In-cells antioxidant potential of herbal preparations and components from Galactites elegans

Galactites is a genus of flowering plants belonging to Asteraceae family. This genus Galactites is mainly represented by the Galactites elegans, the milky thistle, a plant of Mediterranean origin (synonym: Galactites tomentosa). Galactites elegans is consumed as a monofloral boar thistle honey.1-3 The aerial parts of G. elegans were collected in Hamma Bouziane, Constantine, Algeria. Dried and powdered aerial parts of G. elegans (966 g) were macerated with MeOH-H2O (8:2) at room temperature. The residue was suspended in H2O and successively partitioned with petroleum ether, CHCl3, EtOAc, and n-BuOH affording a CHCl3 soluble fraction (2 g), an EtOAc-soluble fraction (5.5 g), and a n-BuOH soluble fraction (19 g). The CHCl3 and n-BuOH extracts were tested for the antioxidant activity showing radical scavenging ability (CHCl3Ext DPPH IC50 0.041±0.001 mg/mL, TPC 116.5±0.7 μgGAE/mg; n-BuOHExt DPPH IC50 0.052±0.001 mg/mL, TPC 94.4±0.9 μgGAE/mg). Chromatography separation of CHCl3 and n-BuOH extracts led to isolation of 18 pure compounds whose structures were elucidated by 1D-and 2D-NMR spectroscopy and confirmed by mass spectrometry analysis. Sinapic aldehyde, abietin, chlorogenic acid, 5- caffeoyl quinic acid, 8α-hydroxypinoresinol, 9α-hydroxypinoresinol, pinoresinol, 4- ketopinoresinol, nor-trachelogenin, erythro-guaiacylglycerol-β-O-4'-dihydroconiferyl alcohol were isolated from CHCl3 extract; while luteolin 4'-O-glucuronide, naringenin-7-Oneohesperidoside, kaempferol-3-O-α-L-rhamnopyranosyl-(1→6)-β-D-glucopyranoside, kaempferol-7-O-α-L-rhamnopyranosyl-(1→6)-β-D-glucopyranoside, quercitrin, quercetin-3- O-α-L-rhamnopyranosyl-(1→6)-β-D-glucopyranoside, ciwujiatone, nor-trachelogenin-4,4'- di-O-β-D-glucopyranoside were obtained from n-BuOH extract. The ability of compounds to reduce the level of peroxides in control and BHP-treated Jurkat cells was studied according to Rothe et al.4 The majority of isolates displayed a significant antioxidant potential in vitro text (DPPH, FRAP, TPC). The lignan derivatives were also able to reduce at 50 μM the basal level of peroxides in Jurkat cells as well as to counteract peroxide increase induced by BHP treatment. Particularly 4-ketopinoresinol was the most active showing 65% of peroxide level inhibition. The slight lower antioxidant potential of nortrachelogenin 4,4'-di-O-β-D-glucopyranoside (45% of peroxide level inhibition) could be ascribed to the presence of a carbohydrate mojety.