# Enzymatic Methoxycarbonylation of Tyrosol and Hydroxytyrosol

## TL;DR

Researchers used enzymes to efficiently create antioxidant compounds from olive oil by-products, which could be useful in food and pharmaceutical applications.

## Contribution

The study identifies Novozym 435 as the most effective enzyme for synthesizing methyl carbonates of tyrosol and hydroxytyrosol.

## Key findings

- Novozym 435 outperformed other enzymes in catalyzing methoxycarbonylation reactions.
- Tyrosol and hydroxytyrosol methyl carbonates were produced in high yields using Novozym 435.
- Enzymatic methoxycarbonylation can serve as a selective protection method in further enzymatic syntheses.

## Abstract

Tyrosol and hydroxytyrosol are powerful phenolic antioxidants occurring in olive oil and in by-products from olive processing. Due to their high polarity, esterification or other lipophilization is necessary to make them compatible with lipid matrices. Hydroxytyrosol methyl carbonate is a more effective antioxidant than dibutylhydroxytoluene or α-tocopherol and together with tyrosol methyl carbonate exerts interesting pharmacological properties. The purpose of this work was the enzymatic preparation of alkyl carbonates of tyrosol and hydroxytyrosol. A set of 17 hydrolases was tested in the catalysis of tyrosol methoxycarbonylation in neat dimethyl carbonate to find an economically feasible alternative to the recently reported synthesis of methyl carbonates catalyzed by Novozym 435. Novozym 435 was, however, found to be the best performing catalyst, while Novozym 735, pig pancreatic lipase, lipase F-AK and Lipex 100T exhibited limited reactivity. No enzyme accepted 1,2-propylene carbonate as the acylation donor. Under optimized reaction conditions, Novozym 435 was used in the batch preparation of tyrosol methyl carbonate and hydroxytyrosol methyl carbonate in quantitative yields. The enzymatic methoxycarbonylation of tyrosol and hydroxytyrosol can also be used as a method for their selective protection in enzymatic syntheses of phenylethanoid glycosides catalyzed with enzymes comprising high levels of acetyl esterase side activity.