Antioxidant properties of Galium verum L. (Rubiaceae) extracts

Abstract

The antioxidant properties of methanol extracts of Lady’s Bedstraw (Galium verum L., Rubiaceae) herb from two different localities in Serbia were evaluated. Antioxidant activity was assessed in four different model systems. Free radical scavenging capacity (RSC) was examined by measuring the scavenging activity of extracts on 2,2-diphenyl-1-pycrylhydrazil (DPPH) and hydroxyl radical (OH), as well as on hydrogen peroxide. In addition, the protective effects of lipid peroxidation (LP) in corn oil were evaluated by the TBA-assay using the Fe2+/ascorbate system of induction. The amount of dried extract, the content of total phenolics, flavonoids and chlorophylls was also determined. Extracts from both locations expressed very strong scavenger activity, reducing the DPPH⊙ (IC50=3.10 µg/mland 8.04 µg/ml) and OH radical formation (IC50=0.05 µg/ml and 0.54 µg/ml) and neutralising H2O2 (IC50=4.98 µg/ml and 3.80 µg/ml), in a dose dependant manner. Also, examined extracts showed notable inhibition of LP (IC50=11.69 µg/ml and 19.47 µg/ml). The observed differences in antioxidant activity could be partially explained by the levels of phenolics (2.44–4.65 mg and 4.57–5.16 mg gallic acid equivalents/g dry extract), flavonoids (6.38–10.70 µg and 15.56–17.96 µg quercetin equivalents/g dry extract) and chlorophylls in the investigated Lady’s Bedstraw extracts.