fig1 illustrates the general chemical structure of the series of quaternary n -( halomethyl ) ammonium salts according to the invention . anion a − is a halide ( chloride , bromide , iodide ), acetate , p - toluenesulfonate or any other pharmaceutically acceptable anion . r and r ′ are alkyl groups such as methyl , ethyl , propyl or butyl ( they are either the same group or different from each other ). w is a chemical tether , characterized by a carbon chain ( ch 2 ) n constituted by a number n of methylene units such that n = 1 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 ; the structure of the chemical tether w either a normal or a branched hydrocarbon chain . w is also a chemical tether constituted by an oxycarbonated chain with structure represented by —( ch 2 ) s [( ch 2 ) 2 — o —] t ( ch 2 ) u —, made of a number s of methylene units such that s = 0 , 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , and a number t of ethyleneoxy units such that t = 0 , 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , and a number of u methylene units such that u = 0 , 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 . in addition , w is also a chemical tether constituted by a chain with structure ( ch 2 ) p [— o — si ( ch 3 ) 2 ] q — o — ch 2 ) r — made of a number p of methylene units such that p = 1 , 2 , 3 , 4 , and a number q of dimethylsiloxane units such that q = 0 , 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , and a number of r methylene units such that r = 0 , 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 . the tail g is a methyl group , a hydroxyl group , or an alkenyl system with groups v , y and z attached to the vinylic carbons . v , y and z are either the same group or they are different from each other when g is an alkenyl system . substituents v and / or y and / or z correspond to hydrogen , phenyl group or any aromatic or heteroaromatic group , or any alkyl , alkenyl or alkynyl group . the aromatic or heteroaromatic group bears hydrogen atoms or any kind and number of substituents in any place of the ring , with the aromatic substituents including hydroxyl , methoxy or any alkoxy group , o - acetyloxy or any o - acyloxy group , amino , n - acetylamino or any n - acylamino group , fluorine , chlorine , bromine , iodine , α , α , α - trifluoromethyl , any alkyl substituent , or any other pharmaceutically acceptable substituent and any substitution pattern , with a total number of substituents in the ring being zero , one , two , three , four , five or six . these substituents may also be chemically connected with some others generating additional annular patterns . according to fig1 , the screening revealed that compounds inhibit the growth of parasites , even though they work out with different capacities . quaternary n -( halomethyl ) ammonium salts as therapeutic agents , is a series of compounds that are characterized by a general structure consisting of a quaternary n -( halomethyl ) ammonium cation head , a tail g , a chemical tether w , and a counter ion a − . the counter ion a − is chloride ( cl − ), bromide ( br − ), iodide ( i − ), acetate ( ch 3 coo − ), tosylate ( p - ch 3 c 6 h 4 so 3 − ), or any other pharmaceutically acceptable anion . the quaternary n -( halomethyl ) ammonium cation head is constituted by a nitrogen atom which is coordinated to four ligands with the following specific description : ( i ) a halomethyl group ( ch 2 — x ) where the halogen x is fluorine ( f ), chlorine ( cl ), bromine ( br ) or iodine ( i ); ( ii ) an alkyl group r , such as methyl , ethyl , n - propyl or n - butyl ; ( iii ) another alkyl group r ′, such as methyl , ethyl , n - propyl or n - butyl ; ( iv ) a chemical tether w which joins the quaternary nitrogen head to the tail g . the tail g is a methyl group , a hydroxyl group , or an alkenyl system with groups v , y and z attached to the vinylic carbons . v , y and z are either the same group or different from each other when g is an alkenyl system . substituents v and / or y and / or z correspond to hydrogen , phenyl group or any aromatic or heteroaromatic group , or any alkyl , alkenyl or alkynyl group . the aromatic or heteroaromatic group bears hydrogen atoms or any kind and number of substituents in any place of the ring , with the aromatic substituents including hydroxyl , methoxy or any alkoxy group , o - acetyloxy or any o - acyloxy group , amino , n - acetylamino or any n - acylamino group , fluorine , chlorine , bromine , iodine , α , α , α - trifluoromethyl , any alkyl substituent , or any other pharmaceutically acceptable substituent and any substitution pattern , with a total number of substituents in the ring being zero , one , two , three , four , five or six . these substituents may also be chemically connected with some others generating additional annular patterns . the chemical tether w is a carbon chain ( ch 2 ) n constituted by a number n of methylene units such that n = 1 , 2 , 3 , 4 , 5 , 9 , 10 , 11 , 12 , 13 , 14 . this chemical tether w could also be a branched hydrocarbon chain . quaternary n -( halomethyl ) ammonium salts as therapeutic agents with a chemical tether w is characterized by a chain with structure —( ch 2 ) p [— o — si ( ch 3 ) 2 ] q — o —( ch 2 ) r — made of a number p of methylene units such that p = 1 , 2 , 3 , 4 , and a number q of dimethylsiloxane units such that q = 0 , 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , and a number of r methylene units such that r = 0 , 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 . also , the chemical tether w is characterized by an oxycarbonated chain with structure represented by —( ch 2 ) s [( ch 2 ) 2 — o -] t ( ch 2 ) u —, made of a number s of methylene units such that s = 0 , 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , and a number t of ethyleneoxy units such that t = 0 , 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , and a number of u methylene units such that u = 0 , 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 . quaternary n -( halomethyl ) ammonium salts as therapeutic agents are effective against leishmania tarentolae parasites , non - pathogenic species that are used for pre - screening processes in the promastigote stage . some of the quaternary n -( halomethyl ) ammonium salts as therapeutic agents are effective against axenic l . ( v ) panamensis and l . ( l ) amazonensis parasites , human pathogenic species that causes cutaneous and mucocutaneous leishmaniasis . also , some of the quaternary n -( halomethyl ) ammonium salts as therapeutic agents are effective against l . ( v ) panamensis and l . ( l ) amazonensis parasites , in the amastigote stage that have infected macrophage cells . quaternary n -( halomethyl ) ammonium salts as therapeutic agents is a series of compounds that inhibit the growth of parasites , even though they work out with different capacities . those compounds with a terminal arylalkenyl or diarylalkenyl ( i . e . g = alkenyl system with v = h , y = h , z = c 6 h 5 or v = h , y = c 6 h 5 , z = h or v = h , y = c 6 h 5 , z = c 6 h 5 ) were more effective against the parasites than those without this moiety . interestingly , compounds with g being a terminal diarylalkenyl moiety ( i . e . v = h , y = c 6 h 5 , z = c 6 h 5 ) are the most effective . the use of quaternary n -( halomethyl ) ammonium salts as therapeutic agents for a topical treatment of cutaneous leishmaniasis on infected golden hamsters led to 100 % healing of the lesion after three months of treatment . the invention originates from the study of the effect of some quaternary n -( halomethyl ) ammonium salts on the in vitro viability of l . tarentolae parasites . in consideration of the structural similarity of this salts and choline , it was hypothesized that quaternary n -( halomethyl ) ammonium salts should have an effect on the choline transport and metabolic role in the formation of the parasite membrane , resulting in consequence in a possible active ingredient for a pharmaceutical composition against trypanosomal parasites . so , compounds shown in fig4 were tested for their in vitro efficacy against l . tarentolae parasites ( a non - pathogenic species ) in the promastigote stage . the screening revealed that compounds inhibit the growth of parasites , even though they work out with different capacities . of all these tested compounds fig4 the compounds with a terminal arylalkenyl moiety ( compounds 4 , 6 - 9 , 11 ) or diarylalkenyl moiety ( compound 3 ) were more effective against the parasites than those without this moiety ( compound 1 ). interestingly , compound 3 , having a terminal diarylalkenyl moiety is the most effective . then , a series of compounds analogous to compound 3 ( characterized by a tail g being a diarylalkenyl moiety ) were synthesized in order to assess their in vitro effectiveness against l . ( v ) panamensis , a pathogenic species which causes human mucocutaneous leishmaniasis . other halogenated analogs of choline were also synthesized and included in this in vitro effectiveness study . fig2 illustrates the compounds evaluated for their in vitro effectiveness against axenic amastigotes of l . ( v ) panamensis . given that leishmania parasites are known to infect monocyte cells , mostly macrophages and neutrophils , the in vitro effectiveness of some of the compounds was also tested on l . ( v ) panamensis in the amastigote stage that have been set to infect macrophage cells . fig5 contains the list of compounds evaluated . it was decided then to carry out a preliminary in vivo animal study according to standard practices using the golden hamster model for cutaneous leishmaniasis , using the compounds with the better profile as therapeutic agents against leishmaniasis . for that purpose the in vivo effectiveness of compounds 3b , 13b and 14c were tested fig6 . the table shown in fig7 contains the ec 50 values ( molar amount of compound that kills 50 % of parasites in sample ) obtained against axenic amastigotes of l . ( v ) panamensis . quaternary n -( halomethyl ) ammonium salts as therapeutic agents were compared with the respective non - halogenated ( i . e . n , n , n - trimethyl quaternary ammonium salts ) and with two compounds commonly used to treat leishmaniasis ( meglumine antimoniate and amphotericin b ). as shown in fig7 compound 14a is the most effective of them , being more efficient than compound 3a . the ec 50 values for meglumine antimoniate and amphotericin b are 312 ± 18 . 6 μm and 0 . 041 ± 0 . 001 μm respectively . on the other hand , the results of the in vitro activity study of some quaternary n -( halomethyl ) ammonium salts as therapeutic agents shown in fig5 against infected macrophage cells with leishmania panamesis are shown in fig8 . the ec 50 values for meglumine antimoniate and amphotericin b are 6 . 33 ± 0 . 86 μg / ml and 0 . 05 ± 0 . 001 μg / ml respectively . it was decided then to carry out a small in vivo animal study according to standard practices using the golden hamster model for cutaneous leishmaniasis . for that purpose the in vivo effectiveness of compounds 3b , 13b and 14c were tested . treatment consisted of a topical application of the compound suspended in an aqueous buffer ( neutral ph ) daily for ten days . the results are summarized in fig9 ( a - d ) and evidence that application of the compounds topically is conductive to the cure of the majority of the animals in the study , with similar results to those found when using meglumine antimoniate via intramuscular injection . the required dosage of compounds 3b , 13b , and 14c is smaller than that of meglumine antimoniate . some additional studies show that the compounds induce parasites death via an apoptotic mechanism . an understanding of the mechanism of parasite &# 39 ; s death is of importance in the future development of compounds that are better against the parasites . choline is a quaternary ammonium salt that is necessary for the construction of cell membranes . choline is used by cells to biosynthesize phosphatidyl choline , one of the primary phospholipids that constitute cellular membranes . given the similarity between the compounds tested and choline ( see compound 12c in fig7 , it was hypothesized that the compounds of the invention may inhibit the uptake of choline by the parasites , or that they may inhibit some enzymes which are catalyzing the transformation of choline . phosphatidyl choline can be synthesized by the parasite following the traditional kennedy pathway ( zhang and beverley , 2010 ), in which choline is converted to phosphatidyl choline via a sequence of steps , each catalyzed by a specific enzyme . the first step involves the phosphorylation of choline with the enzyme choline kinase . kinetic studies using the choline kinase of l . ( l ) infantum reveal that some of the compounds , especially compound 14a is able to inhibit this enzyme , lowering its catalytic efficiency . other studies reveal that some of the compounds with structure 1 , especially compound 14a , interferes with the in vitro uptake of choline by promastigotes of l . tarentolae and , also inhibits the in vitro production of phosphatidyl choline by these parasites according to an embodiment of the invention , a daily topical application of a composition based on the quaternary n -( halomethyl ) ammonium salts in an aqueous buffer solution ( neutral ph ) is proposed . the syntheses of some representative quaternary n -( halomethyl ) ammonium salts are accomplished according to standard procedures , fig3 . the starting materials for this three - step sequence are ω - bromoacyl chlorides 1 which are converted into ω - bromo - α , α - diphenyl - α - alkenes 2 via a grignard reaction with excess of phenylmagnesium bromide and the further dehydration of the resulting tertiary ω - bromo - α , α - diphenylcarbinols with p - toluenesulfonic acid . then , bromide anion is displaced by dimethylamine affording the respective tertiary amine 15 , which is in turn made to react with diiodomethane or chloroiodomethane giving rise to the target quaternary n -( halomethyl ) ammonium salts 3 , 13 or 14 . in a typical run , 2 . 6 equivalents of phenyl magnesium bromide are added to 1 . 0 equivalent of 5 - bromopentanoyl chloride dissolved in dried diethyl ether under inert atmosphere at 0 ° c . and stirred during 15 minutes . after this time the mixture is warmed up to room temperature , and then ammonium chloride is added slowly to the mixture , and worked up in the usual manner to produce 5 - bromo - 1 , 1 - diphenyl - 1 - pentanol as a white solid . the crude product is then refluxed during 6 hours with p - toluenesulfonic acid ( ratio 60 : 1 ) under benzene , and worked up in the usual manner to yield 5 - bromo - 1 , 1 - diphenyl - 1 - pentene as a yellow oil . next , an aqueous solution ( 40 %) of dimethyl amine ( 25 equivalents ) is added slowly to a thf solution of 1 . 0 equivalent of 5 - bromo - 1 , 1 - diphenyl - 1 - pentene that has been obtained in the previous step . the mixture is then stirred at room temperature for 24 hours , and worked up in the usual manner to yield 5 -( n , n - dimethyl ) amino - 1 , 1 - diphenyl - 1 - pentene as a yellow oil . finally , 1 . 0 equivalent of the resulting amine is mixed with 4 . 0 equivalents of diiodomethane in acetonitrile . the mixture is stirred for 20 hours or until the quaternary n -( halomethyl ) ammonium salt precipitates as a white solid . the product is then recrystallized from hot water . although the invention has been described in conjunction with specific embodiments , it is evident that many alternatives and variations will be apparent to those skilled in the art in light of the foregoing description . accordingly , the invention is intended to embrace all of the alternatives and variations that fall within the spirit and scope of the appended claims .
the use of quaternary halogenated ammonium salts for treating leishmaniasis infections and other parasitic diseases is described . although there have been previous reports in which quaternary ammonium salts are used as antimalarial , antifungal , and antileishmanial compounds , the use of such salts containing a halogenated n - methyl substituent as a therapeutic agent against leishmaniasis had not been reported . the compounds described here , in specific those with a terminal arylalkenyl or diarylalkenyl moiety , are shown to inhibit the growth of leishmania panamensis parasites , a known causative agent of leishmaniasis disease . in addition , the series of compounds are also extensive against malaria , chagas disease , toxoplasmosis , and other parasitic diseases .