Silyamandin, a new flavonolignan isolated from milk thistle tinctures.

Our investigations into the stability of tincture preparations of milk thistle fruit [ Silybum marianum L. Gaertn. (Asteraceae)] have led to the characterization of a new flavonolignan 4-(4-hydroxy-3-methoxyphenyl)-7-[(2 R,3 R)-3,5,7-trihydroxy-4-oxochroman-2-yl]-1-oxo-1,3,3a,4,5,7a-hexahydro-2-benzofuran-5-carboxylic acid called silyamandin (1). Incubation of the tincture at 40 degrees C for 3 months resulted in an increase in the level of this compound, as observed in the LC/DAD silymarin profile.