2.1. Materials

PVA powder (M_w = 30,000–80,000 Da, degree of hydrolysis = 98%) was bought from Sigma-Aldrich (St. Louis, MO, USA). Hydroalcoholic solutions of Thymus vulgaris, Salvia officinalis folium, and Hyperici herba were purchased from SC HOFIGAL EXPORT-IMPORT SA (Bucharest, Romania). The Folin–Ciocalteu reagent (Sigma-Aldrich, St. Louis, MO, USA), sodium carbonate (Sigma-Aldrich, St. Louis, MO, USA), gallic acid (Sigma-Aldrich, Darmstadt, Germany), and chromatographic grade ethanol (Merck, Darmstadt, Germany) were also purchased from commercial sources and used as received in the analyses.