Content of phenolic compounds in herbs used in the Czech Republic

Herbs are recognized as sources of natural antioxidants and thus play a significant role in the chemoprevention of diseases resulting from lipid peroxidation. The Trolox equivalent antioxidant capacities (TEAC) and phenolic contents of the aqueous extracts of 17 spices from 6 botanical families grown in the Czech Republic were investigated. The herbs were extracted by means of different extraction techniques. Classical solvent extraction (Randall extraction), ultrasonication, maceration and shaking were used and compared. The antioxidant capacity (AC) was estimated by method based on ABTS free radical scavenging abilities. Qualitative and quantitative analyses of major phenolics were conducted by reverse-phase ultrahigh-performance liquid chromatography (RP-UHPLC). The phenolic compounds identified in the analyzed species were caffeic acid, ferulic acid, p-coumaric acid, protocatechuic acid and cinnamic acid as the major constituent obtained. From all extraction methods, Randall extraction and maceration were considered the best, because the extracts obtained revealed the highest phenolic contents and the best antioxidant properties measured by chemical assays. The highest contents of phenolic compounds were determined in the Lamiaceae family – in lavender (319.75 ± 1.77 mg/100 g dry weight) and lemon balm (249.00 ± 0.35 mg/100 g dry weight) – by means of Randall extraction.