Methods to quantify active substances in hawthorn berries and hawthorn berry medicinal products

Introduction. The State Pharmacopoeia of the Russian Federation requires that the total flavonoid content in hawthorn berries and hawthorn tincture should be determined using spectrophotometry. The current analytical procedure has significant limitations, including low selectivity, poor accuracy, and inability to determine the components of active substances individually. These limitations can be eliminated by using other instrumental methods. In a previous paper, the authors proposed an analytical procedure for the quantitative determination of active substances in hawthorn flowers by high-performance liquid chromatography (HPLC). With the similar chemical compositions of hawthorn flowers and berries, a similar analytical procedure can be developed to determine the total flavonoid content in hawthorn berries and hawthorn tincture.

Aim. This study aimed to develop an HPLC procedure to determine the total flavonoid content in hawthorn berries and hawthorn tincture; additionally, the authors aimed to suggest approaches to harmonising the methods for the quantitative determination of active substances in hawthorn berries with the methods outlined in the leading pharmacopoeias.

Materials and methods. The study focused on the Hawthorn Berries and Hawthorn Tincture herbal medicines from Russian manufacturers. The authors used HPLC on an Infinity II 1260 DAD chromatograph, spectrophotometry on an Agilent 8453E spectrophotometer, and acid–base titration. The sample preparation procedure involved using a continuous extraction apparatus. The loss on drying was determined using a drying chamber. Quercetin dihydrate CRS (European Pharmacopoeia) was used as a reference standard.

Results. A comprehensive review of the approaches of the leading pharmacopoeias to the standardisation of assays for hawthorn berries showed the potential for developing a selective analytical procedure for flavonoid quantification by HPLC. The review demonstrated that it was feasible to standardise procyanidins, expressed as cyanidin chloride. The authors considered it unnecessary to introduce an analytical procedure to determine the organic acids in hawthorn berries, similar to that required by the Pharmacopoeia of the People’s Republic of China, in the State Pharmacopoeia of the Russian Federation since the berries of Russian officinal species have much lower organic acid levels than the berries of the hawthorn species described in the Pharmacopoeia of the People’s Republic of China.

Conclusions. The authors suggested and validated an HPLC procedure to determine the total flavonoid content, expressed as hyperoside, in hawthorn berries and hawthorn tincture and recommended that the pharmacopoeia monograph on hawthorn berries should include the quantitative determination of procyanidins, expressed as cyanidin chloride.