Abstract:
The invention concerns four novel secondary metabolites of the  Burkholderia rhizoxina  endosymbiont, a method for isolating said compounds from cultures of the bacteria and the use of said substances. 
     The invention aims at providing novel rhizoxin derivatives with an antimitotic effect. Therefore, the following substances 1-4 are isolated, said substances exhibiting potential antifungal, cytotoxic and antiproliferative properties.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The invention concerns four novel secondary metabolites of the  Burkholderia rhizoxina  endosymbiont, a method for isolating said compounds from cultures of the bacteria and the use of said substances. 
         [0002]    Apart from cardiovascular diseases, malign tumors are the second commonest cause of death in Germany (DKFZ, 2000). 
         [0003]    Despite intensive research in the last years, the treatment of some types of cancer is still a great challenge. 
         [0004]    Rhizoxin is a macrocyclic polyketide with an antimitotic effect that has been isolated from fungi of the  Rhizopus  genus (Iwasaki, S. et al.  J. Antibiot.,  1984, 37, 354-362): It has a high activity against a number of human cancer cell lines, particularly against vincristin-resistent cells, too, and therefore it has become the focus of interest as a potential chemotherapeutic drug. Its effect is based on a bonding to beta-tubulin eukaryotic cells that inhibits the assembling of microtubuli. Recently, we could show that rhizoxin is not formed by  Rhizopus  but by endosymbionts of the fungus (L. Partida-Martinez and C. Hertweck,  Nature,  2005, 437, 884-888). By cultivating the endosymbiont the production of rhizoxin and of derivatives thereof could be considerably increased. 
       SUMMARY OF THE INVENTION 
       [0005]    It is the object of the present invention to make novel, antimitotic rhizoxin derivatives available and to provide a method for their production. Moreover, the use of said substances is described. 
         [0006]    According to the invention, the following antimiotic rhizoxin derivatives are provided: 
         [0000]    
       
                 
         
             
             
         
       
     
     
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0007]    The production of the substances according to the formulas is carried out by the cultivation of the endosymbiotic bacteria strain  Burkholderia rhizoxina , the subsequent extraction of the culture and the isolation of the compounds by means of chromatographic methods. 
         [0008]    For this purpose,  Burkholderia rhizoxina  DSM 17360 is cultivated as a shaking culture on a liquid medium and then the grown culture is extracted with organic solvents. 
         [0009]    Afterwards, the extract is fractioned via size exclusion chromatography on dextrangels (Sephadex LH-20). The final purification of the substances is performed by means of preparative HPLC by using an RP-18 phase and acetonitril/water-mixtures in the gradient mode. 
         [0010]    The structure of the compounds 1-4 is made clear by IR spectroscopy, high-resolution mass spectrometry, and 1D and 2D NMR spectroscopy. 
         [0011]    The inventive substances 1-4 show very strong antiproliferative and cytotoxic effects (e.g. for L-929 mouse fibroblast, K-562 human leukemia cells and HeLa human cervix carcinoma line) and an antifungal activity (e.g. against  Glomerella cingulata, Penicillium notatum, Fusarium culmorum, Hamigera avellanea, Aspergillus fumigatus ). (See Table 1.) 
         [0012]    Due to their antiproliferative and cytotoxic properties, the substances 1-4 are very well suited as chemotherapeutic drugs for the treatment of cancer diseases. 
         [0013]    Furthermore, the good antifungal effect of the substances 1-4 allows to use them in the therapy of mycoses. 
         [0014]    The compounds (1-4) as such can be used in substance or as a pharmaceutical preparation in combination with common additives. 
       Exemplary Embodiments 
       [0015]      Burkholderia rhizoxina  DSM 17360 is cultivated as a shaking culture by means of fermentation on a liquid medium (composition: cornstarch 1%, glycerin 0.5%, yeast extract 1%, corn steep water 1%, CaCO 3  1%) at 30° C. (4 d). The complete grown culture is extracted with ethyl acetate via stirring and afterwards filtered. This procedure is repeated twice. The combined extracts are dried over sodium sulphate and concentrated. The extract obtained is dissolved in methanol and fractioned via size exclusion chromatography on Sephadex LH-20. The substances 1 through 4 are isolated via preparative HPLC by using an RP-18 phase and acetonitril/water-mixtures (method: MeCN/H 2 O 25:75 5 min, then to MeCN/H 2 O 80:20 during 35 min, then to MeCN 100% during 5 min, detection at 311 nm). 
       Substance 1: 
       [0016]    White powder. IR (ATR, solid film) v max /cm −1  2980, 2926, 2886, 1704, 1654, 1577, 1483, 1380, 1275, 1202, 1153, 1105, 1046, 963, 865, 827, 780, 746, 701.  1 H NMR (300 MHz) and  13 C NMR (75 MHz) in d-methanol [see Table 2]. (+)-ESI-MS m/z 614 [M+H] + , m/z 636 [M+Na] + . HRESI-MS: m/z [M+Na] + =636.3143 (calculated for C 34 H 47 NO 9 Na 636.3143) 
       Substance 2: 
       [0017]    White powder. IR (ATR, solid substance) v max /cm −1  2977, 2935, 2924, 1705, 1652, 1577, 1437, 1377, 1260, 1202, 1152, 1105, 1048, 1007, 966, 863, 827, 780, 748, 702.  1 H NMR (300 MHz) and  13 C NMR (75 MHz) in d-chloroform [see Table 2]. (+)-ESI-MS m/z 628 [M+H] + , m/z 650 [M+Na] + . HRESI-MS: m/z [M+H] + =628.3478 (calculated for C 35 H 50 NO 9  628.3486) 
       Substance 3: 
       [0018]    White powder. IR (ATR, solid substance) v max /cm −1  2960, 2938, 2928, 1710, 1654, 1577, 1437, 1367, 1275, 1199, 1151, 1108, 1084, 1048, 1008, 971, 862, 827, 753, 706.  1 H NMR (300 MHZ) and  13 C NMR (75 MHz) in d-chloroform [see Table 2]. (+)-ESI-MS m/z 642 [M+H] + , m/z 664 [M+Na] + . HRESI-MS: m/z [M+H] + =642.3612 (calculated for C 36 H 52 NO 9  642.3637) 
       Substance 4: 
       [0019]    White powder. IR (ATR, solid substance) v max /cm −1 1 H NMR (300 MHz) and  13 C NMR (75 MHz) in d-methanol [see Table 2]. (+)-ESI-MS m/z 642 [M+H] + , m/z 664 [M+Na] + . HRESI-MS: m/z [M+Na] + =664.3434 (calculated for C 36 H 51 NO 9 Na 664.3456) 
         [0000]    
       
         
               
               
               
               
               
             
           
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                   
                 L-929 
                 K-562 
                 HeLa 
               
               
                   
                   
                 GI 50   
                 GI 50   
                 CC 50   
               
               
                   
                 Substance 
                 [μg/ml] 
                 [μg/ml] 
                 [μg/ml] 
               
               
                   
                   
               
             
             
               
                   
                 1 
                   
                 1.5 × 10 −2   
                 9 × 10 −2   
               
               
                   
                 2 
                 5 × 10 −2   
                  3 × 10 −5   
                 2.8 × 10 −4    
               
               
                   
                 3 
                 5 × 10 −2   
                 &lt;3 × 10 −5   
                 &lt;3 × 10 −5   
               
               
                   
                 4 
                 1.2 × 10 −2    
                 &lt;3 × 10 −5   
                     2 × 10 −53   
               
               
                   
                   
               
             
          
         
       
     
         [0020]    The examination of the antiproliferative and cytotoxic properties of the substances 1-4 has been performed via the method described in the literature (H. M. Dahse, B. Schlegel, U. Gräfe,  Pharmazie  2001, 56, 489-491). The antifungal activity has been determined via the agar diffusion test. (See Table 2.) 
         [0000]    
       
         
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 2 
               
               
                   
               
               
                   
                   
                   
                   
                   
                   
                   
                 4 
                   
               
               
                   
                 1 
                 1 
                 2 
                 2 
                 3 
                 3 
                 δH (J 
                 4 
               
               
                 position 
                 δH (J [Hz]) 
                 δC 
                 δH (J [Hz]) 
                 δC 
                 δH (J [Hz]) 
                 δC 
                 [Hz]) 
                 δC 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                  1 
                 — 
                 167.0 
                 — 
                 165.7 
                 — 
                 165.1 
                 — 
                 166.9 
               
               
                  2 
                 5.78 d (15.6) 
                 126.2 
                 5.70 d (15.6) 
                 124.6 
                 5.67 d (15.6) 
                 124.9 
                 5.77 d (15.6) 
                 126.2 
               
               
                  3 
                 6.79 ddd (15.5, 8.1, 
                 147.7 
                 6.78 ddd (15.5, 9.0, 
                 147.1 
                 6.74 ddd (15.5, 9.0, 
                 146.4 
                 6.78 ddd (15.6, 8.2, 
                 147.6 
               
               
                   
                 7.5) 
                   
                 6.5) 
                   
                 6.6) 
                   
                 7.6) 
               
               
                  4 
                 2.50 m* 
                 36.8 
                 2.40 m 
                 37.7 
                 2.39 m* 
                 37.5 
                 2.47 m 
                 36.8 
               
               
                   
                 2.15 m 
                   
                 2.06 m* 
                   
                 2.06 m 
                   
                 2.13 m 
               
               
                  5 
                 2.24 m 
                 32.8 
                 2.21 m 
                 32.2 
                 2.21 m 
                 32.1 
                 2.28 m 
                 33.0 
               
               
                  5a 
                 2.50 dd* 
                 41.3 
                 2.52 dd (15.8, 6.9) 
                 40.5 
                 2.51 dd (15.8, 6.8) 
                 40.4 
                 2.52 dd (15.2, 5.6) 
                 41.2 
               
               
                   
                 2.35 dd 
                   
                 2.35 d (6.9) 
                   
                 2.34 dd (15.7, 6.9)* 
                   
                 2.36 dd (15.2, 8.2) 
               
               
                  5b 
                 — 
                 176.6 
                 — 
                 173.5 
                 — 
                 173.5 
                 — 
                 174.8 
               
               
                  6 
                 1.75 m 
                 39.2 
                 1.75 dd (14.5, 5.9) 
                 37.9 
                 1.71 m 
                 37.8 
                 1.71 m 
                 39.1 
               
               
                   
                 1.10 m 
                   
                 1.09 m 
                   
                 1.09 m 
                   
                 1.05 m 
               
               
                  7 
                 3.13 m 
                 73.9 
                 3.20 m 
                 74.3 
                 3.16 m 
                 74.2 
                 3.11 m 
                 73.9 
               
               
                  8 
                 2.02 m 
                 46.8 
                 2.03 m* 
                 45.5 
                 2.02 m 
                 45.5 
                 2.00 m* 
                 46.8 
               
               
                  8a 
                 1.02 d (6.0)* 
                 17.7 
                 1.03 d (6.65) 
                 17.0 
                 1.02 d (6.6) 
                 17.0 
                 1.02 d (6.7) 
                 17.7 
               
               
                  9 
                 5.45 dd (15.6; 
                 142.3 
                 5.51 dd (15.6; 9.4) 
                 141.6 
                 5.48 dd (15.6; 
                 141.4 
                 5.43 dd (15.6; 9.3) 
                 142.3 
               
               
                   
                 9.2) 
                   
                   
                   
                 9.4) 
               
               
                 10 
                 5.16 dd (15.7; 
                 127.3 
                 5.14 dd (15.6; 8.4) 
                 125.4 
                 5.12 dd (15.6; 
                 125.6 
                 15.16 dd (15.6; 8.2) 
                 127.3 
               
               
                   
                 8.1) 
                   
                   
                   
                 8.5) 
               
               
                 11 
                 3.00 (8.2) 
                 63.4 
                 3.16 d (8.5) 
                 64.2 
                 3.11 d (8.3) 
                 63.9 
                 3.00 d (8.3) 
                 63.3 
               
               
                 12 
                 — 
                 66.3 
                 — 
                 65.6 
                 — 
                 65.6 
                 — 
                 66.2 
               
               
                 12a 
                 1.29 s 
                 11.2 
                 1.33 s 
                 11.1 
                 1.31 s 
                 11.1 
                 1.29 s 
                 11.2 
               
               
                 13 
                 2.96 dd (11.0; 
                 79.5 
                 3.09 dd (10.2, 3.6) 
                 78.2 
                 3.00 dd (10.8, 
                 78.3 
                 2.94 dd (11.0; 2.6) 
                 79.5 
               
               
                   
                 2.7) 
                   
                   
                   
                 2.8) 
               
               
                 14 
                 2.03 m* 
                 34.0 
                 1.95 m* 
                 33.1 
                 1.94 m 
                 31.8 
                 1.95 m* 
                 34.0 
               
               
                   
                 1.80 m 
                   
                 1.89 m 
                   
                 1.78 m 
                   
                 1.76 m 
               
               
                 15 
                 4.76 m 
                 75.3 
                 4.85 m 
                 74.1 
                 4.76 dd (9.9, 
                 73.3 
                 4.75 dd (9.7; 3.5) 
                 74.9 
               
               
                   
                   
                   
                   
                   
                 3.6) 
               
               
                 16 
                 2.05 m 
                 41.4 
                 1.98 m* 
                 40.3 
                 2.09 m 
                 39.4 
                 2.06 m 
                 40.6 
               
               
                 16a 
                 0.99 d (6.5)* 
                 10.3 
                 0.94 d (6.8) 
                 9.6 
                 0.97 d (6.8) 
                 10.2 
                 1.00 d (6.8) 
                 10.6 
               
               
                 17 
                 3.80 d (8.6) 
                 80.7 
                 3.88 d (6.0) 
                 77.2 
                 3.21 d (8.6) 
                 89.2 
                 3.33 d (8.9) 
                 90.8 
               
               
                 17- 
                 — 
                 — 
                 — 
                 — 
                 3.13 s 
                 56.2 
                 3.17 s 
                 56.5 
               
               
                 OCH3 
               
               
                 18 
                 — 
                 140.7 
                 — 
                 138.2 
                 — 
                 136.3 
                 — 
                 138. 
               
               
                 18a 
                 1.89 s 
                 12.0 
                 1.83 s 
                 12.9 
                 1.82 s 
                 11.6 
                 1.84 s 
                 11.7 
               
               
                 19 
                 6.14 d (10.9) 
                 128.4 
                 6.17 d (10.8) 
                 126.6 
                 6.06 d (10.8) 
                 129.2 
                 6.22 d (10.9) 
                 131.3 
               
               
                 20 
                 6.65 dd (15.1; 
                 125.9 
                 6.54 dd (15.1, 10.7) 
                 124.3 
                 6.57 dd (15.1, 
                 124.1 
                 6.71 dd (15.5; 
                 127.4 
               
               
                   
                 10.8) 
                   
                   
                   
                 10.7) 
                   
                 11.0) 
               
               
                 21 
                 6.40 d (15.2) 
                 138.3 
                 6.35 d (15.2) 
                 137.6 
                 6.34 d (15.2) 
                 137.6 
                 7.27 d (15.3) 
                 132.8 
               
               
                 22 
                 — 
                 139.0 
                 — 
                 136.9 
                 — 
                 136.9 
                 — 
                 137.2 
               
               
                 22a 
                 2.09 s 
                 14.7 
                 2.11 s 
                 14.4 
                 2.12 s 
                 14.3 
                 2.04 s 
                 21.0 
               
               
                 23 
                 6.21 s 
                 120.9 
                 6.22 s 
                 120.5 
                 6.23 s 
                 120.7 
                 5.78 s 
                 118.8 
               
               
                 24 
                 — 
                 139.5 
                 — 
                 138.8 
                 — 
                 138.7 
                 — 
                 139.1 
               
               
                 25 
                 7.79 s 
                 137.7 
                 7.50 s 
                 135.9 
                 7.50 s 
                 135.9 
                 7.74 s 
                 138. 
               
               
                 26 
                 — 
                 162.9 
                 — 
                 160.9 
                 — 
                 160.9 
                 — 
                 163.2 
               
               
                 26a 
                 2.43 s 
                 13.4 
                 2.43 s 
                 13.8 
                 2.43 s 
                 13.8 
                 2.43 s 
                 13.5 
               
               
                 27 
                 — 
                 — 
                 3.68 s 
                 51.7 
                 3.67 s 
                 51.7 
                 3.67 s 
                 52.0 
               
               
                   
               
               
                 *Partial overlapping of signals