Sonja M. Djilas

Summary: A reversed‐phase high performance liquid chromatography (RP‐HPLC) separation on C₈ column and quantitative method were developed to analyse hydroxyl derivatives of benzoic and cinnamic acid and flavonoids in horsetail (Equisetum arvense L.) extracts. Total phenolic content of n‐butanol, ethyl acetate and water extracts, determined by the Folin‐Ciocalteu method, was 96.4, 26.4 and 15.4 mg g⁻¹ of dry extracts, respectively. The antioxidative activity of horsetail extracts was tested by measuring their ability to scavenge stable 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) and reactive hydroxyl radicals by electron spin resonance spectroscopy. The results demonstrated that the free radical scavenging activity (versus both DPPH and hydroxyl radicals) depended on the type and concentration of applied extracts; the highest DPPH (EC₅₀ = 0.65 mg mL⁻¹) and hydroxyl radical scavenging activities (EC₅₀ = 0.74 mg mL⁻¹) were obtained in the case of n‐butanol extract. The radical scavenging activity of extracts significantly correlated with total phenolic content. The antimicrobial tests showed that ethyl acetate and n‐butanol extracts inhibited the growth of tested bacteria.

The antioxidant activity of different Satureja montana L. subsp. kitaibelii extracts was tested by measuring their ability to scavenge reactive hydroxyl radical during the Fenton reaction, using ESR spectroscopy. Also, the influence of these extracts on lipid peroxyl radicals obtained during lipid peroxidation of: (I) sunflower oil (37°C, 3h) inducedby 4,4'-azobis(4-cyanovaleric acid) (ACVA) and (II) liposomes induced by 2,2'-azobis(2-amidino-propane)dihydrochloride (AAPH) was studied. n-Butanol extract had the bestantioxidant activity (100% at 0.5 mg/mL in Fenton reaction system; 89.21% at 5 mg/mL in system I; 83.38% at 5 mg/mL in system II). The antioxidant activities of the extracts significantly correlated with total phenolic content. The antimicrobial activity of Satureja montana L. subsp. kitaibelii extracts was investigated. Petroleum ether, chloroform and ethyl acetate extracts expressed a wide range of inhibiting activity against both gram-positive and gram-negative bacteria.

Summary: The sequential extraction of Teucrium montanum L. was realised with five solvents of different polarities (70% methanol, petroleum ether, chloroform, ethyl acetate, and n‐butanol) and HPLC method was used for identification of phenolic compounds. The total phenolic content of the extracts was determined spectrophotometrically according to the Folin–Ciocalteau procedure and range from 0 to 296 mg g⁻¹. The antioxidant activity of extracts was tested by measuring their ability to scavenge reactive hydroxyl radical during the Fenton reaction, using electron spin resonance (ESR) spectroscopy. Moreover, the influence of these extracts on lipid peroxyl radicals obtained during lipid peroxidation of: (1) sunflower oil (37 °C, 3 h) induced by 4,4′‐azobis(4‐cyanovaleric acid) (ACVA) and (2) liposomes induced by 2,2′‐azobis(2‐amidino‐propane)dihydrochloride (AAPH) was studied. n‐Butanol extract, because of the highest content of total phenolic compounds (296 mg g⁻¹) had the best antioxidant activity (100% at 0.16 mg mL⁻¹ in Fenton reaction system; 90.57% at 5 mg mL⁻¹ in system I; 100% at 5 mg mL⁻¹ in system II).