**3. Materials and Methods**

#### *3.1. Materials*

Drug substance echinochrome A and drug product Histochrome were produced by G.B. Elyakov Pacific Institute of Bioorganic Chemistry (Vladivostok, Russia). TSKgel Toyopearl HW-40 (TOYO SODA, Tokyo, Japan), and Sephadex LH-20 (GE Healthcare Bio-Sciences AB, Uppsala, Sweden) were used for column chromatography. HPLC-grade water and acetic acid were purchased from Panreac Quimica (Barcelona, Spain). MeCN grade 0 was sourced from Cryochrom (Saint Petersburg, Russia). Other solvents used in this study were of analytical grade. Deuterated solvents acetone-*d*6, CDCl3, CD3CN, and Bruker® SampleJet NMR tubes WIMWG10007SJ (178 mm, cap, O.D. 5.0 mm) for NMR experiments were purchased from Sigma (St. Louis, MO, USA).
