Four new constituents from Taraxacum mongolicum

Two new flavone glycosides, isoetin-7-O-β-d-glucopyranosyl-2′-O-α-l-arabinopyranoside (1) and isoetin-7-O-β-d-glucopyranosyl-2′-O-α-d-glucopyranoside (2), a new lignan, mongolicumin A (3), and a new guaianolide, mongolicumin B (4) were isolated from the aerial part of Taraxacum mongolicum. Their structures were elucidated mainly by spectral analyses.