the term &# 34 ; lower alkyl &# 34 ; as is used throughout the specification and claims means a straight - or branched - chain alkyl group having 1 to 4 carbon atoms such as a methyl group , an ethyl group and n - propyl , isopropyl , n - butyl , sec - butyl and tert - butyl groups . the novel guanidinobenzoic acid derivatives can be prepared according to the following reaction scheme : ## str6 ## wherein the various symbols are as defined above . the compounds of the general formula [ i ] can be prepared by reacting a p - guanidinobenzoyl halide represented by the general formula [ ii ] or an acid addition salt thereof with a compound represented by the general formula [ iii ] in an inert solvent in the presence of a dehydrohalogenating agent at a temperature ranging from - 20 ° c . to room temperature for about 1 to 5 hours . suitable examples of dehydrohalogenating agents , which can be used in the above reaction , include tertiary amines such as triethylamine , tri - n - butylamine , n , n - dimethylaniline , n - methylpiperidine , pyridine , etc . suitable examples of inert solvents , which can be used in the above reaction , include benzene , toluene , diethyl ether , tetrahydrofuran , dioxane , acetone , acetonitrile , pyridine , etc . the inert solvents described above can be used individually or as a mixture thereof . of these inert solvents , pyridine is most preferred since it serves both as a solvent and as a dehydrohalogenating agent . the reaction product is produced in the form of an acid addition salt thereof . when the reaction product is obtained as crystals in the reaction mixture , it may be isolated by filtering the crystals . when the reaction product is not obtained as crystals in the reaction mixture , it may be isolated by filtering the crystals , which is precipitated by adding an aqueous solution of sodium bicarbonate to the reaction mixture or the residue obtained by concentration under reduced pressure of the reaction mixture or the solution obtained by adding a solvent which is not disolve the reaction product . if desired , the compounds represented by the general formula [ i ] can further be converted into pharmaceutically acceptable acid addition salts thereof with ease according to conventional methods . suitable examples of acids which can be used to produce the pharmaceutically acceptable acid addition salts include inorganic acids such as hydrochloric acid , sulfuric acid , phosphoric acid , hydrobromic acid , nitric acid , etc ., and organic acids such as acetic acid , lactic acid , oxalic acid , maleic acid , fumaric acid , succinic acid , tartaric acid , malic acid , citric acid , benzenesulfonic acid , toluenesulfonic acid , methanesulfonic acid , etc . preferred examples of pharmaceutically acceptable acid addition salts of the compound represented by the general formula [ i ] include methanesulfonates , toluene sulfonates , hydrochlorides , phosphates , etc . the compounds of the general formula [ ii ] can be prepared from p - guanidinobenzoic acid in a conventional manner . for example , p - guanidinobenzoic acid is heated with thionyl chloride to form p - guanidinobenzoyl chloride hydrochloride , which can be used per se for further reaction in this invention . the compounds represented by the general formula [ iii ], wherein z represents so 2 group and the other symbols are as defined above , can be prepared in a conventional manner , for example , described beilstein , 11 , iii , 506 , j . med . chem ., 8 , 377 ( 1965 ), etc . the compounds represented by the general formula [ iii ], wherein z represents z &# 39 ;-- co group and z &# 39 ;, r 1 and r 2 are as defined above , can be prepared in a conventional manner , for example , by the methods described in beilstein , 10 , 164 , arzneimittel - forsch , 14 , 324 ( 1964 ) or beilstein , 10 , 191 , or by reacting a ester , for example methyl , ethyl , propyl , phenyl , p - nitrophenyl or cyanomethyl ester , of the general formula : ## str7 ## ( wherein z &# 39 ; is as defined above ) with a primary or secondary amine in the presence or absence of a solvent such as diethyl ether , tetrahydrofuran , methanol , ethanol , benzene , toluene , acetonitrile , etc ., at a temperature ranging from room temperature to 150 ° c . at normal or elevated pressure . examples of the amines are methylamine , ethylamine , n - propylamine , isopropylamine , n - butylamine , sec - butylamine , dimethylamine , diethylamine , di - n - propylamine , di - n - butylamine , diisopropylamine , n - ethyl - n - butylamine , ammonia , etc . the compounds represented by the formula [ i ] and the acid addition salts thereof have potent anti - plasmin and anti - trypsin activities even at very low dosage levels . further , the compounds of the present invention are excellent in solubility and , therefore , are suitable for administration as a pharmaceutical in the form of an aquious solution , a physiological salt solution , liquid glucose or other solutions . the inhibitory activities of representative compounds of the general formula [ i ] against plasmin and trypsin in vitro were determined in a manner similar to the method described by m . muramatsu et al j . biochemistry , 58 , 214 ( 1964 ) for trypsin and the method described by m . muramatsu et al ibid , 57 , 402 ( 1965 ) for plasmin . the procedures used are described more specifically below . ( 1 ) trypsin : 0 . 4 ml of trypsin ( 1 . 25 μg / ml ), 0 . 5 ml of p - tosylarginine methyl ester ( 20 mm ) in tris - hcl buffer ( ph 8 . 5 ) and 0 . 1 ml of a solution of each of the following compounds represented by the general formula [ i ] at various concentrations was reacted at a temperature of 37 ° c . for 30 minutes , and the concentration of each of the test compounds at which the activity of trypsin 0 . 5 μg to hydrolyze p - tosylarginine methyl ester was inhibited to an extent of 50 % is shown in table 1 below . ( 2 ) plasmin : 0 . 1 ml of human euglobulin ( 10 fold dilution ), 0 . 1 ml of streptokinase ( 2000 unit / ml ), 0 . 4 ml of fibrinogen ( 4 % solution ), 0 . 3 ml of a 0 . 1 m borate saline buffer solution ( ph 7 . 4 ) and 0 . 1 ml of a solution of each of the following compounds represented by the general formula [ i ] at various concentrations was allowed to react at a temperature of 37 ° c . for 30 minutes . the concentration at which the test compound exhibited inhibition against plasmin to an extent of 50 % was determined , and the results obtained are shown in table 1 below . table 1______________________________________compound 50 % inhibition concentration solubility inno . anti - trypsin anti - plasmin water______________________________________1 3 . 0 × 10 . sup .- 9 m 3 . 1 × 10 . sup .- 9 m & gt ; 20 mm2 2 . 0 × 10 . sup .- 9 m 6 . 4 × 10 . sup .- 9 m & gt ; 20 mm3 2 . 2 × 10 . sup .- 9 m 4 . 8 × 10 . sup .- 9 m & gt ; 20 mm4 3 . 4 × 10 . sup .- 9 m 2 . 7 × 10 . sup .- 7 m & gt ; 20 mm5 9 . 1 × 10 . sup .- 9 m 4 . 1 × 10 . sup .- 7 m & gt ; 20 mm6 1 . 1 × 10 . sup .- 8 m 9 . 5 × 10 . sup .- 8 m & gt ; 20 mm______________________________________ compound no . 1 : ## str8 ## compound no . 2 : ## str9 ## compound no . 3 : ## str10 ## compound no . 4 : ## str11 ## compound no . 5 : ## str12 ## compound no . 6 : ## str13 ## as is apparent from the above results , guanidinobenzoic acid derivatives represented by the general formula [ i ] and the acid addition salts thereof according to this invention are highly inhibitory to proteolytic enzymes of plasmin and trypsin and , therefore , are useful as pharmaceuticals , i . e ., as an anti - trypsin agent for treating acute pancreatitis and the like or an anti - plasmin agent for treating bleeding disorders and the like . furthermore , it has been suggested that a protease is concerned in promotion of cancer and it is well known that a compound which inhibits a protease in vitro or in vivo , obstructs the production of cancer and , therefore , it is thought that the compounds of the present invention , which inhibit proteases such as trypsin and plasmin , are useful as anti - cancer agent . this invention also includes in its scope pharmaceutical compositions comprising at least one of the compounds represented by the general formula [ i ] or pharmaceutically acceptable salts thereof and pharmaceutically acceptable carriers , diluents and excitients . usually the compounds or pharmaceutical compositions comprising the same are administered orally . suitable examples of solid formulations for oral administration include tablets , pills , powders and granules . in these solid formulations one or more active ingredients are mixed with at least one inactive diluent such as calcium carbonate , potato starch , alginic acid , lactose , etc . the formulation may contain additives other than the diluents , for example , lubricants such as magnesium stearate , etc . suitable example of liquid formulations for oral administration include pharmaceutically acceptable emulsions , solutions , suspensions , syrups or elixirs . conventionally used liquid diluents are , for example , water or liquid paraffin . this formulation may also contain , in addition to the diluents , auxiliary agents , for example , humectants , suspension aids , sweeteners , flavors , fragrants or antiseptics . capsules comprising an assimilable substance such as gelatin and which contain one or more active ingredients and a diluent or an excipient can also be used in this invention as a suitable example of formulation for oral administration . in this invention the amount of the active ingredient in the formulation can be varied and a suitable amount determined depending on the therapeutic purpose . dosage is determined based on the therapeutic effects desired , the number of times administered and the period of treating . usually , the dosage for an adult is about 100 mg to about 1 g for treating acute pancreatitis and hemorrhagic diseases by oral administration . preferred specific examples of guanidinobenzoic acid compounds represented by the general formula [ i ] of this invention include this invention is illustrated in further detail by reference to the following reference example and examples , but it should be understood that they are given for illustrative purposes only and are not to be construed as limiting the scope of the invention . 2 . 7 g of p - guanidinobenzoic acid was heated with 25 ml of thionylchloride at 70 °- 75 ° c . for 30 minutes with stirring . to the reaction mixture was added petroleum ether to precipitate crystals of p - guanidinobenzoyl chloride hydrochloride , which were filtered and washed with petroleum ether . the crystals thus obtained were added to a solution of 3 . 0 g of n , n - dimethyl - p - hydroxybenzenesulfonamide in 20 ml of pyridine at 0 ° c . and the mixture was stirred for 2 hours . to the reaction mixture was added a saturated aqueous solution of sodium bicarbonate and the resulting crystals were filtered out , washed with water and acetone , and dried . the crystals thus obtained were suspended in methanol and dissolved by adding of methanesulfonic acid , the mixture was filtered and diethyl ether was added to the filtrate . the resulting crystals were filtered out , dried and recrystallized from dimethylformamide to obtain 2 . 75 g of the title compound . ______________________________________elemental analysis for c . sub . 16 h . sub . 18 n . sub . 4 o . sub . 4 s . ch . sub . 3so . sub . 3 h c h n s______________________________________calculated (%): 41 . 91 3 . 96 12 . 22 13 . 98found (%): 42 . 22 3 . 74 12 . 47 14 . 19______________________________________ 4 . 48 g of p - guanidinobenzoic acid was converted into p - guanidinobenzoyl chloride hydrochloride in the same manner as described in example 1 . the crystals thus obtained were added to a solution of 4 . 68 g of n - methyl - p - hydroxybenzenesulfonamide in 32 ml of pyridine at 0 ° c . and the mixture was stirred for 2 hours . the post - treatments and recrystallization were carried out in the same manner as described in example 1 to obtain 3 . 89 g of the title compound . ______________________________________elemental analysis for c . sub . 15 h . sub . 16 n . sub . 4 o . sub . 4 s . ch . sub . 3so . sub . 3 h c h n s______________________________________calculated (%): 40 . 53 3 . 63 12 . 61 14 . 43found (%): 40 . 71 3 . 90 12 . 44 14 . 65______________________________________ 3 . 58 g of p - guanidinobenzoic acid was converted into p - guanidinobenzoyl chloride hydrochloride in the same manner as described in example 1 . the crystals thus obtained were added to a solution of 3 . 46 g of p - hydroxybenzenesulfonamide in 26 ml of pyridine at room temperature and the mixture was stirred for 2 hours . the post - treatments and recrystallization were carried out in the same manner as described in example 1 to obtain 3 . 87 g of the title compound . ______________________________________elemental analysis for c . sub . 14 h . sub . 14 n . sub . 4 o . sub . 4 s . ch . sub . 3so . sub . 3 h c h n s______________________________________calculated (%): 39 . 06 3 . 28 13 . 02 14 . 90found (%): 39 . 23 3 . 06 13 . 15 14 . 81______________________________________ to a solution of 7 . 6 g of p - hydroxyphenylacetic acid in 100 ml of acetonitrile were added 8 . 4 g of p - nitrophenol and 10 . 3 g of dicyclohexylcarbodiimide at room temperature with stirring , and the resulting crystals of dicyclohexylurea were filtered out . an ethereal solution of 7 . 8 g of methylamine was added to the filtrate containing p - nitrophenyl p - hydroxyphenylacetate , the mixture was allowed to stand to precipitate crystals . the crystals obtained were filtered out and washed with diethyl ether to obtain 4 . 0 g of the title compound . 5 . 37 g of p - guanidinobenzoic acid was converted into p - guanidinobenzoyl chloride hydrochloride in the same manner as described in example 1 . the crystals thus obtained were added to a solution of 5 . 37 g of n , n - dimethyl - p - hydroxyphenylacetamide , which was prepared by the same procedure as described in reference example 1 , in 20 ml of pyridine at 0 ° c . and the mixture was stirred for 2 hours . to the reaction mixture was added 100 ml of diethyl ether and the supernatant solution was separated by decantation . to the resulting crystals were filtered out , washed with water and acetone , and dried . the crystals thus obtained were suspended in methanol and dissolved by adding of methanesulfonic acid ( ph 3 ), and the mixture was filtered and diethyl ether was added to the filtrate . the resulting crystals were filtered out and recrystallized from methanol to obtain 7 . 71 g of the title compound . ______________________________________elemental analysis for c . sub . 18 h . sub . 20 n . sub . 4 o . sub . 3 . ch . sub . 3so . sub . 3 h c h n s______________________________________calculated (%): 49 . 53 4 . 96 12 . 84 7 . 35found (%): 49 . 71 4 . 43 12 . 98 7 . 13______________________________________ 7 . 16 g of p - guanidinobenzoic acid was converted into p - guanidinobenzoyl chloride hydrochloride in the same manner as described in example 1 . the crystals thus obtained were added to a solution of 6 . 93 g of n - methyl - p - hydroxyphenylacetamide ( prepared as described in reference example 1 ) in 26 ml of pyridine at 5 ° c . and the mixture was stirred for 2 hours . the post - treatments and recrystallization were carried out in the same manner as described in example 4 to obtain 8 . 92 g of the title compound . ______________________________________elemental analysis for c . sub . 17 h . sub . 18 n . sub . 4 o . sub . 3 . ch . sub . 3so . sub . 3 h c h n s______________________________________calculated (%): 48 . 33 4 . 29 13 . 27 7 . 59found (%): 48 . 57 4 . 42 13 . 03 7 . 45______________________________________ 4 . 48 g of p - guanidinobenzoic acid was converted into p - guanidinobenzoyl chloride hydrochloride in the same manner as described in example 1 . the crystals thus obtained were added to a solution of 4 . 95 g of n , n - dimethyl - p - hydroxybenzamide in 17 ml of pyridine at 0 ° c . and the mixture was stirred at 5 ° to 10 ° c . for 2 hours . the post - treatments were carried out in the same manner as described in example 4 and the crystals thus obtained were recrystallized from dimethylformamide to obtain 5 . 31 g of the title compound . ______________________________________elemental analysis for c . sub . 17 h . sub . 18 n . sub . 4 o . sub . 3 . ch . sub . 3so . sub . 3 h c h n s______________________________________calculated (%): 48 . 33 4 . 29 13 . 27 7 . 59found (%): 48 . 65 4 . 03 13 . 44 7 . 73______________________________________
guanidinobenzoic acid derivatives represented by the general formula ## str1 ## wherein r 1 , r 2 and z are as defined hereinafter , having antiplasmin and anti - trypsin activities and process for their preparation as well as a pharmaceutical composition and a method of inhibiting the activity of plasmin and trypsin is disclosed .