Chromatographic resolution of atropisomers for toxicity and biotransformation studies in pharmaceutical research.
Atropisomerism can be a complex concept for those who have not encountered it before. This paper discusses the experiments for identification, isolation, thermal stability, toxicity and biotransformation of various species. The identified atropisomers are a series of rotational hindered biaryl, rotational hindered amide, ring flip, and macrocycles atropisomers identified using supercritical fluid chromatography (SFC) and high performance liquid chromatography (HPLC). These technologies offered the advantage of separating various atropoenantiomers, atropdiastereomers and mixed atropisomers with other forms of stereoisomers in both analytical and preparative scales. With ultra-performance convergence chromatography (UPC(2)), the detection of N-oxide atropisomer metabolites can be obtained at very low level thus enabling the observation of conversion in human plasma possible. As the resolution of atropisomers are related to the energy barriers on the rotational axis, a calculated computational protocol was developed to predict the formation. A threshold of 10kcal/mol was established for possible detection of the atropisomers' existence with chromatographic technologies at room temperature or above. The atropisomer with higher energy barrier (>20kcal/mol) were isolated via preparative chromatography and the isolates studied in vitro and in vivo for evaluation of their stability in human plasma. The detailed analytical method development to analyze the biotransformation of the atropisomers in human plasma are also discussed in this paper.
Pfizer Global R&D, Pfizer Inc. Eastern Point Road, Groton, CT 06340, USA. Electronic address: qi.yan@pfizer.com.
Tony Qi
TQ
Yan
Pfizer Global R&D, Pfizer Inc. Eastern Point Road, Groton, CT 06340, USA.
Frank
F
Riley
Pfizer Global R&D, Pfizer Inc. Eastern Point Road, Groton, CT 06340, USA.
Laurence
L
Philippe
Pfizer Global R&D, Pfizer Inc. Eastern Point Road, Groton, CT 06340, USA.
Jennifier
J
Davoren
Pfizer Global R&D, Pfizer Inc. Eastern Point Road, Groton, CT 06340, USA.
Loretta
L
Cox
Pfizer Global R&D, Pfizer Inc. Eastern Point Road, Groton, CT 06340, USA.
Christine
C
Orozco
Pfizer Global R&D, Pfizer Inc. Eastern Point Road, Groton, CT 06340, USA.
Brajesh
B
Rai
Pfizer Global R&D, Pfizer Inc. Eastern Point Road, Groton, CT 06340, USA.
Mark
M
Hardink
D001711:Biotransformation; D002623:Chemistry Techniques, Analytical / Q000379:methods*; D002626:Chemistry, Pharmaceutical / Q000379:methods*; D002851:Chromatography, High Pressure Liquid; D025924:Chromatography, Supercritical Fluid; D006801:Humans; D009930:Organic Chemicals / Q000032:analysis* / Q000097:blood / Q000737:chemistry / Q000633:toxicity; D010949:Plasma / Q000737:chemistry; D013237:Stereoisomerism
D009930:Organic Chemicals
Absolute configuration; Atropisomers; Chiral chromatography; Energy barrier calculation; Liquid chromatography and supercritical fluid chromatography; Stability test