Hydrolases-mediated transformation of oleuropein into demethyloleuropein.

Phenolic compounds present in extra virgin olive oil have recently attracted considerable attention due to their pharmacological activities. Among them oleacein (3,4-DHPEA-EDA), structurally related to oleochantal (4-HPEA-EDA), is one of the most studied. 3,4-DHPEA-EDA has been synthesized through decarboxylation of demethyloleuropein catalyzed by Er(OTf) ₃ . Demethyloleuropein is extracted from black olives drupes in very limited amounts and only in particular periods of the year. The availability of demethyloleuropein could be increased by a selective hydrolysis of the methyl ester moiety of oleuropein, a secoiridoid present in large amount in olive leaves. In this work we describe a new enzymatic method for carrying out a selective hydrolysis of oleuropein via the screening of a panel of hydrolases (lipases, esterases and proteases). Among all the enzymes tested the best results was obtained using α-chymotrypsyn from bovine pancreas as biocatalyst, thus revealing a classic example of catalytic enzyme promiscuity.
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