Biotransformations with the enzymatic secretome of Botrytis cinerea combined with organic solvents for the generation of novel complex stilbene derivatives

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.

Acknowledgments

The authors are thankful to the Swiss National Science Foundation for providing financial support for this project (grant 205321_182438/1 E.F.Q. and K.G.).

• References

• 1 Gindro K, Schnee S, Righi D, Marcourt L, Nejad Ebrahimi S, Codina JM, Voinesco F, Michellod E, Wolfender J-L, Queiroz EF. Generation of antifungal stilbenes using the enzymatic secretome of Botrytis cinerea. J Nat Prod 2017; 80: 887-898.
• 2 Queiroz EF, Alfattania A, Afzana A, Marcourt L, Guillarme D, Wolfender J-L. Utility of dry load injection for an efficient natural products isolation at the semi-preparative chromatographic scale. J Chromatogr A. 2019 DOI: 10.1016/j.chroma.2019.03.042