3,4-DHPEA-EA (methyl-4-(2-(3,4-dihydroxyphenethoxy)-2-oxoethyl)-3-formyl-2-methyl-3,4-dihydro-2H-pyran-5-carboxylate) was obtained by enzymatic hydrolysis of oleuropein, as a molecular evolution consequence of the hemiacetal functionality of the aglycon 2 , formed by glycosidic bond cleavage (Figure 1 ). The lipidic/water interface promotes the rapid rearrangement of the intermediate oleuropeinenol 3 into the final stable biomolecule, the transposed secoiridoid 4 , within 5 min [18 (link)].
Thus, to a solution of 100 mg of oleuropein, previously extracted from olive leaves, endogenous β-glucosidase was added at 40°C for 6 h in 20 ml of a H2O/CHCl3 1:1 mixture, The mixture was evaporated and purified using Waters XTerra C18 column on a Varian HPLC system (H2O/MeCN H2O/MeCN gradient) with a flow rate of 2 ml/min.
Methyl-4-(2-(3,4-dihydroxyphenethoxy)-2-oxoethyl)-3-formyl-2-methyl-3,4-dihydro-2H-pyran -5-carboxylate was obtained as a yellow oil (20% yield). 1H and 13C NMR spectra were in agreement with literature data [10 (link)].
Thus, to a solution of 100 mg of oleuropein, previously extracted from olive leaves, endogenous β-glucosidase was added at 40°C for 6 h in 20 ml of a H2O/CHCl3 1:1 mixture, The mixture was evaporated and purified using Waters XTerra C18 column on a Varian HPLC system (H2O/MeCN H2O/MeCN gradient) with a flow rate of 2 ml/min.
Methyl-4-(2-(3,4-dihydroxyphenethoxy)-2-oxoethyl)-3-formyl-2-methyl-3,4-dihydro-2H-pyran -5-carboxylate was obtained as a yellow oil (20% yield). 1H and 13C NMR spectra were in agreement with literature data [10 (link)].