THE METHOD OF QUANTITATIVE DETERMINATION OF THE AMOUNT OF FLAVONOIDS IN THE FLOWERS OF GIANT CEPHALARIA

Abstract

Giant cephalaria (Cephalaria gigantea (LEDEB.) BOBROV) is a powerful perennial whose height reaches two meters. This plant is found in Southern Europe, Western and Central Asia, as well as in North and South Africa. It is cultivated in the Botanical garden of Samara University. The extracts of giant cephalaria have been used in traditional medicine for many years due to their antimicrobial, antifungal, cytotoxic, antioxidant, antidiabetic and antipyretic activities, which may be due to various biologically active compounds. It is known that the leaves contain triterpenoids, phenolic carboxylic acids and their derivatives, flavonoids, and the flowers contain flavonoid compounds: luteolin, quercetin, cynaroside, quercimeritrin and gigantoside A. The article describes the development of a technique for quantifying of the amount of flavonoids in the flowers of giant cephalaria. Spectrophotometric analysis of water-alcohol extracts from giant cephalaria flowers allowed us to establish that the main contribution to the absorption curve of their UV-spectra in the presence of AlCl3 is made by flavonols having a free OH group at the C-3 position, and in the differential version, the maximum absorption of the tested solution is close to that of the standard sample of quercetin (428±2 nm). Optimal conditions for the extraction of flavonoids in giant cephalaria flowers were determined: extractant 70% ethyl alcohol; the ratio "raw material-extractant" – 1 : 50; extraction time – extraction in a boiling water bath for 60 minutes, the degree of grinding of raw materials – 2 mm, analytical wavelength – 426 nm. It was determined that the content of the total flavonoids calculated on quercetin in the flowers of giant cephalaria varies from 1.58±0.05% to 2.63±0.05%. The error of a single determination with a 95% confidence probability is ±1.75%. The obtained results were used in the development of the FS project for a new type of medicinal plant raw materials "Cephalaria giant flowers" for introduction into the State Pharmacopoeia of the Russian Federation.