3 4 dihydroxy l phenylalanine l dopa 2 2 diphenyl 1 picrylhydrazyl dpph

Glycerine (>99.8%), Folin–Ciocalteau reagent, and K₂S₂O₈ were obtained from Chempur (Piekary Śląskie, Poland). Ethanol (>99.8%) was obtained from Honeywell (Charlotte, NC, USA). Tyrosinase from Agaricus bisporus, 3,4-dihydroxy-l-phenylalanine (L-DOPA), 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS), kojic acid (≥98.5% purity), quercetin (>95% purity), gallic acid (>97.5%), Dulbecco’s phosphate buffered saline (DPBS), Dulbecco’s modified Eagle’s medium (DMEM), bovine serum albumin (BSA), neutral red solution in DPBS (3.3 g/L) were purchased from Sigma Aldrich (Merck, Darmstadt, Germany). Fetal bovine serum (FBS) was obtained from Pan-Biotech (Aidenbach, Germany). The solvents used for phytochemical studies by HPLC-MS (water, acetonitrile, and formic acid) were purchased from Merck (Darmstadt, Germany).

A375 (ATCC CRL-1619) human malignant melanoma and human squamous cell carcinoma SCC-15 (ATCC CRL-1623) cell lines were purchased from LGC Standards (Łomianki, Poland). HaCaT immortalized human keratinocytes were purchased from CLS Cell Lines Service GmbH (Eppelheim, Germany). Fetal bovine serum (FBS) was obtained from Pan-Biotech (Aidenbach, Germany). Dulbecco’s modified Eagle’s medium (DMEM)/high glucose, Dulbecco’s phosphate buffered saline (DPBS), mushroom tyrosinase from Agaricus bisporus, 3,4-Dihydroxy-l-phenylalanine (l-DOPA), 2,2-Diphenyl-1-picrylhydrazyl (DPPH), neutral red solution (3.3 g/L), gallic acid, rutoside, quercetin, kojic acid, and DMSO were purchased from Sigma-Aldrich (St. Louis, MO, USA). The purity of the reference compounds exceeded 95%. Acetonitrile, water, and formic acid for LC-MS analyses were purchased from Merck (Darmstadt, Germany). All other reagents were purchased from Honeywell (Warszawa, Poland). All solutions were prepared with ultrapure water (MilliQ Integral II, Merck, Darmstadt, Germany).