Quick development of an analytical enantioselective high performance liquid chromatography separation and preparative scale-up for the flavonoid Naringenin

The HPLC enantioselective separation of (R/S)-Naringenin, a chiral flavonoid found in several fruits juices and well-known for its beneficial health-related properties, including antioxidant, anti-inflammatory, cancer chemopreventive, immunomodulating and antimicrobial activities, has been performed on both analytical and (semi)-preparative scale using an amylose derived Chiralpak AD chiral stationary phase (CSP). A standard screening protocol for cellulose and amylose based CSPs was firstly applied to analytical Chiralcel OD-H and Chiralpak AD-H, as well as to Lux Cellulose-1, Lux Cellulose-2 and Lux Amylose-2 in order to identify the best experimental condition for the subsequent scaling-up. Using Chiralpak AD-H and eluting with pure methanol (without acidic or basic additives) relatively short retention times, high enantioselectivity and good resolution (α=1.49, R(s)=3.48) were observed. Therefore, these experimental conditions were properly scaled-up to (semi)-preparative scale using both a pre-packed Regispack column and a Chiralpak AD column packed in house with bulk CSP. The developed preparative method proved to be superior to previously published methods in terms of elution times, separation and resolution and is suitable for obtaining a quick access to the desired enantiomers with high enantiomeric excess and amounts sufficient for biological investigations. Future scale-up options (enantioselective supercritical fluid chromatography or HPLC in the Simulated Moving Bed mode) were also evaluated. It could be shown that both methodologies have a high potential for future production of Naringenin enantiomers by enantioselective chromatography.