Megastigmane, benzyl and phenethyl alcohol glycosides, and 4,4'- dimethoxy-β-truxinic acid catalpol diester from the leaves of Premna subscandens Merr.

Abstract

Extensive isolation work on the n-BuOH-soluble fraction obtained from the leaves of Premna subscandens, collected on Ishigaki island, Okinawa, afforded six compounds. Two were identified as megastigmane glucosides, 7- (3,5-dihydroxy-1,1,5-trimethylcyclohexylidene)-9-methylprop-8-enyl 9-O-β-D- glucopyranoside and 3-hydroxy-5,6-epoxy-β-ionol 9-O-β-D-glucopyranoside. The structures of the remaining four new compounds were elucidated to be a 2'-O-β-D-apiofuranosyl derivative of 3-hydroxy-5,6-epoxy-β-ionol 9-O-β-D- glucopyranoside, named premnaionoside, benzyl alcohol β-D-(2'-O-β-D- xylopyranosyl)glucopyranoside, phenethyl alcohol β-D-(2'-O-β-D- glucopyranosyl)glucopyranoside, and 4,4'-dimethoxy-β-truxinic acid catalpol diester by spectroscopic analyses.