Antioxidant and Hepatoprotective Activity of Phenyl Glycosides Isolated From

A new macrocyclic glycoside named helilobatoside A ( 1 ) and 5 known phenyl glycosides as 3,5-dimethoxy-4-hydroxyphenyl-1- O-β - d -glucopyranoside ( 2 ), tachioside ( 3 ), isotachioside ( 4 ), 1-(4-hydroxy-3-methoxyphenyl)-1-propanone-3- O-β - d -glucopyranoside ( 5 ), and 1-(4-hydroxy-3,5-dimethoxyphenyl)-1-propanone-3- O- β- d -glucopyranoside ( 6 ), were isolated from the wood of Heliciopsis lobata (Merr.) Sleumer. Their chemical structures were elucidated using a combination of high-resolution electrospray ionization mass spectrometry, 1-dimensional (1D) and 2D nuclear magnetic resonance (NMR) spectral data as well as by comparison with data in the previous literature. This is the first time the 13 C NMR data of compounds 5 and 6 were reported and also were assigned by heteronuclear single quantum correlation and heteronuclear multiple bond correlation spectra. Compounds 2 - 6 were first isolated from Heliciopsis genus. The isolated compounds were evaluated for their antioxidant and hepatoprotective activities in vitro. Compound 2 showed potential as an antioxidant in a 2,2-diphenyl-1-picryl-hydrazyl-hydrate assay half-maximal inhibitory concentration [IC 50 ] = 6.07 ± 0.17 µg/mL and in thio-barbituric acid reactive substances assay IC 50 = 89.55 ± 8.26 µg/mL. This compound could also reduce the toxic effects of carbon tetrachloride on HepG2 survival and significantly protect the viability of cells up to 52.25 ± 4.36% at the 100 µg/mL treatment ( P < 0.05). Thus, with obtained results, the hepatoprotective activity of compound 2 could be related to radical scavenging and limited the lipid peroxidative activities.