Novel therapeutic compounds useful as hypolipidemic and hypocholesteremic agents
The present invention provides novel alkali metal salts of substituted α-(3-pentadecylphenoxy)-isobutyric acid of the general formula: ##STR1## wherein R is hydrogen or halogen, M is an alkali metal and x is 1 or 2 depending on the nature of the alkali metal. 
     The preferred halogen substitute for R in the above-mentioned formula is chlorine while the preferred alkali metals denoted by M are sodium, magnesium and calcium. 
     The novel compounds of the present invention carry a long alkyl chain of C 15  carbon atoms in the meta position to the side chain. The compounds have been found to possess particularly beneficial therapeutic activity in the reduction of serum cholesterol and triglyceride levels in rodents and evince substantially little toxicity. 
     According to a further feature of the invention, the novel alkali metal salts of the general formula: ##STR2## wherein R, M and x are as defined herein are prepared by a process which comprises reacting a correspondingly substituted α-(3-pentadecylphenoxy)-isobutyric acid of the general formula: ##STR3## wherein R is as defined above with an alkali metal salt followed by recovery of the desired product. 
     Preferably, the reaction is carried out in the presence of an aqueous alcoholic medium wherein the alcohol is selected from aliphatic alcohols having from 1 to 5 carbon atoms. The pH of the reaction mixture is conveniently maintained at about 8. 
     The alkali metals whose salts are employed for the reaction are as identified above and the salts in question can include the hydroxides, carbonates and halides. 
     In the case of the sodium salt of α-(3-pentadecylphenoxy)-isobutyric acid, x in the general formula stated above is 1. In the case of the calcium and magnesium salts of this acid, x is 2. 
     In the examples that follow, the preparation of the sodium, magnesium and calcium salts of α-(3-pentadecylphenoxy)-isobutyric acid is described in greater detail. However, the sodium and magnesium salts have been found not to possess justifiable cholesterol and triglyceride reducing action. Hence, it is only the calcium salt of α-(3-pentadecylphenoxy)-isobutyric acid which has been investigated in detail and which possesses significant cholesterol and triglyceride reducing action in experimental animals. 
    
    
     The following examples describe non-limitatively the preparation of the novel compounds of the invention. 
     EXAMPLE 1 
     Sodium α-(3-pentadecylphenoxy)-isobutyrate 
     100 g α-(3-pentadecylphenoxy)-isobutyric acid were dissolved in 250 ml ethanol. To this ethanolic solution, 15 g sodium hydroxide were added dropwise and the entire reaction mixture was refluxed with stirring for about 30 minutes. The solvent was recovered and the residue was washed with acetone and dried. 
     The yield of the recovered product sodium α-(3-pentadecylphenoxy)-isobutyrate was 95% with the product having a melting point of from 89°-91° C. 
     EXAMPLE 2 
     Calcium α-(3-pentadecylphenoxy)-isobutyrate 
     100 g α-(3-pentadecylphenoxy)-isobutyric acid were dissolved in 250 ml ethanol. To this solution, 10 g aqueous sodium hydroxide in 60 ml water, were added until the pH of the reaction mixture was about 8.0. A solution of 35 g calcium chloride in 300 ml water was added dropwise with stirring and the separated white solid was filtered, washed with water and dried. 
     The yield of the recovered product calcium α-(3-pentadecylphenoxy)-isobutyrate was 98% with the product having a melting point of from 106° C. to 108° C. 
     EXAMPLE 3 
     Magnesium α-(3-pentadecylphenoxy)-isobutyrate 
     100 g α-(3-pentadecylphenoxy)-isobutyric acid were dissolved in 250 ml ethanol. To this solution, 10 g aqueous sodium hydroxide in 60 ml water were added until the pH of the reaction mixture was 8.0. A solution of 65 g magnesium sulphate in 500 ml water was added dropwise with stirring and the gummy white solid which separated out was filtered, washed with water and dried. 
     The yield of the gummy product identified as magnesium α-(3-pentadecylphenoxy)-isobutyrate was 94% which could not be purified. 
     In the further examples which follow, the hypolipidemic activity of different doses of the novel calcium salts of α-(3-pentadecylphenoxy)-isobutyric acid of the present invention when administered over varying periods of time is compared with the activity of a known hypolipidemic, viz. clofibrate, administered over similar periods. 
     EXAMPLE 4 
     HYPOLIPIDEMIC ACTIVITY OF CALCIUM SALT OF α-(3-PENTADECYLPHENOXY)-ISOBUTYRIC ACID AND CLOFIBRATE 
     4 DAYS TREATMENT 
     Rats of both sexes were divided into three groups. Group I served as control and was treated with vehicle, i.e. gum acacia or carboxymethyl cellulose, (1 ml/100 g body weight). Group II was treated with the calcium salt of α-(3-pentadecylphenoxy)-isobutyric acid (200 mg/kg body weight) and Group III was treated with clofibrate (200 mg/kg body weight). On the fifth day, all were sacrificed. Blood was collected by cardiac puncture under light ether anaesthesia and lipid profile in serum were studied. The results are expressed as mean±SE in Table I hereafter: 
     
                                           TABLE I                                 
__________________________________________________________________________
          GROUP I                                                         
                 GROUP II GROUP III                                       
LIPID PROFILE                                                             
          (n = 7)                                                         
                 (n = 8)  (n = 6)                                         
__________________________________________________________________________
Triglycerides mg %                                                        
          65.71 ± 2.02                                                 
                 56.25*** ± 2.23                                       
                          43.33**** ± 1.67                             
Serum Cholesterol                                                         
Total mg %                                                                
          107.14 ± 1.84                                                
                 75.62**** ± 2.20                                      
                          72.50**** ± 2.14                             
Esterified mg %                                                           
          63.57 ± 2.25                                                 
                 59.37* ± 1.48                                         
                          60.00* ± 1.83                                
Free mg % 42.14 ± 2.14                                                 
                 16.25**** ± 1.83                                      
                          12.50**** ± 1.12                             
Total lipid mg %                                                          
          370.71 ± 4.24                                                
                 356.87** ± 2.49                                       
                          290.17**** ± 6.40                            
Free fatty acids                                                          
          1.01 ± 0.02                                                  
                 0.93** ± 0.01                                         
                          0.87**** ± 0.01                              
mEq/lit                                                                   
Serum lipoproteins                                                        
Alpha %   39.86 ± 0.18                                                 
                 35.00** ± 1.74                                        
                          38.67*** ± 0.18                              
Beta %    60.14 ± 0.18                                                 
                 65.00** ± 1.74                                        
                          60.14* ± 0.18                                
__________________________________________________________________________
 Significance: Compared with control values                               
 p values: *ns **&lt;0.05 ***&lt;0.01 ****&lt;0.001                                
 n: Number of animals used.                                               
 
    
     EXAMPLE 5 
     HYPOLIPIDEMIC ACTIVITY OF CALCIUM SALT OF α-(3-PENTADECYLPHENOXY)-ISOBUTYRIC ACID AND CLOFIBRATE 
     7 DAYS TREATMENT 
     Rats of either sex were divided into 3 groups. Group I served as control and were treated with vehicle (1 ml/100 g body weight). Group II was treated with calcium salt of α-(3-pentadecylphenoxy)-isobutyric acid (200 mg/kg p.o.) and group III was treated with clofibrate (200 mg/kg body weight). On the eighth day, the rats were sacrificed and blood was collected by cardiac puncture under light ether anaesthesia. The lipid profile was studied and the results are expressed as mean±SE in Table II hereafter: 
     
                                           TABLE II                                
__________________________________________________________________________
          GROUP I GROUP II GROUP III                                      
LIPID PROFILE                                                             
          (n = 7) (n = 6)  (n = 6)                                        
__________________________________________________________________________
Triglycerides mg %                                                        
          65.71 ± 2.97                                                 
                  28.33**** ± 2.79                                     
                           30.83**** ± 1.54                            
Serum Cholesterol                                                         
Total     105.00 ± 2.44                                                
                  75.00**** ± 2.58                                     
                           80.83**** ± 2.39                            
Esterified                                                                
          63.57 ± 1.43                                                 
                  57.50* ± 2.39                                        
                           65.83* ± 1.54                               
Free      41.43 ± 2.10                                                 
                  17.50**** ± 2.01                                     
                           15.00**** ± 1.83                            
Total lipid mg %                                                          
          389.28 ± 11.63                                               
                  301.33**** ± 5.07                                    
                           342.83**** ± 8.70                           
Free fatty acid                                                           
          1.027 ± 0.03                                                 
                  0.89**** ± 0.02                                      
                           0.82**** ± 0.01                             
mEq/lit                                                                   
Serum lipoproteins                                                        
Alpha %   40.00 ± 0.17                                                 
                  39.33* ± 2.56                                        
                           39.84* ± 0.31                               
Beta %    60.00 ± 0.17                                                 
                  62.67* ± 2.56                                        
                           60.16* ± 0.31                               
__________________________________________________________________________
 Significance: Compared with control values                               
 p values: *ns **&lt;0.05 ***&lt;0.01 ****&lt;0.001                                
 n: Number of animals used                                                
 
    
     EXAMPLE 6 
     HYPOLIPIDEMIC ACTIVITY OF DIFFERENT DOSES OF CALCIUM SALT OF α-(3-PENTADECYLPHENOXY)-ISOBUTYRIC ACID 
     7 DAYS TREATMENT 
     Rats of either sex were divided into four groups. Group I served as control and were treated with vehicle (1 ml/100 g body weight). Groups II, III and IV were treated with calcium salt of α-(3-pentadecylphenoxy)-isobutyric acid with doses of 100 mg/kg, 200 mg/kg and 400 mg/kg orally, respectively. On the eighth day all were sacrificed and blood was collected by cardiac puncture under light ether anaesthesia. The lipid profile was studied and the results are expressed as mean±SE in Table III hereafter: 
     
                                           TABLE III                               
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          GROUP I GROUP II                                                
                          GROUP III                                       
                                   GROUP IV                               
LIPID PROFILE                                                             
          (n = 7) (n = 6) (n = 6)  (n = 6)                                
__________________________________________________________________________
Triglycerides mg %                                                        
          65.71 ± 2.97                                                 
                  64.16* ± 1.54                                        
                          28.33**** ± 2.79                             
                                   30.83**** ± 2.39                    
Serum Cholesterol                                                         
Total mg %                                                                
          105.00 ± 2.44                                                
                  92.50** ± 2.50                                       
                          75.00**** ± 2.58                             
                                   65.00**** ± 1.29                    
Esterified mg %                                                           
          63.57 ± 1.43                                                 
                  63.34* ± 2.19                                        
                          57.50* ± 2.39                                
                                   57.50*** ± 1.12                     
Free mg % 41.43 ± 2.10                                                 
                  29.16*** ± 1.70                                      
                          17.50**** ± 2.01                             
                                   7.50**** ± 1.12                     
Total lipid mg %                                                          
          389.28 ± 11.63                                               
                  367.33* ± 0.91                                       
                          301.33**** ± 5.07                            
                                   218.50**** ± 4.23                   
Free fatty acids                                                          
          1.03 ± 0.03                                                  
                  1.01* ± 0.01                                         
                          0.89**** ± 0.02                              
                                   0.79**** ± 0.01                     
mEq/lit                                                                   
Serum lipoproteins                                                        
Alpha %   40.00 ± 0.17                                                 
                  38.17* ± 1.70                                        
                          39.33* ± 2.56                                
                                   32.83**** ± 0.87                    
Beta %    60.00 ± 0.17                                                 
                  61.50* ± 1.98                                        
                          60.67* ± 2.56                                
                                   67.17**** ± 0.87                    
__________________________________________________________________________
 Significance: Compared with control values                               
 p values: *ns **&lt;0.05 ***&lt;0.01 ****&lt;0.001                                
 n: Number of animals used.                                               
 
    
     EXAMPLE 7 
     HYPOLIPIDEMIC ACTIVITY OF CALCIUM SALT OF α-(3-PENTADECYLPHENOXY)-ISOBUTYRIC ACID AND CLOFIBRATE 
     15 DAYS TREATMENT 
     Rats of either sex were divided into three groups. Group I served as control and were treated with vehicle (1 ml/100 g body weight). Group II was treated with calcium salt of α-(3-pentadecylphenoxy)-isobutyric acid (dose 200 mg/kg p.o.) and Group III was treated with clofibrate (200 mg/kg p.o.). On the sixteenth day the rats were sacrificed and blood was collected by cardiac puncture under light ether anaesthesia. The lipid profile was studied and the results are expressed as mean±SE in Table IV hereafter: 
     
                                           TABLE IV                                
__________________________________________________________________________
          GROUP I GROUP II GROUP III                                      
LIPID PROFILE                                                             
          (n = 7) (n = 0)  (n = 6)                                        
__________________________________________________________________________
Triglycerides mg %                                                        
          64.28 ± 2.97                                                 
                  21.25**** ± 2.63                                     
                           23.33**** ± 1.05                            
Serum Cholesterol                                                         
Total mg %                                                                
          105.71 ± 2.02                                                
                  65.62**** ± 1.99                                     
                           62.50**** ± 1.12                            
Esterified mg %                                                           
          62.86 ± 1.01                                                 
                  53.12**** ± 1.88                                     
                           53.33*** ± 2.11                             
Free mg % 42.86 ± 2.41                                                 
                  11.25**** ± 1.83                                     
                           9.17**** ± 1.54                             
Total lipid mg %                                                          
          383.29 ± 11.11                                               
                  251.25**** ± 6.11                                    
                           251.67**** ± 4.01                           
Free fatty acids                                                          
          1.03 ± 0.04                                                  
                  0.83**** ± 0.01                                      
                           0.79**** ± 0.004                            
mEq/lit                                                                   
Serum lipoproteins                                                        
Alpha %   39.00 ± 0.69                                                 
                  30.37**** ± 1.02                                     
                           35.50**** ± 0.22                            
Beta %    61.00 ± 0.69                                                 
                  69.63**** ± 1.02                                     
                           64.50**** ± 0.22                            
__________________________________________________________________________
 Significance: Compared with control values                               
 p values: *ns **&lt;0.05 ***&lt;0.01 ****&lt;0.001                                
 n: Number of animals used.                                               
 
    
     EXAMPLE 8 
     HYPOLIPIDEMIC ACTIVITY OF CALCIUM SALT OF α-(3-PENTADECYLPHENOXY)-ISOBUTYRIC ACID AND CLOFIBRATE 
     30 DAYS TREATMENT 
     Rats of either sex were divided into three groups. Group I served as control and received 1 ml of vehicle per 100 g body weight. Group II was treated with 200 mg/kg p.o. of calcium salt α-(3-pentadecylphenoxy)-isobutyric acid and Group III was treated with clofibrate 200 mg/kg p.o. On the thirty first day all were sacrificed and blood was collected by cardiac puncture under light ether anaesthesia. The lipid profile of serum was studied and the results are expressed as mean±SE in Table V hereafter: 
     
                                           TABLE V                                 
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          GROUP I                                                         
                 GROUP II GROUP III                                       
LIPID PROFILE                                                             
          (n = 7)                                                         
                 (n = 7)  (n = 6)                                         
__________________________________________________________________________
Triglycerides mg %                                                        
          66.43 ± 2.61                                                 
                 22.86**** ± 1.01                                      
                          21.67**** ± 1.05                             
Serum Cholesterol                                                         
Total mg %                                                                
          101.43 ± 1.80                                                
                 60.71**** ± 2.54                                      
                          59.17**** ± 1.54                             
Esterified mg %                                                           
          60.71 ± 2.54                                                 
                 50.71*** ± 1.30                                       
                          51.67** ± 1.67                               
Free mg % 42.14 ± 1.01                                                 
                 7.14**** ± 1.01                                       
                          7.50**** ± 1.12                              
Total lipids mg %                                                         
          372.57 ± 4.30                                                
                 234.28**** ± 5.17                                     
                          226.67**** ± 3.33                            
Free fatty acids                                                          
          0.993 ± 0.04                                                 
                 0.76**** ± 0.01                                       
                          0.75**** ± 0.004                             
mEq/lit                                                                   
Serum lipoproteins                                                        
Alpha %   38.29 ± 1.78                                                 
                 28.57**** ± 1.43                                      
                          33.17** ± 0.87                               
Beta %    61.71 ± 1.78                                                 
                 71.43*** ± 1.43                                       
                          66.83** ± 0.87                               
__________________________________________________________________________
 Significance: Compared with control values                               
 p values: *ns **&lt;0.05 ***&lt;0.01 ****&lt;0.001                                
 n: Number of animals used.