This study reports the isolation, characterization, and biological evaluation of constituents of Colchicum tauri Siehe ex Stef. (Colchicaceae), an unexplored Colchicum species native to Jordan. Methanolic extraction, crude alkaloid fractionation, and separation using several different chromatographic techniques (open columns, preparative TLC, and semi-preparative HPLC), as directed by the brine shrimp lethality test (BST), resulted in the isolation and identification of nine compounds: (-)-colchicine (1), (-)-2-demethylcolchicine (2), (-)-3-demethylcolchicine (3), (-)-demecolcine (4), (-)-N-methyldemecolcine (5), (-)-3-demethyl-N-methyldemecolcine (6), β-lumicolchicine (7), 3-demethyl-β-lumicolchicine (8), and apigenin (9). Compounds 1–5 and 7–8 were isolated for the first time from this species, while compound (6) represents a new colchicinoid. The structure elucidations were achieved using a series of spectroscopic and spectrometric techniques, principally 1D-NMR (1H, and 13C), 2D-NMR (COSY, ROESY, HMBC, and HSQC), and low resolution EI-MS. All compounds were tested for general toxicity using the BST, and compounds 1 and 4 were found to be the most potent, with LC50 values of 2.5 and 8.1 μg/mL, respectively.
