Cell differentiation inducing steroids from Withania somnifera L-(Dun.)

In the course of screening for cell differentiation inducers from botanical sources, the methanol extract of Withania somnifera L. (DUN.) showed activ ity. From the aerial parts of the plant, sixteen withanolides, including th ree new compounds, 14, 15 and 16, were isolated and their structures elucid ated to be (20S,22R)-4 beta,5 beta,6 alpha,27-tetrahydroxy-1-oxo-witha-2,24 -dienolide, (20R,22R,24S,25R)-4 beta,20 beta-dihydroxy-5 beta,6 beta-epoxy- 3 beta-methoxy-1-oxo-withanolide and 3-O-[beta-D-glucopyranosyl(1-->6)-beta -D-glucopyranosyl]-(20S,22R)-1 alpha,3 beta-dihydroxywitha-5,24-dienolide, respectively, from the spectral data. Of these withanolides, 1, 2, 3 and 4 showed potent cell differentiation inducing activity against M1 cells. The most potent compound, 3, show ed more potent activity than dexamethasone, t he positive control. These active compounds have the same partial structure of the AB ring part, having a 4 beta-hydroxy-5 beta,6 beta-epoxy-2-en-1-on e moiety.