6-Methoxyflavonol Glycosides with In Vitro Hepatoprotective Activity from Chenopodium bonus-henricus Roots

One new, namely 6-methoxykaempferol 3-O-[β-apiofuranosyl(l-->2)]-f-glucopyranosyl(l->6)-fl-glucopyranoside (2), and two known flavonoid glycosides, spinacetin 3-O-[β-apiofuranosyl(1-->2)]-β-glucopyranosyl(1-->6)-β-glucopyranoside (1) and spinacetin 3-O-gentiobioside (3), were isolated from the roots of Chenopodium bonus-henricus L. Their structures were determined by means of spectroscopic methods (ID, 2D NMR, UV, IR) and HR-ESI-MS. Radical scavenging and anti-oxidant activities of 1 and 3 were established using DPPH and ABTS free radicals, FRAP assay and inhibition of lipid peroxidation (LP) in a linoleic acid system by the ferric thiocyanate method. Compound 3 was found to possess stronger DPPH and ABTS radical scavenging activity (IC50 0.44 +/- 0.008 mM and 0.089 +/- 0.002 mM, respectively) compared with 1 (IC50 1.22 +/- 0.0 10 mM and 0.11 +/- 0.004 mM, respectively). Both flavonoids inhibited the lipid peroxidation of linoleic acid significantly. Additionally, 1 and 3 significantly reduced the cellular damage caused by the hepatotoxic agent CCI4 in rat hepatocytes and preserved cell viability and GSH level, decreased LDH leakage and reduced lipid damage. Effects were similar to those of the positive control silymarin. Control of self-toxic effects made in a MTT based assay using HepG2 cells revealed statistically significant cytotoxic effects only in very high concentrations (exceeding mM) and an incubation time of 72 h, making flavonoid glycosides with a 6-methoxykaempferol skeleton a promising and safe class of hepatoprotective compounds.