Colchicinoids from Colchicum crocifolium Boiss.: A case study in dereplication strategies for (-)-Colchicine and related analogs using LC-MS and LC-PDA techniques

As a part of a project designed to investigate Colchicum species in Jordan [1,2], the chemical constituents of Colchicum crocifolium Boiss. (Colchicaceae) were investigated using LC-MS and LC–UV/Vis PDA. A decision tree for working with colchicinods has been developed by incorporating data from LC-UV/PDA and LC-MS. This dereplication strategy draws upon the UV/PDA spectra to classify compounds into one of four structural groups and combines this with retention time and mass spectra/molecular weight to identify the compounds. This strategy was applied on a small amount of extract (2mg) of Colchicum crocifolium to dereplicate 10 known compounds from four different structural groups, namely: (-)-demecolcine, 2-demethyl-(-)-colchicine or 3-demethyl-(-)-colchicine, N-deacetyl-(-)-colchicine, (-)-colchiciline, (-)-colchicine, β-lumidemecolcine, 2-demethyl-β-lumicolchicine or 3-demethyl-β-lumicolchicine, N,N-dimethyl-N-deacetyl-β-lumicornigerine; (-)-isoandrocymbine; and (-)-autumnaline. Furthermore, a new compound was identified as N,N-dimethyl-N-deacetyl-(-)-cornigerine (Figure 1). Three compounds, which had molecular ions at m/z of 325, 340, and 374, could not be dereplicated into any obvious structural classes that have been isolated in our labs previously or reported in the literature.