Efficient 2-Step Enzymatic Cascade for the Bioconversion of Oleuropein into Hydroxytyrosol

Abstract

Among the plant bioactive components, oleuropein (OLE) is the most abundant phenolic compound in all parts of olive trees (Olea europaea L.), particularly concentrated in olive leaves. It has been shown to present various remarkable biological actions, such as antimicrobial, antioxidant, anticancer and anti-inflammatory ones. On the other hand, hydroxytyrosol (HT), the main degradation product of OLE, is considered one of the most powerful antioxidant agents, with higher beneficial properties than the OLE parent compound. In this work, oleuropein was efficiently transformed into hydroxytyrosol using a 2-step biotransformation involving a thermo-halophilic β-glucosidase from Alicyclobacillus herbarius (Ahe), which gave the corresponding aglycone with complete conversion (>99%) and rapid reaction times (30 min), and an acyltransferase from Mycobacterium smegmatis (MsAcT), here employed for the first time for its hydrolytic activity. After cascade completion, hydroxytyrosol was obtained in excellent yield (>99% m.c., 96% isolated yield) in 24 h. Starting from a natural substrate and employing enzymatic approaches, the final hydroxytyrosol can be claimed and commercialized as natural too, thus increasing its market value.

Recovery of Hydroxytyrosol from Olive Mill Wastewater Using the Promiscuous Hydrolase/Acyltransferase PestE

“…Accordingly, the darkest OMWW had the highest HT content (Figure S4; Table S2). Further studies could be conducted to couple HT‐releasing enzymes, such as β‐glucosidase, with PestE, to form HTA from the HT precursor, oleuropein [35] . This could lead to better HTA yields regardless of the maturity of the olives.…”

“…Further studies could be conducted to couple HT-releasing enzymes, such as βglucosidase, with PestE, to form HTA from the HT precursor, oleuropein. [35] This could lead to better HTA yields regardless of the maturity of the olives. In addition, procedural measures, such as the application of the immobilized enzymes in a flow application, could increase the productivity and activity of PestE_I208A_L209F_N288A.…”

Populus root exudates are associated with rhizosphere microbial communities and symbiotic patterns

“…Here we found seven differential root exudates. Oleuropein and gentisic acid are phenolic compounds, and gentisic acid is one of the most common aromatic acids in plants (Zhang et al, 2017;Catinella et al, 2022) can vary with genotype and the developmental stage of the plants (Veach et 2019). Salicylic acid regulates plant growth and development that as a common plant phenolic compound in Salicaceae, and acts as an inducible defense chemical expressed in response to a pathogen.…”

Current Progress in the Chemoenzymatic Synthesis of Natural Products

“…Recently several patents and papers have been published for the synthesis of this compound among others, many of which are chemoenzymatic syntheses [ 72 , 73 , 74 ]. One such report by Pinto et al leverages 10–20% of the mass of dry olive leaves isolated as intermediate 55 to form hydroxytyrosol ( 56 ), a potentially useful antioxidant compound ( Scheme 17 a ) [ 75 ]. This is performed by sequential enzymatic hydrolysis of a hemiacetal moiety and an ester moiety using a glucosidase and an acyl transferase acting as an esterase.…”