)oxy]-16-hydroxy-(3β ,16α)-olean-12-en-28-oic acid O-β - D-xylopyranosyl-(1 → 3)-O-β -D-xylopyranosyl-(1→4)-O-[β -D-glucopyranosyl-(1 → 3)]-O-6-deoxy- α-L-mannopyranosyl-(1 → 2)-6-O-[(2E,6S)-6-[[2-O-[(2E,6S)-6-[[2-O-[(2E,6S)-2,6-dimethy- l1-oxo-6-(β -D-xylopyranosyloxy)-2,7-octadienyl]-β -D-xylopyranosyl]oxy]-2,6-dimethyl-1-oxo- 2,7-octadienyl]-β -D-xylopyranosyl]oxy]-2,6-dimethyl-1-oxo-2,7-octadienyl]-β -D-glucopyranosyl ester. Its 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.