Mechanism of time-dependent inhibition of 5 alpha-reductases by delta 1-4-azasteroids: toward perfection of rates of time-dependent inhibition by using ligand-binding energies.

Published

Journal Article

Finasteride (17 beta-N-tert-butylcarbamoyl-4-aza-5 alpha-androstan-1-en-3- one) is a time-dependent, apparently irreversible inhibitor of 5 alpha-reductases, but does not fully inhibit the activity of 5 alpha-reductase in vivo. This limited efficacy has been attributed to its slow rate of inhibition against the type-1 isozyme [Tian, G. (1995) J. Pharm. Sci. (in press)]. Here the feasibility of increasing the rate of inhibition of 5 alpha-reductases by providing binding energies with the inhibitor at a site remote from the center of chemical transformation was explored. Substitution of N-(2,5-bis(trifluoromethyl)phenyl) group, which had been shown to benefit 6-azasteroids in the binding to 5 alpha-reductases [Frye, S., Haffner, C. D., Maloney, P. R., Hiner, R. N., Unwalla, R. J., Batchelor, K. W., Bramson, H. N., Stuart, J. D., Schweiker, S. L., Van Arnold, J., Bickett, D. M., Moss, M. L., Tian, G., Lee, F. W., Tippin, T. K., James, M. K., Grizzle, M. K., Long, J. E., & Croom, D. K. (1995) J. Med. Chem. 38, 2621-2627], for the N-tert-butyl substituent at C-17 of finasteride did not perturb the mechanism of inhibition but significantly increased the rate of inhibition of type-1 5 alpha-reductase. The rate of inhibition was too fast to determine accurately when the normal substrate testosterone was used in the progress curve analysis as this inhibition rate is approaching the value of kcat/Km for the enzyme reaction.

Full Text

Duke Authors

Cited Authors

  • Tian, G; Mook, RA; Moss, ML; Frye, SV

Published Date

  • October 17, 1995

Published In

Volume / Issue

  • 34 / 41

Start / End Page

  • 13453 - 13459

PubMed ID

  • 7577933

Pubmed Central ID

  • 7577933

International Standard Serial Number (ISSN)

  • 0006-2960

Digital Object Identifier (DOI)

  • 10.1021/bi00041a024

Language

  • eng

Conference Location

  • United States