An increase in side-group hydrophobicity largely improves the potency of ritonavir-like inhibitors of CYP3A4

Bioorg Med Chem. 2020 Mar 15;28(6):115349. doi: 10.1016/j.bmc.2020.115349. Epub 2020 Jan 31.


Identification of structural determinants required for potent inhibition of drug-metabolizing cytochrome P450 3A4 (CYP3A4) could help develop safer drugs and more effective pharmacoenhancers. We utilize a rational inhibitor design to decipher structure-activity relationships in analogues of ritonavir, a highly potent CYP3A4 inhibitor marketed as pharmacoenhancer. Analysis of compounds with the R1 side-group as phenyl or naphthalene and R2 as indole or naphthalene in different stereo configuration showed that (i) analogues with the R2-naphthalene tend to bind tighter and inhibit CYP3A4 more potently than the R2-phenyl/indole containing counterparts; (ii) stereochemistry becomes a more important contributing factor, as the bulky side-groups limit the ability to optimize protein-ligand interactions; (iii) the relationship between the R1/R2 configuration and preferential binding to CYP3A4 is complex and depends on the side-group functionality/interplay and backbone spacing; and (iv) three inhibitors, 5a-b and 7d, were superior to ritonavir (IC50 of 0.055-0.085 μM vs. 0.130 μM, respectively).

Keywords: CYP3A4; Crystal structure; Inhibitor design; Ligand binding; Structure-activity relations.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Cytochrome P-450 CYP3A / metabolism*
  • Cytochrome P-450 CYP3A Inhibitors / chemical synthesis
  • Cytochrome P-450 CYP3A Inhibitors / chemistry
  • Cytochrome P-450 CYP3A Inhibitors / pharmacology*
  • Dose-Response Relationship, Drug
  • Humans
  • Hydrophobic and Hydrophilic Interactions
  • Molecular Structure
  • Ritonavir / chemical synthesis
  • Ritonavir / chemistry
  • Ritonavir / pharmacology*
  • Structure-Activity Relationship


  • Cytochrome P-450 CYP3A Inhibitors
  • Cytochrome P-450 CYP3A
  • CYP3A4 protein, human
  • Ritonavir