QUANTITATIVE DETERMINATION OF FLAVONOIDS OF MARIGOLD FLOWERS

Improving existing and developing new methods for analyzing biologically active substances of medicinal plants by reducing material and time costs is considered a priority task of modern pharmacognosy. Objective. Development of parameters for quantitative determination of calendula flower flavonoids. Matherials and Methods. Object of study – calendula flowers. We tested 16 methods for quantitative spectrophotometric determination of flavonoids from the State Pharmacopoeia of the Republic of Belarus on Calendula flowers. The basic method for developing the parameters for quantitative determination was selected by comparing the results obtained using the spectrophotometric method with high-performance liquid chromatography and by comparing the absorption spectra of rutin, caffeic acid standard samples and the extracts under study. We studied the effect of the following parameters on the optical density of the system: concentration of aluminum chloride solution in alcohol (70%, v/v); volume of aluminum chloride solution in alcohol (70%, v/v); volume of acetic acid in buffer solution S; volume of buffer solution S and duration of heating in a water bath. Statistical processing of the data was performed using Student's criterion. Results. It is shown that direct spectrophotometry is not suitable for quantitative determination of Calendula flower flavonoids, since hydroxycinnamic acids and unreacted reagents contribute to absorption. Based on the data of high-performance liquid chromatography and assessment of the ratio of optical densities of rutin and caffeic acid, a technique for quantitative determination of flavonoids was selected. When using this technique, the absorption spectra of rutin and calendula flower extracts coincide. The optimal parameters for spectrophotometric determination of calendula flower flavonoids are: concentration of aluminum chloride solution – 50 g / l; added volume of aluminum chloride solution – 8.0 ml; volume of acetic acid in buffer solution S – 2.5 ml; added volume of buffer solution S – 5.0 ml and duration of heating in a water bath – 4 min. Conclusion. Parameters for spectrophotometric determination of total flavonoid content in calendula flowers with recalculation to rutin have been developed. The choice of method for quantitative determination of calendula flower flavonoids has been substantiated.