The chemical composition of hydroxytyrosol from different sources

Hydroxytyrosol, with the chemical name 3,4-dihydroxyphenylethanol and the molecular formula C₈H₁₀O₃, has a basic structure consisting of a benzene ring attached to two hydroxyl groups and one ethanol group, regardless of its source. However, there are still some differences in chemical composition between hydroxytyrosol from different sources, as detailed below:

Plant-extracted hydroxytyrosol: Hydroxytyrosol is mainly derived from the fruits and branches of Olea europaea (olive tree) in the Oleaceae family. During the ripening of olive fruits, oleuropein is enzymatically hydrolyzed by β-glucosidase and esterase to produce hydroxytyrosol, which mainly exists in the form of esters at this stage. In addition to hydroxytyrosol itself, the extract from olives may contain oleuropein, other polyphenolic compounds, fatty acids, vitamin E, and other components. Furthermore, leaves of Plukenetia volubilis (sacha inchi) also contain a certain amount of hydroxytyrosol, and their extracts may be accompanied by unique components of sacha inchi leaves, such as other terpenoids.

Chemically synthesized hydroxytyrosol: Artificially produced hydroxytyrosol through chemical methods usually has high purity, with the main component being hydroxytyrosol itself. However, some impurities such as residual reaction reagents, catalysts, or intermediates may remain during the synthesis process. Nevertheless, the content of these impurities can generally be controlled at a low level through purification steps. Compared with naturally extracted hydroxytyrosol, chemically synthesized hydroxytyrosol lacks other naturally occurring components in plants like olives and thus does not possess the synergistic biological activities that those components might produce.

Biosynthetic hydroxytyrosol: Biosynthesis has been a key focus in hydroxytyrosol production in recent years, typically involving the use of genetic engineering techniques to enable microorganisms to synthesize hydroxytyrosol using carbon sources such as glucose. Biosynthetic hydroxytyrosol can also achieve high purity. For example, hydroxytyrosol synthesized through Escherichia coli fermentation mainly contains hydroxytyrosol as the primary component, with possible traces of microbial metabolites and residual medium components. However, through subsequent separation and purification processes, products with a purity exceeding 99.0% can be obtained.