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| Other Sizes |
| Targets |
Microtubules (stabilization via an indirect mechanism that does not involve direct binding to purified tubulin or the taxane-binding site on tubulin; no IC50, Ki, EC50, or DC50 values for direct target binding are reported). [2]
βIII-tubulin (overcoming resistance mediated by this isotype; no binding affinity data). [3] |
|---|---|
| ln Vitro |
Taccalonolide A causes a notable increase in the cellular density of interphase microtubules and initiates bundling of interphase microtubules in A-10 smooth muscle cells at low micromolar concentrations, comparable to the effects of paclitaxel. The first noticeable effect is increased microtubule density around the nucleus at 500 nM. Treatment with 2.5 μM Taccalonolide A initiates the formation of short, compact microtubule tufts that constitute the entire microtubule mass of the cell. [2]
Taccalonolide A induces mitotic arrest and the formation of aberrant mitotic spindles in cancer cell lines, with most cells containing 2-4 spindles at concentrations near the IC50 for inhibition of proliferation. The number of spindles increases to an average of five per cell at 10 times the IC50 value. It also causes the formation of micronuclei, Bcl-2 phosphorylation, and initiation of apoptosis. [2] The antiproliferative IC50 values of Taccalonolide A in drug-sensitive cancer cell lines are in the high nanomolar range: 622 ± 39 nM in SK-OV-3 cells, 594 ± 43 nM in HeLa cells, and 208 ± 14 nM for Taccalonolide B (a derivative) in SK-OV-3 cells (note: exact value for Taccalonolide A in HeLa is 594 nM). [3] Against Pgp-overexpressing SK-OV-3/MDR-1-6/6 cells, Taccalonolide A shows an IC50 of 2,523 ± 317 nM, with a relative resistance (Rr) of 4.1, indicating it effectively circumvents Pgp-mediated resistance compared to paclitaxel (Rr 860). [3] In MRP7-transfected HEK293 cells, Taccalonolide A shows IC50 values of 2.40 ± 0.31 μM (HEK-MRP7-C17) and 2.20 ± 0.56 μM (HEK-MRP7-C18), with relative resistance values of 1.4 and 1.3, respectively, indicating it is not a substrate for MRP7. [3] In a HeLa cell line ectopically expressing βIII-tubulin (wild-type βIII), Taccalonolide A shows an IC50 of 541 ± 240 nM, compared to 594 ± 43 nM in parental HeLa cells, giving a relative resistance of 0.9, indicating that βIII-tubulin expression does not confer resistance but rather slightly increases sensitivity. [3] |
| ln Vivo |
Taccalonolide A has excellent antitumor activity in the Pgp-expressing, multidrug-resistant syngeneic murine mammary adenocarcinoma model (Mam17/ADR). When administered at a total dose of 38 mg/kg (8 mg/kg on day 1 and 15 mg/kg on days 3 and 5), it resulted in 91% growth inhibition (9% T/C), 2.3 log cell kill, and a 9-day tumor growth delay. This level of antitumor activity is rarely achieved against the aggressive Mam17/ADR model. [3]
A lower total dose of 33.2 mg/kg (lower individual doses given more frequently) resulted in minimal antitumor action (33% growth inhibition, 67% T/C, 0.3 log kill, and 1-day tumor growth delay), showing that the antitumor efficacy of Taccalonolide A is dose- and schedule-dependent. [3] |
| Enzyme Assay |
Taccalonolide A was evaluated for its ability to induce the assembly of purified bovine brain tubulin. Unlike paclitaxel, Taccalonolide A was unable to induce the assembly of purified tubulin even when present at equimolar concentrations with tubulin. Additional experiments performed under conditions sufficient for spontaneous tubulin polymerization demonstrated that Taccalonolide A was not capable of lowering the critical concentration of tubulin required for microtubule assembly, even in the presence of purified microtubule-associated proteins (MAPs). [2]
The interaction of Taccalonolide A with the taxane binding site on tubulin was assessed by anisotropy using the fluorescent paclitaxel analog, Flutax-2. Centrifugation studies showed that Taccalonolide A was unable to displace Flutax-2 from microtubules. Preincubation of microtubules with Taccalonolide A did not inhibit Flutax-2 binding, consistent with a lack of overlap between the taccalonolide and the taxane binding site. Direct binding of Taccalonolide A to purified microtubules with and without the addition of a crosslinking agent was measured by extraction and HPLC detection. No Taccalonolide A was detected in the microtubule pellet, confirming that it does not directly bind to purified tubulin or microtubules. [2] |
| Cell Assay |
The effects of Taccalonolide A on cellular microtubule structures were evaluated by indirect immunofluorescence techniques in A-10 embryonic aortic smooth muscle cells and various cancer cell lines (HeLa, SK-OV-3, etc.). Cells were grown on glass coverslips, treated with vehicle or drug (e.g., 500 nM or 2.5 μM Taccalonolide A) for 18 hours, then fixed and stained with an antibody to β-tubulin, followed by a fluorescent secondary antibody. Images were acquired by digital camera and processed using software. [2][3]
For antiproliferative assays, the sulforhodamine B (SRB) assay was used to evaluate the effects of Taccalonolide A on SK-OV-3 and HeLa cell line pairs. Cells were seeded in 96-well plates, treated with at least seven drug concentrations spanning the entire range of growth inhibition for 48 hours, then fixed, stained with SRB, and the optical density was measured. IC50 values were calculated from three independent experiments each using triplicate points. [3] For MRP7-transfected HEK293 cells, the antiproliferative effects of Taccalonolide A were assessed with a tetrazolium-based assay (MTS/PMS). Cells were seeded at 3,000 cells per well in 96-well plates, treated with various drug concentrations for 72 hours, then colorimetric analysis was performed. [3] Immunoblot analysis was performed to confirm βIII-tubulin expression in HeLa and wild-type βIII cells. Cells were harvested, lysed in cell extraction buffer with protease inhibitors, and equal amounts of total protein were separated by SDS-PAGE, transferred to nitrocellulose membranes, and probed with isotype-specific monoclonal antibodies against β-tubulin isotypes. [3] |
| Animal Protocol |
Female C3H mice (8 weeks old, mean body weight 25 g) were bilaterally implanted subcutaneously with 30-50 mg fragments of the doxorubicin- and paclitaxel-resistant Mam17/ADR tumor on day 0. Mice were randomly placed into treatment and control groups (n=5 per group). Taccalonolide A was administered by intravenous (i.v.) bolus injection. The drug was formulated as a 65:35 (v/v) DMSO/Cremophor EL solution at pH 7.0 (18 mg/mL liquid stock), then diluted with cyclodextrin to a 0.2 mL injection volume just before use. For the effective regimen, Taccalonolide A was given at 8 mg/kg on day 1 and 15 mg/kg on days 3 and 5 (total dose 38 mg/kg). A lower-dose regimen used 33.2 mg/kg total given more frequently. Mice were observed and weighed daily before treatment, and tumors were measured two to three times weekly by caliper. Tumor mass was calculated as [length (mm) × width (mm)^2]/2. Efficacy endpoints included T/C (median tumor mass of treated/control × 100%), tumor growth delay (T-C), and log cell kill. [3]
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| Toxicity/Toxicokinetics |
In the in vivo efficacy study using the Mam17/ADR model, Taccalonolide A at a total dose of 38 mg/kg (8 mg/kg on day 1, 15 mg/kg on days 3 and 5) caused a mean weight loss nadir of 25.8%, which was considered significant toxicity. However, despite this large weight loss, the mice recovered 91.5% of their starting weights within 6 days of nadir, indicating good host recovery potential. No drug-related deaths occurred with this dosing schedule. At a lower total dose of 33.2 mg/kg, weight loss was less than 2%. [3]
The formulation of Taccalonolide A used in studies contained Cremophor EL and DMSO, which are known to cause undesirable effects (hypersensitivity reactions) in patients, similar to clinical paclitaxel formulations. [2] |
| References |
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| Additional Infomation |
Taccalonolide A is a solanolide. It has been reported to exist in Tacca chantrieri and Tacca plantaginea, and relevant data are available.
Taccalonolide A is a pentacyclic steroid with a C2-C3 epoxide and a C23-C26 lactone ring. Its chemical formula is C36H46O14. It differs from taccalonolide B by the replacement of a C15 acetyl group with a C15 hydroxyl. The presence of a C11 acetate group (as in taccalonolide A vs. E) makes little difference in in vitro potency but has a significant effect on in vivo activity against Pgp-expressing tumors. [2][3] Taccalonolide A is unique among microtubule stabilizers because it does not bind directly to tubulin, which allows it to retain efficacy in cell lines harboring mutations in the paclitaxel-binding site on tubulin. It also overcomes resistance mediated by Pgp, MRP7, and βIII-tubulin, giving it advantages over taxanes and epothilones. [2][3] The supply of Taccalonolide A currently relies on purification from Tacca chantrieri roots and rhizomes. The yield from roots and rhizomes is 10-fold higher than the yield of paclitaxel from the bark of the Pacific Yew, and the plants are relatively fast-growing. No total or partial synthesis has been reported. Formulation challenges include low water solubility; current in vivo studies used a Cremophor EL/DMSO mixture diluted with water or cyclodextrin. Alternative formulations such as encapsulation into microparticles are being considered for clinical development. [2] |
| Molecular Formula |
C36H46O14
|
|---|---|
| Molecular Weight |
702.7421
|
| Exact Mass |
702.288
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| CAS # |
108885-68-3
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| PubChem CID |
441685
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| Appearance |
White to off-white solid powder
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| Density |
1.4±0.1 g/cm3
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| Boiling Point |
776.8±60.0 °C at 760 mmHg
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| Flash Point |
237.8±26.4 °C
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| Vapour Pressure |
0.0±6.1 mmHg at 25°C
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| Index of Refraction |
1.590
|
| LogP |
2.49
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| Hydrogen Bond Donor Count |
2
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| Hydrogen Bond Acceptor Count |
14
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| Rotatable Bond Count |
8
|
| Heavy Atom Count |
50
|
| Complexity |
1620
|
| Defined Atom Stereocenter Count |
18
|
| SMILES |
C[C@@H]1C=C2[C@@]([C@H]3[C@H]1[C@@]4([C@@H]([C@H]3OC(=O)C)[C@H]5[C@H]([C@@H]([C@@H]4OC(=O)C)OC(=O)C)[C@@]6([C@H](C[C@H]7[C@@H]([C@@H]6OC(=O)C)O7)C(=O)[C@@H]5O)C)C)([C@](C(=O)O2)(C)O)C
|
| InChi Key |
PTTJLTMUKRRHAT-VJAKQJMOSA-N
|
| InChi Code |
InChI=1S/C36H46O14/c1-12-10-19-35(8,36(9,44)32(43)50-19)24-21(12)34(7)22(28(24)45-13(2)37)20-23(29(46-14(3)38)31(34)48-16(5)40)33(6)17(25(41)26(20)42)11-18-27(49-18)30(33)47-15(4)39/h10,12,17-18,20-24,26-31,42,44H,11H2,1-9H3/t12-,17-,18+,20+,21+,22-,23-,24+,26-,27+,28-,29+,30+,31+,33+,34-,35+,36-/m1/s1
|
| Chemical Name |
[(1S,2S,3R,5S,7S,9S,10R,11R,12S,13S,14R,15R,16S,17S,22S,23S,24R,25R)-10,14,25-triacetyloxy-3,22-dihydroxy-11,15,17,22,23-pentamethyl-4,21-dioxo-8,20-dioxaheptacyclo[13.10.0.02,12.05,11.07,9.016,24.019,23]pentacos-18-en-13-yl] acetate
|
| 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: 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 : ~100 mg/mL (~142.30 mM)
|
|---|---|
| Solubility (In Vivo) |
Solubility in Formulation 1: ≥ 2.5 mg/mL (3.56 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 25.0 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: ≥ 2.5 mg/mL (3.56 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 25.0 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. View More
Solubility in Formulation 3: ≥ 2.5 mg/mL (3.56 mM) (saturation unknown) in 10% DMSO + 90% Corn Oil (add these co-solvents sequentially from left to right, and one by one), clear solution. |
| Preparing Stock Solutions | 1 mg | 5 mg | 10 mg | |
| 1 mM | 1.4230 mL | 7.1150 mL | 14.2300 mL | |
| 5 mM | 0.2846 mL | 1.4230 mL | 2.8460 mL | |
| 10 mM | 0.1423 mL | 0.7115 mL | 1.4230 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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