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sepiapterin   Click here for help

GtoPdb Ligand ID: 14278

Synonyms: CNSA-001 [1] | L-sepiapterin | PTC-923 | PTC923 | Sephience®
Approved drug
sepiapterin is an approved drug
Compound class: Synthetic organic
Comment: Sepiapterin (PTC923) is an orally bioavailable phenylalanine hydroxylase (PAH) activator. It is a precursor of the PAH cofactor BH4 (tetrahydrobiopterin/sapropterin).
2D Structure
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2D Structure

An image of the ligand's 2D structure. For small molecules with SMILES these are drawn using the NCI/CADD Chemical Identifier Resolver. Click on the image to access the chemical structure search tool with the ligand pre-loaded in the structure editor. For other types of ligands, e.g. longer nucleotides and peptides, a manually drawn representation of the molecule may be provided.

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Physico-chemical Properties
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Physico-chemical Properties

Calculated molecular properties are available for small molecules and natural products (not peptides). Properties were generated using the Chemistry Development Kit (CDK) (Willighagen EL et al. Journal of Cheminformatics vol. 9:33. 2017, doi:10.1186/s13321-017-0220-4; https://cdk.github.io/). All properties were selected to enable the prediction of the Lipinski Rule-of-Five profile or ‘druglikeness’ for each ligand. For more info on each category see the help pages.

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Hydrogen bond acceptors 8
Hydrogen bond donors 4
Rotatable bonds 2
Topological polar surface area 129.17
Molecular weight 237.22
XLogP -0.67
No. Lipinski's rules broken 0

Generated using the Chemistry Development Kit (CDK) (Willighagen EL et al. Journal of Cheminformatics vol. 9:33. 2017, doi:10.1186/s13321-017-0220-4; https://cdk.github.io/)
SMILES / InChI / InChIKey
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SMILES / InChI / InChIKey

SMILES (Simplified Molecular Input Line Entry Specification) A specification for unambiguously describing the structure of chemical molecules using short ASCII strings. Canonical SMILES specify a unique representation of the 2D structure without chiral or isotopic specifications. Isomeric SMILES include chiral specification and isotopes.

Standard InChI (IUPAC International Chemical Identifier) and InChIKey InChI is a non-proprietary, standard, textual identifier for chemical substances designed to facilitate linking of information and database searching. An InChIKey is a simplified version of a full InChI, designed for easier web searching.

Generated using the Chemistry Development Kit (CDK) (Willighagen EL et al. Journal of Cheminformatics vol. 9:33. 2017, doi:10.1186/s13321-017-0220-4; https://cdk.github.io/)

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Canonical SMILES C[C@@H](C(=O)C1=NC2=C(NC1)NC(=NC2=O)N)O
Isomeric SMILES O=C1C2=C(NCC(C([C@H](C)O)=O)=N2)NC(N)=N1
InChI InChI=1S/C9H11N5O3/c1-3(15)6(16)4-2-11-7-5(12-4)8(17)14-9(10)13-7/h3,15H,2H2,1H3,(H4,10,11,13,14,17)/t3-/m0/s1
InChI Key VPVOXUSPXFPWBN-VKHMYHEASA-N

Generated using the Chemistry Development Kit (CDK) (Willighagen EL et al. Journal of Cheminformatics vol. 9:33. 2017, doi:10.1186/s13321-017-0220-4; https://cdk.github.io/)
No information available.
Summary of Clinical Use Click here for help
Sepiapterin (PTC923) was advanced to clinical trials to evaluate safety and efficacy as a treatment to reduce neurotoxic phenylalanine accumulation (hyperphenylalaninemia) in patients with phenylketonuria [2,5]. The EU EMA approved the drug in April 2025 for this indication [3], with US FDA approval covering all subtypes of the disease following in July 2025. Sepiapterin is used alongside dietary phenylalanine restriction.
Clinical Trials
Clinical Trial ID Title Type Source Comment References
NCT05099640 A Study of PTC923 in Participants With Phenylketonuria Phase 3 Interventional PTC Therapeutics The phase 3 APHENITY trial was pivotal in sepiapterin's clinical approval. 4
NCT06302348 A Study of Sepiapterin in Participants With Phenylketonuria (PKU) Phase 3 Interventional PTC Therapeutics