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

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-beta-D-glucopyranoside and 3-hydroxy-5,6-epoxy-beta-ionol 9-O-beta-D-glucopyranoside. The structures of the remaining four new compounds were elucidated to be a 2'-O-beta-D-apiofuranosyl derivative of 3-hydroxy-5,6-epoxy-beta-ionol 9-O-beta-D-glucopyranoside, named premnaionoside, benzyl alcohol beta-D-(2'-O-beta-D-xylopyranosyl)glucopyranoside, phenethyl alcohol beta-D-(2'-O-beta-D-glucopyranosyl)glucopyranoside, and 4,4'-dimethoxy-beta-truxinic acid catalpol diester by spectroscopic analyses.