Comparison of Infusions from Black and Green Teas (Camellia sinensis L. Kuntze) and Erva-mate (Ilex paraguariensis A. St.-Hil.) Based on the Content of Essential Elements, Secondary Metabolites, and Antioxidant Activity

The aim of the research was to compare chemical composition and antioxidant activity of black and green teas with those of erva-mate. Therefore, essential elements (P, Mg, Fe, Zn, Mn, and Cu), phenolic acids (gallic, caffeic, p-coumaric, and ferulic), flavonoids (catechin, rutin, myricetin, apigenin, and quercetin), and alkaloids (caffeine, theobromine, and theophylline) were determined. Phenolics and alkaloids were quantified by HPLC, metallic elements by atomic absorption spectrometry, and antioxidant activity by a 2,2'-azino-bis(3-ethylbenzthiazoline)-6-sulfonic acid method. Total P, inorganic P, and Mg expressed in milligrams per gram dry weight (d.w.) and other metals expressed in milligrams per kilogram d.w.) in the order Mn > Zn > Fe > Cu were assayed. Caffeine was found above 25 mg/g d.w. in all samples. Among the phenolic compounds, caffeic acid and quercetin were on the highest level, whilst apigenin and p-coumaric acid were on the lowest. Correlation analysis revealed frequently occurring relations between P and several metals and phenolics and also between Zn and other metabolites from flavonoids, phenolic acids, and alkaloids. Within organic compounds, correlations were often found among gallic and caffeic acids and other analytes, like p-coumaric, ferulic acids, and myricetin. Antioxidant activity of studied infusions from different types of teas was very similar. Cluster analysis grouped the studied materials into clear clusters, generally separating erva-mate samples from Camellia sinensis. Principal component analysis indicated total P, Mg, Cu, caffeic acid, myricetin, and p-coumaric acid as factors influencing mostly the diversity among analyzed samples.