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Bis-Tos-(2-hydroxyethyl disulfide)

Cat No.:V7850 Purity: ≥98%
Bis-Tos-(2-hydroxyethyl disulfide) is a cleavable (degradable) ADC (Antibody-drug conjugate) linker that may be utilized to prepare antibody-conjugated active molecules (ADC).
Bis-Tos-(2-hydroxyethyl disulfide)
Bis-Tos-(2-hydroxyethyl disulfide) Chemical Structure CAS No.: 69981-39-1
Product category: New1
This product is for research use only, not for human use. We do not sell to patients.
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Product Description
Bis-Tos-(2-hydroxyethyl disulfide) is a cleavable (degradable) ADC (Antibody-drug conjugate) linker that may be utilized to prepare antibody-conjugated active molecules (ADC).
Bis-Tos-(2-hydroxyethyl disulfide) (CAS#: 69981-39-1) is a cleavable, bifunctional disulfide-based crosslinking reagent used primarily in the synthesis of antibody-drug conjugates (ADCs). It features two terminal tosylate (p-toluenesulfonate) leaving groups and a central cleavable disulfide bond. The tosylate groups serve as excellent leaving groups for nucleophilic substitution reactions, allowing the compound to react with a wide range of nucleophiles, such as amines, thiols, or alcohols, to form stable covalent bonds. This makes it a valuable linker for connecting different molecular components. The central disulfide bond confers cleavability, as it can be reduced in the intracellular environment (e.g., by glutathione), enabling the controlled release of a payload inside target cells. Bis-Tos-(2-hydroxyethyl disulfide) has a molecular weight of 462.62 g/mol and a molecular formula of C18H22O6S4. It has a melting point greater than 255°C, indicating high thermal stability. It is soluble in DMSO (10 mM). Beyond its use in ADC synthesis, this compound is also used as a reducing agent and a linker in the synthesis of various active pharmaceutical ingredients (APIs). It is a research-use-only reagent and is not a therapeutic drug. It is a valuable tool for creating ADCs with tunable release kinetics and for studying the mechanisms of intracellular drug delivery.
Biological Activity I Assay Protocols (From Reference)
Targets
Bis-Tos-(2-hydroxyethyl disulfide) does not have a specific biological target, as it is a chemical linker. Its function is to serve as a covalent connector between two or more molecular components. The "targets" of this linker are the specific functional groups on the molecules it is designed to conjugate. The two tosylate groups are excellent leaving groups and are targets for nucleophilic attack by amines, thiols, or alcohols, forming stable covalent bonds. This allows the linker to be attached to a wide range of molecules. The disulfide bond is a target for reduction in the intracellular environment, specifically by the high concentrations of glutathione (GSH) found inside cells. This reductive cleavage is the mechanism by which the linker releases its payload. Therefore, the biological "target" is the intracellular environment of the target cell, where the high GSH concentration triggers the cleavage of the disulfide bond. The hydroxyethyl groups provide reactive handles for further derivatization. In the context of ADC design, the linker's role is to ensure that the potent cytotoxic drug is stably attached to the antibody in circulation but is efficiently released once the ADC is internalized by the cancer cell.
ln Vitro
ADC cytotoxins are connected to antibodies through an ADC connector to form ADCs [1].
As a chemical linker, Bis-Tos-(2-hydroxyethyl disulfide) does not possess any direct in vitro biological activity. Its biological relevance is entirely indirect, stemming from its use in the synthesis of bioactive conjugates. The in vitro activity of this linker is assessed through the characterization of the final conjugates it helps to create. For instance, when used to synthesize an ADC, the activity of the conjugate is evaluated in cell-based assays for target binding, internalization, and cytotoxicity. The cleavable disulfide bond contributes to the conjugate's overall activity by ensuring the efficient release of the toxic payload inside the target cell, which is a critical factor for the ADC's potency. In a typical in vitro experiment, the ADC is incubated with cancer cells, and cell viability is measured. The potency of the ADC depends on the linker's ability to be cleaved intracellularly, releasing the active drug. The performance of the linker can be assessed by comparing the activity of an ADC made with this cleavable linker to one made with a non-cleavable linker. Thus, the "activity" of Bis-Tos-(2-hydroxyethyl disulfide) is a measure of its ability to function as a cleavable bridge that enables the targeted delivery of a therapeutic payload.
ln Vivo
As a chemical linker, Bis-Tos-(2-hydroxyethyl disulfide) does not possess any direct in vivo biological activity. It is not administered as a therapeutic agent and does not exert pharmacological effects in animal models. Its in vivo relevance is strictly as a component of larger, biologically active conjugates. When incorporated into an ADC, the cleavable disulfide linker plays a critical role in the drug's in vivo efficacy. The linker must be stable in the bloodstream (where glutathione concentrations are low) to prevent premature release of the toxic payload and systemic toxicity. However, once the ADC is internalized into the target cell, the high concentration of glutathione in the cytoplasm reduces the disulfide bond, releasing the active drug. This targeted release mechanism is known as the "bystander effect" and is a key design consideration for ADCs. The specific in vivo activity—such as tumor regression—is determined by the conjugate's warhead and targeting ligand, but the linker's stability and cleavage kinetics are essential for the overall therapeutic outcome. Therefore, while Bis-Tos-(2-hydroxyethyl disulfide) has no direct in vivo activity, it is a critical component that influences the efficacy and safety of the therapeutics it is used to construct.
Enzyme Assay
There are no specific in vitro enzyme or receptor binding assays for Bis-Tos-(2-hydroxyethyl disulfide), as it is not a biologically active compound. Its characterization is performed using analytical chemistry techniques such as NMR, HPLC, and MS to verify its structure and purity. To confirm its functionality, chemical assays are used. The reactivity of the tosylate groups can be tested by reacting the compound with a model nucleophile (e.g., an amine) and monitoring the formation of the product by HPLC or LC-MS. The cleavability of the disulfide bond can be tested in vitro by incubating the linker or a model conjugate with a reducing agent such as dithiothreitol (DTT) or glutathione, and monitoring the cleavage products by HPLC. These are quality control and functional validation steps to ensure the linker is active and can be used for its intended purpose. There are no biological assays for this compound.
Cell Assay
There are no standard in vitro cell-based assays for Bis-Tos-(2-hydroxyethyl disulfide), as it is not a bioactive molecule. Its use in cell biology is indirect, as a reagent for constructing ADCs. In such cases, the cell-based assay would involve treating cells with the final ADC and then measuring a biological readout, such as cell viability. The performance of the linker would be evaluated by the potency and selectivity of the ADC, which depend on the linker's ability to release the payload inside the cell. For example, a common assay is to treat cancer cells with varying concentrations of the ADC and measure cell viability after 72 hours using an MTT or CellTiter-Glo assay. The IC50 of the ADC is then calculated. To confirm that the activity is dependent on the cleavable linker, a control ADC with a non-cleavable linker can be used. However, there is no direct assay for the linker itself in cells, as it is not designed to interact with cells in its unconjugated form. Any cell-based work involving this linker is always part of a larger experimental design to evaluate a specific therapeutic conjugate.
Animal Protocol
Bis-Tos-(2-hydroxyethyl disulfide) is not used in in vivo animal experiments as a standalone compound. It is a synthetic building block for creating ADCs and other bioconjugates. Animal studies involving this compound would only be conducted on the final, larger conjugates that incorporate it. In such studies, the linker's contribution to the overall pharmacokinetic and pharmacodynamic profile of the conjugate would be assessed. For example, researchers might compare the in vivo efficacy, stability, and toxicity of an ADC synthesized with this cleavable disulfide linker to an ADC synthesized with a non-cleavable linker. The cleavable linker is expected to release the toxic payload inside the tumor, leading to better efficacy and a wider therapeutic index. However, there is no standard animal protocol for the linker itself. Its use is limited to the research and development phase, where it is employed in the chemical synthesis of test articles. The storage recommendations (e.g., -20°C, protect from light) are for maintaining the chemical integrity of the reagent. In summary, there are no in vivo animal experiments for this linker as a single agent.
ADME/Pharmacokinetics
The pharmacokinetic (PK) properties of Bis-Tos-(2-hydroxyethyl disulfide) are not studied as it is not a therapeutic agent. However, its physicochemical properties provide insight into its behavior. It has a molecular weight of 462.62 g/mol and a molecular formula of C18H22O6S4. It is a relatively large, lipophilic molecule. It has a high melting point (>255°C), indicating high thermal stability. It is soluble in DMSO (10 mM). For storage, it is recommended to keep it at -20°C in a dry, dark environment, and to protect it from light. As a small molecule, if introduced into the bloodstream, it would be expected to have a short half-life, likely being rapidly cleared. However, when conjugated to larger molecules like antibodies, the overall PK is dominated by the larger component. The "PK" properties of this linker are thus not an independent consideration but are integral to the design and performance of the bioconjugates it helps to create, particularly its cleavable disulfide bond which is designed to release the payload specifically in the target tissue.
Toxicity/Toxicokinetics
As a PEG-based linker, Bis-Tos-(2-hydroxyethyl disulfide) is considered to have low toxicity. The compound is classified as a research reagent, and standard laboratory safety precautions should be followed when handling it. The safety of this linker is primarily considered in the context of its use in ADCs. A cleavable linker is designed to be stable in circulation but to release its payload inside the target cell. If the disulfide bond were to be reduced prematurely (e.g., in the bloodstream), it could lead to the release of the toxic payload into the bloodstream, causing off-target toxicity. Therefore, the toxicity of the linker itself is not the primary concern, but rather the toxicity of the payload it is designed to carry if the linker fails to perform its function correctly. Its toxicity profile has not been extensively studied independently, but due to its intended use and chemical class, it is not expected to be acutely toxic. All handling should be done with appropriate personal protective equipment (PPE) in a well-ventilated area, and the compound should be protected from light.
References
[1]. Beck A, et al. Strategies and challenges for the next generation of antibody-drug conjugates. Nat Rev Drug Discov. 2017 May;16(5):315-337.
Additional Infomation
Bis-Tos-(2-hydroxyethyl disulfide) is a research-use-only reagent and is not a drug, nor is it approved for any clinical or therapeutic use. It is a highly versatile chemical tool with key applications in the synthesis of antibody-drug conjugates (ADCs). Its structure features two reactive tosylate groups and a central cleavable disulfide bond, making it an ideal linker for creating ADCs with controlled intracellular drug release. The tosylate groups serve as excellent leaving groups for nucleophilic substitution, allowing the linker to be attached to a wide range of molecules. The disulfide bond is cleaved by the high concentration of glutathione in the intracellular environment, ensuring that the cytotoxic payload is released specifically inside the target cancer cell. Beyond its use in ADC synthesis, this compound is also used as a reducing agent and a linker in the synthesis of various active pharmaceutical ingredients (APIs). The hydroxyethyl groups provide reactive handles for further derivatization, making it a useful intermediate for linker design, thiol-modified reagents, and redox-sensitive conjugates. It is therefore an essential tool for medicinal chemists and chemical biologists working on targeted drug delivery and bioconjugation.
These protocols are for reference only. InvivoChem does not independently validate these methods.
Physicochemical Properties
Molecular Formula
C18H22O6S4
Molecular Weight
462.623680591583
Exact Mass
462.03
CAS #
69981-39-1
PubChem CID
12452547
Appearance
White to off-white solid powder
LogP
5.957
Hydrogen Bond Donor Count
0
Hydrogen Bond Acceptor Count
8
Rotatable Bond Count
11
Heavy Atom Count
28
Complexity
579
Defined Atom Stereocenter Count
0
SMILES
S(C1C=CC(C)=CC=1)(=O)(=O)OCCSSCCOS(C1C=CC(C)=CC=1)(=O)=O
InChi Key
BBGVCMPJFAYXLJ-UHFFFAOYSA-N
InChi Code
InChI=1S/C18H22O6S4/c1-15-3-7-17(8-4-15)27(19,20)23-11-13-25-26-14-12-24-28(21,22)18-9-5-16(2)6-10-18/h3-10H,11-14H2,1-2H3
Chemical Name
2-[2-(4-methylphenyl)sulfonyloxyethyldisulfanyl]ethyl 4-methylbenzenesulfonate
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

Note: This product requires protection from light (avoid light exposure) during transportation and storage.
Shipping Condition
Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)
Solubility Data
Solubility (In Vitro)
May dissolve in DMSO (in most cases), if not, try other solvents such as H2O, Ethanol, or DMF with a minute amount of products to avoid loss of samples
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
(e.g. IP/IV/IM/SC)
Injection Formulation 1: DMSO : Tween 80: Saline = 10 : 5 : 85 (i.e. 100 μL DMSO stock solution 50 μL Tween 80 850 μL Saline)
*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 : PEG300Tween 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).
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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)]
*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.
Injection Formulation 5: 2-Hydroxypropyl-β-cyclodextrin : Saline = 50 : 50 (i.e. 500 μL 2-Hydroxypropyl-β-cyclodextrin 500 μL Saline)
Injection Formulation 6: DMSO : PEG300 : castor oil : Saline = 5 : 10 : 20 : 65 (i.e. 50 μL DMSO 100 μLPEG300 200 μL castor oil 650 μL Saline)
Injection Formulation 7: Ethanol : Cremophor : Saline = 10: 10 : 80 (i.e. 100 μL Ethanol 100 μL Cremophor 800 μL Saline)
Injection Formulation 8: Dissolve in Cremophor/Ethanol (50 : 50), then diluted by Saline
Injection Formulation 9: EtOH : Corn oil = 10 : 90 (i.e. 100 μL EtOH 900 μL Corn oil)
Injection Formulation 10: EtOH : PEG300Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL EtOH 400 μLPEG300 50 μL Tween 80 450 μL 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).
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Oral Formulation 3: Dissolved in PEG400
Oral Formulation 4: Suspend in 0.2% Carboxymethyl cellulose
Oral Formulation 5: Dissolve in 0.25% Tween 80 and 0.5% Carboxymethyl cellulose
Oral Formulation 6: Mixing with food powders


Note: Please be aware that the above formulations are for reference only. InvivoChem strongly recommends customers to read literature methods/protocols carefully before determining which formulation you should use for in vivo studies, as different compounds have different solubility properties and have to be formulated differently.

 (Please use freshly prepared in vivo formulations for optimal results.)
Preparing Stock Solutions 1 mg 5 mg 10 mg
1 mM 2.1616 mL 10.8080 mL 21.6160 mL
5 mM 0.4323 mL 2.1616 mL 4.3232 mL
10 mM 0.2162 mL 1.0808 mL 2.1616 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.

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What is the mass of compound required to make a 10 mM stock solution in 5 ml of DMSO given that the molecular weight of the compound is 350.26 g/mol?
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Note: Chemical formula is case sensitive: C12H18N3O4  c12h18n3o4
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In vivo Formulation Calculator (Clear solution)
Step 1: Enter information below (Recommended: An additional animal to make allowance for loss during the experiment)
Step 2: Enter in vivo formulation (This is only a calculator, not the exact formulation for a specific product. Please contact us first if there is no in vivo formulation in the solubility section.)
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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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