Analysis of Amaryllidaceae alkaloids from Narcissus by GC–MS and capillary electrophoresis

Abstract

Amaryllidaceae are known as ornamental plants, furthermore some species of this family contain galanthamine, an acetylcholinesterase inhibitor approved for the treatment of Alzheimer's disease, and other alkaloids with interesting pharmacological activity. In the present work, the quali- and quantitative analysis of Amaryllidaceae-type alkaloids in the bulbs of Narcissus species is presented using different analytical approaches. Extracts of Narcissus pseudonarcissus cv. Carlton and Narcissus jonquilla Quail, were first examined by GC–MS using a Rtx ®-5 MS (programmed temperature) and the major alkaloids were identified. Together with galanthamine, high contents of haemanthamine, were found. Galanthamine was reliably quantified by GC–MS, whereas haemanthamine partly decomposed under the GC conditions, thus alternative analytical methods were investigated. Firstly, reversed-phase HPLC–ESI-MS was applied to identify and isolate at semipreparative levels haemanthamine. The compound was fully characterized by MS/MS and 1H NMR and then used as a reference substance. The quantitation of both galanthamine and haemanthamine was then accomplished by capillary electrophoresis with spectrophotometric detection. A non-aqueous (NACE) approach was selected in order to use a running buffer fully compatible with samples in organic solvent. In particular, a mixture methanol–acetonitrile (75:25, v/v) containing ammonium acetate (90 mM) was used as a background electrolyte. The same analytical sample was subjected to GC–MS and NACE analysis; the different selectivity displayed by these techniques allowed different separation profiles that can be useful in phytochemical characterization of the extracts. The GC–MS and NACE methods were validated and applied to the quantitation of galanthamine (GC–MS and NACE) and haemanthamine (NACE) in bulbs of N. jonquilla.