Free radical scavenging and antioxidant activities of Glinus oppositifolius (carpet weed) using different in vitro assay systems

Glinus oppositifolius (L.) Aug. DC. (Aizoceae), commonly called slender carpet weed, is a prostrate or diffuse herb which acts as stomachic, uterine stimulant, aperient and lochia. It is used traditionally in the treatment of earache, itch and skin diseases. Glinus oppositifolius was extracted with ethanol (70%) and used for the evaluation of various in vitro antioxidant assays which includes H-donor activity, nitric oxide scavenging, superoxide anion scavenging, reducing ability, hydroxyl radical, hydrogen peroxide scavenging, total phenolic content, total flavonoid content, total antioxidant activity by thiocyanate and phosphomolybdenum method, metal chelating, β-carotene bleaching, total peroxy radical assays. The pro-oxidant activity was measured using bleomycin-dependent DNA damage. Ex vivo models such as lipid peroxidation were used to study the antioxidant property of the extract. The various antioxidant activities were compared with suitable standard antioxidants such as ascorbic acid, butylated hydroxyl toluene (BHT), α-tocopherol, curcumin, quercetin and Trolox. The generation of free radicals, viz., O2·−, OH·, H2O2, NO· and peroxyl radicals, were effectively scavenged by the ethanol extract of Glinus oppositifolius. The antioxidant activity depends on concentration and increases with increasing amounts of the extract. The total phenolic content, flavonoid content and total antioxidant activity in Glinus oppositifolius were determined as microgram (μg) pyrocatechol, quercetin and α-tocopherol equivalent/mg, respectively. The extract did not exhibit any pro-oxidant activity when compared with ascorbic acid. The results obtained in this study indicate that Glinus oppositifolius scavenges free radicals and reduces lipid peroxidation, ameliorating the damage imposed by oxidative stress in different disease conditions and serve as a potential source of natural antioxidant.