title: Evaluation of commercial ginkgo and echinacea dietary supplements for colchicine using liquid chromatography-tandem mass spectrometry.
abstract: In response to concerns that commercial dietary supplements containing Ginkgo biloba (ginkgo) and Echinacea purpurea, Echinacea angustifolia, or Echinacea pallida (echinacea) might be contaminated with colchicine, a highly selective and sensitive assay was developed for colchicine that is based on high-performance liquid chromatography-tandem mass spectrometry (LC-MS-MS). The method utilizes reversed-phase HPLC separation of compounds in a methanolic extract of the dietary supplement or botanical sample followed by positive ion electrospray ionization with collision-induced dissociation and multiple reaction monitoring of three characteristic fragmentation pathways of the protonated molecule of colchicine, m/z 400 --> 358, 400 --> 326, and 400 --> 310. The minimal detectable concentration of colchicine using this assay was 10 pg on-column, which is equivalent to 20 ppb colchicine in a 0.5 g ginkgo leaf sample. The method was validated by analyzing 0.5 g samples spiked with colchicine and determining the recovery. A total of 26 commercial ginkgo and echinacea dietary supplements were purchased from pharmacies in Chicago, IL, and analyzed for colchicine. In contrast to a recent report, no colchicine was detected in any of the samples. In addition, authenticated ginkgo leaves were collected, assayed, and found to contain no colchicine, which is consistent with the botanical literature. On the basis of the results obtained using this new LC-MS-MS assay, which is more sensitive and more selective than previously published methods for colchicine, we find no cause for concern regarding colchicine contamination of ginkgo or echinacea dietary supplements.
authors.affiliation: Department of Medicinal Chemistry and Pharmacognosy, UIC/NIH Center for Botanical Dietary Supplements Research, College of Pharmacy, University of Illinois at Chicago, 833 South Wood Street, Chicago, Illinois 60612, USA.
authors.forename: Wenkui
authors.initials: W
authors.lastname: Li
authors.forename: Yongkai
authors.initials: Y
authors.lastname: Sun
authors.forename: John F
authors.initials: JF
authors.lastname: Fitzloff
authors.forename: Richard B
authors.initials: RB
authors.lastname: van Breemen
mesh_terms: D002851:Chromatography, High Pressure Liquid / Q000379:methods; D003078:Colchicine / Q000032:analysis* / Q000737:chemistry; D019587:Dietary Supplements / Q000032:analysis*; D020900:Echinacea / Q000737:chemistry*; D005069:Evaluation Studies as Topic; D020441:Ginkgo biloba / Q000737:chemistry*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods
chemical_list: D003078:Colchicine