The reduction of dihydrofolic acid to chiral tetrahydrofolic acid has been investigated by enzymic and non-enzymic means. With dihydrofolate reductase from E. coli as catalyst and recycling systems for NADPH, up to 1 g of optically pure stable tetrahydrofolate derivatives was obtained. The technique makes the possibility of synthesising chiral 5- formyltetrahydrofolate (leucovorin) for use in cancer rescue therapy attainable. In contrast, ...
