ESI-MSⁿ as a Tool to Characterize Isoquinoline Alkaloids and Identify Possible Adulterant from Dietary Supplements that Claimed to Contain Goldenseal

Hydrastis canadensis L., commonly known as goldenseal, is a perennial herb in the buttercup family Ranunculaceae, native to southeastern Canada and the northeastern US, and an economically important North American medicinal plant that has been subject to adulteration in commerce. The phytochemicals of interest in goldenseal are the isoquinoline alkaloids hydrastine, berberine, and canadine. Other compounds of interest are palmatine, coptisine and jatrorrhizine, alkaloids that are found in potential adulterant species but not in goldenseal [1–2]. Isoquinoline alkaloids β-hydrastine, hydrastinine, canadine, berberine, coptisine, jatrorrhizine and palmatine have been characterized by using electrospray ionization multi-stage tandem mass spectrometry (ESI-MSⁿ) coupled with an ion-trap analyzer. Fragments C₁₁H₁₂NO₂ ⁺ are dominant or major products ions in hydrastinine and β-hydrastine, respectively. The C-ring is relative weak and likely broken in tetrahydrisoquinoline alkaloid canadine. In ESI source, the product ions of canadine are found at m/z 176 corresponding to fragments C₁₀ H₁₀ NO₂ ⁺. This fragment bears the core skeleton of dominant ions in hydrastinine. However, for highly unsaturated isoquinoline alkaloids, its skeleton is relatively stable. In this sub-group, the major ions, such as presenting ions at m/z 308, 294 and 292 in palmatine, jatrorrhizine and beberine respectively, may involve the re-arrangement of D-ring. The results of the current study have classified the fragmentation pathway of each sub-group into isoquinoline alkaloids. It can be used to characterize the structures of trace isoquinoline alkaloids in dietary supplements that claimed to contain goldenseal, and will benefit to identify adulterant in dietary supplements. Acknowledgements: This research is funded in part by “Science Based Authentication of Dietary Supplements” Funded by the Food and Drug Administration grant number 2 U01 FD 002071-07. References: [1] Weber HA, et al. (2003), J Agric Food Chem, 51: 7352–7358. [2] Brown PN, et al. (2008) Pharm Biol, 46: 135–144.

Fig. 1 Fragmentation Pattern Proposed for M⁺ Ions of Palmatine.