GC-MS of Some Haemanthamine- and Crinine-Type Amaryllidaceae Alkaloids

The search for novel natural compounds and the identification of known ones is a challenge for the scientists working in different fields of plant science. Due to its accessibility, GC-MS is the most frequently applied method for analysis of extracts and fractions from plants of the subfamily Amaryllidoideae (Amaryllidaceae s.s.), known as a source of molecules with potent anti-acetylcholinesterase, anti-tumour, and antiprotozoal activities.

Thirty-four standard alkaloids with haemanthamine- and crinine-type scaffolds were subjected to electron impact gas chromatography-mass spectrometry (GC-MS) to determine their fragmentation patterns. Additionally, underivatised and silylated alkaloid fractions from several Amaryllidoideae plants were also analysed by GC-MS.

Most of the compounds showed excellent separation and specific MS fragmentation allowing rapid structural determination. The degree of saturation of ring C and the substituents at C3, C6, and C11 impact the fragmentation of these molecules. GC-MS allowed differentiation of the epimers at C3. Silylation of compounds with hydroxyl groups at C6 and C11 improved the resolution, especially of C6-OH epimers. Analyses of alkaloid fractions from different Amaryllidaceae plants resulted in the tentative identification of five new alkaloids on the basis of their fragmentation pattern and comparison of their mass spectra with those of standard compounds.

GC-MS can be effectively employed for the discovery of novel bioactive compounds and the identification of known ones, as well as for chemotaxonomic and chemoecological studies, among other applications, within the Amaryllidoideae subfamily.