| Size | Price | Stock | Qty |
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| 5mg |
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| 10mg |
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| Other Sizes |
| Targets |
IC50: 0.1 μM (papain-like protease)[1]
The primary molecular target of XR8-89 is the SARS-CoV-2 papain-like protease (PLpro), a cysteine protease within nsp3. PLpro is essential for viral replication, processing the viral polyprotein at three sites. It also has deubiquitinating (DUB) and deISGylating activities that antagonize the host type I interferon response, promoting immune evasion. XR8-89 is a PLpro antagonist. By binding to the enzyme, it induces conformational changes, primarily in the BL2 region, which are crucial for activity. This inhibition directly blocks viral replication and restores the host's innate antiviral immune response. |
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| ln Vitro |
XR8-89 boosts the activity against PLpro and causes conformational alterations, primarily in the BL2 region[1].
In vitro, XR8-89 is a potent inhibitor of SARS-CoV-2 PLpro with an IC₅0 of 0.1 uM in enzymatic assays. Mechanistically, XR8-89 induces conformational changes, primarily in the BL2 region of the protease, a flexible loop involved in substrate recognition and catalysis, thereby blocking proteolytic activity. By inhibiting PLpro, XR8-89 also inhibits SARS-CoV-2 replication in cell-based assays, with an EC₅0 typically in the low micromolar range. The compound is selective for PLpro over other human deubiquitinating enzymes. It also reduces the activity of related PLpro from other coronaviruses. The exact selectivity profile has not been fully disclosed. |
| Enzyme Assay |
A typical non-cellular biochemical assay is a fluorescent PLpro activity assay. SARS-CoV-2 PLpro is expressed in E. coli and purified. In a 384-well black plate, 20 uL reaction contains 50 mM Tris (pH 7.4), 150 mM NaCl, 5 mM DTT, 10 nM PLpro, and XR8-89 at 0.1 nM to 10 uM (pre-incubated 15 min). Reaction is initiated by adding fluorogenic substrate Z-RLRGG-AMC (10 uM). Fluorescence increase (Ex/Em 360/460 nm) is measured every 2 min for 30 min at 25degC. Initial rate (V0) is calculated. Percent inhibition relative to DMSO control is used to determine IC₅0 by non-linear regression. For XR8-89, reported IC₅0 = 0.1 uM.
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| Cell Assay |
A standard in vitro cell-based antiviral assay uses Vero E6 cells infected with SARS-CoV-2. Vero E6 cells are cultured in DMEM with 10% FBS at 37degC, 5% CO2. Cells are seeded in 96-well plates at 1 × 10⁴ cells/well. After overnight incubation, medium is replaced with DMEM containing 2% FBS. Cells are infected with SARS-CoV-2 (e.g., USA-WA1/2020) at MOI 0.05 for 1 h. Unbound virus is removed, and serial dilutions of XR8-89 (0.01-10 uM) are added. After 48 h, viral RNA in supernatant is quantified by RT-qPCR. EC₅0 is calculated. Cytotoxicity is measured on uninfected Vero E6 cells using MTT assay to determine CC₅0 and selectivity index.
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| Animal Protocol |
An in vivo animal study for XR8-89 would follow a standard protocol for antivirals in a mouse-adapted SARS-CoV-2 model. Female BALB/c mice (6-8 weeks) are intranasally administered AdV-hACE2 (2 × 10⁸ PFU/mouse) 5 days before infection. Mice are then infected intranasally with 1 × 10⁵ PFU of mouse-adapted SARS-CoV-2 (e.g., MACSL6). One hour post-infection, mice are randomized (n=8). XR8-89 is formulated in a vehicle (e.g., 10% DMSO, 40% PEG300, 5% Tween-80, 45% saline) and administered intraperitoneally (IP) at 10, 25, and 50 mg/kg twice daily for 4 days. Control receives vehicle. Body weight is monitored daily. On day 4, mice are euthanized, lungs harvested for viral titer by plaque assay and for histopathology. All procedures require IACUC approval.
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| ADME/Pharmacokinetics |
The pharmacokinetic (PK) properties of XR8-89 are not well-characterized. As a small molecule with molecular weight 504.69 g/mol (C2₉H3₆N4O2S), it is likely moderately lipophilic. It is soluble in DMSO; aqueous solubility unknown. Based on structure, moderate to high plasma protein binding is predicted. Oral bioavailability is unknown; likely formulated for intraperitoneal injection in animal studies. No specific PK parameters (half-life, clearance, volume of distribution) have been reported. Human PK data is not available.
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| Toxicity/Toxicokinetics |
No toxicological data is available for XR8-89. As a potent viral protease inhibitor, it is not expected to be highly toxic to mammalian cells at therapeutic concentrations, but this has not been formally tested. In vitro cell viability assays likely show a CC₅0 substantially higher than its EC₅0, indicating a favorable selectivity index. Standard safety precautions should be followed (gloves, lab coat, safety goggles). For research use only; not for human administration.
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| References | |
| Additional Infomation |
XR8-89 is not an approved drug and has not entered clinical trials. It is a potent research tool for studying the role of the papain-like protease (PLpro) in the SARS-CoV-2 lifecycle. Its mechanism involves inducing conformational changes in PLpro, inhibiting its protease, deubiquitinating, and deISGylating functions. This dual mode inhibits viral replication and restores host antiviral immune response. XR8-89 is a valuable benchmark for developing new PLpro inhibitors. No clinical trials have been registered. For research use only; not for diagnostic or therapeutic applications.
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| Molecular Formula |
C29H36N4O2S
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| Molecular Weight |
504.686745643616
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| Exact Mass |
504.255
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| CAS # |
2817811-16-6
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| PubChem CID |
155801617
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| Appearance |
Light yellow to yellow solid powder
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| LogP |
3.9
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| Hydrogen Bond Donor Count |
5
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| Hydrogen Bond Acceptor Count |
6
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| Rotatable Bond Count |
9
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| Heavy Atom Count |
36
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| Complexity |
721
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| Defined Atom Stereocenter Count |
3
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| SMILES |
C(N[C@@H](C1=CC=CC(C2SC(CN[C@H]3CC[C@@H](O)C3)=CC=2)=C1)C)(=O)C1=CC(NC2CNC2)=CC=C1C
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| InChi Key |
IGVYCVBUHQMNRZ-RZTXVSJASA-N
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| InChi Code |
InChI=1S/C29H36N4O2S/c1-18-6-7-23(33-24-15-30-16-24)14-27(18)29(35)32-19(2)20-4-3-5-21(12-20)28-11-10-26(36-28)17-31-22-8-9-25(34)13-22/h3-7,10-12,14,19,22,24-25,30-31,33-34H,8-9,13,15-17H2,1-2H3,(H,32,35)/t19-,22+,25-/m1/s1
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| Chemical Name |
5-(azetidin-3-ylamino)-N-[(1R)-1-[3-[5-[[[(1S,3R)-3-hydroxycyclopentyl]amino]methyl]thiophen-2-yl]phenyl]ethyl]-2-methylbenzamide
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| HS Tariff Code |
2934.99.9001
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| Storage |
Powder -20°C 3 years 4°C 2 years In solvent -80°C 6 months -20°C 1 month Note: Please store this product in a sealed and protected environment (e.g. under nitrogen), avoid exposure to moisture and light. |
| Shipping Condition |
Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)
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| Solubility (In Vitro) |
DMSO: 50 mg/mL (99.07 mM)
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| Solubility (In Vivo) |
Note: Listed below are some common formulations that may be used to formulate products with low water solubility (e.g. < 1 mg/mL), you may test these formulations using a minute amount of products to avoid loss of samples.
Injection Formulations
Injection Formulation 1: DMSO : Tween 80： Saline = 10 : 5 : 85 (i.e. 100 μL DMSO stock solution → 50 μL Tween 80 → 850 μL Saline)(e.g. IP/IV/IM/SC) *Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH ₂ O to obtain a clear solution. Injection Formulation 2: DMSO : PEG300 ：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL DMSO → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline) Injection Formulation 3: DMSO : Corn oil = 10 : 90 (i.e. 100 μL DMSO → 900 μL Corn oil) Example: Take the Injection Formulation 3 (DMSO : Corn oil = 10 : 90) as an example, if 1 mL of 2.5 mg/mL working solution is to be prepared, you can take 100 μL 25 mg/mL DMSO stock solution and add to 900 μL corn oil, mix well to obtain a clear or suspension solution (2.5 mg/mL, ready for use in animals). View More
Injection Formulation 4: DMSO : 20% SBE-β-CD in saline = 10 : 90 [i.e. 100 μL DMSO → 900 μL (20% SBE-β-CD in saline)] Oral Formulations
Oral Formulation 1: Suspend in 0.5% CMC Na (carboxymethylcellulose sodium) Oral Formulation 2: Suspend in 0.5% Carboxymethyl cellulose Example: Take the Oral Formulation 1 (Suspend in 0.5% CMC Na) as an example, if 100 mL of 2.5 mg/mL working solution is to be prepared, you can first prepare 0.5% CMC Na solution by measuring 0.5 g CMC Na and dissolve it in 100 mL ddH2O to obtain a clear solution; then add 250 mg of the product to 100 mL 0.5% CMC Na solution, to make the suspension solution (2.5 mg/mL, ready for use in animals). View More
Oral Formulation 3: Dissolved in PEG400 (Please use freshly prepared in vivo formulations for optimal results.) |
| Preparing Stock Solutions | 1 mg | 5 mg | 10 mg | |
| 1 mM | 1.9814 mL | 9.9071 mL | 19.8141 mL | |
| 5 mM | 0.3963 mL | 1.9814 mL | 3.9628 mL | |
| 10 mM | 0.1981 mL | 0.9907 mL | 1.9814 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.
Calculation results
Working concentration： mg/mL；
Method for preparing DMSO stock solution： mg drug pre-dissolved in μL DMSO (stock solution concentration mg/mL). Please contact us first if the concentration exceeds the DMSO solubility of the batch of drug.
Method for preparing in vivo formulation:：Take μL DMSO stock solution, next add μL PEG300, mix and clarify, next addμL Tween 80, mix and clarify, next add μL ddH2O，mix and clarify.
(1) Please be sure that the solution is clear before the addition of next solvent. Dissolution methods like vortex, ultrasound or warming and heat may be used to aid dissolving.
(2) Be sure to add the solvent(s) in order.
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