The enzymatic biotransformation of natural products (NPs) using the Botrytis cinerea enzyme secretome has proven to be an innovative and effective way to produce original
derivatives [1]. Such reactions from simple natural stilbenes such as resveratrol and pterostilbene
have led to various dimerization products, some with interesting biological activities.
One of the difficulties of the approach is that the reactions take place in water,
which is limiting because of the low solubility of NPs in this type of medium. This
may explain the low yields obtained by some reactions. In order to overcome this problem,
organic solvents were added to the reaction medium. Several organic solvents such
as methanol, isopropanol, butanol and isobutanol were examined. The reactions were
carried out at the analytical scale using different amounts of each organic solvent.
UHPLC-PDA-ELSD-MS profiling of the crude reaction mixtures revealed the presence of
compounds with different molecular weights as a function of the organic solvent used.
In order to isolate these unusual compounds, the reactions were optimized, scaled-up
and fractionated by semi-preparatory HPLC with a new dry load injection method to
favor high resolution fractionation [2]. This approach has enabled the isolation of more than 60 pure compounds fully characterized
by HRMS and NMR spectroscopic methods. Surprisingly, some have adopted a solvent molecule
into their structures, which explains the unusual chemical profiles observed. This
fortuitous discovery opened the door to obtaining series of derivatives of NPs with
great value for biological screening campaigns.
