CA1105939A

CA1105939A - Antiperspirants

Info

Publication number: CA1105939A
Application number: CA301,943A
Authority: CA
Inventors: Keith Gosling; Michael R. Hyde
Original assignee: Unilever PLC
Current assignee: Unilever PLC
Priority date: 1977-04-26
Filing date: 1978-04-25
Publication date: 1981-07-28
Also published as: JPS6216928B2; JPS53136531A; FR2388553A1; DE2818322C2; DE2818322A1; IE46800B1; FR2388553B1; IE780786L; GB1597498A

Abstract

ABSTRACT OF THE DISCLOSURE

The invention concerns an improvement in the preparation of an aqueous solution of an antiperspirant active compound of enhanced activity according to the process described in copending Canadian application No.269,656 in which process a solution of a basic aluminium chloride, bromide, iodide or nitrate having an aluminium to chloride, bromide, iodide or nitrate molar ration of 6.5 to 1.3:1 is heated under such conditions as to produce polymeric species having a size greater than 100 Angstroms within which species there is contained at least 2%
by weight of the total aluminium. The improvement consists in the inclusion in the solution of an amino acid which enhances the production of such polymeric species.

Description

~'S ~ q9 J.494 (CA) ~ his invention relates to materials having antiperspirant activity, more especially to processes for their production.
~ or inhibiting perspiration, the application to the skin of many different antiperspirant active compounds has been described in the li-terature. However, those compounds most widely used in commercial products at the present time are basic aluminium halides, especially aluminium chlorhydrate, which has an Al/Cl molar ratio of about 2. These active compounds are applied to the skin from a variety of applicator types including aerosol sprays, pump sprays, squeeze packs, roll-ons and stick applicators. ~hus aluminium chlorhydrate, for example, is employed as the active ingredient of various liquid, cream, stick or dry powder antiperspirant compositions~ However, in spite of the popularity of al~minium chlorhydrate the presently available products are capable of producing only limited reduction in perspiration.
In copending Canadian application ~o. 269 656 there is described an improved antiperspirant active compound which comprises a basic aluminium chloride, bromide, iodide and nitrate having an aluminium to chloride, bromide, iodide or nitrate molar ratio of from 6.5 to 1.3:1, and which compound forms in water a solution containing polymeric species of a size grea-ter than 100 Angstroms within which species there is contained at least 2/o by weight of -the total aluminium.
Since in aqueous solutions of the basic aluminium compounds the halide or nitrate is in ionic form the polymeric species present are hydroxy-aluminium species. ~he antiperspirant active ,. . :
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J.~94 compound may be employed in tbe form of an aqueous solution or the solution may be spray dried to give a hydrated compound of the empirical formula Al2(OH)6_aXa-nH20 where X is Cl, Br9 I or N03 _ is from about 0.3 to 1.5 _ is from about 0.5 to 8.
As described in said copending application these special forms of basic aluminium compounds which in aqueous solution contain polymeric species having a size greater than 100 Angstroms within which at least 2% by weight of the total aluminium is contained~ may be prepared by heating aqueous solutions of basic aluminium compounds at elevated temperature. ~he production of the desired species depends on the appropriate choice of the reaction conditions which are interrelated. It is preferred to use temperatures of from 80C to 140C. The period of heating may be shorter as higher temperatures are used~ ranging for example from 0.5 hour to 30 days. Of importance is the concentration of the basic aluminium compound starting material.
The rate of production of the higher polymeric species of the basic aluminium compound decreases as the concentration of the solution is increased and at the above temperatures the concentration should be no more than about 35% by weight.
The present invention in one aspect relates to an improvement in the above-described process.

' J.494 We haYe discovered that the presence of an amino acid, preferably glycine, in the aqueous solution of the basic aluminium compound increases the rate at which the species having a size above 100 Angstroms are formed. ~y including an amino acid in the reaction mixture either at the commencement or during the reaction one can produce the desired polymeric species from starting solutions of higher concentration and/or produce a given amount of the polymeric species in a shorter time and/or at a lower temperature.

The process of the present invention comprises heating an aqueous solution of a mixture of a basic aluminium chloride, bromide9 iodide or nitrate having an aluminium to chloride, bromide, iodide or nitrate molar ratio of 6.5 to 1.3:1 and an amino acid, the concentration of the basic aluminium compound in such solution and the temperature and time of heating the solution being such that there is produced in the solution polymeric speeies having a size greater than 100 Angstroms, said species being produced in such amount that 2 to 80% by weight of the total aluminium is contained within such species.
The amino acid, whieh preferably contains 2 to 10 earbon atoms, may be a neutral amino aeid by which is meant an amino aeid eontaining an equal number of unneutralised amino and aeidie groups. Examples of neutral amino aeids are glyeine, alanine, phenylalanine, valine, sareosine, leueine and lysine hydroehloride. ~owever, other amino aeids may be used, for example arginine, ornithine and lysine whieh are basie amino aeids, that it amino acids which contain more unneutralised amino than aeidie groups.

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J.494 The amount of the amino acid is preferably such that the aluminium to amino acid molar ratio is from 20:1 to 1:1.
The basic aluminium compound in the solution subjected to the heat treatment preferably has an aluminium to chloride, bromide, iodide or nitrate molar ratio of from 4 to i.3:1, more particularly 2.5 to 1.6:1.
The weight of the aluminium in the species having an effective diameter above 100 ~ngstroms is preferably 5 to 60%.
The production of the desired species-depends on the appropriate choice of the reaction conditions which are inter-related. It is preferred to use temperatures of from 80C to 140C. The period of heating may be shorter as higher temperatures are used, ranging for example from 0.5 hour to 30 days. Of importance is the concentration of the basic aluminium compound. As higher concentrations are used (other conditions being constant) the rate of production of the species having an effective diameter greater than 100 Angstroms decreases.
Eowever, by the inclusion of an amino acid in the reaction mixture in accordance with the invention, the rate of reaction, for a given temperature, is increased. Thus in the process of . .
the invention higher concentrations can be used to obtain a given amount of the desired polymeric species in a given time. In particular, substantial amounts of the polymeric species have been obtained at 120C from solutions of aluminium chlorhydrate of a concentration of 40% and even higher concentrations. The concentration of the solution of the basic aluminium compound will usually be at least 5%. Under appropriate conditions, solutions of concentration up to 60% can be used.

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~5~9 J.494 The conditions of heat treatment described above have beenfound to give rise to the improved basic aluminium compound in amorphous form, and in particu]ar the formation of boehmite, as determined by X-ray diffraction, has not been observed. The production of a substantial amount of boehmite or other crystal-line forms of alumina would be considered to be disadvantageous.
The aqueous solution of the more active antiperspirant compound comprising the higher polymeric species as defined, and produced by the process of the invention, may, if desired~ be evaporated to concentrate the solution or it may be dried to give a solid hydrated material. As with untreated aluminium chlor-hydrate~ for example, drying conditions which lead to both the loss of water of condensation and hydrochloric acid should be avoided as these may lead to irreversible degradation of the i5 treated basic aluminium compound. Any suitable method of drying may be used~ spray drying being a particularly useful method.
The spray drying method described in US Patent No.3,887,692 may be employed. The solld material may be ground or milled as required~ more particularly to a particle size below 100 microns such that the particulate compound is suitable for use in an aerosol powder spray product. Drying should be effected in such manner as to give a product having a water content consistent with the following empirical formula 12(OH)6_aXanH20.(Amino acid)m 25 where X is Cl, Br~ I or N03~ _ is from about 0.3 to 1.5~ n is from about 0.5 to 8~ preferably 0.5 to 4~ and m indicates the amount of amino acid added and is preferably about 0.1 to 2.

' ~35~39 J.~94 The invention in another aspect also relates to these novel solid antiperspirant active complex materials.
The antiperspirant agent produced by the process of the invention may be employed directly as an antiperspirant composition in the form of the solution, or it may be used in antiperspirant compositions in the form of a powder obtained from such solution, or again as a solution obtained from such powder. Various examples of suitable antiperspirant compositions are described in the copending application referred to above.
Thus in accordance with one aspect of the invention there is provided an antiperspirant composition comprising an aqueous solution of an antiperspirant active material produced by the process of the invention in combination with an adjunct which is a perfume, thickener, alcohol or propellant. ~he anti-perspirant composition may be in the form of a lotion comprising an aqueous or aqueous alcoholic solution of the basic aluminium compound in a concentration of from 1 to 30% by weight and 0.1 to 5% by weight of a thickening agent. Suitable thickening agents for antiperspirant lotions are well known to those skilled in the art, and include for example, magnesium aluminium silicates. ~hickening may also be effected by emulsifying an oil or the like in the composition. Furthermore9 the composition may comprise an aqueous or aqueous alcoholic solution of the basic aluminium compound in a concentration of from 1 to 30% by weight 9 the amino acid and from ~.1 to 2% by weight of parfume.

- 7 _ ~5~9 J.~94 Tbe composition may comprise an aqueous alcoholic solution of the basic aluminium compound and amino acid containing from up to 75% by weight of a C1-C3 aliphatic alcohol. These aqueous alcoholic compositions preferably contain ethanol, propanol, iso-5 propanol or a mixture thereof as the alcohol. ~ntiperspirantcompositions comprising an aqueous solution of the basic alumin-ium compound and the amino acid may contain from about 1 to 80%
by weight of a propellant.
The antiperspirant composition may also comprise in combina-tion a powdered antiperspirant active material obtained by drying a solution obtained by the process of the invention and a powder-ed inert solid diluent or organic liquid carrier. The composi-tion may be in the form of a powder aerosol composition comprising a suspension of the basic aluminium compound/amino acid complex 15 in particulate form in a liquid carrier, said composition also comprising a propellant. In particular the composition may be in the form of a powder aerosol composition comprising A. from about 1% to about 12% by weight of said basic aluminium compound/amino acid comple~ in powder form;

B. from about 0.1% to about 5% by weight of a suspending agent;

C. from about 1% to about 15% by weight of a carrier liquid; and D. from about 70% to about 96% by weight of a propellant.
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~ 5~ J.~94 The carrier liquid may for example be a non-volatile non-hygroscopic liquid as suggested in US Patent No.3,968~203.
Especially useful are carrier liquids which have emollient properties and a number of these are referred to in British Patent Specification No.19393,860. Especially preferred are fatty acid esters such as isopropyl myristate and those esters referred to in British Patent Specification No.19353,914 such as dibutyl phthalate and diisopropyl adipate.
Various other carrier liquids for powder suspension aerosols are suggested in US Patent Specifications Nos.
39833,721, 3,833,720, 3,920,807, 3,949,066 and 3,974,270 and in British Patent Specifications Nos.19341,748, 1,300,260, 1,369,872 and 1,411,547. Volatlle carrier liquids may also be used such as ethanol or a volatile silicone as described in 15 South African and British Patent Specifications Nos.75/3576 and 1,467~676, respectively.
The ratio of total solids in the compositions to the carrier liquid may vary over a wide range9 for example from 0.1 to 3 parts of the powder per part by weight of the carrier liquid.

2~ The propellant can be a liquefied hydrocarbon, halogenated hydrocarbon or a mixture thereof. Examples of materials that are suitable for use as propellants are given in the above-mentioned patents and include trichlorofluoromethane, dichloro-difluoromethane, dichlorotetrafluoroethane, monochlorodifluoro-methane, trichlorotrifluoroethane, propane, butane, 1,1 difluoro-ethane, 1,1 difluoro-1-chloroethane~ dichloromonofluoromethane, methylene chloride, isopentane and isobutane, used singly or ''' ' ' .

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~ 5~`9 tJ.494 admixed. Trichlorofluoromethane, dichlorodifluoromethane, dichlorotetrafluoroethane, and isobutane, used singly or admixed, are preferred.
Examples of materials that are suitable for use as permanent gas propellants are nitrogen, carbon dioxide and nitrous oxide.
It is common practice to include in aerosol powder spray compositions a material to assist in the suspending of the powder in the liquid vehicle. The materials prevent compacting of the powder and they may also act as thickening or gelling agents for the liquid vehicle. Especially preferred are hydrophobic clays and colloidal silicas. Hydrophobic clays are available under the trade name Bentone, eg Bentone 34 or Bentone 38, and their use as suspending agents are describcd in a number of patent specifications including US Patent Specification No.3,773,683. Suitable colloidal silicas L~ include Aerosil 200 and Cab-0-Sil M-5 as well as other grades.
The antiperspirant composition may simply comprise from 5 to 40% by weight of the amino acid-containing aluminium compound in powder form, the remainder consisting essentially of an inert powder material, such as talc or starch, for example.
The invention also relates to packages consisting of the combination of an antiperspirant composition comprising an antiperspirant active agent produced by the process of the invention and an applicator for applying the antiperspirant composition to the skin. The package may be one in which tbe applicator is a container fitted with a valve for dispensing ~ c~e~< ~e-S t~e . .

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~ J.494 liquid in aerosol form and -the antiperspira~t composition comprises a suspension of said antiperspirant active agent in particulate form in a liquid carrier which may be in admixture with a propellant. Furthermore, the package may be one wherein the applicator is a container fitted with a valve for dispensing liquid in aerosol form and the antiperspirant composition comprises an aqueous or aqueous alcoholic solution of said antiperspirant active agent. In this case the aqueous solution may be discharged by a propellant gas or by a finger-operated pump mechanism or by containing the composition within a container of pliable material whereby by squeezing the container the composition is expelled through the spray valve.
~nother form of package is one in which the applicator is a roll-on applicator and the antiperspirant composition comprises an aqueous or aqueous alcoholic solution of the said anti-perspirant active agent. Furthermore, the package may be one wherein the applicator is an applicator for dispensing a powdered material and the antiperspirant composition is a powdered composition including said antiperspirant active agent in powder form. The applicator may also be a stick applicator for holding an antiperspirant composition in the form of a stick or it may be tissue or cloth which is impregnated with the antiperspirant active material.
The invention also relates to a method of inhibiting the exudation of perspiration comprising applying the amino acid-containing polymeric aluminium antiperspirant active material to the skin.

J.494 ~5~

Tes_ Method for Assessment of Effic _~ of A tiperspirants In the Examples given herein a test method is referred to for the assessment of the efficacy of an antiperspirant active agent. Details of the test procedure are descri,bed below.
The test method for,the assessment of antiperspirant efficacy depended on subjecting human volunteers to thermal stress and gravimetric determination of axillar sweat.
Tes _~Iet_od Subjects A panel of up to'54 women who use no - 10 antiperspirant for the 14 days before the test.

Hot Room ' T,emperat,ure 37C - 1C, relative humidity approximately 35%.

-Test Product 10% solution of treated aluminium chlorhydrate (unless stated otherwise) ~ in water.

Control Product 10~ solution of untreated aluminium chlorhydrate (unless stated otherwise) in water.

20 Product Application Approximately 0.5 g of solution was applied to each axilla with a pump-spray applicator.

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~5~9 J.494 Sweat Collection Absorbent cotton pads are used to collect the sweat. On entering the hot room each subject has a pair of pads placed in her axillae. After 40 minutes these are removed and rejected.
Sweat ls then collected for two consec-utive periods of 20 minutes, fresh tared pads being used for each collection, and sweat weight determined.
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iO Test Design Subjects attend daily for 3 consecutive days. They receive one treatment with the products each day. On the third day the treatment is immediately followed by a hot room sitting and sweat collection.

Analysis of Data The statistical treatment includes an analysis of variance which allows for subject, side and product effects.
The efficacy Is calculated from the geometric mean weight of sweat collected from the axillae treated with each - product.

% reduction = 100 (C

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where C is -the geometric mean sweat weight ~rom the axillae treated with the control product and T is the geometric mean sweat weight from the axillae treated with the test product.
The C/o reduction is usually calculated for each day separately and for the entire test.
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Significance is calculated by applying - 10 Student's T-test to the logarithmically ___ transformed weights.

Determination of Percentage Aluminium in Polymeric Species havin a size ~reater than iO0 An~stroms The heat-treated basic aluminium compounds described herein were defined by molecular sieve~chromatography. For this purpose there was used a 1.2 m x 6.0 mm column packed with spherlcal porous silica beads of particle size 75-125 microns, and of surface area 350-500 m /g, and having a magimum pore size of 100 Angstroms. The silica employed, available B 20 commercially as Porasil A~, had been deactivated to eliminate adsorption in molecular size separations. The use of Porasil silica beads as a column packing in chromatography is referred to in "Gel Permeation Chromatography" by K.H. Altgelt and L. Segan, i971, pages 16 to 1~. The silica was conditioned before use by passage of a single large sample (eg ~.5 ml of a 2% W/w solution) of a heat-treated aluminium chlorhydrate.
Samples to be tested were dissolved in deionized water to .
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~5~39 J.~94 approximately 0.2 M aluminium and thoroughly dispersed by treatment (4 minutes) with a sonic probe. About 0.1 ml samples of approximately 0.2 M aluminium solutions were applied to the column by a sample loop system and eluted with 10 2 M aqueous hydrochloric acid solution using a peristaltic pump. A
- differential refractive index monitor linked to a pen recorder was used to detect fractions as they were eluted. These fractions were collected and analysed for aluminium by atomic absorption. Complete elution of all aluminium applied in each sample was checked by direct analysis of another sample of the same volume. The percentage of the total aluminium which appeared in the fraction eluted at the void volume of the column was considered as that deriving from polymeric material of a size greater than 100 Angstroms in effective diameter. None of this polymeric material was found in any untreated aluminium chlorhydrate solutions.
Determination of Water Content of Powdered Materials The water content of powdered materials was estimated by thermogravimetric analysis (TGA). On heating to 1,000C, aluminium cblorhydrate undergoes the following reaction:

A12(E)5Cl(E2)X ~ A1203 + ~IC11` + (X + 2)H2 From a knowledge of Al/Cl ratio of the material (and hence the empirical weight of the anhydrous Al2(0H)6 aCla) it is possible to calculate the number of moles of water (x) associated with each anhydrous unit from an accurate determination of the weight loss on heating a known weight of sample to l,000C.
The following equation shows the method of calculation:

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~ 5~ ~ J.494 x _ (~\re~ht of sol]d_before he~ g x 102) Empirical weight ~ Weight of solid after heating of anhydrous -- 18 ~Al2(OH~G aCla7 5 The percentage of water is given by 1 ,800Y ____ Empirical weight of anhydrous . Al2(~)6_aCla + 18x The following Examples illustrate~the invention. Percentages are by weight.
Example 1 A solution was prepared from 50 g of aluminium chlorhydrate, having an Al/Cl ratio of 1.91 and a water content of 18.8%~ and 8.9 g of glycine in 500 g of solution to give an Al/glycine ratio of 4. Samples of this solution were heated in 20 ml Pyrex glass screw cap tubes equipped with polytetrafluoroethylene washers to 120C over 2 hours and maintained at this temperature for a further 3 ~ours. The resulting,solution contained 20.2%
of the aluminium as polymeric species exceeding iO0 Angstroms in effective diameter. When tested for antiperspirancy by the method described herein~ employing a panel of 22 subjects, this solution gave a 19% reduction in sweat collected compared to a 10% solution of untreated aluminium chlorhydrate as control.
This result was significant at the 5% level.
Example 2 A batch of aluminium chlorhydrate having an Al/Cl molar ratio of 2.04 and a water content of 18.5% was dissolved in deionised water to give a 10% solution. Aliquots of this solution were taken, to which varying amounts of glycine were added, and the whole heated at 120C for 3 hours. The : - - ' .

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~s~q9 J.494 percentage aluminium present as polymeric species with effective diameters in excess of 100 Angstroms is listed as a function of the amount of glycine present (per 100 g of solution).

Wt glycine (g) /c Al in polymers Al:glycine __ > 100 ~st _ms molar ratio 19.2 0.75 21.1 10.00 1.87 22.5 4.00

3.75 28.1 2.00 5.62 31.7 1.33 7.50 42.4 1.00 Example 3 Aluminium chlorhydrate (Al:Cl ratio 2.01) was made up as a 10% solution in deionised water. 100 g aliquots of this solution were taken and heated in Z5 ml Pyrex screw cap tubes - equipped with polytetrafluoroethylene washers, at 120C, for times of 0, 1~ 2, 3~ 4 and 5 hours. To each 100 g of these heated solutions were added 3.75 g glycine and the samples then returned to the oven at 120C for a further 6, 5, 4, 3, 2 and 1 hours, respectively, giving a total reaction time of 6 hours.
The aluminium:glycine molar ratio of these solutions is 2.
The percentage aluminium found as polymeric material with effective diameter in excess of 100 Angstroms is listed as a function of reaction conditions.

~ J.~94 Heating time with Heating time in % Al in polymers no glycine added the presence of > 100 ~ngstroms (hours) ~Iy~ine (hours)_ _ _ 0 6 63.8 1 5 53.4 2 4 55.0 3 3 50.8

4 2 46.8 1 49.5-Example 4 Solutions of aluminium chlorhydrate having an ~l/Cl molar ratio of 2.00 were made up at concentrations between iO% and 40/0. Each 100 g of these solutions contained 7.5 g glycine, with corresponding aluminium:glycine molar ratios varying between 1:1 to.4:1. The solutions were heated at 120C for a period of 6 hours and the percentage aluminium found as polymeric species with effective diameters in excess of 100 Angstroms, determined. These results are tabulated along with data for reactions in which aluminium chlorhydrate is heated with no glycine present.

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~1~5~3~ J.494 Ex~les 5 to 8 A 50~0 w/~ solution of aluminium chlorhydrate having an Al¦Cl molar ratio of 2.00 was diluted with deionised water to give a lU% W/w solution. Aliquots of this solution were taken and quantities of various neutral amino acids were added. The resulting solutions were heated in 20 ml Pyrex glass tubes, equipped with screw caps and polytetrafluoroethylene washers, to 120C over 30 mlnutes and maintained at this temperature for a further 3 hours. The percentage of aluminium present as polymeric species with effective diameters greater than 100 Angstroms is listed as a function of the type and amount of amino acid present.

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_ 21 -- /- -~5~qg J.494 Example _ 9 and 10 . A 12.1% W/w solution of a basic aluminium bromide having an Al~Br molar ratio of 2.00 was prepared. Aliquots of this solution were taken and quantities of a neutral or basic amino acid were added. Pyrex glass tubes, equipped with screw caps and polytetrafluoroethylene washers, to 120C over 30 minutes and maintained at this temperature for a further 3 hours. ~he percentage of aluminium present as polymeric species with effective diameters greater than 100 Angstroms is listed as a iunction o~ the type and am~unt of amino acid present.

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~ 1~5~q9 E~x amp 1 e 11 A solution was prepared from 9.34 g of 500,b WJw aluminium chlorhydrate having an Al/Cl molar ratio of 2.00, 0.76 g of aluminium chloride hexahydrate and deionised water to give 50 g of a solution with an Al/Cl molar ratio of 1.50. An aliquot of this solution was taken and the amino acid added. The resulting solution was placed in a Pyrex glass tube equipped with a screw cap and polytetrafluoroethylene washer and heated to 120C over 30 minutes and maintained at this temperature for 3 hours. The percentage of aluminium present as polymeric species with effective diameters in excess of 100 ~ngstroms is listed as a function of the amount of the amino acid present.

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Claims

J.494 (CA) The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A process of preparing an aqueous solution of an antiperspirant active compound comprising heating at 80 to 140°C for 0.5 hour to 30 days a 5 to 60% by weight aqueous solution of a basic aluminium chloride, bromide, iodide or nitrate having an aluminium to chloride, bromide, iodide or nitrate molar ratio of 6.5 to 1.3:1 said solution also containing an amino acid, having 2 to 10 carbon atoms, in such amount that the aluminium to amino acid molar ratio is from 20:1 to 1:1, the concentration of the basic aluminium compound in such solution and the temperature and time of heating the solution being such that there is produced in the solution polymeric species having a size greater than 100 Angstroms, said species being produced in such amount that 2 to 80% by weight of the total aluminium is contained within such species.

2. A process as claimed in Claim 1, wherein the amino acid is a neutral amino acid.

3. A process as claimed in Claim 2, wherein the amino acid is glycine, alanine, phenylalanine, valine, sarcosine, leucine or lysine hydrochloride.

4. A process as claimed in Claim 1, wherein the amino acid is a basic amino acid.

5. A process as claimed in Claim 4, wherein the amino acid is arginine, ornithine or lysine.

6. A process as claimed in Claim 1 or Claim 2 or Claim 4, wherein the weight of the aluminium in the species having a size greater than 100 Angstroms is 5 to 60% of the total weight of the aluminium.

J.494 (CA)

7. A process of preparing an antiperspirant active compound in solid form by drying the aqueous solution prepared according to the process claimed in Claim 1 to obtain an antiperspirant active complex having the empirical formula Al2(OH)6-aXa.nH20.(Amino acid)m where X is Cl, Br, I or N03, a is from about 0.3 to 1.5, n is from about 0.5 to 8, and m indicates the amount of the amino acid.