Elaboration of approaches to standardizing walnut (Juglans regia) leaves

Introduction. Medicinal plant raw materials of representatives of the genus Juglans of walnuts have antimicrobial and general tonic effects due to the fact that it contains naphthoquinone derivatives (juglone, hydrojuglone) and other phenolic compounds. Despite a wide spectrum of pharmacological activities, walnut (Juglans regia L.) is not pharmacopoeial in the Russian Federation. For inclusion of walnut leaves into the State Pharmacopoeia of the Russian Federation, it is necessary to conduct a set of pharmacognostic studies, including the development of regulatory documents that confirm the quality of medicinal plant materials. Objective: to develop a procedure for the quantitative determination of total flavonoid contents in walnut leaves. Material and methods. The investigation used the walnut leaves stored in the Samara State Medical University Botanical Garden in 2018-2019, as well as differential spectrophotometry. Results. A study of spectral characteristics showed that the total content of flavonoids in the walnut leaves could be determined with reference to rutin at an analytical wavelength of 412 nm. A procedure for quantification of the amount of flavonoids in the investigated plant raw materials was developed and validated. The error of a single determination with a confidence level of 95% is ±3.49%. Conclusion. The developed procedure was used to analyze a number of samples of walnut leaves growing in the Samara State Medical University Botanical Garden. The total flavonoid contents calculated with reference to rutin ranged from 3.58 to 3.72%. The developed procedure can be used in further investigations of this type of medicinal plant material.