Perulactone, a new ergostane-type steroid from Physalis peruviana (Solanaceae)

Abstract

Perulactone, C30H46O7, is the naturally occurring 1-acetate of (20R,22R,24S,25R)-1α,3β,20,22- tetrahydroxyergost-5-en-26,28-olide. It was isolated from a variety of Physalis peruviana growing in India (Varanasi). The carbocyclic moiety was identified by cleavage of the 20,22-bond to give 1α-acetoxy-3β-hydroxypregn-5-en- 20-one. The structure assigned to the side-chain is based on chemical and spectroscopic evidence. This is the first instance when a steroid oxidised at C-28 has been isolated from a Solanaceae plant. Treatment of perulactone with base afford, after acetylation, the corresponding equilibration product (7) (γ-lactone), but no trace of the isomeric 26,22-olide (δ-lactone).