ABSTRACT
Inhibition of the MDM2-p53 interaction can stabilize the p53 protein and offer a novel strategy for cancer therapy. The imidazoline compound (Nutlin-3) is a promising small molecule antagonist of the MDM2-p53 interaction. This compound was synthesized as a racemic mixture, and one enantiomer is 100-200-fold more active than the other enantiomer. In this study, various enantiomeric separation approaches were explored to resolve the Nutlin-3 enantiomers using chiral supercritical fluid chromatography (SFC) as well as chiral liquid chromatography (LC) under normal phase mode, reversed phase mode and polar organic phase mode. The chiral SFC method based on Chiralcel OD column showed superior separation in terms of selectivity and efficiency. Optimization of the chiral separation method enabled high throughput preparative scale purification. Ultimately, 5 g of racemic mixture were purified on Prep-SFC in 75 min with the recovery rate above 92%.
Subject(s)
Chromatography, Liquid , Chromatography, Supercritical Fluid/methods , Imidazoles/isolation & purification , Piperazines/isolation & purification , Proto-Oncogene Proteins c-mdm2/antagonists & inhibitors , Technology, Pharmaceutical/methods , Imidazoles/chemical synthesis , Imidazoles/chemistry , Molecular Structure , Piperazines/chemical synthesis , Piperazines/chemistry , Stereoisomerism , Time FactorsABSTRACT
Nobiletin (NOB), a polymethoxylated flavone found in sweet orange (Citrus sinensis) peel, is currently recognized as a promising anti-inflammatory and anti-tumor agent. It is believed that, by undergoing metabolic biotransformation in vivo, nobiletin is demethylated by hepatic P450 enzymes, yielding multiple hydroxylated metabolites. However, it has not been possible to date to separate the two demethylated nobiletin metabolites, 3'-demethyl-NOB and 4'-demethyl-NOB (regio-isomers) on reversed-phase liquid chromatography (RPLC). Additionally, both display similar mass spectrometric fragmentation, resulting in difficulties to identify the dominant metabolite. A successful separation method was developed by utilizing supercritical fluid chromatography (SFC) with chiral stationary phase. The separation was also attempted with normal-phase liquid chromatography (NPLC) in both chiral and non-chiral modes. Chromatographic separation for the two nobiletin metabolites was superior by SFC than by LC, especially using chiral stationary phase. By comparing the SFC profile of the synthesized standards, the major nobiletin metabolite in mouse urine was identified as 4'-demethyl-NOB, with the concentration of 28.9 microg/mL.
