| Popis: |
Seven steroidal lactones of the withanolide series have been isolated as minor constituents of the leaves of Withania somnifera Dun. (Solanaceae) chemotype I , along with the major component withaferin A. Structures have been assigned to the new compounds: withanolide N (17α,27-dihydroxy-1-oxo-20 R ,22 R -witha-2,5,14,24-tetraenolide) ( 6a ) and withanolide O (4β,17α-dihydroxy-1-oxo-20 R ,22 R -witha-2,5,8(14),24-tetraenolide) (7a). Similarly the leaves of W. somnifera chemotype II afforded three new withanolides along with the major component withanolide D ( 9a ) and trace amounts of withanolide G ( 10 ). The new compounds are: 27-hydroxywithanolide D(4β,20α,27-trihydroxy-1-oxo-5β,6β-epoxy-20 R ,22 R -witha-2,24-dienolide) ( 11a ), 14α-hydroxywithanolide D (4β,14α,20α-trihydroxy-1-oxo-5β,6β-epoxy-20 R ,22 R -witha-2,24-dienolide) ( 12 a) and 17α-hydroxywithanolide D (4β,17β,20α-trihydroxy-1-oxo-5β,6β-epoxy-20 S ,22 R -witha-2,24-dienolide) ( 13a ). Whereas all the withanolides of chemotype I are unsubstituted at C-20 (20α-H), those of chemotype II possess an OH at this position (20α-OH). |
