Polyphenol Content, Mineral Compounds Composition, Antimicrobial and Antioxidant Activities of Selected Medicinal Herbs from Slovak Republic

Abstract

The aim of this study was to determine antioxidant activity (DPPH and phosphomolybdenum method), polyphenols content (total polyphenols, flavonoids, and phenolic acids), mineral compounds composition (Cu, Zn, Mn, Fe, Cr, Ni, Co, Pb and Cd) and antimicrobial activity (with disc diffusion method) of medicinal herbs traditionally used in the Slovak republic. The tested plants belonged to the Primulaceae, Urticaceae, Grossulariaceae, Rosaceae, Lamiaceae, Asteraceae, Equisetaceae, Tropaeolaceae, and Plantaginaceae families. The highest antioxidant activities were found in samples of Rosa canina L. (DPPH—29.43 ± 0.11 mg TE/g; TE—Trolox equivalent) and Fragaria vesca L. (phosphomolybdenum method—679.56 ± 3.06 mg TE/g), both from the Rosaceae family. Total polyphenols (determined using the Folin–Ciocâlteu-reagent) were most abundant in a sample of Fragaria vesca L.—124.51 ± 5.05 mg GAE/g (GAE—gallic acid equivalent), total flavonoids (determined using the aluminum chloride method)—in a sample of Primula veris L.—48.35 ± 3.77 mg QE/g (QE—quercetin equivalent), and total phenolic acids (determined using Arnova reagent)—in a sample of Thymus serpyllum L.—102.31 ± 2.89 mg CAE/g (CAE—caffeic acid equivalent). Regarding mineral compounds composition, samples of Fragaria vesca L. and Thymus serpyllum L. showed the highest levels of iron. In samples of Calendula officinalis L. and Trapaeolum majus L., the highest amounts of zinc were determined, while copper was the most abundant in samples of Urtica dioica L. and Melissa officinalis L. The amounts of heavy metals were within legally acceptable limits. The extract of Equisetum arvense L. showed the strongest inhibitory activity towards Clostridium perfringens CCM 4991 (6 mm), while the one from Mentha piperita L.—towards Candida glabrata CCM 8270 (4.83 mm) and Candida tropicalis CCM 8223 (4.33 mm).