A-ring modified steroidal azoles retaining similar potent and slowly reversible CYP17A1 inhibition as abiraterone

- Abiraterone analogs with modified A/B-rings retain nanomolar affinity for CYP17A1.
- CYP17A1 inhibition by abiraterone and analogs is mixed competitive/noncompetitive.
- Dissociation of abiraterone from CYP17A1 is slow (koff < 0.01 min−1) and incomplete.
- The 3β-hydroxyl Δ5-system of abiraterone is not required for high CYP17A1 affinity.