JP6468549B2 - Benzothiophene derivatives with anticancer activity - Google Patents

Description

  The present invention relates to a compound having an anticancer effect and a pharmaceutical composition.

Cancer is the leading cause of death in Japan, and the morbidity rate is very high at about 50%.
Chemotherapy with anticancer drugs plays an important role in cancer treatment, and in recent years it has also been successful as an adjunct therapy to the most advanced treatments.
On the other hand, severe side effects such as complete hair loss, severe diarrhea and vomiting due to administration of cytotoxic substances, cytopenia, systemic allergies, etc. are major issues to be found as soon as possible.
Yet another major problem to be overcome is the multidrug resistance (MDR) of cancer cells by continuous administration of chemotherapeutic agents.
Cancer cells in which MDR is expressed overexpress transporters that excrete foreign substances from the cells.
As a result, not only the administered anticancer drug but also all kinds of drugs are released to the outside of the cell, and the effects of the drugs are significantly reduced.
Patent Document 1 discloses a 10′-fluoro-vinca alkaloid compound that inhibits microtubule formation or inhibits mitosis for MDR cancer cells, but the structure of the compound is different from that of the present invention.

Special table 2013-520499 gazette

  An object of this invention is to provide the novel compound which has the outstanding anticancer effect | action.

The compound according to the present invention is a benzothiophene derivative represented by the following general formula (1) or a pharmaceutically acceptable salt thereof.
“In the formula, R ₁ is H, OH, a halogeno group, an alkyl group having 1 to 12 carbon atoms, an alkenyl group, an alkynyl group, an alkoxy group, an alkylamino group, or an alkylthio group, An optionally substituted aryl group, an optionally substituted benzyl group, an optionally substituted carbocyclic or heterocyclic ring fused to the 5-6 position.
R ₂ is H, OH, a halogeno group, an alkyl group having 1 to 12 carbon atoms, an alkenyl group, an alkynyl group, an alkoxy group, an alkylamino group, an alkylthio group, an optionally substituted aryl group, A benzyl group which may be substituted. "

One embodiment of the compound according to the present invention is a benzothiophene derivative represented by the following general formula (2) or a pharmaceutically acceptable salt thereof.
"In the formula, R ₁₁ and R ₁₃ are H, an alkyl group having 1 to 12 carbon atoms, an alkenyl group, an alkynyl group, an optionally substituted aryl group, and an optionally substituted benzyl group. It is.
R ₁₂ and R ₁₄ are H, OH, an alkyl group having 1 to 12 carbon atoms, an alkenyl group, an alkynyl group, an alkoxy group, an alkylamino group, or an alkylthio group, and an optionally substituted aryl group , An optionally substituted benzyl group.
R ₂ is H, OH, a halogeno group, an alkyl group having 1 to 12 carbon atoms, an alkenyl group, an alkynyl group, an alkoxy group, an alkylamino group, an alkylthio group, an optionally substituted aryl group, A benzyl group which may be substituted. "

Among the compounds according to the present invention, a particularly preferred compound is a benzothiophene derivative represented by the following chemical formula (3) or a pharmaceutically acceptable salt thereof.
“In the formula, Me is a methyl group, and iPr is an isopropyl group.”

A pharmaceutical composition comprising the above-mentioned compound as an active ingredient acts on microtubules constituting the cytoskeleton, and inhibits microtubule polymerization or depolymerization, or inhibits mitotic spinning system formation.
Among the compounds according to the present invention, for example, a compound having a hydroxyl group at the 6′-position of benzothiophene shown in the following scheme (1) does not act in the G ₁ phase of the cell cycle, but in the G ₂ / M phase. Some work.
The pharmaceutical composition according to the present invention also has a high microtubule inhibitory action against multidrug resistant (MDR) cancer cells.

Since the compound according to the present invention has a skeleton similar to a flavonoid widely biosynthesized in many plants as a natural product, it is presumed to have high biological stability.
The taxol and vinca alkaloids that have been proposed so far act on the tubulin taxol binding site and vinca alkaloid binding site, respectively, whereas the compounds according to the present invention act on the colchicine binding site. Presumed to be.

The evaluation result of the growth inhibitory effect of a cancer cell is shown. No. The photograph of the cell cycle change with respect to 5 compounds is shown. The cell cycle photograph with respect to a compound (6) is shown. The analysis result of a binding site is shown.

The benzothiophene derivative according to the present invention can be easily synthesized from acetophenone and benzothiophene-3-carbaldehyde.
The general scheme is shown in the following scheme (1).
<Scheme (1)>

Next, specific reaction scheme examples are shown in the following scheme (2) and scheme (3).
<Scheme (2)>
Here, MOM represents a methoxymethyl group that functions as a protecting group.
<Scheme (3)>

<Evaluation>
Substituents R11, R12, R13 of the following chemical formula (4) were selected as shown in the table of FIG. 1-No. The cancer cell growth inhibition evaluation results of 6 are shown in the table of FIG.
In the table, Bn represents a benzyl group.
In the table, Chrysin compared as Reference 1 is shown in the following chemical formula (5).
The value of 50% inhibitory concentration IC ₅₀ is shown for the types of cancer cells shown below the table in FIG.
Here, KB-V cells are multidrug resistant cancer cells in which P-glycoprotein is overexpressed by continuous administration of Vincristin (anticancer agent) to KB cells (human oral epidermoid carcinoma cells).
Evaluation of the growth inhibitory effect test on cancer cells was performed as follows.
Stock cell lines were grown in T-75 flasks at 37 ° C. in 5% CO ₂ air.
Trypsinized cell suspensions were seeded in 96-well microplates with compounds to be evaluated (4,000-12,000 cell density).
After 72 hours of culture, the cells were fixed with 50% trichloroacetic acid and then stained with 0.04% sulforhodamine B.
The protein-bound dye was solubilized with 10 mM Tris base and the concentration of the compound at which cell growth was reduced by 50% compared to DMSO subjects was determined.
As a result, no. “2- (Benzo [b] thiophen-3-yl) -5-hydroxy-7-isopropoxy-6-methoxy-4H-chromen-4-one”, a compound of 5, has an IC ₅₀ against various cancer cells. , Showed a strong growth inhibitory effect of 0.1 μM or less.
This compound can also represent a benzothiophenylchromone derivative.
No. FIG. 2 shows a cell photograph of the α-tubulin inhibitory effect on the concentration of 5 compounds.
In FIG. 2, DMSO is a control and CA-4 is combretastine CA-4.
As a result, mitotic spindle dysplasia and chromosomal aggregation are frequently observed, and it is presumed that the cell cycle is stopped at the mitotic stage.
Moreover, when comparing the IC ₅₀ values of the compounds against KB cancer cells and multi-drug resistant KB-V cancer cells, The compound of No. 5 has a much larger cancer cell growth inhibitory effect than Chrysin.
In particular, compared with Paclitaxel, a multidrug resistant cancer cell inhibitory effect is observed.

Next, an example of a compound having a hydroxyl group at the 6′-position of benzothiophene will be described.
The compound represented by the following chemical formula (6) is 6,8,8-triethyl-5-hydroxy-2- (6'-hydroxybenzo [b] thiophen-3-yl) -4H-chromene-4,7 (8H)- dione.
According to cell cycle analysis of human cancer cells (PC-3) by flow cytometry, as shown in FIG. 3, accumulation of G ₂ / M phase cells was recognized in the hydroxy derivative of compound (6).
As a result of immunostaining the cancer cells treated with the hydroxy derivative with an anti-tubulin antibody, formation of multipolar mitotic spindles was observed.
From this, it was clarified that the hydroxy derivative caused multipolar spindle formation induction by the inhibitory action of bipolar spindle formation and inhibited the transition from the pre-phase to the mid-phase.
On the other hand, stationary phase microtubules in cells showed normal morphology.
Excessive stabilization was observed in quiescent microtubules of human cancer cells treated with a high concentration (20 μM) of compound.
From these results, it was clarified that the compound (6) selectively inhibits only mitotic spindle formation without destroying the dynamics of stationary microtubules.
That is, compound (6) has a unique physiological activity that does not inhibit quiescent microtubule dynamics at concentrations that prevent normal bipolar spindle formation.
From the analysis of the binding mode to the tubulin dimer by computer modeling, it was inferred that hydrogen bonds were formed with α-tubulin and β-tubulin as shown in FIG.
Therefore, it is speculated that the formation of hydrogen bonds with both α and β tubulins suppresses the polymerization-inhibiting action on stationary microtubules to a minimum, but may completely prevent mitotic spindle formation.

Claims (7)

A benzothiophene derivative represented by the following general formula (4) or a pharmaceutically acceptable salt thereof.
“In the formula, R ₁₁ is any one of hydrogen, a methyl group, and an isopropyl group.
R ₁₂ is hydrogen or a methoxy group.
R ₁₃ is any one of hydrogen, a methyl group, a benzyl group, and an isopropyl group. " A benzothiophene derivative represented by the following chemical formula (3) or a pharmaceutically acceptable salt thereof.
“In the formula, Me is a methyl group, and iPr is an isopropyl group.” A benzothiophene derivative represented by the following chemical formula (6) or a pharmaceutically acceptable salt thereof.
“In the formula, Et is an ethyl group.”   The pharmaceutical composition which has the microtubule inhibitory effect or spindle formation inhibitory effect which uses the compound in any one of Claims 1-3 as an active ingredient. 4. The pharmaceutical composition according does not act on microtubules G ₁ phase.   The pharmaceutical composition according to claim 4 or 5, which has a microtubule inhibitory action against multidrug resistant (MDR) cancer cells. The pharmaceutical composition according to claim 4, wherein the cell cycle is stopped at the mitotic phase.