Patent Abstract:
this invention relates to a pharmaceutical composition for treating cancer , comprising an effective amount of a compound represented by formula : wherein r is — ccoccocc — or — ccoccoccocc —; and a pharmaceutical acceptable carrier . this invention also relates to a method for treating cancer , comprising administering a therapeutically effective amount of said compound to a subject ; and a method for stabilizing g4 structure of telomere by using this compound .

Detailed Description:
3 , 6 - bis ( 1 - methyl - 4 - vinylpyridinium ) carbazole diiodide ( bmvc ) is known as a fluorescent marker for cancer diagnosis ( see kang et al ., 2007 ) and a g4 stabilizer for possible anti - tumor agent ( see chang et al ., 2004b ). bmvc can not only stabilize the g4 structures of human telomeres , but also accelerate telomere shortening and inhibit cancer proliferation ( see huang et al ., 2008 ). in the present invention , the inventors have modified bmvc by substituting the tetraethylene glycol with a methyl - piperidinium cation at n - 9 position of bmvc to obtain bmvc - 8c3o . it is found that the tetraethylene glycol moiety with a methyl - piperidinium cation can induce the formation of g4 structures and convert the g4 structures of human telomeres from nonparallel to parallel forms in a k + solution , which cannot be achieved by the un - modified bmvc . moreover , bmvc merely increase the melting temperature of the g4 structures of human telomeres by approximately 20 ° c ., but the bmvc - 8c3o of the present invention significantly increases the melting temperature by about 50 ° c ., which is far greater than that of bmvc . the examples of the present invention are provided hereinafter , however , these examples are not used for limit the scope of the present invention . those skilled in the art will recognize and understand them without further explanation . all the references are hereby incorporated by reference in its entirety herein . the synthesis of the target bmvc derivatives were shown in scheme 1 . first , compound b2b was synthesized from 3 , 6 - dibromocarbazole 1 ( 2 g , 6 . 15 mmole , aldrich ) through 9 - position substitution by sodium hydride ( 0 . 295 g , 12 . 3 mmole , aldrich ) in dmf ( 20 ml ) under nitrogen . a dibromo alkane represented by the formula br — r — br ( r ≡ ccoccoccocc —) ( 100 mmole ) was then added and the mixture was refluxed for 12 hours . methanol was slowly added into the reaction system to cool and quench the waste sodium hydride . then the solution was extracted with h 2 o / ethyl acetate ( 1 / 1 , v / v ) twice and the organic layer was dried by mgso 4 . the product b2b was collected and purified via flash column chromatography by silica gel column with hexane / ethyl acetate ( 2 / 1 , v / v ) as the eluent . the dry powder of compound b2b , piperidine ( 0 . 5 ml , aldrich ) and nah ( 1 . 5 mmole ) were refluxed in ethanol ( 20 ml ) for 6 hours to obtain the compound b3b which was terminated by piperidine . the solvent was evaporated in vacuum and the residue was purified via flash column chromatography by silica gel column with hexane / ethyl acetate ( 1 / 2 , v / v ) as the eluent to collect the yellow product b3b . then the product b3b , 4 - vinylpyridine and the mixed powders of palladium ( ii ) acetate and tri - o - tolylphosphine were dissolved in the triethylamine / acetonitrile solvent pairs and coupled in a high - pressure system , and this system was kept under about 105 ° c . for two days . the precipitant was collected and then extracted with h 2 o / ch 2 cl 2 ( 1 : 1 , v / v ) twice . the solids insoluble in ch 2 cl 2 layer were filtered and collected , washed with hot thf twice , and then dried by mgso 4 . the product was purified by flash column chromatography with ch 2 cl 2 / n - hexane ( 1 : 1 , v / v ) as the eluent to obtain the crude powders b4b , which was then added into a 5 %- 10 % triethylamine solution . after that , b4b was refluxed with excess ch 3 i in dmf and the target product , n9 - substituted bmvc derivatives ( bmvc - 8c3o ), was obtained as an orange - red powder . the yield and nmr information are listed below : 3 , 6 - bis ( 1 - methyl - 4 - vinylpyridium iodide )- 9 -( 1 -( 1 - methyl - piperidinium iodide )- 3 , 6 , 9 - trioxaundecane ) carbazole ( bmvc - 8c3o ): ( yield : 86 %, mp & gt ; 300 ° c . ), 1 h nmr ( 400 mhz , dmso - d6 ) δ : 8 . 80 ( d , j = 6 hz , 4h ), 8 . 68 ( s , 2h ), 8 . 23 ( d , j = 16 hz , 2h ), 8 . 20 ( d , j = 7 . 2 hz , 4h ), 7 . 90 ( d , j = 8 . 8 hz , 2h ), 7 . 76 ( d , j = 8 . 4 hz , 2h ), 7 . 59 ( d , j = 16 hz , 2h ), 4 . 64 ( t , 2h ), 4 . 24 ( s , 6h ), 3 . 82 ( t , 2h ), 3 . 71 ( t , 2h ), 3 . 47 ( m , 4h ), 3 . 38 ( m , 10h ), 2 . 97 ( s , 3h ), 1 . 67 ( m , 4h ), 1 . 43 ( m , 2h ). another n9 - substituted bmvc derivative , bmvc - 6c20 , can be obtained in accordance with the above scheme , but dibromo alkane is different ( r ═— ccoccocc —). the yield and nmr information of bmvc - 6c20 are listed below : 3 , 6 - bis ( 1 - methyl - 4 - vinylpyridium iodide )- 9 -( 1 -( 1 - methyl - piperidinium iodide )- 3 , 6 - dioxaoctane ) carbazole ( bmvc - 6c20 ): ( yield : 83 %, mp & gt ; 300 ° c . ), 1 h nmr ( 400 mhz , dmso - d6 ) δ : 8 . 81 ( d , j = 6 hz , 4h ), 8 . 68 ( s , 2h ), 8 . 23 ( d , j = 16 hz , 2h ), 8 . 21 ( d , j = 7 . 2 hz , 4h ), 7 . 92 ( d , j = 8 . 8 hz , 2h ), 7 . 76 ( d , j = 8 . 4 hz , 2h ), 7 . 58 ( d , j = 16 hz , 2h ), 4 . 68 ( t , 2h ), 4 . 33 ( s , 6h ), 3 . 85 ( t , 2h ), 3 . 68 ( t , 2h ), 3 . 51 ( m , 2h ), 3 . 42 ( m , 6h ), 2 . 99 ( s , 3h ), 1 . 67 ( m , 4h ), 1 . 43 ( m , 2h ). all oligonucleotides were purchased from bio basic inc . and used without further purification , including the single strand sequence derived from telomere of human chromosome , d ( ttaggg ) 4 ( ht24 ) ( seq id no : 1 ). solutions of 10 mm tris - hcl ( ph 7 . 5 ) and its mixed solutions with kcl were mixed with each dna sample and heated to 95 ° c . for 10 min first , cooled slowly to room temperature , and then stored for 48 h at 4 ° c . before use . first , circular dichroism spectroscopy ( cd spectra ) was used to examine whether bmvc - 8c3o could induce the formation of g4 structure of human telomere , ht24 , under a salt - deficient condition ( chang et al ., 2007 ; bugaut et al ., 2008 ; giraldo et al ., 1994 ). it is well - known that the linear parallel g4 structures , such as a propeller form , give a positive band at around 265 nm and a negative band at around 240 nm , while the anti - parallel g4 structures , such as a basket or chair form , show two positive bands at around 295 nm and 240 nm and a negative band at around 265 nm . in addition , the hybrid type g4 structures ( 3 + 1 , including 3 parallel and 1 anti - parallel g4 structures ) give a positive cd band at around 290 nm and a positive shoulder band at around 265 nm . the anti - parallel and hybrid type are both so - called “ non - parallel ” g4 structures . these spectral features are mainly attributed to the specific guanine stacking in various g4 structures . j - 815 spectropolarimeter ( jasco , japan ) with a 2 nm bandwidth at a 50 nm / min scan speed and a 0 . 2 nm step resolution was used to obtain cd spectra , and the following data was provided as an average of 10 scan results . the cd spectra were measured by monitoring the g4 structures under n 2 over the range of 210 nm to 350 nm , and the thermal melting curves , as a function of temperature , were obtained by monitoring the cd intensity at 265 nm . three independently scans were recorded for each sample . the melting temperature ( tm ) was measured from the first differentiation of the melting curve . fig1 a shows the cd spectra of 20 μm ht24 obtained under a salt - deficient condition at room temperature . this function graph is obtained by titrating 20 μm ht24 with bmvc - 8c3o , in which the equivalence ratio of ht24 : bmvc - 8c3o is from 1 : 0 to 1 : 10 . upon this titration , the cd band at around 295 nm gradually increases , which shows the anti - parallel g4 structures gradually increase . the cd band at 295 nm increases until the equivalence ratio of ht24 : bmvc - 8c3o ( g4 ligand ) reaches 1 : 3 . meanwhile , the cd band at around 265 nm gradually increases during the titration until the equivalence ratio of ht24 : bmvc - 8c3o reaches 1 : 10 , which shows the parallel g4 structures also gradually increase . at last , a hybrid of parallel and anti - parallel g4 structures is formed . these data show that bmvc - 8c3o can induce g4 formation under a salt - deficient condition at room temperature , and the parallel and anti - parallel g4 structures possibly coexist under a higher concentration of bmvc - 8c30 . in addition , fig1 b , a function graph of bmvc - 8c3o concentration , shows the normalized data of cd intensity at around 265 nm . when the concentration of bmvc - 8c3o is higher , the cd intensity at 265 nm is stronger , which means that bmvc - 8c3o induces the formation of parallel g4 structures . from above , it should be clear that ht24 itself does not have any g4 structure , and the addition of bmvc - 8c3o induces ht24 to form g4 structures which is a hybrid of parallel and anti - parallel g4 structures . 5 μm ht24 and 1 eq . bmvc - 8c3o ( the equivalence ratio of ht24 : bmvc - 8c30 is 1 : 1 ) were used to detect whether bmvc - 8c3o could convert the g4 structure conformation of ht24 from non - parallel to parallel . the cd spectra of the ht24 and its complexes with 1 eq . bmvc - 8c3o mixed in a 150 mm k + solution or in a 150 mm na + solution were measured right after the mixing step under room temperature , as shown in fig2 a and 2b (+ bmvc - 8c3o × 1 ). another set of spectra were obtained after these samples were annealed , i . e . heated at 95 ° c ., and then gradually cooled down to room temperature (+ bmvc - 8c3o × 1 anneal ). after comparing the cd spectra before and after annealing , it has been found that the cd pattern shows significant spectral changes in k + solution before and after annealing , but in na + solution , only cd intensity changes are observed . these spectral features are consistent with the spectral changes of d [ g 3 ( t 2 ag 3 ) 3 ] ( ht21 ) in k + or na + solution upon the addition of 40 % peg ( see xue et al ., 2007 ). that is to say , the peak at 265 nm ( parallel g4 structure ) increases and the peak at 290 nm ( non - parallel g4 structure ) decreases . this is , bmvc - 8c3o and 40 % peg can converse the g4 structures from the non - parallel to the parallel . fig2 c shows the spectral changes upon addition of 5 eq . bmvc - 8c3o at 37 ° c ., as a function of time . the cd results suggest that bmvc - 8c3o can convert the conformation of g4 structures from non - parallel to parallel at 37 ° c . in k + solution without annealing . in addition , 0 . 1 mm ht24 was mixed with 5 eq . bmvc - 8c3o and dissolved in a h 2 o / d 2 o ( 90 %/ 10 %) solution containing 10 mm tris - hcl ( ph 7 . 5 ) and 150 mm kcl to prepare samples for nmr ( control sample was without bmvc - 8c3o ). then the imino protons in the chemical shift range of 9 - 14 ppm were measured on a bruker aviii 800 mhz spectrometer using a pulsed - gradient spin - echo sequence with a selective refocusing pulse , and the chemical shift was measured relative to a d 2 o solution of dss as an external reference . fig2 d shows the imino proton spectra ( i . e . 1 h nmr spectra ) of ht24 and its complex with bmvc - 8c3o in 150 mm k + solution after adding bmvc - 8c3o 2 h and 12 h . the nmr spectra show significant changes after adding 5 eq . bmvc - 8c3o , which indicate that bmvc - 8c3o can induce the structural change of ht24 in k + solution . when 1 eq . bmvc - 8c3o is used , the spectra changes are only induced after annealing . however , when the concentration of bmvc - 8c3o is increasing , the necessity of the annealing step decreases . for example , 5 eq . bmvc - 8c3o induces spectra changes of the complex of ht24 and bmvc - 8c3o in 150 mm k + solution at 37 ° c . ( converting from non - parallel to parallel ), and the annealing step is not necessary ( see fig2 c ). from the data shown in fig1 and 2 , it should be clear that the bmvc - 8c3o of the present invention induces parallel and non - parallel g4 structures of ht24 in a salt - deficient condition ( i . e . without na + or k + ions ). yet , in a condition with k + ions , the bmvc - 8c3o of the present invention converts g4 structure of ht24 from non - parallel to parallel . the bmvc - 8c3o of the present invention can not only induce the formation of g4 structures , but also stabilize g4 structures . fig3 a and 3b show the cd spectra of ht24 and its complex with 5 eq . bmvc - 8c3o in 5 mm k + solution at 25 ° c . and 95 ° c ., respectively . fig3 c shows the normalized cd intensity of ht24 and its complex with 5 eq . bmvc - 8c3o in 5 mm or 150 mm k + solution at 265 nm , as a function graph of temperature . after adding 5 eq . bmvc - 8c3o at 37 ° c . 24 hours , the melting temperature ( tm ) of ht24 in 5 mm k + solution is significantly increased from approximately 41 ° c . to & gt ; 90 ° c ., and the temperature is enhanced by about 50 ° c . this shows that bmvc - 8c3o is a better g4 stabilizer , and can be used as an anti - tumor agent . cl1 - 0 lung cancer cells and mrc - 5 normal human lung fibroblasts were used in the following experiments , wherein cl1 - 0 cells were cultured in rpmi - 1640 medium containing 10 % fbs ( fetal bovine serum ) and 1 % antibiotics ( including penicillin and streptomycin ), and mrc - 5 cells were cultured in mem medium containing 10 % fbs and 1 % antibiotics . when these cells were subcultured , culture medium containing 1 . 0 μm bmvc - 8c3o ( 1 % dmso for the control ) was used to separate these cells into 5 × 10 5 cells / petri dish having a diameter of 6 cm . after 2 or 3 days , these cells were trypsinized and counted , and subcultured again with the same density and method . cells were subcultured repeatedly until the total cell number was less than 5 × 10 5 . the result is shown in fig4 . fig4 a and 4b show the cell proliferation curves of cl1 - 0 cancer cells and mrc - 5 normal cells that long - term treated with 1 . 0 μm bmvc - 8c3o . from fig4 a , it is obvious that the proliferation of cl1 - 0 cancer cells is slowed from around day 10 , and stopped at around day 20 . fig4 b shows that bmvc - 8c3o does not significantly affect mrc - 5 normal cells . from above , it shows that bmvc - 8c3o is an excellent g4 stabilizer and a good candidate for inhibiting proliferation of cancer cells . the present invention has taken advantage of the molecular crowding effect to modify g4 ligands , thereby inducing g4 structural changes of ht24 at 37 ° c . particularly , the bmvc derivatives ( such as 3 eq . or more of bmvc - 8c3o ) induce an extremely stable propeller g4 structure , enhance the melting temperature by approximately 50 ° c ., and stop proliferation of cancer cells ( such as cl1 - 0 cells ) without affecting normal cells ( such as mrc - 5 cells ). furthermore , similar results are also observed in the case of bmvc - 6c20 ( data not shown ). the present invention provides a better g4 stabilizer and the anti - cancer application thereof . the preferred examples of the present invention are disclosed herein ; 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