In vitro antioxidant activity of Satureja kitaibelii Wierzb. ex Heuff. subcritical water extract

Abstract

Satureja kitaibelii Wierzb. ex Heuff. or Rtanj tea is an endemic species of the Carpathian mountain chain on the Balkan Peninsula. It grows in Eastern Serbia, Northwest Bulgaria, and Southwest Romania. As traditional remedy, it is used for treatment of different stomach discomforts such as pains in the lower abdomen, upset stomach, diarrhoea and nausea, for the regulation of the menstrual cycle and fertility, for muscle relaxation, and in the treatment of the upper respiratory tract infections. Therefore, the aim of this research was to examine the phytochemical composition and antioxidant activity of S. kitaibelii in form of subcritical water extract (SWE). HPLC analysis of SWE of S. kitaibelii showed the presence of ten compounds in a total concentration of 89.33 mg/g of the extract. It was demonstrated that the polarity of subcritical water was the most selective for extracting syringic acid (37.88 mg/g), caffeic acid (18.06 mg/g), and epicatechin (10.04 mg/g). Flavonoids like rutin, luteolin, and apigenin were the least abundant in this extract (<2 mg/g). Additionally, this study investigated in vitro antioxidant activities of S. kitaibelii SWE by five antioxidant assays. Four assays present radical scavenging activity while the last assay indicates transitional metal reduction. The highest scavenging abilities were observed against superoxide anion and ABTS•+ radicals (437.35 and 412.09 μmol TE/g), followed by lipid radicals (69.61 μmol TE/g), and DPPH• (32.28 μmol TE/g).