Colchicinoids from Colchicum crocifolium Boiss.: A case study in dereplication strategies for (-)-colchicine and related analogues using LC-MS and LC-PDA techniques
As a part of a project designed to investigate Colchicum species in Jordan, 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 (2 mg) of Colchicum crocifolium to dereplicate 10 known compounds from four different structural groups, namely (-)-demecolcine, 2-demethyl-(-)-colchicine or3-demethyl-(-)-colchicine, N-deacetyl-(-)-colchicine, (-)-colchiciline, (-)-colchicine, -lumidemecolcine, 2-demethyl--lumicolchicine or 3-demethyl--lumicolchicine, N,N-dimethyl-N-deacetyl--lumicornigerine, (-)-isoandrocymbine and (-)-autumnaline. Furthermore, a new compound was identi?ed as N,N-dimethyl-N-deacetyl-(-)-cornigerine. Three compounds, which had molecular ions at m/z 325, 340 and 374, could not be dereplicated into any obvious structural classes that have been isolated in our laboratories previously or reported in the literature.