[Identification of an antimicrobially active constituent isolated from propolis (author's transl)]

On isolating and identifying antimicrobially active propolis constituents, the authors detected a substance that must be regarded as a mixture of caffeic acid esters. The caffeic acid moiety was unequivocally identified by various chemical and spectroscopic methods. The results obtained from the gas chromatographic study of the alcohol fraction after hydrolysis of the isolated compound identify benzyl alcohol, phenyl ethyl alcohol and cinnamic alcohol as ester components. Furthermore, the mass spectroscopic findings are indicative of the presence of a caffeic acid pentenyl ester in the mixture. Attempts to separate this ester mixture by recrystallization and thin-layer chromatography failed.