Loganin Derivatives from Winchia calophylla

From the stem barks of Winchia calophylla A.DC.,four iridoid glycosides were isolated.Their structures were elucidated as loganin,7-O-formyl loganin,6′-O-formyl loganin and 7,6′-O-diformyl loganin by means of spectroscopic methods.Three loganin derivatives were new compounds.