2 2 diphenyl 1 picrylhydrazyl dpph sodium chloride

Aluminum chloride hexahydrate, sodium carbonate, sodium hydroxide, hydrochloric acid, acetone, methanol, were purchased from Avantor Performance Materials Poland S.A. (Gliwice, Poland). The Folin-Ciocalteu′s phenol reagent was from Merck (Darmstadt, Germany). DMEM and antibiotics were purchased from Biowest (Nuaillé, France), FBS was obtained from EURx (Gdansk, Poland). Chitosan medium molecular weight, CS MMW (200–800 cP, 1 wt. % in 1% acetic acid) was supplied by Sigma-Aldrich (Poznan, Poland) as well as all the other chemicals (2,2-Diphenyl-1-picrylhydrazyl (DPPH), sodium chloride, bovine serum, hexadecyltrimethylammonium bromide (CTAB), hyaluronic acid (HA), phosphate buffer), tyrosinase, 3,4-Dihydroxy-L-phenylalanine (L-DOPA), quercetin, gallic acid.

Baicalin (≥95%, HPLC), baicalein (≥98%, HPLC), and wogonin (phyproof^® Reference Substance) were obtained from Sigma-Aldrich (Poznan, Poland). Excipients, such as chitosans with a degree of acetylation of 70%, 80%, and 90% with a viscosity range of 500 mPas (marked as 70/500, 80/500, and 90/500, respectively) were supplied from Heppe Medical Chitosan GmbH (Halle, Germany). Reagents for activity assays: 2,2-Diphenyl-1-picrylhydrazyl (DPPH), sodium chloride, bovine serum, hexadecyltrimethylammonium bromide (CTAB), hyaluronic acid (HA), for dissolution studies: potassium chloride, sodium chloride, di-potassium hydrogen orthophosphate, magnesium chloride, calcium chloride, and xylitol, and mucoadhesive tests: mucin from porcine stomach were obtained from Sigma-Aldrich (Poznan, Poland). HPLC grade acetonitrile and water were obtained from Merck. High-quality pure water and ultra-high-quality pure water were prepared using an Direct-Q 3 UV Merck Millipore purification system.