Ansamitocin p-3 (Maytansinol isobutyrate, NSC292222)

Catalog No.S2447 Synonyms: Antibiotic C 15003P3

For research use only.

Ansamitocin p-3 (Maytansinol isobutyrate, NSC292222, Antibiotic C 15003P3) is a potent inhibitor of tubulin polymerization with IC50 of 3.4 μM.

Ansamitocin p-3 (Maytansinol isobutyrate, NSC292222) Chemical Structure

CAS No. 66584-72-3

Purity & Quality Control

Choose Selective ADC Cytotoxin Inhibitors

Biological Activity

Description Ansamitocin p-3 (Maytansinol isobutyrate, NSC292222, Antibiotic C 15003P3) is a potent inhibitor of tubulin polymerization with IC50 of 3.4 μM.
Features Ansamitocin p-3 does not inhibit the growth of bacteria, but very markedly inhibits the growth of eukaryotic organisms.
In vitro

Ansamitocin p-3 at 5 μM completely inhibits the polymerization of tubulin isolated from bovine brains, but in contrast to VCR, Ansamitocin p-3 at a high concentration of 80 μM does not leads to the aggregation of tubulin. Ansamitocin p-3 at 16 μM also potently depolymerizes the polymerized tubulin (IC50 = 3.8 μM). The addition of Ansamitocin p-3 to culture cells blocks the morphological alteration of AC cells from fibroepithelioid to a glial cell type caused by the exposure to a certain concentration of dibutyryl cyclic adenosine 3':5'-monophosphate. In addition, Ansamitocin p-3 treatment at 16 nM causes the well-defined network of cytoplasmic microtubules of A31 cells rapidly dispersed. Short-term Ansamitocin p-3 treatment also inhibits the synthesis of DNA in A31 cells or KB cells. These results confirm that Ansamitocin p-3 acts by interfering with the microtubule assembly system, thus resulting in an inhibition of mitotic spindle fiber formation and, ultimately, cytokilling. [1] Ansamitocin p-3 displays potent cytotoxicity against A-549, HT-29, and MCF-7 cells in a dose-dependent manner with ED50 of 4 ×10-7, 4 × 10-7, and 2 × 10-6 μg/mL, respectively. [2] Ansamitocin p-3 also exhibits cytotoxicity against HCT-116 cells with a much low EC50 of 0.081 nM. [3] Ansamitocin p-3 enhances the effect of radiation both in Drosophila cells and human cancer cells in a p53 dependent manner. [4]

In vivo

Ansamitocin p-3 treatment (>1 μg) significantly suppresses the growth of leukemia SN36, and induces an increased arrest in metaphase of P388 leukemia cells. Ansamitocin p-3 treatment at 25 μg/kg/day significantly prolongs the survival time of mice bearing i.p. B16 melanoma by 130%. Ansamitocin p-3 treatment also significantly prolongs the survival time of mice bearing Ehrlich ascites carcinoma, Sarcoma 180, and P815 mastocytoma, while slightly prolongs the survival time of mice bearing ascites MOPC-104E myeloma,leukemia L1210, and leukemia C1498. [1]

Protocol (from reference)

Kinase Assay:


  • Polymerization inhibition assay:

    After the addition of 100 μL of various concentrations of Ansamitocin p-3 solution (GTP minus MES buffer) or 1 M Tris buffer, pH 8.4 (for blank), to 400 μL of bovine tubulin solution (1 mg/mL in cold MES buffer), maintained at 0 °C for 10 to 15 minutes, the mixture is warmed in a water bath at 37 °C for 30 to 60 minutes. The polymerization of tubulin is followed by an increase in turbidity of the mixture during warming. The turbidity measurement is performed at 460 nm with a Hitachi type 101 spectrophotometer.

Cell Research:


  • Cell lines: A31 and KB
  • Concentrations: Dissolved in DMSO, final concentrations ~10 μM
  • Incubation Time: ~24 hours
  • Method:

    Cells are synchronized, and then exposed to various concentrations of Ansamitocin p-3 for ~24 hours. Cells are labeled with [3H]thymidine (5 Ci/mM, 1 μCi/mL) in 1 mL of the medium. After pulse-labeling at 37 °C for 1 hour, the cells on coverslips are fixed with methanol:acetic acid (3:1). The acidsoluble fraction is washed out from the cells, and the radio activity of each coverslip is determined by a liquid scintillation counter.

  • (Only for Reference)
Animal Research:


  • Animal Models: Female DBA/2 mice bearing P388, L1210, or P815 cells, C57BL/6 mice bearing B16, or C1498 cells, ICR mice bearing sarcoma 180 and EAC, and BALB/c mice bearing MOPC-104E cells
  • Dosages: ~200 μg/kg
  • Administration: Administered i.p. or i.v. daily
  • (Only for Reference)

Solubility (25°C)

In vitro

DMSO 100 mg/mL
(157.44 mM)
Ethanol 55 mg/mL
(86.59 mM)
Water Insoluble

* Please note that Selleck tests the solubility of all compounds in-house, and the actual solubility may differ slightly from published values. This is normal and is due to slight batch-to-batch variations.

Chemical Information

Molecular Weight 635.14


CAS No. 66584-72-3
Storage 3 years -20°C powder
2 years -80°C in solvent
Smiles CC1C2CC(C(C=CC=C(CC3=CC(=C(C(=C3)OC)Cl)N(C(=O)CC(C4(C1O4)C)OC(=O)C(C)C)C)C)OC)(NC(=O)O2)O

In vivo Formulation Calculator (Clear solution)

Step 1: Enter information below (Recommended: An additional animal making an allowance for loss during the experiment)

mg/kg g μL

Step 2: Enter the in vivo formulation (This is only the calculator, not formulation. Please contact us first if there is no in vivo formulation at the solubility Section.)

% DMSO % % Tween 80 % ddH2O

Calculation results:

Working concentration: mg/ml;

Method for preparing DMSO master liquid: mg drug pre-dissolved in μL DMSO ( Master liquid 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 master liquid, next addμL PEG300, mix and clarify, next addμL Tween 80, mix and clarify, next add μL ddH2O, mix and clarify.

Method for preparing in vivo formulation: Take μL DMSO master liquid, next add μL Corn oil, mix and clarify.

Note: 1. Please make sure the liquid is clear before adding the next solvent.
2. Be sure to add the solvent(s) in order. You must ensure that the solution obtained, in the previous addition, is a clear solution before proceeding to add the next solvent. Physical methods such
as vortex, ultrasound or hot water bath can be used to aid dissolving.

Molarity Calculator

Mass Concentration Volume Molecular Weight

Tech Support

Answers to questions you may have can be found in the inhibitor handling instructions. Topics include how to prepare stock solutions, how to store inhibitors, and issues that need special attention for cell-based assays and animal experiments.

Handling Instructions

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