Abstract

The aim of this study was to investigate free radical-scavenging activity of Salvia officinalis L.,Thymus vulgaris L., Urtica dioica L. extracts and mixture of extracts, and to evaluate the effect of these extracts on the ability of mitochondria to generate free radicals. The evaluation of the activity of extracts using 2,2-diphenyl-1-picrylhydrazyl (DDPH), 2,2’-azinobis-(3-ethylbenzothiazoline-6-sulfonate) (ABTS) radicals scavenging assays and tyrosine nitration inhibition (TNI) techniques showed that thyme extract had the strongest free-radical-scavenging activity. This extract was also found to contain the highest amount of phenols. Mixture of extracts showed slow and identical DPPH and ABTS radical-scavenging activity, with the strongest activity demonstrated during the first minute. Investigation of the ability of extracts to neutralize hydrogen peroxide showed that the lowest extract amount used (0.01 mg) neutralized 24 to 50% and the highest amount (0.1 mg) – 72 to 88% of H₂O₂. In all cases, thyme extract, had the strongest antioxidant effect. Rat liver mitochondria incubated with 0.1 mg of extracts generated by 45 to 55% less radicals than control mitochondria did. Mitochondria incubated with 1 mg of extracts generated smaller amounts of ROS than incubated with 0.1 mg of extract – in case of thyme extract or even more – in case of stinging nettle or sage extracts.

Key words: Salvia officinalis L., Thymus vulgaris L., Urtica dioica L., antioxidant activity.