In vitro protective effect of Hypericum androsaemum extract against oxygen and nitrogen reactive species

Hypericum androsaemum L. (Gutiferae) is a medicinal plant growing in Western Europe that has been used in traditional medicine in the prevention or treatment of liver diseases. Oxidative stress and nitrosative stress are common pathogenetic mechanisms contributing to initiation and progression of hepatic damage in several liver disorders. In the present study, an ethanol:water (4:6) extract from H. androsaemum branches and leaves were evaluated for its putative in vitro scavenging effects on 1,1-diphenyl-2-picrylhydrazil radical, on reactive oxygen species, namely HO•, O₂•-, ROO•, ¹O₂ and H₂O₂ and on reactive nitrogen species, namely •NO and ONOO⁻. The hypericum extract presented a remarkable capacity to scavenge all the tested reactive species, all the IC₅₀ values being found at the μg/ml level. IC₅₀ values for 1,1-diphenyl-2-picrylhydrazil, and for the reactive oxygen species O₂•-, H₂O₂, HO• and ¹O₂ were 11.3 ± 0.7, 32.7 ± 3.4, 944 ± 47, 595 ± 82, 28.3 ± 1.2 μg/ml respectively. The oxygen radical absorbance capacity value obtained for ROO• was 1.5 ± 0.1 μmol Trolox equivalents/mg extract. The IC₅₀ values for •NO and ONOO⁻ were 2.2 ± 0.2 and 1.2 ± 0.1 μg/ml respectively. The content of total phenolics was 281 ± 2 mg of gallic acid equivalents/g of lyophilized extract. The observed antioxidant activity provides scientific support for the reported therapeutic use of H. androsaemum, though further in vitro and in vivo studies are required to ascertain the risk/benefit score at therapeutic concentrations.