SPECTROPHOTOMETRIC DETERMINATION OF THE AMOUNT OF FLAVONOIDS IN SOME ASTRAGALUS SPECIES

Introduction. Astragalus L. is the largest genus in the legume family Fabaceae. The raw material contains saponins, flavonoids, polysaccharides, and other biologically active substances and has a wide range of biological activities. The amount of flavonoids in the herb of different Astragalus species was spectrophotometrically determined using various standard samples (SSs) of hyperoside, luteolin-7-O-glucoside. The lack of a single method for determining the total content of flavonoids complicates the comparative analysis of the examined Astragalus species. Objective: to spectrophotometrically determine the amount of flavonoids calculated with reference to rutin in four representatives of the genus Astragalus. Material and methods. The investigation objects were the herb samples of Astragalus varius, Astragalus dasyanthus, Astragalus testiculatus, and Astragalus henningii, collected in the Saratov Region in July 2020. A Shimadzu UV-1800 spectrophotometer (Japan) was used for the spectrophotometric determination and obtaining UV spectra of plant extracts. Results. The amount of flavonoids in the aboveground part of Astragalus species was comparatively determined. All the UV spectra of aqueous alcoholic extracts from the herb of the examined Astragalus species showed a bathochromic shift in the longwave band in the presence of a 2% alcohol solution of AlCl3, which suggests that flavonoids are present. Differential spectrophotometry revealed the absorption maximum in the 402-407 nm region, which confirms the feasibility of using the standard sample of rutin that has the absorption maximum at a wavelength of 412±1 nm in the spectrophotometric determination of the amount of flavonoids in the herb of Astragalus species. The total content of flavonoids calculated with reference to rutin was determined at a wavelength of 405 nm in all the examined samples. Conclusion. Astragalus testiculatus was found to contain the lowest levels of flavonoids (0.96%), Astragalus henningii had their highest content (3.30%).

Astragalus varius S.G.Gmel, Astragalus dasyanthus Pall, Astragalus testiculatus Pall, Astragalus henningii (Stev.) Klok, Astragalus varius S.G.Gmel, Astragalus dasyanthus Pall, Astragalus testiculatus Pall, Astragalus henningii (Stev.) Klok, flavonoids, quantitative determination, differential spectrophotometry, rutin