n g - acyl derivatives of arginine are prepared according to the following general procedure . the sodium salt of n . sup . α - cbz - l - arginine is prepared by reacting n . sup . α - cbz - l - arginine with sodium ethoxide in ethanol and evaporating to dryness . the dry salt is dissolved in n , n - dimethylformamide and the solution cooled to 5 ° c . an aliphatic acid chloride in dmf is added dropwise to the cold solution to provide a mole ratio of acid chloride to n . sup . α - cbz - l - arginine sodium salt of 1 : 2 . the reaction mixture is brought to room temperature and stirred for 24 hours . the mixture is then chilled and diluted by pouring into ice water , and a solid product precipitated by adjusting the ph to 5 using glacial acetic acid . the precipitated solid is washed with water and allowed to air dry , then recrystallized from an organic solvent such as ethanol . the recrystallized solid which is pure n . sup . α - cbz - n g - acylarginine is dissolved in a mixture of ethanol and glacial acetic acid . after adding a palladium - on - carbon catalyst , the mixture is shaken in an atmosphere of hydrogen gas and the n . sup . α - cbz group removed by catalytic hydrogenolysis . the solution is then filtered and the filtrate evaporated to dryness . the residual solid is recrystallized from 95 % ethanol to obtain the desired n g - acyl derivative of arginine . a more complete understanding of the process for preparing compounds of this invention and oral compositions comprising such compounds will be obtained by reference to the following specific examples , which are included for purposes of illustration only and are not intended to be limiting . 50 . 00 g ( 0 . 1622 mole ) of n . sup . α - cbz - l - arginine were suspended in 100 ml of absolute ethanol . to this suspension was added , in one portion , a solution of sodium ethoxide prepared by reacting 3 . 73 g ( 0 . 162 mole ) of sodium metal with 100 ml of absolute ethanol . the mixture was vigorously stirred at room temperature until all the solid had dissolved . the solution was then evaporated to dryness , first using a rotary evaporator at 40 °, followed by more complete drying under vacuum at room temperature to obtain the sodium salt of n . sup . α - cbz - l - arginine as a white solid . this material was dissolved in 200 ml of dry n , n - dimethylformamide and placed in a 1 - liter , 3 - neck flask equipped with mechanical stirrer , drying tube and addition funnel . a solution of 15 . 47 g ( 0 . 0811 mole ) of decanoyl chloride in 25 ml of dry dmf was then added dropwise during 1 . 5 hr . while the reaction mixture was kept at 5 ° using an ice bath . when addition was complete , the mixture was allowed to slowly warm to room temperature and was stirred at room temperature for 24 hrs . the mixture was filtered to remove insoluble material , poured over 1 , 000 g of a mixture of ice and water , and the bright yellow solution acidified with glacial acetic acid ( the ph was changed from 9 to 5 during this process ). a solid precipitated at this stage ; it quickly became gummy and adhered to the walls and bottom of the beaker . the water and ice were poured off and the wet solid was treated with approximately 1 , 000 ml of absolute methanol . this mixture was heated on a hot plate until all the solid dissolved , and then slowly cooled to room temperature . the solid which crystallized during the cooling process was collected by filtration and identified as pure n . sup . α - cbz - n g - decanoylarginine having the formula : ## str4 ## compound ( i ) ( 2 . 77 g , 5 . 99 mmol ) was dissolved in a solution of 30 ml glacial acetic acid and 100 ml of abs . ethanol . to this solution was added a suspension of 0 . 25 g 10 % palladium on activated carbon in 10 ml glacial acetic acid . this mixture was treated with hydrogen gas by vigorously stirring the suspension while blowing hydrogen gas continuously over the surface . the catalytic hydrogenolysis was monitored for cessation of carbon dioxide evolution by bubbling the effluent gasses through a saturated barium hydroxide solution . when the reaction was complete , the mixture was filtered through celite to remove the catalyst . the filtrate was evaporated to dryness , first on a rotary evaporator at 40 °, and finally under vacuum at room temperature . the dry residue was recrystallized from 95 % ethanol to yield 1 . 94 g ( 83 . 3 %) of n g - decanoylarginine as the acetic acid salt having the formula : ## str5 ## exactly the same procedure was used to prepare the following n g - acyl derivatives of arginine : it is also possible to prepare n g - acyl derivatives of arginine by reacting the sodium salt of n . sup . α - cbz - l - arginine with the ethyl ester or the succinimidyl ester of the desired aliphatic acid instead of the acid chloride . this is illustrated in examples 2 and 3 . the sodium salt of n . sup . α - cbz - l - arginine was prepared from 12 . 03 g ( 0 . 0390 mole ) of n . sup . α - cbz - l - arginine as described in example 1 , and dissolved in 50 ml of dry dmf . to this solution was added , dropwise , during 15 minutes , 10 . 00 g ( 0 . 039 mole ) of ethyl myristate , followed by rapid addition of 10 ml of dmf . the reaction mixture was stirred at room temperature for 48 hours , then poured over 1 , 000 g of a mixture of ice and water . this basic mixture ( ph 12 ) was acidified with glacial acetic acid to a ph of 5 . a pale yellow , slightly gummy solid immediately precipitated . this was collected by gravity filtration and was dried in an oven at 45 °. the dry solid was recrystallized from absolute methanol to obtain pure n . sup . α - cbz - n g - myristoylarginine which was dissolved in a 50 : 50 mixture of glacial acetic acid / ethanol and subjected to catalytic hydrogenolysis as described in example 1 . the sodium salt of n . sup . α - cbz - l - arginine was prepared from 12 . 03 g ( 0 . 0390 mole ) of n . sup . α - cbz - l - arginine as described in example 1 and dissolved in 50 ml of dry dmf . to this solution was added , dropwise , during 15 minutes , 12 . 69 g ( 0 . 039 mole ) of succinimidyl myristate , followed by rapid addition of 10 ml of dmf . the reaction mixture was stirred at room temperature for 24 hours , then poured over 1 , 000 g of a mixture of ice and water . this basic mixture ( ph 12 ) was acidified with glacial acetic acid to a ph of 5 . a pale yellow , slightly gummy solid immediately precipitated . this was collected by gravity filtration and was dried in an oven at 45 °. the dry solid was recrystallized from absolute methanol to obtain pure n . sup . α - cbz - n g - myristoylarginine which was dissolved in a 50 : 50 mixture of glacial acetic acid / ethanol and subjected to catalytic hydrogenolysis as described in example 1 . representative compounds of the present invention were assayed to determine their effectiveness in reducing acid production from sugar by s . mutans as a measure of their efficacy in oral compositions . this assay measures the rate of acid production from the metabolism of sucrose by streptococcus mutans 6715 . the assay solution consists of 10 . 00 ml of a phosphate buffer at ph 5 . 5 under nitrogen . to this solution are added 8 × 10 9 cells of s . mutans 6715 , followed by 50 μl of 25 × 10 - 3 m sucrose . a known volume of a 10 mg / ml solution of the test arginine derivative is then added , and the rate of acid production is monitored with the automatic addition of a 5 × 10 - 3 n koh solution by a ph - stat . table i______________________________________ concen - reduction in tration rate of acidarginine derivative ( w / v %) formation (%) ______________________________________n . sup . g -- octanoylarginine 3 . 0 55n . sup . g -- nonanoylarginine 2 . 0 43n . sup . g -- decanoylarginine 6 . 0 67n . sup . g -- undecanoylarginine 2 . 0 80n . sup . g -- lauroylarginine 1 . 0 100n . sup . g -- myristoylarginine 0 . 5 100n . sup . g -- palmitoylarginine 3 . 0 29n . sup . g -- stearoylarginine 1 . 0 33______________________________________ the combination of n g - acyl derivatives of arginine with a fluoride compound , e . g . sodium fluoride , zinc fluoride , stannous fluoride , sodium monofluorophosphate , acidulated phosphate fluoride , ammonium fluoride , ammonium bifluoride and amine fluoride is more effective in preventing the development of caries in rodents than either compound alone . while both naf and n g - acyl derivative of arginine were effective in preventing the development of caries in the rodent model when they were used alone under the given test conditions , the combination of the above two ingredients resulted in a substantially enhanced anticaries activity . the results of this test are summarized in table ii . table ii______________________________________anticaries activity of n . sup . g -- myristoylarginine % % total reduction severity reductiontest caries in total of caries in severitycomposition lesions lesions lesions of lesions______________________________________control . sup . ( 1 ) 11 . 1 ± 0 . 81 0 31 . 9 ± 2 . 68 0example 5 10 . 1 ± 0 . 94 8 29 . 1 ± 2 . 97 9control + 8 . 1 ± 0 . 80 26 24 . 1 ± 2 . 50 240 . 22 % nafexample 6 6 . 5 ± 0 . 81 41 18 . 9 ± 2 . 52 41______________________________________ . sup . ( 1 ) the composition of the control is the same as in example 5 without the n . sup . g -- acylarginine . in general , the n g - acyl derivative of arginine should be present in an effective amount up to a saturated solution , while the fluoride ion should be present from as low as 0 . 0001 % to 10 %. the preferred concentration of the n g - acyl derivative of arginine is 0 . 05 to 10 %, while that of the fluoride ion is 0 . 001 to 1 . 0 %. the most preferred concentration of n g - acyl derivative of arginine is 0 . 5 to 5 %, and the fluoride ion , 0 . 01 to 0 . 1 %. while higher concentrations of both n g - acyl derivatives of arginine and fluoride ions could be used , no particular advantage is afforded thereby . while it is presently preferred to have a polyol - containing aqueous vehicle as an acceptable carrier for the above composition , other nonaqueous compositions are not excluded from the list of suitable carriers , as for example various alcohols , polyols , and dimethylsulfoxide . the composition of this invention may be in the form of a mouthwash , spray , dentifrice , gel , powder , solution , lotion , varnish , lozenge , chewing gum , slow releasing device or other forms suitable for oral application . any pharmaceutically acceptable materials such as those ordinarily used in such oral compositions that are compatible with n g - acyl derivatives of arginine and fluoride ions may be employed in the compositions of this invention . in accordance with the present invention , the compositions are supplied to teeth with an appliance , e . g ., toothbrush , swab , impregnated dental floss and the like by gently brushing the teeth , both the buccal and lingual sides , at least once daily . the most preferred application of the above compositions to teeth is from lozenge and from chewing gum , whereby one slowly dissolves the lozenge in the mouth over 10 to 15 minutes , and by chewing the gum over 30 to 45 minutes after each meal . the following examples will further serve to illustrate typical oral compositions of this invention . ______________________________________ w / w % ______________________________________glycerol , u . s . p . 10 to 40n . sup . g -- acylarginine 0 . 1 to 5naf 0 . 2flavors 1 . 0preservatives 0 . 3pluronic f - 108 2 . 0water , q . s . to 100 parts______________________________________ the n g - acyl derivative of arginine was dissolved in water with continuous stirring at 80 ° c . the remaining ingredients were dissolved in glycerol and mixed with the n g - acylarginine solution at room temperature . ______________________________________ w / w % ______________________________________pluronic f - 127 20 . 0flavors 0 . 8preservatives 0 . 3n . sup . g -- acylarginine 2 . 0water , q . s . to 100 parts______________________________________ ______________________________________ w / w % ______________________________________n . sup . g -- acylarginine 2 . 0naf 0 . 2pluronic f - 127 20 . 0flavors 0 . 8preservatives 0 . 3water , q . s . to 100 parts______________________________________ the gels of examples 5 and 6 were prepared as follows : the n g - acylarginine was dissolved in 50 ml water while continuously stirring at 80 ° c . after the arginine derivative had dissolved , the solution was cooled to room temperature and the naf ( if present ) and preservatives were added . separately , the pluronic f - 127 and flavors were dissolved at 4 ° c . the solution was allowed to warm up to room temperature and then blended into the arginine containing solution with continuous stirring . the mixture was homogenized and the ph of the gel adjusted to 5 . 5 by the addition of naoh or hcl as required . ______________________________________ w / w % ______________________________________n . sup . g -- acylarginine 1 to 5naf 0 . 2glycerol 15 . 0sorbitol 10 . 0sodium lauryl sulfate 1 . 2calcium pyrophosphate 40 . 0propylene glycol 10 . 0flavors 1 . 0preservatives 0 . 3pluronic f - 127 10 . 0water , q . s . to 100 parts______________________________________ the n g - acylarginine was dissolved in glycerol , sorbitol , propylene glycol , pluronic f - 127 and water at 80 ° c . the ph was adjusted to 5 . 5 and the flavors , naf , preservatives and sodium lauryl sulfate were added . the calcium pyrophosphate was blended into the mixture with continuous stirring at room temperature , and the mixture was homogenized with a roller mill . in this formulation , the sodium fluoride component is optional and may be omitted in the preparation of a non - fluoride dentifrice . ______________________________________ w / w % ______________________________________n . sup . g -- acylarginine 1 to 5flavors 4 . 0sodium lauryl sulfate 2 . 0saccharin 0 . 4abrasive , q . s . to 100 parts______________________________________ ______________________________________ w / w % ______________________________________n . sup . g -- acylarginine 1 to 5sorbitol 20 . 0mannitol 20 . 0starch 12 . 0flavors 2 . 0preservatives 0 . 4saccharin 0 . 2magnesium stearate 0 . 8talc 0 . 5corn syrup , q . s . to 100 parts______________________________________ the mixture of example 9 was granulated into a homogeneous blend and pressed into a lozenge . although the present invention has been described with reference to particular embodiments and examples , it will be apparent to those skilled in the art that variations and modifications of this invention can be made and that equivalents can be substituted therefore without departing from the principles and the true spirit of the invention .
oral hygiene formulations incorporating n g - acyl derivatives of arginine , or the pharmaceutically acceptable salts thereof , optionally in combination with fluoride compounds , are effective in combatting microorganisms , inhibiting acid production and reducing dental caries .