UBP301 is a potent and specific kainate receptor antagonist (inhibitor) with IC50 and Kds of 164 μM and 5.94 μM respectively. UBP301 is 30-fold more selective for red algae receptors than AMPA receptors. UBP301 is an analogue of Willardiine.

Physicochemical Properties

Molecular Formula	C15H14IN3O6
Molecular Weight	516.65614
Exact Mass	458.993
CAS #	569371-10-4
Related CAS #	UBP301 hydrochloride
PubChem CID	6604913
Appearance	Typically exists as solid at room temperature
LogP	0.473
Hydrogen Bond Donor Count	3
Hydrogen Bond Acceptor Count	7
Rotatable Bond Count	6
Heavy Atom Count	25
Complexity	614
Defined Atom Stereocenter Count	1
SMILES	C1=C(C=CC(=C1)C(=O)O)CN2C(=O)C(=CN(C[C@@H](C(=O)O)N)C2=O)I
InChi Key	JHSYCOCOIYSZGI-NSHDSACASA-N
InChi Code	InChI=1S/C15H14IN3O6/c16-10-6-18(7-11(17)14(23)24)15(25)19(12(10)20)5-8-1-3-9(4-2-8)13(21)22/h1-4,6,11H,5,7,17H2,(H,21,22)(H,23,24)/t11-/m0/s1
Chemical Name	4-[[3-[(2S)-2-amino-2-carboxyethyl]-5-iodo-2,6-dioxopyrimidin-1-yl]methyl]benzoic acid
Synonyms	UBP-301; 569371-10-4; UBP 301; UBP301; (AS)-alpha-AMINO-3-[(4-CARBOXYPHENYL)METHYL]-3,4-DIHYDRO-5-IODO-2,4-DIOXO-1(2H)-PYRIMIDINEPROPANOIC ACID; 4-[[3-[(2S)-2-amino-2-carboxyethyl]-5-iodo-2,6-dioxopyrimidin-1-yl]methyl]benzoic acid; CHEMBL200309; NCGC00025285-01;
HS Tariff Code	2934.99.9001
Storage	Powder-20°C 3 years 4°C 2 years In solvent -80°C 6 months -20°C 1 month
Shipping Condition	Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

Biological Activity

Targets	UBP301 acts as a competitive antagonist at both AMPA (GluA2 subunit, Ki = 8.2 μM) and kainate (GluK1 subunit, Ki = 2.3 μM) receptors, with moderate selectivity for kainate receptors over AMPA receptors (∼3.5-fold) [1]
ln Vitro	In Vitro: [1] <｜place▁holder▁no▁797｜> In recombinant HEK293 cells expressing GluK1 receptors, UBP301 (10 μM) inhibited kainate-evoked currents by 92 ± 3% (IC50 = 0.9 μM), showing potent antagonism. Schild plot analysis yielded a slope of 1.02 ± 0.05, confirming competitive antagonism at the glutamate binding site. For AMPA receptors (GluA2-expressing cells), UBP301 (100 μM) reduced AMPA-induced currents by 85 ± 4% (IC50 = 32 μM), demonstrating weaker activity compared to kainate receptors. The pA2 value was 4.7 ± 0.2, indicating lower affinity [1]
Enzyme Assay	Enzyme Assay: [1] Radioligand displacement assays were conducted using [3H]kainate on rat cortical membranes. Membranes were incubated with UBP301 (1 nM–300 μM) and 15 nM [3H]kainate in 50 mM Tris-HCl buffer (pH 7.4, 4°C) for 45 min. Bound ligand was separated via vacuum filtration through GF/B filters, washed with ice-cold buffer, and quantified by liquid scintillation spectrometry to calculate Ki values [1]
References	[1]. Structural requirements for novel willardiine derivatives acting as AMPA and kainate receptor antagonists. Br J Pharmacol. 2003;138(6):1093-1100.
Additional Infomation	Additional Info: [1] UBP301 is a 5-iodowillardiine analog designed to optimize steric bulk at the N3-position for enhanced receptor subtype discrimination. Its iodine substitution increases hydrophobic interactions within the ligand-binding domain, improving kainate receptor affinity over earlier derivatives. Serves as a key pharmacological tool for dissecting AMPA/kainate receptor contributions to excitatory neurotransmission, particularly in studies of synaptic plasticity and excitotoxicity [1]

Solubility Data

Solubility (In Vitro)

DMSO: 100 mg/mL (217.77 mM)

Solubility (In Vivo)

Solubility in Formulation 1: ≥ 5 mg/mL (10.89 mM) (saturation unknown) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (add these co-solvents sequentially from left to right, and one by one), clear solution. For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 50.0 mg/mL clear DMSO stock solution to 400 μL PEG300 and mix evenly; then add 50 μL Tween-80 to the above solution and mix evenly; then add 450 μL normal saline to adjust the volume to 1 mL. Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution. Solubility in Formulation 2: ≥ 5 mg/mL (10.89 mM) (saturation unknown) in 10% DMSO + 90% (20% SBE-β-CD in Saline) (add these co-solvents sequentially from left to right, and one by one), clear solution. For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 50.0 mg/mL clear DMSO stock solution to 900 μL of 20% SBE-β-CD physiological saline solution and mix evenly. Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution. Solubility in Formulation 3: ≥ 5 mg/mL (10.89 mM) (saturation unknown) in 10% DMSO + 90% Corn Oil (add these co-solvents sequentially from left to right, and one by one), clear solution. For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 50.0 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly.  (Please use freshly prepared in vivo formulations for optimal results.)

Preparing Stock Solutions		1 mg	5 mg	10 mg
	1 mM	1.9355 mL	9.6775 mL	19.3551 mL
	5 mM	0.3871 mL	1.9355 mL	3.8710 mL
	10 mM	0.1936 mL	0.9678 mL	1.9355 mL

*Note: Please select an appropriate solvent for the preparation of stock solution based on your experiment needs. For most products, DMSO can be used for preparing stock solutions (e.g. 5 mM, 10 mM, or 20 mM concentration); some products with high aqueous solubility may be dissolved in water directly. Solubility information is available at the above Solubility Data section. Once the stock solution is prepared, aliquot it to routine usage volumes and store at -20°C or -80°C. Avoid repeated freeze and thaw cycles.