Oleuropein is the major phenolic constituent extracted from the olive leaf, constituting about 19% from virgin olive oil. Oleuropein is reported to be hydrolyzed to another biologically active compound, hydroxytyrosol, in vivo. A variety of anitimicrobial actions of oleuropein and its associated compounds have been demonstrated in the laboratory.
The inhibitory action of oleuropein against the growth and toxin production of Staphylococcus aureus, Bacillis cerus, Pseudomonas syringae, and several other bacterial strains has been reported in the scientific literature, although the precise mechanism of antimicrobial action has as yet to be elucidated.
Oleuropein and related compounds appear to have surface-active properties that interfere with microbial cell membranes. Oleuropein could also interfere with the synthesis of amino acids crucial to viral replication and, in the case of retroviruses, neutralize the production of reverse transcriptase and protease. Additionally, oleuropein is also reported to stimulate the immune response to infection (phagocytosis). See Olive Oil.