Drug · PARP inhibitor · PARP inhibitor · Sourced compound
Niraparib structure · mechanism
PubChem CID 24958200. Molecular formula C19H20N4O. Independently assigned structure; reviewed 2026-10-08. Family grouping is editorial and does not establish shared activity.
Niraparib 2D structure
- Role
- Drug
- Mechanism class
- PARP inhibitor
- InChIKey
PCHKPVIQAHNQLW-CQSZACIVSA-N
- Structure checked
- 2026-10-08
- Molecular formula
- C19H20N4O
- Structure source
- PubChem
- PubChem CID
- 24958200
- InChI Key
- PCHKPVIQAHNQLW-CQSZACIVSA-N
Read the two structures
Distinguish ring nitrogens from side-chain nitrogens in niraparib and inspect corresponding regions in olaparib. Do not stop at counts of rings or elements: check bond sequence and attachment positions. A structural comparison does not substitute for experimental PARP measurements.
| Observation | Niraparib | Olaparib |
|---|---|---|
| C(=O)–N connections | 1 | 3 |
| Fluorine atoms | 0 | 1 |
Connect the structural observations with the fingerprint result
The selected query detects three C(=O)–N connections and one fluorine in olaparib, versus one such connection and no fluorine in niraparib. Ring connections are included. We state the query definition rather than mixing this count with an unspecified “amide count”. [Niraparib] · [Olaparib]
Fourteen shared set bits across a union of 88 give 0.159. Members of the same PARP class can show limited overlap in this representation, illustrating why target-class grouping does not establish the same molecular architecture.
No PARP trapping, cellular activity or tissue-distribution measurements enter this calculation. Those questions require separate experimental conditions and results; the fingerprint value cannot replace them.
Calculated structural similarity: 0.159 · Morgan radius 2 / 2048 bits · Tanimoto
Calculation: 14 / (48 + 54 − 14) = 14 / 88 ≈ 0.159. Set-bit counts are not counts of unique atoms or functional groups.
Query definitions and reproducibility
- C(=O)–N connections:
[#6](=[#8])[#7] - Fluorine atoms:
[F]
RDKit 2025.03.4 · Matches with identical atom sets are counted once. Colours mark atoms and bonds matching selected queries, not a proven shared scaffold or synthesis route.
- Read elemental composition from the formulas.
- Trace ring and substituent connections in each drawing.
- Compare your observations with the fingerprint score calculated under identical settings.
- Check stereochemistry and the complete InChIKey in the source records.
The score is fingerprint overlap, not a percentage of efficacy or safety. RDKit
Structure-source check: 2026-10-08 / 2026-10-08 · Editorial update and calculation check: 2026-10-16
Download source structures, queries and bit counts for this comparison (JSON)
StructureMoa editorial · source review 2026-10-08
Molecular identity
Niraparib: independently retrieved PubChem CID 24958200, formula C19H20N4O.
How to compare
Distinguish ring nitrogens from side-chain nitrogens in niraparib and inspect corresponding regions in olaparib. Do not stop at counts of rings or elements: check bond sequence and attachment positions. A structural comparison does not substitute for experimental PARP measurements.
Interpretation limits
The Morgan/Tanimoto score measures fingerprint overlap. It does not establish efficacy, safety, clinical superiority or full stereochemical identity.
SMILES
C1C[C@H](CNC1)C2=CC=C(C=C2)N3C=C4C=CC=C(C4=N3)C(=O)NTags
External IDs · BioMoa
StructureMoa is a chemical-structure exploration tool. Structural similarity, clustering, and SAR relationships are intended for research exploration and do not establish shared potency, selectivity, safety, efficacy, or clinical performance.
Editorial responsibility and corrections
Operated and edited by the independent StructureMoa project. Explanations use AI assistance; structural identity and similarity are checked against source records and calculation tests. Molecular data and clinical or regulatory evidence have separate review scopes.
- Source structures
- PubChem · CID / SMILES / InChIKey
- Calculations and automated checks
- RDKit · Morgan / SMARTS
- Disclosed specialist review
- No separate external specialist review is disclosed. Passing automated tests is not specialist review of clinical claims.
For a correction, include the page URL, molecule name or CID, the field in question and a supporting source. Corrections are checked against sources, and the affected editorial update date is changed when a correction is published. [email protected]