Highly Effective, Regiospecific Hydrogenation of Methoxychalcone by Yarrowia lipolytica Enables Production of Food Sweeteners

We describe the impact of the number and location of methoxy groups in the structure of chalcones on the speed and efficiency of their transformation by unconventional yeast strains. The effect of substrate concentration on the conversion efficiency in the culture of the Yarrowia lipolytica KCh 71 strain was tested. In the culture of this strain, monomethoxychalcones (2′-hydroxy-2″-, 3″- and 4″-methoxychalcone) were effectively hydrogenated at over 40% to the specific dihydrochalcones at a concentration of 0.5 g/L of medium after just 1 h of incubation. A conversion rate of over 40% was also observed for concentrations of these compounds of 1 g/L of medium after three hours of transformation. As the number of methoxy substituents increases in the chalcone substrate, the rate and efficiency of transformation to dihydrochalcones decreased. The only exception was 2′-hydroxy-2″,5″-dimethoxychalcone, which was transformed into dihydrochalcone by strain KCh71 with a yield comparable to that of chalcone containing a single methoxy group.