2- (P-Methoxy-benzoyl)-hydrazono-formyl!-quinoxaline-1,4-dioxide
This is a continuation-in-part application of application Ser. No. 630,762 filed on Nov. 11, 1975, now abandoned. 
    
    
     The present invention relates to a novel heterocyclic compound. More particularly the invention provides 2- (p-methoxy-benzoyl)-hydrazone-formyl!-quinoxaline-1,4-dioxide of the formula ##STR1## and its pharmaceutically acceptable acid addition salts. 
     The compound according to the invention has excellent bactericidal (antibacterial) properties wherein its toxicity is very low. The bactericidal effect was investigated with the following bacterium strains: 
     1. Pseudomonas pyocyanaea 14K 
     2. Proteus vulgaris A.H. 
     3. Bacillus subtilis ATCC 6633 
     4. Salmonella Typhi murium 
     5. Shigella Sonnei 
     6. Staphylococcus areus Duncan 
     7. Staphylococcus areus 209 P. 
     8. Escherichia coli 0111 
     The lowest concentration inhibiting the multiplication of the test bacteria (MIC, mg./ml.) was determined in vitro. The antibacterial effect of the claimed compound was compared with that of known quinoxaline-1,4-dioxide derivatives, further of known and in the therapy extensively used compounds, such as Thiamphenicol  dichloro-N-(2-hydroxy-1-hydroxymethyl-2-/p-methane-sulphonyl-phenyl/-ethyl)-acetamide! and nitrofurantoin (3-/5-nitrofurfurylidene-amino/-hydantoin). 
     The in vitro MIC values determined in this way as well as the peroral LD 50  values determined on mice are given in the following Table I. 
     
                                           Table I                                 
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                             MIC values in mg./ml. with bacterium         
                             strains                                      
Compound            LD.sub.50 mg./kg.                                     
                             1   2   3   4   5   6   7    8               
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2- (p-Methoxy-benzoyl)-hydrazono-                                         
formyl-!-quinoxaline-1,4-dioxide                                          
                    10,000   1.9 1.9 1.9 1.9 3.9 3.9 3.9  0.9             
2-(Methoxy-carbonyl-hydrazono-                                            
formyl)-quinoxaline-1,4-dioxide                                           
                    4,000    100 25  5   50  10  75  100  25              
(Carbadox) (comparative compound                                          
on the basis of US Pat. No.                                               
3,493,572)                                                                
2-(Hexyl-carbonyl-hydrazono-                                              
formyl)-quinoxaline-1,4-dioxide                                           
                    4,000    100 100 100 100 100 75  100  100             
(comparative compound on the basis                                        
of British Pat. No. 1,058,047)                                            
2-(Benzoyl-hydrazono-formyl)-                                             
quinoxaline-1,4-dioxide                                                   
                    4,000    100 100 100 100 100 100 100  100             
(comparative compound on the basis                                        
of British Pat. No. 1,058,047)                                            
Thiamfenicol (comparative compound)                                       
                    15,000   15.6                                         
                                 15.6                                     
                                     31.2                                 
                                         31.2                             
                                             62.5                         
                                                 62.5                     
                                                     62.5 62.5            
Nitrofurantoin (comparative                                               
                    895      7.8 15.6                                     
                                     31.2                                 
                                         7.8 31.2                         
                                                 62.5                     
                                                     31.2 31.2            
compound)                                                                 
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     It appears from Table I that the compound according to the invention is, depending on the tested bacterium strain, 8 to 70 times more effective than Thiamphenicol and generally 25 to 50 times more potent than the tested known quinoxaline-1,4-dioxide derivatives but its toxicity is 2.5 times lower. 
     This excellent bactericidal effect is surprising especially when compared with the similar effect of 2-(benzoyl-hydrazono-formyl)-quinoxaline-1,4-dioxide because, as shown in Table I, the introduction of a p-methoxy group into the molecule results in an increase of the effect of two orders of magnitude e.g. against the strain Escherichia coli 0111. 
     The compound according to the invention may be converted into its acid addition salts by reaction with pharmaceutically acceptable organic or inorganic acids in a manner known per se. Examples of acids which may be used for acid addition salts formation are: hydrochloric, hydrobromic, sulfuric, phosphoric, fumaric, maleic, malic, acetic and tartaric acid. 
     The claimed compounds may be used as pharmaceuticals on their own or in the form of appropriate medicinal preparations for administration e.g. enterally or parenterally. In order to produce suitable medicinal preparations the compound is worked up with organic or inorganic adjuvants which are inert and physiologically acceptable. Examples of such adjuvants are lactose, starch, talc and stearic acid for tablets and dragees; solutions of sugar and glucose for syrups; water, alcohols, glycerin and vegetable oils for injectable solutions; and natural or hardened oils and waxes for suppositories. 
     The pharmaceutical preparations may furthermore contain suitable preserving, stabilizing and wetting agents, solubilizers, sweatening and coloring substances or flavorings. 
     The term &#34;in a manner know per se&#34; as used herein designates methods in use or described in the literature on the subject. 
     The compound of the invention can be prepared, for example, as follows: 
     11.8 g (0.05 moles) of 2-formyl-quinoxaline-1,4-dioxide-dimethylacetal are suspended in 75 ml. of water. 4 ml. of concentrated aqueous hydrochloric acid are added. The obtained mixture is boiled for 10 minutes and then the suspension of 8.3 g. (0.05 moles) of p-methoxy-benzoic acid hydrazide in 50 ml. of warm water is added. The reaction mixture is allowed to cool to room temperature and stirred for 3 hours at this temperature. The separated product is filtered and then washed with water and ethanol. The 2- (p-methoxy-benzoyl)-hydrazono-formyl!-quinoxaline-1,4-dioxide is obtained with a yield of 79%; m.p.: 260° C.