Solid acid-catalyzed one-step synthesis of oleacein from oleuropein

Abstract

In this study, we developed a new synthetic strategy to convert secoiridoid glucosides into unique dialdehydic compounds using solid acid catalysts. Specifically, we succeeded in the direct synthesis of oleacein, a rare component of extra-virgin olive oil, from oleuropein, which is abundant in olive leaves. Whereas the conventional total synthesis of oleacein from lyxose requires more than 10 steps, these solid acid catalysts enabled the one-step synthesis of oleacein from oleuropein. A key step in this synthesis was the selective hydrolysis of methyl ester. Density functional theory calculations at the B3LYP/631+G (d) level of theory revealed the formation of a tetrahedral intermediate bonded to one H2O molecule. These solid acid catalysts were easily recovered and reused at least five times by simple cleaning. Importantly, this synthetic procedure was not only applicable to other secoiridoid glucosides, but could also be employed for the corresponding scale-up reaction using oleuropein extracted from olive leaves as the starting material.

A Rare Olive Compound Oleacein Improves Lipid and Glucose Metabolism, and Inflammatory Functions: A Comprehensive Whole-Genome Transcriptomics Analysis in Adipocytes Differentiated from Healthy and Diabetic Adipose Stem Cells

“…Similarly, OLE demonstrated favorable stability in a gastric digestion model [ 56 , 57 ]. Here, we utilized OLE by employing a one-step synthesis method from oleuropein, which demonstrated higher efficiency compared with the more complex over 10-step synthesis method [ 58 ] and the use of H-mont did not result in any decrease in the yield of OLE [ 20 ]. This suggests that the stable and highly pure structure of OLE may have a significant role in regulating adipocyte fat and glucose metabolism.…”

“…OLE was chemically synthesized from oleuropein using proton-exchanged montmorillonite as a catalyst and used after column separation and freeze-drying [ 20 ]. Briefly, oleuropein powder (1.53 g, purity = 88.0%) was treated in the presence of proton-exchanged montmorillonite (3.06 g) in DMSO (10.0 mL) containing 7.16 mmol of H 2 O at 150 °C for 3 h without stirring.…”

“…Oleacein (OLE) is a secoiridoid present in both the fruit and leaves of the Olea europaea L. plant (Oleaceae), as well as in EVOO. OLE is synthesized by combining the dialdehydes form of decarboxymethyl elenolic acid with hydroxytyrosol, also known as 3,4-DHPEA-EDA [ 19 ] and also can be synthesized from oleuropein [ 20 ]. For OLE functions, studies have shown that OLE possesses potent anti-inflammatory properties.…”

A rare olive compound oleacein functions as a TrkB agonist and mitigates neuroinflammation both in vitro and in vivo

“…OC was synthesized following the methods previously reported [ 18 ] and provided for this study. For gene expression analysis, SH-SY5Y cells (2 × 10 6 cells/5 ml growth medium) were seeded into 60 mm dishes.…”

“…However, due to its relatively low occurrence, its biological functions have not been as extensively investigated as those of oleocanthal or other olive compounds. Nevertheless, there has been a resurgence of interest in OC following the discovery of a one-step synthesis method from OP [ 18 ].…”