Phenolic Compounds and Pyrrolizidine Alkaloids of Two North Bluebells: Mertensia stylosa and Mertensia serrulata

Two North bluebells, Mertonian stylosa and M. serrulata, are plants used in the traditional medicine of the Buryats as wound healing and antitumor remedies. Both mertensias have been used by local healers as substitutes for the rare Tibetan raw material Cynoglossum amabile. The lack of information on the chemical composition of M. stylosa and M. serrulata herbs has prompted the study of metabolites, in particular phenolic compounds and alkaloids, as components with high biological activity. In this study, the application of liquid chromatography–mass spectrometry for the metabolite profiling of both Mertensia species resulted in the identification of 30 compounds, including hydroxycinnamates, flavonoids, and pyrrolizidine alkaloids. In particular, lycopsamine N-oxide was the dominant alkaloid in M. stylosa (5.27 mg/g) and M. serrulata (2.14 mg/g) herbs, 5-O-caffeoylquinic acid (43.41 mg/g) and rutin (42.40 mg/g) prevailed among the phenolic compounds in M. stylosa herb, while rutin (25.72 mg/g) was the dominant compound of the M. serrulata herb. The investigated extracts of M. stylosa and M. serrulata herb revealed good scavenging capacity against DPPH•, ABTS•+, and DMPD•+ radicals. To our knowledge, this is the first study of M. stylosa and M. serrulata alkaloids and phenolic compounds and antioxidativity.