ISSN:
0899-0042
Keywords:
stereoselective protein binding
;
chiral HPLC
;
circular dichroism
;
stereoselective receptor binding
;
HSA
;
preparative HPLC
;
atropisomeric benzodiazepine
;
stereochemistry
;
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The chromatographic resolution of 7-chloro-1,3-dihydro-1-(1,1-dimethylethyl)-5-(2-fluorophenyl)-2H-1,4-benzodiazepin-2-on (7), the 2′-fluoro, N1-tert-butyl analogue of diazepam, was attained on both analytical and preparative (mgs) scales, by using several chiral stationary phases (CSPs). The stereochemistry of this compound was characterized by means of 1H-NMR Nuclear Overhauser Effect (NOE) analysis. The single enantiomers of 7 were tested for their configuration and stereochemical stability by circular dichroism (CD), and their interaction with the central nervous system (CNS) benzodiazepine receptor was assayed, showing a significant difference in their binding affiities. Protein binding studies with human serum albumin (HSA, the main benzodiazepine carrier in human plasma) immobilized on a silica stationary phase revealed that HSA also preferentially binds one stereoisomer of 7. However, both on line CD detection and stereospecific interaction with other common drugs clearly demonstrated that the stereoselectivity of immobilized HSA for 7 is opposite to that for all the other studied benzodiazepines. In addition, HSA stereoselectivity for 7 is opposite to CNS receptor binding stereoselectivity for the same compound. Such HSA anomalous stereoselectivity for 7 was also confirmed in aqueous buffer solution by competitive displacement studies. Compared to other chiral 1,4-benzodiazepines, compound 7 thus shows several anomalous binding properties: HSA and the CNS receptor demonstrated opposite enantioselective discrimination; HSA has reversed enantioselectivity for compound 7; and HSA stereospecifically binds the low-affinity enantiomer. Chirality 9:495-505, 1997. © 1997 Wiley-Liss, Inc.
Additional Material:
8 Ill.
Type of Medium:
Electronic Resource
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