DE1493807A1 - Process for the preparation of oligopeptide mixtures - Google Patents

Description

U93807

RAN 4440/75

F. Hoffmann-La Roche A Co. Public Company. Basel, Switzerland)

procedure for the production of oligopeptide mixtures

The present invention relates to a process for the preparation of an oligopeptide mixture of the general formula

R ₁ ( MH-R-CO) j-R ₂ (I)

where R is a radical of a basic α-aminocarboxylic acid freed from the α-amino and carboxyl groups, R _{1 is} an acyl radical of a long-chain , saturated or unsaturated, aliphatic carboxylic acid, R _{2 is} a hydroxy, alkoxy, amino, alkylamino, dialkyl represent amino or hydrazino group and the symbol χ indicates a low degree of polymerization, and acid addition salts of these compounds.

The cligopeptide mixture illustrated by the above general formula I expediently comprises peptides in which x tlnen value up to approx. Preferably

HM / Oe / C yr. §08181 / HS «coll. Og. · ·

4.6.1963

U9-3807

the oligopeptide mixture contains di-, TrI-, tetra-, penta- or hexapeptides, in particular dipeptides and tripeptides, as main components. The oligopeptides of the formula I are derived from basic (! -Aminocarboxylic acids, such as lysine, arginine, ornithine, α, γ-diaminobutyric acid, α, γ-diamino propionic acid, histidine, etc. These amino acids can be in an optically active form or In the reaction according to the invention, the optical configuration of the selected starting compounds is retained. The radicals represented by the R symbols can be derived from the same or from different types of basic α-aminocarboxylic acids. The alkoxy, alkylamino and dialkylamino groups mean for the radical R ₂ is preferably derived from lower alkyl radicals, for example methyl or ethyl. The long-chain acyl radical is preferably derived from a carboxylic acid containing at least 10 carbon atoms. Preferred radicals of this type are, for example, the palmitoyl or the stearoyl radical.

The inventive method consists in that one compound of the general formula

CO 0

R ¹ -HH-CO (II)

In H ¹ one of the α-amine and carboxyl groups

U93807

freed residue of a basic α-aminocarboxylic acid means whose basic residue is protected, in the presence of an organic solvent with ammonia, an alkylamine, a dialkylamine, hydrazine or a compound * of the general formula

-R'-CO-R ₂ (III)

wherein R ¹ and R _{2 have} the above meaning, reacts the product obtained in any order with a reactive derivative of an acid of the general formula

R ₁ -OH (IV)

where R, has the above meaning,

acylated, the reaction product optionally saponified, post-esterified or both post-esterified and post-amidated and the protective groups present are split off, whereupon the peptide obtained is optionally converted into an acid addition salt will.

The N-carboxyanhydrides of the formula II required as starting compounds can be prepared, for example, from basic amino acids and phosgene protected on the egg-air ino group by uni · ;;;. Etching in an inert solvent, v: ie Oalcroform _v tetra-

909851 / itiÖ

BATH ORIGINAL

U93807

produce hydrofuran, dioxane, etc. They are mostly crystalline and can be kept for some time at low temperatures.

By treating compounds of the formula II with ammonia, an alkylamine, a dialkylamine, hydrazine or Alcoholic hydrochloric acid can also be used as reaction components usable compounds of the formula III as follows Manufacture: For the production of amides it is advantageous to leave ammonia or an excess of an amine in an inort Solvents such as dioxane, tetrahydrofuran or chloroform act on a compound of formula II. This implementation can e.g. under pressure with nitrogen gassing at about 0-40 ° or without pressure at higher temperatures up to about 80 °. The esters can, for example, by treatment with gaseous Hydrogen chloride and the desired alcohol at ώι ~ at room temperature. The compounds can be removed by evaporation of the solvents and, if desired can be isolated by recrystallization. Those that arise in the case of treatment with alcoholic hydrogen chloride; Amino acid hydrochlorides can be converted into corresponding ones by customary methods Ester bases are transferred.

The first stage of the process according to the invention; the Implementation of the Carboxyanhydriäs of the formula II with ammonia. -. Alkylamine, a dialkylamine, hydrazine or a compound / g

909851 / 17S9

BATH ORIGINAL

H93807

of the formula III is conveniently carried out in the presence of an organic solvent such as dioxane, chloroform, methanol or dimethylformamide. One can vary the ratio of carboxy anhydride and amine component within wide limits and, for example also work with a 3 "fold excess of carboxyanhydride. Conveniently, heating the reaction mixture for about 1-3 hours to 0-90 °, preferably 50-80 °. After Removal of the solvent, the oligomer mixture obtained can be purified by reprecipitation.Another possibility of working up is precipitation with aqueous hydrochloric acid, in which case some of the monomers present in the reaction mixture can be removed.

As is customary in feptide chemistry, the reactive groups that are not involved in the first stage are protected from the reaction. With regard to the carboxyl group, this can be achieved in a simple manner by using the corresponding ester or the amide. Free to-amino groups that should not take part in the reaction can be split into the starting compounds of the formulas II and III by converting them into the corresponding carbobensoxy derivatives, for example by the action of carbobenaoxyliloride on the corresponding copper complexes of the amino acids according to Schotten-Baumann. Another possibility of protecting the amino acids consists in converting them into P-talyl derivatives, for example by reacting the

BADORJGiNAL

Copper complex of the amino acid with carbalkoxyphohalimide. The amino groups may be protected by formyl v / _t for which purpose ground to act on the copper complexes of the amino acids can Ameisensäureester.

The oligopeptide mixtures obtained are in any Sequence subjected to various follow-up operations.

Esters obtained after the condensation can be saponified in a conventional manner, e.g. with alkali at room temperature will.

The introduction of the long-chain residue R. takes place z.3. by treatment with a reactive derivative, e.g. a halide, in particular the chloride or an anhydride of a satire of the formula IV in the presence of a tertiary bar, such as triethylamine or pyridine, in an inert solvent, such as dimethylformamide.

It has proven to be expedient to be fully available Carboxyl residues by post-esterification or by post-esterification and to convert post-amidation into esters or amides. This happens, for example, before or after the acylation by treatment with alcoholic hydrochloric acid or better with thionyl chloride and alcohol and, if necessary, reaction with ammonia, primary or secondary amines or hydrazine.

909851 / 17S9

BATH ORIGINAL

U93807

Carbobenzoxy radicals present as protective groups of the amino groups are expediently carried out by catalytic Hydrogenation split off again. Any phosphorus residues present can be removed by treatment with hydrochloric acid after adding hydrazine. Amino groups protected by formyl groups can e.g. Cold can be released.

The Ollgopeptldgemlsch obtained can be In per se Conversion of known catfish into an acid addition salt mixture by treatment with inorganic or organic acids. Preferred salts are obtained, for example, with the acids listed below: hydrohalic acid, in particular Hydrochloric acid, phosphoric acid, sulfuric acid, acetic acid or citric acid.

The products of the process are characterized by their antibacterial effectiveness, both against gram-positive and against gram-negative pathogenic and non-pathogenic bacteria, as well as against yeasts the end. The compounds are not very toxic. This effect is inherent in both stereoisomeric D and L porms of the amino acids. The process products of the L-Porm decompose under the action of intestinal juice, whereby decomposition products are formed no or little antibacterial effectiveness. The compounds can therefore be used as a preservative and Disinfectants are used.

909851/1759 bad original

U93807 - β -

The products of the process can also be used as remedies, e.g. in the form of pharmaceutical preparations, which they or their salts in a mixture with a pharmaceutical, organic or inorganic inert carrier material suitable for enteral or parenteral administration, how is.B. Water, gelatin, lactose, starch, magnesium stearate, talc, vegetable oils, polyalkylene glycols, petroleum jelly, etc. included. The pharmaceutical preparations can be in solid form e.g. as tablets, coated tablets, suppositories, Capsules, or in liquid form, e.g. as solutions, suspensions or emulsions. If necessary, they are sterilized and / or contain auxiliaries, such as coaervation, Stabilizing, butchering or emulsifying agents, salts to change the osmotic pressure or buffers. You can also contain other therapeutically valuable substances.

The following abbreviations are used in the following examples:

Z m Carbobenzoxy

Palm «palmitoyl DMF «dimethylformamide

IjB = Lysyl = -HH-CH-CO-

Orn «Ornithyl = -HH-CH-CO-

909851/1759

U93807

example 1

45.8 g (0.15 mol) of "" -carboxy - (! "- Zj-Ir-lye-anhydride in 200 ml of Oioxaa are added to a solution of 14.7 g (0.03 mol) H- (I * -Z) -L-Ijjre-OCH- added in 30 al of dioxane, with stirring one hour · heated to 80 °, cooled, bit 4 η more ethanolic Chlorinated acid adjusted to a pH of 3 and in Evaporated in a vacuum at 45 ° to dryness. 52 g of one are obtained hard crude product, on the main, consists of H-oligo-

Am · Lttsung of 60 g of this crude product in 700 ml of methanol is added a ait prepared at -10 ° mixture of 7 al thionyl chloride and methanol, and 100 al Calciuachloridverechluss stirred for 48 hours at 20 ° · Bs ent is a suspension, which ia vacuum at 45 ° is evaporated . 60 g of a sähen harses are obtained, the terminal carboxyl groups of which are completely in esterified form.

52 § of the crude product obtained in accordance with the first paragraph are generally dissolved in 400 al of dimethylformamide and mixed with 30 ml of triethylaalA. While stirring at 10-20 °, 24.4 g of alaitineture chloride are added dropwise over the course of 20 minutes. The mixture is stirred for a further 16 hours at a pH of 8-9. The thick oil obtained is liquefied by heating and then in 2 liters

O ₁ I a Hydrogen chloride geesea, Wan is sucked off,

tO985Y / 17 | t BAD ORIGINAL

U93807 - ίο -

the precipitate was washed with water and also dimethylformamide / OfI n I — mil nlr with the addition of some ammonium chloride. One nut see from old washed Vasser _v dried in vacuo at 50 ° and precipitated again from methanol / ether vm. The mixture is for 24 hours at 0 ° left "then filtered off with suction, the Butsch residue was washed with ether and dried in vacuo at 50 ° . One receives 1 ^a -Palm-oligo- (1 «-Z) -I ^ Lyβ-OCH ₃ rom melting point 124-130 °.

With an analogous treatment of the post-esterified product obtained according to the second paragraph of this example with Falmitic acid chloride is obtained in a corresponding manner, an oligomeric product with a melting point of 120-136 °.

66 g of the crude product obtained according to the 3rd paragraph of this example are stirred for 48 hours in a mixture of 500 ml of methanol and 7 ml of thionyl chloride prepared at -10 ° under a calcium chloride seal. The suspension is evaporated in vacuo at 45 ° and the residue from dimethylformamide / 1 η hydrochloric acid, dimethylformamide / 1 η ammonia and from methanol / ether is reprecipitated. 60 g of I ^a -Palm-01IgO- (IC-Z) -L-IyS-OCH- with a melting point of 120-130 ° are obtained.

53 g of the I ^ -Palm-oligo- (l * -Z) -L-fy8-0CH- obtained by Bach esterification are dissolved in 500 ml of dimethylformamide and 100 g of 100 g of ammonia are added in the autoclave. Then there is true «- <l | t * | 4M ¹ It | °° *** 3 ° *** · nitrogen pressure

BAD OWGLAL

U93807 - left -

shaken, then quenched in 2 liters of aqueous ammonium chloride solution, the precipitate sucked off, old Washed water and dried in vacuo at 80 °. It is precipitated from dimethylformamide / ether and 40 g are obtained! "- Palm-oligo- ^ το «melting point 180-196 ° (sinters at 175 °).

20 g of the methyl ester obtained according to the 4th paragraph of this example are dissolved in 200 ml of glacial acetic acid with heating, the solution is cooled and, after addition of 2 g of palladium carbon, hydrogenated with hydrogen at normal pressure and room temperature. The catalyst is separated off, the solution is evaporated at 45 ° in vacuo, the syrup is evaporated twice with 50 ml of benzene each time and dried. The residue is taken up in a little methanol, adjusted to a pH of 3 with 4 η methanolic hydrochloric acid and the solution is triturated in ethyl acetate. The bodice is sucked off and precipitated from methanol / ethyl acetate. 10 g of H ^a -Palm-oligo-L-Lys-OCH_-hydrochlorld are obtained, which slowly under Zer when heated from 170 ° put melts; [a] J ° - -19.5 ° (c - 2 in Yasser); H «12.859t, Cl» 15.75Ji, OCH ₃ m 2.44Jt.

Example 2

According to the information in Example 1, 45.8 g (0.15 Mol) B ^ -Carboxy-i ^ -Zj-L-Lys-anhydride and 15.3 g (0.05 mol) (^) implemented «ad worked up. You get

909851/1710

U93807

5 g of a crude product ..

40 g of this crude product are palmitoylated analogously to Example 1, 59 gl ^ -Palm-oligo-iJT-Z) -L-Lys-OCpH ₁

obtained from melting point 125-136 °.

By re-esterification according to the information in Example 1 by means of ethanolic hydrochloric acid, 58 g are obtained this substance has a melting point of 140-150 °.

26 g! ^ - Palm-oligo-il ^ -Z) -L-Lys-OC "He are decarbobenzoxylated and worked up according to the information in Example 1, 14 g of N ^a -Palm-oligo-L-Lys-OCpH _t - hydrochloride is obtained, which from 170 ° slowly melts with decomposition; [oc] _D = - -7.5 (c = 2 in water); N = 12.33 #; Cl = 13.92 #, OC ₂ H ₅ * 5.78 #.

Example 3

A solution of 45.8 g (0.15 mol) of I ^ Lys anhydride in 200 ml of dioxane is ^{mixed with a solution of 13.95 g (0.05 mol) of H- (N €} -Z) -L-LyS- HH _{2 combined} in 50 ml of dioxane, the reaction mixture is heated to 80 ° for one hour with stirring and then poured out in 1.5 liters of ice-cold 0.1 η hydrochloric acid. The precipitate is seen, washed with water and dried in vacuo at 50 °. 45 g of H ^ olitb ^ iH ^ -Äj-L-lysine-HHp-hydrbc'hlörid ^ from the "melting

^,. ,, -., 9, o, 9 8 5i ./- i7: M,;,.: Χ ά. «Vi -. ■" ■ '■:, ■■■■, - * ο ^: "';_;;

, -.... ^: 'i - ^; ; ; ^ ■ i "^ D 3 BAD OWGINAL

U93807

- 13 -ptuakt 178-190 ° (sinters at 155 °).

35 g of this compound are analogous to the information in Example 1 reacted with palmitic acid chloride. The reaction mixture is poured into 1 η aqueous acid and reprecipitated from dimethylformamide / 1 η immoniak. 45 g of one are obtained raw product, which mainly consists of ^ -Palm-oligo- (N * -Z) -L-Lys-HHp and melts between 160 and 190 °.

66 g of this compound are re-esterified with methyl alcohol according to the information in Example 1 and from dimethylformamide / 1 η acetic acid, dimethylformamide / 1 η hydrochloric acid and Dimethylformamide / Waeser reprecipitated. 53 g of a product are obtained which melts between 154 ° and 180 °.

20 g of the product obtained are post-amidated in the same way as in Example 1, the work-up yielding 16 g of ^ -Palm-oligo-f ^ -Z) -L-LyB-HH ₂ with a melting point of 183-196 ° (sinters at 178 ° ).

33 g of these "amides" are made according to the information in Example 1 decarbobenzoxylated by hydrogenation and the reaction product isolated as the hydrochloride. After falling over twice from vaseer / acetone you get 20 g ^ - hydrochloride, since from 228 ° it slowly melts with decomposition; [oc] * ° «-29.2 °, (o« 2 in Vaaser) f * »13.85 *, Cl * 15.58 *.

• 0 9 8 51 / T 7 S 9 bad original

U93807

By hydrogenolytic cleavage of the non-post-esterified and post-amidated product, 23 g of an mixture of ^ -Palm-oligo-L-Lys-RTBL-hydrochloride and H ^ Palm-oligo-L-Lys-OH-hydrochloride are obtained in an analogous manner ° melts with decomposition; Ε ^Α 1τ) * -28 (c «2 in water); Cl - 14.29Ji.

Example 4

13.95 g (0.05 mol) of H- (» ^C -ZJ-L-LyS-IH ₂ in 50 ml of dimethylformamide are mixed with a solution of 45.8 g (0.15 mol) of B ** -carboxy- ( H * -Z) -L-Ly8-anhydride in 100 ml of dimethylformamide is added, the reaction mixture is stirred at 80 ° for one hour and then stirred in 0.1 η hydrochloric acid and worked up as in Example 3. 46 g of H-oligo- ( N ^€ -Z) -L-Lys-IHg hydrochloride with a melting point of 190-200 ° (sinters at 170 °).

Example 5

A solution of 45.8 g (0.15 mol) of H ⁰ L-lys anhydride in 300 ml of chloroform is treated at 0 ° with a solution of 850 mg of 100% ammonia (0.05 mol) in 30 ml of chloroform and the Mixture stirred at 50 ° for 3 hours. The thick gel is stirred with 700 ml of ether, suction filtered, the residue is washed with ether and dried in vacuo at 50 °.

90 985 f / i? $ 9 BAD ORIGINAL

The substance is dissolved in dimethylformamide and, as described in Example 3, extracted and worked up in 0.1 μm hydrochloric acid. 40 g of crude H-oligo- (N ^e -Z) -L-Iys-HH ₂ -hydrochlorld with a melting point of 188-200 ° (sinters at 170 °) are obtained.

Example 6

A suspension of 45.8 g (0.15 mol) of l ^ -carboxy- (I ^ -Zj-L-Lys-anhydrld in 250 ml of methanol is at 0 ° with a solution of 850 mg of 100% ammonia (0.05 mol) in 26 ml of methanol added and the mixture stirred at 50 ° for 3 hours. The solution is evaporated in vacuo at 50 °, the residue in 60 ml Dissolved dimethylformamide and, as in Example 3, stirred and worked up in 0.1 η hydrochloric acid. 37 g are obtained crude H-oligo-iJ ^ -Zj-L-Lys-OH-hydrochloride of melting point 190-200 ° (ends at 168 °).

Example 7

14.2 g of the H-oligo- (N ^€ -Z) -L-Lys-HHp hydrochloride obtained according to Example 3 are reacted with phytanoyl chloride in a manner analogous to that described in Example 1 for the palmitoylation to form 13 g of crude I ^ -Phytanoyl-oligo- ^ Z) -IrrLyö> HH ^ hydrochloride with a melting point of 190-203 °.

10 g of this compound are split hydrogenolytically in a manner analogous to Example 1 and the reaction product isolated as the hydrochloride. 4.8 g of a mixture of ^ -Phytanoyl-oligo-L-Lys-NHp-hydrochloride and l ^ -Phytanoyloligo-L-Lys-OH-hydrochloride are obtained, Melting point from 220 ° (decomp.); [a] ^ ° = -36.5 ° (c «2 in water)} N = 13.59 *, Cl = 14.75 *.

Example 8

27 g of the l ^ -Palm-oligo- (N ^e -Z) -L-Lys-OCH- obtainable according to Example 1 are dissolved in 250 ml of dimethylformamide, a total of 36 ml of 1 n sodium hydroxide solution are added in portions and the mixture is stirred at 20 ° for 20 hours . The solution is filtered and extracted with 1 liter of 1 η hydrochloric acid, the precipitate is filtered off with suction, washed with water and dried. After falling over from dimethylformaaid / water, 24 g of It * - palm-oligo- (N * -Z) -Ir-Lys-OH with a melting point of 125-140 ° are obtained.

20 g of this compound are in an analogous manner ^ as in Example 1 split hydrogenolytically and isolated as the hydrochloride. 11 g of H ^ palm oligo-L-Lys-OH hydrochloride are obtained, which melts from 245 ° with decomposition (from 200 ° brown color); [a] ^ ° = -13.5 (c = 2 in water); N = 12.58 *.

909851/1759

BATH ORIGINAL

H93807

Example 9

6.8 g (23 mmol) of H- (N ^ -Z) -L-Om-OC ₂ H ₅ are heated to 80 ° in 150 ml of absolute dioxane and, while stirring, quickly with 20 g (68 mmol) of S ^ - Carboxy-iN ^ -Zj-L-Orn-anhydride added in dioxane. Sun is refluxed for 1 hour and the reaction mixture is then stirred into 800 ml water / 65 ml Bieeseig while hot. After 15 minutes it is removed, the residue is washed in 1000 ml of water and dried in vacuo. 13.4 g of H-oligo- (N ^ -Z) -L-Om-OC ₂ H ₅ with a melting point of 167 ° are obtained

100 ml of absolute ethanol are cooled to -10 ° and treated with 1.7 ml of thionyl chloride. After adding 13.4 g of the in accordance with the previous paragraph ■ Stand on the reaction mixture for 2 days at tree temperature. Evaporation of the solvent in a vacuum is carried out in 50 ml of dimethylformamide, treated with 7.0 ml of triethylamine and 4.7 g of lauroyl chloride, see below, are added dropwise with rapid stirring at -10 °. Stirring is continued for 30 minutes at room temperature and the reaction then takes place in 120 ml water / 30 ml !! •••• ig let in, laughs the sucking off the The solution was again dissolved in 60 ml of dimethylformamide and dissolved in 150 ml water / 10 ml concentrated ammonia stirred in, lun the residue is filtered off and dried. The dry one

• 09851/171

H93807

The residue is boiled three times with 200 ml of petroleum ether each time and filtered, dried and pulverized. 13.6 g are obtained

from a melting point of 180-190 °.

17 »6 g of this compound are hydrogenolyzed in 200 ml of bisacetic acid at 50 °, the liquid acetic acid is distilled off in vacuo , the residue is taken up in a little water and precipitated with acetone. Repeated precipitation gives aan powdery Γ "-euroyl-oligo-Ir-0rn4XyL-hydrochloride, which sinters at 180 ° and at 270 ° sereetatf [«] «» -102 ° (c * 2 in water).

Example 10

The process products can be s.B. in the form of aqueous solutions, tinctures or tench ointments, medicinal use Find,

a) O ₉ I or Ijiige aqueous solution!

Active ingredient 0.1 or 1 g dist. Water ad: 100 al

b) Ethanol tincture:

Active ingredient 1 g

least. Water 2 g Ethaaol (* 4jt) ad: 100 al

ο) mucus algae

Active ingredient 0.1 c Methocel 4000 1.2 g deet. «Saver ad: 100 al

• 09SI1 / 1TII

Claims (8)

H93807 claims 1. Process for the preparation of an oligopeptide mixture the general formula R ₁ »HR-CO R ₂ (I) wherein R is one of the α-amino and carboxyl groups freed from a basic α-aminocarboxylic acid, R is an acyl radical of a long-chain, saturated or unsaturated aliphatic carboxylic acid, R _{2 is} a hydroxy, alkoxy, amino, alkylamino, dialkylamino or Represent hydrazino group and the symbol χ indicates a low degree of polymerization, and of acid addition salts of these compounds, characterized in that a compound of the general formula CO 0 R'-HH-C R'-HH-CO (II) wherein R ^{1 means} a radical of a basic α-aminocarboxylic acid freed from A t , α-AminQ and carboxyl group, the basic radical of which is protected, in the presence of an organic solvent with ammonia, a _- ■. —- - '.:' ■ ■. · I - '•' ■■ γ- ■ '■ -': ■ ■ · 'ι ■ »" 9098Sf / i7 $ 9 U93807 Alkylaain, a dialkylamine, hydrazine or a compound the general formula H ₂ N-R'-CO-E ₂ (III) wherein R ¹ and R _{2 have} the above meaning, reacts the product obtained in any order with * a reactive derivative of an acid of the general formula R ₁ -OH. (IV) where R, has the above meaning, aoylated, the reaction product optionally saponified, post-esterified or post-esterified and post-amidated and the protective groups present are split off, whereupon the peptide obtained is ^ if necessary, is converted into an acid addition salt. 2. The method according to claim 1, characterized in that that starting compounds of the formula I and II are used which are derived from a D- or L- or D, L-α-aminocarboxylic acid. 3. The method according to claim 1, characterized in that starting compounds of the formula I and II are used, which are derived from D- or L- or D, L-lysine. 909851/1759 U93807 4. Process according to claims 1-3, characterized in that the reaction of the formula II with ammonia, alkylamine, dialkylamine, hydrazine or the compound of the formula III takes place in the presence of an organic solvent at a temperature between 50-80. 5. The method according to claims 1-4, characterized in that the ω-amino groups by carbobenzoxy, Phthalyl or formyl radicals are protected. 6. The method according to claims 1-5, characterized in that the acylation with a reactive Derivative of palmitic acid or stearic acid takes place. 7. Process according to claims 1-6, characterized in that the reaction products are subjected to a post-esterification, and optionally post-amidation. 8. Use of oligopeptide mixtures of the general formula _R { NH-R-CO} - R ₀ ¹ χ ^ά wherein R, R ,, R ₂ and χ have the above meaning as preservatives or disinfectants. 90 98S1 / 1TS9