An approach to standardization of licorice herb (glycyrrhiza glabra l.)

Aim to develop a method for standardization of licorice herb. Material and methods. The material for the study was licorice herb harvested in Alekseevka settlement of the Samara Region (2021), Tatarskaya Kargala village of Sakmarskiy area of the Orenburg Region (2017), Derzhavinsk city of the Republic of Kazakhstan (2018), Bol'shaya Chernigovka village of Bol'shchernigovsk area of the Samara Region (2019), and a commercial sample of licorice root raw material from AO "Krasnogorskleksredstva". In addition, the reference standards (RS) were used: pinostrobin, licuraside, quercetin, rutin, luteolin and glycyram. The authenticity was determined by the thin layer chromatography (qualitative analysis). For the quantitative analysis, we used the differential spectrophotometry, conducted in accordance with Pharmacopoeial monograph 1.2.1.1.0003.15 "Spectrophotometry in ultraviolet and visible spectra". The spectral characteristics of water-alcohol extracts were evaluated on spectrophotometer "Specord 40" (Analytik Jena AG, Germany). Results. The dominant flavonoid substance, pinocembrin, was detected. This compound in chloroform-ethanol (4:1) solvent system had blue fluorescence at 365 nm. During the development of the chromatogram with an alkaline solution of diazobenzene sulphonic acid, a light green stain (pinoсembrin) was detected practically at the level of the pinostrobin stain. It is reasonable to determine the diagnostic flavonoid pinocembrin of licorice herb using pinostrobin as the reference standard. The flavonoids pinocembrin and pinostrobin have similar spectral characteristics and are similar in chemical structure. A method has been developed for quantitative determination of the total flavonoids in terms of pinocembrin in water-ethanol extract of licorice herb (Glycyrrhiza glabra L.) using the differential spectrophotometry. The total flavonoid content in the licorice herb varies from 0.390.002% to 3.480.015% (in terms of pinocembrin).