A study of the flavonoids and phenylpropanoids of the aerial organs of Bupleurum multinerve was carried out. Samples of raw materials were collected in the Baikal region in the vicinity of. Verkholensk, Irkutsk region. The raw materials were collected during the flowering period in 2019 in the herb-grass association. For analysis, raw materials were extracted with 70% ethyl alcohol in an ultrasonic bath for 30 minutes, followed by centrifugation of the extract. Compounds were identified by the UPLC-DAD-ESI-MS method in comparison with standard samples. In the aerial organs of B. multinerve, 15 compounds were identified (8 flavonoids and 7 phenylpropanoids). Flavonoids B. multinerve are derivatives of quercetin, kempferol, isoramnetin; phenylpropanoids – esters of quinic acid with coffee, ferulic, coumaric. The contents of B. multinerve compounds were first established: quercetin-3-O-glucuronide, kempferol-3-O-glucoside (astragaline), 5-O-p-coumaroylquinic acid, 5-O-feruloylquinic acid, 3-O-feruloylquinic acid, 3,5-di-O-caffeoylquinic acid; 4,5-di-O-caffeoylquinic acid. The quantitative content of glycosides of flavonoids isoramnetin-3-O-rutinoside (narcissin) 20.74 mg/g, quercetin-3-O-rutinoside (rutin) 19.53 mg/g, quercetin-3 was determined by MK-HPLC-UV in the aerial organs of B. multinerve -O-glucoside (isocvercitrin) 2.24 mg/g, camperol-3-O-glucoside (astragaline) 0.39 mg/g, quercetin-3-O-glucuronide 0.25 mg/g; quercetin flavonoid aglycones 0.43 mg/g; isoramnetin 0.53 mg/g; the predominant phenylpropanoids were 5-O-caffeoylquinic acid 6.60 mg/g, 3,5-di-O-caffeylquinic acid 1.58 mg/g. The total content of identified flavonoids was 44.97 mg/g, phenylpropanoids 9.53 mg/g.

The article presents the method for the quantitative determination of flavonoids for the analysis of Bupleurum multinerve herb based on the method of differential spectrophotometry. The optimal conditions for analysis have been determined. They include extractant 40% ethyl alcohol, ratio of raw materials and extractant 1 : 100, extraction time of 60 minutes in the boiling water bath, complexing agent of 1 ml of 2% aluminum chloride. The use of rutin as a standard has been experimentally validated, analytical wavelength is 412 nm. The relative error of the mean result (for n = 9) was 3.20%. Validation studies of the method have shown that it meets the criteria: linearity (r = 0.99988), correctness, specificity, and precision. The analytical range of the method is 8.6726.08 g/ml. The method is recommended for the inclusion into the new edition of the Pharmacopoeia Monograph for this type of plant material.