Flavonoids of the Far Eastern Species of the Genus Bupleurum L.

Abstract

Objective: The aim of this study was to investigate the composition of flavonoids in B. euphorbioides Nakai., B. triradiatum Adam ex. Hoffm., B. longiradiatum Turcz., B. scorzonerifolium Willd., B. komarovianum Lincz., and B. atargense Gorovoi species of the genus Bupleurum L., growing in the Russian Far East (Primorskii krai, Magadan oblast). Methods: Compounds of the flavonoid class were isolated from six species of plants of the genus Bupleurum L., growing in the Russian Far East (Primorskii krai, Magadan oblast) by liquid extraction. Five compounds were identified by reversed-phase liquid chromatography: avicularin, rutin, narcissin, quercetin, and isorhamnetin. Avicularin was identified in B. atargense and B. longiradiatum plants for the first time. The structure of the compounds (avicularin, rutin, and narcissin) isolated by preparative column chromatography on Silica gel in the gradient elution mode using a mixture of solvents (carbon tetrachloride and ethanol) was proved by NMR-¹H, ¹³C, and ¹H, ¹³C-HMBC spectroscopy and by ESI mass spectrometry. Use of the differential spectrophotometry method allowed determining the content of total flavonoids in the aerial part of the six species of the genus Bupleurum L., whose mass fraction as calculated for absolutely dry raw material was found to vary from 0.58 to 2.92%. Results and Discussion: The highest content of flavonoids, 2.92 ± 0.58%, was detected in B. euphoiroides, and the lowest content, 0.58 ± 0.12%, in B. longiradiatum. Conclusions: A comparative analysis of individual flavonoids in the studied species of the genus Bupleurum L. revealed the features of their accumulation. The predominant flavonoid in the aerial part of B. atargense and B. euphoiroides was quercetin (1.14 ± 0.23 and 0.92 ± 0.18%, respectively), and that in B. triradiatum, B. komarovianum, B. scorzonerifolium, and B. longiradiatum, rutin (0.47 ± 0.09, 0.18 ± 0.04, 0.32 ± 0.08, and 0.13 ± 0.03%, respectively).