Hydroxytyrosol is a natural polyphenol compound, which can be obtained by hydrolysis of oleopicroside. It has a variety of biological and pharmacological activities. It is found in olive oil and wastewater from olive oil processing. Studies have shown that hydroxytyrosol has many biological and pharmacological activities, such as anticancer, antibacterial, anti-inflammatory and so on. Therefore, the extraction and preparation of hydroxytyrosol has certain practical significance and better economic benefits.

        Hydroxytyrosol mainly exists in the form of oleopicroside in olive. Oleopicroside accounts for a considerable proportion in all parts of olive. At present, hydroxytyrosol is mainly separated from olive fruit, leaves, residues and wastewater produced in the process of preparing olive oil. The purification of hydroxytyrosol mainly adopts column chromatography, such as silica gel column and ion exchange resin. Another method is to synthesize hydroxytyrosol through biosynthesis. The following will be a brief introduction.

        Tyrosinase is the key enzyme that catalyzes the conversion of mono phenol hydroxyl to o-diphenol hydroxyl. Some studies have found that tyrosol is dispersed in sodium phosphate buffer salt (ph=6.6). In the presence of mushroom tyrosinase and ascorbic acid, oxygen is pumped into the system to completely convert tyrosol to hydroxytyrosol. Ascorbic acid is added to reduce the over oxidized quinone compound to hydroxytyrosol. The synthesis of hydroxytyrosol by bacteria has also been reported. The results showed that Serratia marcescens and Pseudomonas aeruginosa. These two bacteria can efficiently convert tyrosol to hydroxytyrosol. Later, Pseudomonas aeruginosa was immobilized on calcium alginate hydrogel by microbial solid-phase coating technology. After being immobilized, tyrosol can be converted to hydroxytyrosol at a higher concentration. The recovery and reuse of this biocatalyst were also realized, and the catalytic efficiency was not significantly reduced.

    Biological synthesisHydroxytyrosol, has the advantages of safety, green and pollution-free. However, at present, the biotransformation of tyrosol to hydroxytyrosol can be realized only at a low concentration, both in terms of cost and large-scale production technology. ）Are subject to certain restrictions. Seeking new high-efficiency specific enzymes or bacteria and using immobilized biocatalysts to realize the conversion of tyrosol to hydroxytyrosol at high concentration will be the research direction with more application prospects for the preparation of hydroxytyrosol by biological methods.