Development and validation of methods for the quantitative determination of dihydroquercetin-glycine lyophilizate components

Introduction. Herbal preparations occupy an important part in medical practice along with synthetic drugs. Flavonoids are the main group of biologically active substances in many of plant medicinal products. Flavonoids are generally slightly soluble in water. To overcome the low solubility, attempts are being made to obtain cocrystalline and coamorphic forms of flavonoids, for example, with amino acids. A neuroprotective effect has been established for both flavanonol dihydroquercetin and the amino acid glycine, which served as a starting point for obtaining a solid-phase product based on them by freeze drying.

The purpose of this work is to develop and validate methods for the identification and quantification of the two active ingredients of the dihydroquercetin-glycine composition.

Material and methods. Glycine was determined spectrophotometrically after reaction with ninhydrin. Dihydroquercetin analysis was performed using the HPLC-UV method on phenyl silica gel. The following validation characteristics were evaluated: accuracy, precision, specificity, linearity, and analytical range.

Results. The linear dependence of the optical density of Ruhemann's purple on the concentration of glycine is observed in the range of 0.1–0.5 mg/mL and obeys the equation A=5.1237C − 0.5553 (r=0.9968). The relative standard deviations of absorption according to the results of 3 determinations for concentrations of 80, 100, and 120% glycine are 3.2, 1.9, and 1.3%, respectively. The linear dependence of the area of the dihydroquercetin peak on its concentration is observed in the range of 10–200 μg/mL and obeys the equation S=121.518C – 47.935 (r=0.9998). The relative standard deviations of the peak area of the base substance according to the results of 3 determinations for concentrations of 10, 50, and 200 μg/mL of dihydroquercetin are 2.8, 3.9, and 1.2%, respectively.

Conclusion. The validated methods are suitable for pharmaceutical analysis and can be used in quality control of the composition, which is being developed as the basis of the dosage form “Lyophilizate for solution preparation for infusion”.