BACKGROUND: Juglans nigra L. is a species of trees in the Juglandaceae family. This plant of the genus Juglans L. has not been sufficiently studied in comparison with other species, including Juglans regia L. It is a perspective medicinal plant raw material, its derivatives have an antimicrobial, general tonic effect. The known antimicrobial and general tonic activity of Juglans L preparations presented on the pharmaceutical market is probably due to substances of a flavonoid nature. These data indicate the relevance of studying the flavonoids of the Juglans nigra L. bark.
 AIM: The aim of this study is to develop methods for qualitative analysis and quantitative determination of biologically active compounds for tincture of Juglans nigra L. bark with the using of spectrophotometry, thin layer chromatography, microcolumn high performance liquid chromatography.
 MATERIALS AND METHODS: The object of the study was the tincture of Juglans nigra L. bark, samples of which were prepared in March-April 2020 on the territory of the Botanical Garden of Samara University, standard samples of myricitrin, myricetin. UV spectra were recorded with the use of Specord 40 spectrophotometer (Analytik Jena). Chromatographic analysis was carried out by thin-layer chromatography (qualitative analysis), reversed-phase high performance liquid chromatography on a Milikhrom-6 microcolumn liquid chromatograph (quantitative analysis).
 RESULTS: As a result of the chromatographic study, myricitrin were revealed, it appeared to be the dominant flavonoid substance. This compound has Rf value of about 0.4 in the solvent system of chloroform-ethanol-water (25:18:2). A method for the quantitative determination of the total flavonoids calculated on myricitrin in tincture of Juglans nigra L. bark was developed by means of differential spectrophotometry. It was determined that the content of the total flavonoids calculated on myricitrin in the tincture of Juglans nigra L. bark was 0.84 0.07%. A method for the quantitative determination of myricitrin in tincture of Juglans nigra L. bark by high performance liquid chromatography was developed. The content of the dominant flavonoid as myricitrin (myricetin-3-O--L-rhamnopyranoside) in the tincture of Juglans nigra L. bark was 0.42 0.06%.
 CONCLUSIONS: The methods of qualitative analysis and quantitative determination of flavonoids for tincture of Juglans nigra L. bark with the use of modern instrumental methods of analysis (spectrophotometry, thin layer chromatography, high performance liquid chromatography) has been developed. These results can be used to standardize the tincture of Juglans nigra L. bark.
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