Phytoconstituents of Phlogacanthus pubinervius Nees: Leaves and their free Radical Scavenging Activities

Investigation on the secondary metabolites of the leaves of Phlogacanthus pubinervius Nees. led to the isolation of a new terpenoidal glycoside, 3-O-[ss-D-glucopyranosyl-(1'-> 2')-alpha-L-rhamnopyranosylphlogaca-nthoside], 5 along with five other compounds including beta-sitosterol (1), beta-sitosterol-D-glucoside (2), Stigmasta-5,22-dien-7-on-3ss-ol (3), 19-hydroxy-phlogacantholide (4), and (2E, 7Z)-2,6-dihydroxycycloocta-2,7-dienone (6). The structures of the compounds (1-6) were established by physical and spectroscopic analysis. Free radical scavenging activities of the isolates were evaluated by using 1,1-diphenyl-2-picrylhydrazyl (DPPH) method and the Isosbestic points of the isolates were also reported.