Antioxidant activity and phenolic compounds in 10 selected herbs from Vrujci Spa, Serbia

There is a growing research interest on investigation of appropriate alternatives of natural origin to synthetic additives used in food products. The aim of this study was to investigate correlation of chemical composition of the best known biomarker plants from the locality of Vrujci Spa, Serbia with their antioxidant activity in vitro, in terms of their potential usage as feedstock materials in the food industry. Total phenolic (IF), total tannins (TT) and total flavonoid (IF) contents were determined using spectrophotometric methods. Qualitative and quantitative analyses of major phenolics by high-performance liquid chromatography (HPLC) were also used. Major phenolic acids identified in analyzed species were chlorogenic, caffeic and ferulic acid, while predominant flavonoids were flavonols (hyperoside, rutin, isoquercitrin, quercetin) and, in lesser extent flavones (luteolin, apigenin and their 7-O-glucosides). Vitexin 2-O ''-rhamnoside was found only in Crataegus species. Antioxidant capacity was estimated by the following methods: 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) test and ferric reducing antioxidant power (FRAP). Majority of investigated plants had high levels of phenolics and exhibited noteworthy antioxidant activity. Moreover, a positive linear correlation was found between TP and IT with antioxidant capacities regarding both methods used. The plants showing the highest antioxidant activities were Veronica officinalis, Mentha pulegium and Fragaria vesca. Hypericum perforatum demonstrated by far the most potent antioxidant activity, as well as TP and TT content. Our results indicate that, in addition to their traditional usage in folk medicine, these plants represent a valuable source of natural antioxidants, and thus may be considered as great potential for the food industry, representing possible alternatives to synthetic additives. (C) 2013 Elsevier B.V. All rights reserved.