The structure of physalin T from Physalis alkekengi var. franchetti

A new steroidal constituent named physalin T (3) was isolated from the aqueous extract of Physalis alkekengi var. francheti. Based on 1H and 13C NMR spectral studies the structure was assigned as 2,3-dihydrophysalin D, i.e., 5alpha,6beta-dihydroxy-2,3,5,6-tetrahydrophysalin B, which is the first example of a natural physalin possessing a saturated ring A moiety. The structure was confirmed by the chemical transformation from the known physalin D (2) to physalin T.