1 beta-Amino-2 alpha,3 beta,5 beta-trihydroxycycloheptane from Physalis alkekengi var Francheti

A cycloheptane bearing an amino and three hydroxyl groups was isolated from the roots of Physalis alkekengi var. francheri, along with calystegins A(3), A(5), B-1, B-2, and B-3. By H-1- and C-13-NMR spectra, combined with extensive decoupling experiments, H-1-C-13 COSY, and NOE enhancements, the structure of this cycloheptane was determined to be 1 beta-amino-2 alpha,3 beta,5 beta-trihydroxycycloheptane. This compound may be a precursor of calystegin A(5) in the biosynthetic pathway or may occur from the enzymic reduction of the 5-aminocycloheptanone derived from the 1,5-bridge scission in calystegin A(5).