RESUMEN
AIM@#To study the chemical constituents of the aerial parts of Cirsium setosum (Willd.) MB..@*METHODS@#The chemical constituents were isolated and purified by various chromatographic techniques. Their structures were determined on the basis of physical properties and spectroscopic data.@*RESULTS@#A new megastigmane glycoside and six known compounds were obtained and identified as (7E, 9R)-9-hydroxy-5, 7-megastigmadien-4-one-9-O-α-L-arabinopyranosyl-(1→6)-β-D-glucopyanoside (1), (6R, 7E, 9R)-9-hydroxy-4, 7-megastigmadien-3-one-9-O-α-L-arabinopyranosyl-(1→6)-β-D-glucopyranoside (2), urolignoside (3), 4, 9, 9'-trihydroxy-3, 3'-dimethoxy-8-O-4$\prime $-neolignan-7-O-β-D-glucopyranoside (4), citroside A (5), salidrosidin (6), and adenosine (7).@*CONCLUSION@#Compound 1 is a new megastigmane glycoside, named as Xiaojiglycoside A.