Antibacterial galloylated alkylphloroglucinol glucosides from myrtle (Myrtus communis)

An investigation of the polar glycosidic fraction from the leaves of myrtle afforded four galloylated nonprenylated phloroglucinol glucosides (3a-d) related to the endoperoxide hormone G3 (4) in terms of structure and biogenesis. Despite their close similarity, significant antibacterial activity was shown only by one of these compounds (3b, gallomyrtucommulone B), while the G3 hormone (4) was inactive.