Two New Acylated Sucroses From the Roots of Canna indica L. and Their Antioxidant Activity

Two new acylated sucroses, (6- O-axetoxyl)- β-d-fructofuranosyl-(2→1)-(6- O-feruloyl- α- d-glucopyranoside (1) and (6- O-axetoxyl)- β-d-fructofuranosyl-(2→1)-(6- O-( E)- p-coumaroyl- α- d-glucopyranoside (2), and four known compounds, 2-(3′,4′-dihydroxyphenyl)-1-propanol-4′- O-[4′′′-hydroxy-3′′′,5′′′-dimethoxybenzoyl-(→6′′)- β-d-fructofuranoside (3), tryptophol glucoside (4), corchonoside C (5), and 2-hydroxy-5-(2-hydroxyethyl)phenyl β-d-fructofuranoside (6), were isolated from the roots of Canna indica L. (Cannaceae). Their structures were determined by extensive analysis of HR-ESI-MS, 1D, and 2D NMR spectral data, as well as by comparison of these with those reported in the literature. Antioxidant activity of compounds 1-6 were evaluated by peroxyl radical absorbance capacity assay. Compounds 1 and 3 neutralized high amounts of peroxyl radical. At a concentration of 1 µM, their ORAC ROO* values were 3.07 ± 0.15 and 4.27 ± 0.30, respectively, many times greater than that of trolox, which was used as an internal standard. At 10 µM, the peroxyl radical absorbance capacity of compounds 1 and 3 exhibited equivalents to 15.60 ± 0.22 and 24.91 ± 0.43 times the net protection by 1 µM of trolox.