Development and validation of method of quantitative determination of flavonoids from the above-ground part of Glycyrrhiza glabra L.

Abstract

The aim of this study was to determine the optimal extraction factors of flavonoids from the above-ground part of licorice (Glycyrrhiza glabra L.) and to develop a method for their quantitative determination by differ-ential spectrophotometry. The object of the study was collected in the Volgograd region during flowering and dried samples of the herb of the medicinal plant. Ethyl alcohol 70% was chosen as the optimal extractant of flavonoids from the studied raw materials. It was found that the extraction of the maximum amount of flavonoid fraction is observed at three times extraction of plant raw material for 30 minutes each in the ratio with extractant 1:30. Quantitative determination of flavonoid compounds was performed by measuring the optical density of coloured complexes formed in extracts from the above-ground part of G. glabra L. with 2.5% aluminum chloride solution. Detection of the optical density of the tested solutions was conducted at a wave-length of 408 nm, corresponding to the maximum of the standard sample solution of rutin (Sigma, USA) after the addition of 2.5% aluminum chloride solution. Determined by differential spectrophotometry method the content of the sum of flavonoids in recalculation on rutin in extracts from the studied samples of plant raw materials of G. glabra L., obtained under the selected conditions, is 4.34±0.06%. The relative error of determination did not exceed 5%. A validation analysis was also conducted, the results of which showed the specificity, linearity and precision of the developed methodology. The studied validation parameters were within the acceptance criteria.