Enantioselective Separation of Racemic Tryptophan with Sonochemically Prepared Egg Albumin Microspheres

New approaches for chiral resolution are gaining importance and are of economic interest for the development of pharmaceuticals, agrochemicals, chiral sensors and food additives. Herein we disclose the first examples in which sonochemically prepared egg albumin microspheres (EAMs) were used for chiral resolution of an amino acid. When EAMs were in contact with an aqueous solution of racemic tryptophan (Trp) they selectively interacted with L-Trp leading to 94% enantiomeric excess (ee) of D-Trp. In a control experiment in which the egg protein, without applying ultrasonic waves to form microspheres, was dissolved and exposed to racemic Trp, no chiral resolution was observed. The effects of temperature and concentration were studied in detail. These preliminary results show that EAMs produced by sonication may provide a simple, cost-effective an unconventional way to chiral separation of racemic amino acids.