Development of a procedure for quantification of the total flavonoid content in the ground burnut (Tribulus terrestris) herb

Introduction. Evaluating the quality of ground burnut (Tribulus terrestris) herb is regulated by the normative document for furostanol glycosides. The literature presents information that raw materials contain not only steroidal saponins, but also a complex of biologically active substances, in particular flavonoids, the content of which can be used to quickly and objectively assess the quality of the raw materials. Objective: to develop a procedure for quantifying the total flavonoid content in the ground burnut herb, by using differential spectrophotometry. Material and methods. The investigation objects were samples of ground burnut herb gathered in the Botanic Garden, All-Russian Research Institute of Medicinal and Aromatic Plants (VILAR) (Moscow), in Crimea, the Republic of Moldova, and Syria during 2016-2018. Spectral studies were conducted in the wavelength range of 350-430 nm with a 1-nm increment, by using an SF-2000 spectrophotometer. Results and discussion. The UV spectra for alcoholic extracts were investigated to determine an analytical wavelength. The differential spectrum for extraction with aluminum chloride had a maximum emission at 410±2 nm, which coincided with that of the State standard sample (SSS) of rutin. The highest amount of flavonoids was extracted with 80% ethanol. The maximum optical density and the greatest yield of total flavonoids from the raw material were observed at a grinding fineness of 2 mm with a single extraction for 60 minutes. Under complexing conditions, the optimal ratio of the volume of the test solution to 2% alcoholic aluminum chloride solution was 2:5. The stability of the complex with the latter was observed 15 minutes after the start of the reaction and retained it for 1 hour. Conclusion. The procedure was developed for quantifying the sum of flavonoids in the ground burnut herb calculated with reference to rutin, by using differential spectrophotometry.

Tribulus terrestris L, ground burnut, Tribulus terrestris L, herb, standardization, flavonoids, spectrophotometry