powerful antioxidant, oleacein, is a compound involved in the production of
extra virgin olive oil, and is associated with numerous health benefits. Introducing
oleacein into other edible oils may enhance the health properties of these
products, and provides motivation for developing simple and effective methods
of oleacein synthesis. Existing methods of oleacein synthesis include a one-step
of oleuropein sourced from black olives, or alternatively the decarboxylation
of demethyl oleuropein. However, these methods give oleacein in low yield and require
either harsh reaction conditions or involve extractions from black olive
drupes, which are only seasonally available and produce limited quantities of oleuropein. Here we show a new
method to synthesize oleacein in high yield using oleuropein naturally sourced
from olive leaves. We found that the oleacein yield doubled when the use of
DMSO as a reaction solvent was replaced for water, and conventional reflux
heating was replaced for the use of a microwave. Furthermore, we found that the
reaction profile was enhanced using aqueous NaCl as a decarboxylation catalyst.
Our results demonstrate that an aqueous
adaption of the decarboxylation
reaction minimized hindering side reactions that had been facilitated by DMSO.
This newly improved synthetic route is the first method to give oleacein in good
yield in a simple and sustainable manner. These findings have made oleacein
widely accessible and could lead to the production of healthier commercial oils.