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

Abstract

One new, namely 6-methoxykaempferol 3-O-[β-apiofuranosyl(1→2)]-β-glucopyranosyl(1→6)-β-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 (1D, 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 ± 0.010 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 CCl₄ 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.