Constitutents of Withania somnifera Dun. Part XII. The withanolides of an indian chemotype

Abstract

Eight new steroidal lactones of the withanolide series have been isolated from the leaves of Withania somnifera(Solanaceae) growing in North-Western India. This population of W. somnifera differs from those investigated so far and constitutes a new chemotype. The new compounds (IV)—(XI) have been investigated by chemical degradation and interconversion reactions, as well as by analysis of their spectral properties. The following structures have been assigned: 5α,17α-dihydroxy-1-oxo-6α,7α-epoxy-22R-witha-2,24-dienolide (IV); 5α,17α-dihydroxy-1-oxo-22R-witha-2,6,24-trienolide (V); 5α,27-dihydroxy-1-oxo-6α,7α-epoxy-22R-witha-2,24-dienolide (VIa); 4β,17α-dihydroxy-1-oxo-5β,6β-epoxy-22R-witha-2,24-dienolide (VIIa); 17α,27-dihydroxy-1-oxo-22R-witha-2,5,24-trienolide (VIIIa); 7α,27-dihydroxy-1-oxo-22R-witha-2,5,24-trienolide (VIIIa); 7α,27-dihydroxyl-1-oxo-22R-witha-2,5,24-trienolide (IXa); 1α,3β,5α-trihydroxy-6α,7α-epoxy-22R-with-24-enolide (Xa); 4β-hydroxy-5β,6β-epoxy-1-oxo-22R-witha-2,14,24-trienolide (XIa).