Method of preparing analogues of somatostatine

The invention relates to a process for the preparation of the tetradecapeptide of the formula I

D-Val-Gly-L-Cys-L-Lys-L-Asn-L-Phe-L-Phe-L-Trp-L-Lys-L-Thr-L-Thr-LSSerLL-yys- OH (I) and pharmaceutically acceptable acid addition salts thereof. The invention also relates to intermediate compounds prepared in the synthesis of this tetradecapeptide

SommtooSaain (also known as sommaotropin release inhibitory factor) is a tetra-decapeptide of the formula _r

L · -A].^and—GL^y—L — C^ýS—d ^ í ^^{s — L}^ Asⁿ-^L-^ρ’^ha—^^—Ph^and-^L-^Trp—d^-lyš^{-Thr — Pha — L}Ř^Thr~^L-^{Sar — Cy}^ s ^ - ^ 0^H.

This tetradecapeptide was isolated from the extracts. hypothalm of sheep and it was found that. is effective in inhibiting growth hormone secretion, also known as sornmaotropin, see P. Brazeau, W. Vale, R. Burgus, N. Ling, M. Butcher, J. River, and R. GuinHemin, Science, 179. 77 (1973)

In addition, U.S. Patent No. 904,594 discloses natural sommatosatin and a generic class of other compounds having a didecapeptide sequence corresponding to positions 3-14 of the natural hormone.

Compound Ú^Ccalled D-Ala^{* 1 * * * * * * *} —Somataftatin ^byla krom^E this described^and at work^andPerland et al^d C ^ loLar ^Endoorinology^, 4 ⁷⁹ to 88 ⁽1⁹7 <э⁾. ^D-Ala^1—somatostatiⁿ although it is structurally the steroomer of the cristal. ^ Мэ^1-^^⁰It is approximately half-effective compared to sommaostatin in the inhibition of gastric secretion in vivo. Compound of the Invention, D-Val¹—StmaaotSatin, differs from. D-Ala¹—Somatostatin by the substitution of two hydrogen atoms can be substituted. When considering the potential feuma202096

By 20209.6 the biological efficacy of D-Val'-somatostatin, it should be concluded that its efficacy should be. p.This activity^--Ala'-tsmaaostat^{* i}.nu. Teorettoty^by now^y b^yit is believed that D-VaP-somatoototin ^bat^de less ^účithan pMrotoi ^ ιήο ^ as to vivo tohibitor te^torece grief^dE^Coxidic acid. ^--Wall^l-ssmatosSatto has a tower^{k ú}activity ^poněkud vySS! than the birth hormone efficacy. This result^dE^to shows that activity or^yl^O can be predicted by comparison with structurally similar known compounds.

The structure of the biologically active tetradecapeptide of formula I as defined above (and its non-toxic addition salts) differs from tsmaostatin and the corresponding salts by the presence of a D-vaiin residue at position I instead of an L-alnito residue. Suitably, the tetradecapeptide of formula (I) is referred to as D-Val '-matontatii.

The invention therefore relates to a process for the preparation of a compound of formula I

HD-Va-G-L-Cys-L-Lys-L-Asn-L-Phe-L-Phe-L-Trp-L-Lys-L-hr-L-Phe-L- ^ ir-L-Ser -L-Cys-OH (I) and its pharmaceutically acceptable non-toxic acid addition salts and intermediates of formula II

RD-Vaa-Gly-L-Cys (Rj) -L-Lys (Rg) -L-Asn-L-Phe-L-Phe-L-Trp (Rj) -L-Lys (R)₂-L-Thr (R₃ bL-Phe-L-ThrR 1 L-Ser (R 1 -L-CysCR 3) -X (II) where

R is hydrogen or an alpha-amino protecting group,

R | R is hydrogen or a epsilon-amino protecting group, and each of the symbols

R₃ and R 6 represents hydrogen or a hydroxy protecting group,

R 1 is hydrogen or formyl;

X is hydroxy or resin

-O-CH wherein the resin is polystyrene, with the proviso that when

X is hydroxy, each of R, R p, R g, R 3, R 6, and R j is hydrogen, and when X is the remainder of the resin formula, each of the symbols

R, R, R 8, R 3 and R 6 are different from hydrogen.

The novel tetradecapeptide of formula I,

D-Val-Gly-L-Ctys-L-Lys-L-Asn-L-Phe-L-Phe-L-Trp-L-Lys-L-Thr-L-Phe-L-Thr-L-Ser- L-Cys-OH (1) is prepared by reacting the corresponding tetradecapeptide of formula III. H-LD-Val-Gly-L-Cys-L-Lys-L-Asn-L-Phe-L-Phe-L-Trp-L-Lys-L-Thr- ^ L- ^ Thi ^ - ^ I ^ - ^ S ^ i-LL4 ^₂S - 1 H (III) with an oxidizing agent. This reaction converts two sulfhydryl groups into disulfide groups. bridge.

Suitable pharmaceutically acceptable non-toxic acid addition salts are addition salts with organic and inorganic acids, for example those derived from hydrochloric, sulfuric, sulfonic acids, tartaric, fumaric, hydrobromic, glycolic, citric, maleic, phosphoric, succinic, acetic acids. , nitric, benzoic, ascorbic, p-toluenesulfonic, benzenesulfonic, naphthalenesulfonic and propionic. Preferred addition. the acid salts are acetates. Acidic salts are prepared by conventional methods.

As examples of intermediate compounds of formula II

RD-Val-Gly-L-Uys (R) -L-Lys (R 2) -L-Ssn-L-PheLL-Phe-LL -Trp (Rj) -L-Lys (R 6 -L-ThrR bL-Phe -L-Thr (R) -L. -Ser (R) -L-Cys (R) -X (II) which is preferred is a compound of formula (III),

HD-Vaa-Gly-L-Cys-L-Lys-L-Asn-L-Phe-L-Phe-L-Trp-L-Lys-L-Thr-L-Phe-L-Thr-L-SeL- L-CyL-OH (III) and a compound of formula '

N-C ^ OCL ^^ - al-L ^ l·lsL ^ - (] M ^] ^ (^ y ^ s - ^: ^ - (C ^ z (^ - 1 · -L ^ ys - ^: ^) - ^ Al ^] ^ - L·L -Phe-L-Phe-LЧFor) Trp-L- (CBz-C) LLys-L- (Bzl) TJlhrLLLPhe-L- (Bzl ^ lw-L-tezl ^ er- L- (PMB) Cys --- CH₂resin

The above formulas defining intermediate compounds also include compounds that encapsulate amino-, hydroxy-, and thio- (sulfydryl) protecting groups. Protecting groups must have properties meeting two aspects. On the one hand, the protecting groups must prevent the reactive moiety present in a particular molecule from undergoing a reaction during the exposure of the molecule to conditions that would otherwise result in the disappearance of the reactive moiety. However, the protecting group must, on the other hand, be of a nature such that it can be readily cleaved while reactivating the origin. groups under flow conditions that would not adversely affect other parts of the molecule. Groups suitable for these purposes, ie protection. amino, hydroxy and thio groups are well known to those skilled in the art. Whole volumes have been devoted to the description of these protecting groups and their use. One of them is the work of Protective Groups in -rgonic ChhΠlíiSrs, red. 'JFW Pc-ume, tyd., Plenie Press, New York, 1973.

In the above formulas defining the intexraedial compounds, R is either an alpha-mini hydrogen, or an alpha-amino protecting group. Amino protecting groups are well known to those skilled in the art. peptides and many of them are listed in McCOnie's above-cited work in Chapter 2 by JW Barton. Illustrative examples of such protecting groups include benzyloxycarbonylcarbonyl, p-chlorobenzyloxycarbonyl, p-bromobenzyloxycarbonyl, t-chlorobenzyloxycarbonyl, 2,6-chlorobenzylthoxycarbonyl, 2,4-dichlorobenzyloxycarbonylbenzyloxycarbonylbenzyloxycarbonylbenzyloxycarbonylbenzyloxycarbonylbenzyloxycarbonylbenzyloxycarbonylbenzyloxycarbonylbenzyloxycarbonylbenzyloxycarbonylbenzyloxycarbonylbenzyloxycarbonylbenzyloxycarbonylbenzyloxycarbonylbenzyloxybenzyloxycarbonylbenzyloxycarbonylbenzyloxycarbonyl , p-nitrobenzyloxycarbonyl-, tert-O-O-oxocarbocyclyl- (BOC), t-tert-butyloxycarbonyl-, 2- (p-Ophezylyl-8-pyrpyloxycarbonyl- (BpOC), adiyl-zyloxycarbonyl, β-cyclopentyl), β-cyclopentyl, β-cyclopentyl, β-cyclopentyl, β-cyclopentyl, β-cyclopentyl. 10 ^ 1 ^^ 0 ^ 1- cycloheptyloxylcarbonyl-, thiophene (methyl) - (p-toluenesulfonyl). A preferred alpha-amino protecting group for R is tert-butyloxycarbinyl.

R 1 represents either a hydrogen atom or a sulfhydryl group of a cysteine ​​or a protecting group of a sulphcydryl substituent. Many of these protecting groups are described in McHme's work cited above in Chapter 7 by RG Hickey, VR Rao and WG. Rnodes. As illustrative. examples of such protecting groups include p-methoxylbenzyl-, benzyl-, β-tolyl-, η-β-β-ε, acetem-dommethyl-, trityl-, ρ-nitrobenzyl-, tert-butyl- isobutyloxymethyl; and any one of a large number of triallyl derivatives. Further examples can be found, for example, in the encyclopedia Houb®n-Weyl, Methodes der Orgunischen Chemie, Synthese von Peptiden, Vol. and 15/2, (1974), Stuttgart, Germany. The preferred protecting group of the R f -sulfonyl group is the p-meoyl group of Beza.

R g represents either hydrogen at the epsilon-amino group of the lysine residue or a suitable protecting group of the epsilon-mints group. Illustrative examples may be the groups listed above Groups suitable for protecting alpha-mizts. As. typical groups suitable for this purpose include benzylthoxycarbornl, tert. butyloxycarbonyl-, tert-amyloxycarbonyl-, adamanylcarbonyl, p-meth: β-carboxy, p-dhlorobezzyloxycarbonyl-, p-brtmbbУzyloDχУУlbbtzl-, t-chlorobezylχ, t-chlorobezyllt, t-chloro-benzoic acid;_J4-Dichlorobenzyloxycarbonyl, ο-γ-β-nitrobenzyloxycarbonyl-1-isopropyloxycarbonyl; cyclothexylphenylcarbonyl-, cycloheptylcarbinyl- and p-toluenesulfonylsyupine.

As will be apparent from the description below, the process for the preparation of tetraaptaptishes of formula I comprises the periodic cleavage of the alpha-mintin protecting group from the termine functional group present in the peptide chain. The only restriction with regard to the identity of the protective group of the epsilon-lmino group of the lysine residue is therefore that the protective group must be of a nature such that it does not cleave under the conditions used for the selective cleavage of the 11a-lysine group. .

. Appropriate choice of alpha-imino and epsosyl-amino protecting groups is readily apparent to those of ordinary skill in peptide chemistry, but the relative ease with which each protecting group can be cleaved is considered. For example, groups such as 2- (p-biphenylyl) sooptopyloxycarbonyl group (BpOC) and У У ^ ^ У Уц ^ are. very labile and can be cleaved even in the presence of a weak acid. A moderately strong acid such as hydrochloric acid, trifluoroacetic acid, or boron trifluoride in acetic acid, is required to cleave some. groups such as tert-butyloxy-tert-butyloxy, tert-butyloxy, tert-butyloxy, or tert-butyloxy groups; amyloxycarbonyl,. and p-methoxybezzylthoxy) carbonyl.

Even stronger acids must be used to cleave other protecting groups,. for example, the cleavage of benzyloxycarbonyl, halobenzyl, cyclobenzyl, p-nitrobenzyl, butyloxycarbonyl, cyclopolyloxycarbonyl and isopropylpyloxycarbozyl groups requires strongly acidic conditions, i.e. the use of hydrogen bromide or hydrogen borohydride. trifluoromethyl. Smiřimyё / that all stronger acids also cleave all the more labile groups. Therefore, when choosing amino protecting groups, it is necessary to ensure that the alpha-mint group is more labile than the epsilon-on-mints group and the cleavage conditions must be. selective,. so that only the alpha5 protecting group is cleaved

-amino groups. A preferred combination of protecting groups satisfying these conditions is a combination of o-chlorobenzyloxycarbonyl or cyclopeityloxycarbonyl-Rg and tert-butyloaycarbonyl as the alpha-amino protecting group used for each amino acid added to the polypeptide chain.

The groups -Rj and Rj represent hydroxyl hydrogens, non-alcoholic protecting groups, hydroxy groups of threonine and lilac. Many such protecting groups are described in the above-cited McOai's Chapter 3 by CB Reese. Typical examples of such protecting groups include C 1 -C 3 alkyl groups such as methyl, tert-butyl, benzyl, sulfated benzyl, such as C 1 -C 6 alkyl, tert-butyl, tert-butyl, tert-butyl, tert-butyl. Β-nitrvieniyl-β-chloroenzyl and o-chloroenzyl, C 1 -C 3 alkenyl groups such as ьЮьУ, acetyl and propionyl. trifeyii ethyl (trity). When Rj and Rj are protecting groups, in some cases ienzyl groups are preferably selected as these groups. The group Rj is also hydrogen, non-formyl and defines

<img file="CS202096B2_D0001.tif" />

tryptoarnium residue. The form group serves as a protecting group. The delay of this protecting group is not obiigatory, and therefore R i may be iud (hydrogen not protected by nitrogen), non-hydrogen (nitrogen protected group).

The group X defines the nature of the carboxyl terminus of the tetradecapeptide chain.

It may be a hydroxyl group, and in this case it is a free carboxyl group. It may, in addition to Xoho, be a solid resin support to which the pegtime carboxyl group is bound during its synthesis. Ziytek solid resin can be represented by a resin pattern

In addition, whenever X represents a hydroxy-cline, each of the symbols p, R-p-, n, R-p-hydrogen is hydrogen. When X represents a solid resin support, each of R, R 1, R 6, R 6 and R 6 is each a protecting group.

The following abbreviations are used throughout the description, most of which are commonly introduced in the art.

Ala - bacon

Asn - asparagine,

Cys - cysteine

Gly - glycine

Lys - lysine

Phe - fen ^ lalanine ·)

Ser - ·· serine

Thr-i-onin.

Trp - tryptophan

Val - valine

DCC · - N 1 N -dicyclohexylcarniodiimide

JMF, N, N-dimethylphomiamide

BOC - t-butyloxycarbonyl

RMB-p-methoxyienzyl. CBzOC - o-chlorobenzyloxycarbonyl

CPOC - cyclopentyloxycarboxylic acid

Bzl - benzyl

For ťoímyL

BpOC-2- (p-bipherylyl) io-o-o-o-7-carbonyl.

While the choice of particular protecting groups to be used in the preparation of compounds of Formula I is within the skill of the art in peptide synthesis, it is self-evident that the sequence of reactions that must be performed influences the choice of particular protecting groups. In other words, the protecting group selected must be stable both to the reagents employed and to the conditions of the subsequent reaction steps. For example, as noted to some extent, the particular protecting group used must remain intact under the conditions used to cleave the α-alpha protecting group of the terminal amino acid residue of the peptide fragment in preparation for condensing the following amino acid fragment to the peptide chain. It is also important to select a protecting group such that it remains intact during construction of the peptide chain and that can be readily cleaved after completion of the synthesis of the desired tetradecapeptide product. However, all of these are within the skill of the art. As can be seen from the above discussion, the tetradecapeptides of formula I can be prepared by solid phase synthesis. This synthesis consists in the gradual build-up of the peptide chain starting at the terminal carbon end of the peptide. In most cases, the cysteine ​​is first bound via a carboxyl function to the resin, by reacting the cysteine ​​with an amino-protected and sulfhydryl-protected group with a chloromethylated or hydroxyl-detached shell. The preparation of a hydro-etched resin is described in Bodnnszky et al., Chem. Indian. (London), J§,. 1597-1589 (1966). The C 1 -methylated resin is commercially available (Lab System, Inc., San Mateo, Cd-iforata, USA).

Ρϋ carrying out the coupling reaction of the carboxyl function of the cysteine ​​and the resin, the protected cysteine ​​is first converted to the cesium salt. This salt is then reacted with the resin as described by BF Gisin, Helv. Chim. Acta., 56 (1476) (1973). Alternatively, the cysteine ​​may bind to the resin by first activating its carboxyl functional group in a conventional manner. For example, the cysteine ​​may be reacted with the industry in the presence of a carboxylic acid compound such as Ν, N i -cyclic hexyl carbide (DCC).

Upon binding of the free carboxy group of the cysteine ​​to the resin support, the peptide chain begins to progressively build up by progressive condensation of the individual aeinolcrilines to the N-terminal portion of the peptide chain. Thus, at each stage, the alpha-amino protecting group in the terminal portion of the peptide fragment is cleaved off and then the successive amino acid residue is attached to the free and reactive N-terminus of the 'terminal aminolytin'. The deprotection of the alpha-amino group can be carried out in the presence of an acid such as hydrobromic acid, hydrochloric acid, trifluorobutyric acid, o-tolylphenone, benzenesulfonate, naphthalenesuffonic acid and acetic acid to form an evaporating acid addition salt of the product.

Another method of cleavage of the protecting group and the eineocoupin, for example, is the action of boron trifluoride. For example, by treatment with diethyl ether of boron trifluoride in glacial acid, the acetic fragment of the amino-protected peptide is converted into a boron trifluoride-comlex complex, which is then converted to the free peptide. a fragment by the action of a base, as an aqueous precipitate^гoPotassium chloride. Any of these methods may be used provided that it is achieved by cleavage of the N-terminal alpha-alpha-amino group without violating any other protecting groups present in the peptide chain. In view of this requirement, it is preferable to cleave the N-terminal protecting group using trichloroacetic acid. Typically, the cleavage is carried out at a temperature of about 0 ° C to about room temperature.

After cleavage of the protecting group at the N-terminal position, the product obtained is usually in the form of an acid addition salt which has been used for the removal of the protecting group, and this product can then be converted to the free amino compound by treatment with a weak base. an amine such as pyridine or triethyylmin.

The peptide chain is now ready for reaction with the following amino acid. The reaction with the amino acid may be carried out by any of several known techniques. Amino acid acids having a free carboxy group but having a suitably protected alpha amino group and all other optionally reactive reactive groups are used for attachment by the successor aminoooksines to the N-terminus of the peptide chain. Aninooyssein must be activated to react with the N-terminus of the peptide chain. One method of activation that can be used in the synthesis is. converting the amino acid to the mixed amino acid. The erioom is a free carboxylic functional. αminoSksslUny group. activated by reaction with another acid, typically with an acid chloride derivative in the form of an acid chloride. Examples of such acid chlorides that can be used to form mixed anhydrides are ityl chloroformate, phenol chloroformate, sec-butyl chloroformate, isobutyl chloroformate and pivaloyl chloride. ,

Another way of activating the carboxylic function of an amino acid to condense with the peptide chain is to convert the amino acid to a reactive ester derivative. As . Examples of such reactive esters are 2,4,5-trichloro-phioylistir, pentachloro-phiyl ester, the ester of 1-hydroxybenzoriazole, and the ester of N-hydrooxosuccinimide. Another way of attaching the C-terminal portion of αminoOkselioy to the peptide fragment is by a method in which the condensation is carried out in the presence of at least an equimolar amount of NN-dicyclohexylcarbodiimide (DCC). The latter method does. preferably used in the preparation of the tetradecapeptide of formula (II) wherein X is -O-CH.

resin

After the peptide chain has been prepared with the desired amino acid sequence, the resulting peptide can be digested from the resin support. This is done by treating the tetradecapeptide bonded with a reactive group protected by hydrogen fluoride. The action of hydrogen fluoride cleaves the peptide from the resin, but furthermore cleaves all other protective groups present on the reactive groups of the peptide chain, as well as the alpha amino group protecting group of the terminal amino acids. When the peptide is cleaved from the resin. with concomitant cleavage of the protecting groups by treatment with hydrogen fluoride, preferably. the reaction is carried out in the presence of anisole. It has been found that the presence of anisole inhibits the potential alkylation of certain amino acid residues present in the peptide chain. In addition, the cleavage is preferably carried out in the presence of ethyl mercaptan. Ethyl mercaptan serves to protect the iniol ring of the tryptophan residue. and also makes it easier. converting the protected cysteine ​​residues into the tolyl form. Also, when R is a form 1 group, it facilitates the presence of ethyl mercaptan. cleavage of formylekupioy by hydrogen fluoride. ,

After cleavage as described above, a 14-amino acid peptide is obtained as an amino acid. To obtain the final product of the general formula. It is also necessary to oxidize the β-chain titraecapeptia under such conditions under. of which. sulfonyl groups present in the microsphere one at a time. on each cysteine ​​residue from which the disulfide bridge is formed. The oxidation may be carried out by diluting it into a dilute solution of the linear tetradecapeptide. operates by some of the series. oxidizing agents such as iodine and potassium. Air may also be used as the oxidizing agent, while the pH of the mixture is usually maintained from about 2.5 to about 9.0, preferably from about 6.2 to about 7.2. When air is used as the oxidizing agent, the concentration of the peptide solution is usually less than about 0.4 mg peptide / ml solution, and typically ass'50 / µg / ml. The compounds of formula (I) may be administered to human subjects, including humans, by any of the following routes: orally, sublingually, subcutaneously, intrimuscularly, urine, or other means. All of these compounds are equally effective, though not all, to the same extent as growth hormone release inhibitors. This inhibitory effect is beneficial in those cases where it is desirable to treat excessive somatotropin secretion. Excessive secretion of somatotropin may be associated with adverse disorders such as juvenile diabetes and acromegaly. These compounds also have other physiological effects, such as inhibition of gastric acid secretion, useful in the treatment of ulcers, inhibition of exocrine pancreatic secretion, potentially useful in the treatment of pancreatitis, and inhibition of insulin and glucagon secretion and decreased bowel mobility useful in gastrointestinal radiology.

The dosage range for sublingual or oral administration is preferably about 1 mg to about 100 mg / kg body weight per day. Dosages for intravenous, subcutaneous or intramuscular administration range from about 10 xcg to about 1 mg / kg body weight per day, and preferably from about&gt; 0 / Mg to about 100 (4g / kg body weight per day). the range is largely dependent on the particular disorder being treated and its severity.

The compounds of formula I may be administered orally or sublingually in association with a pharmaceutical carrier, for example in the form of tablets or capsules. As pharmaceutical carriers, conventional inert diluents and carriers such as magnesium carbonate or lactose are used in conjunction with conventional disintegrating agents such as corn starch and alginic acid and lubricating agents such as magnesium stearate. Typically, the amount of carrier or diluent is in the range of from about 5 to about 95% based on the final formulation, and preferably from about 50 to about 85% based on the final formulation. Suitable flavoring agents to improve the taste of the dosage forms may also be added to the final formulation.

When the compounds of formula I are to be administered intravenously, for example, isotonic sodium chloride solution and phosphate buffer solutions may be used as suitable carriers.

The following examples illustrate the preparation of compounds of formula (I) and intermediates. The examples are illustrative only and do not limit the scope of the invention in any way.

Example

Oxidation to D-Val -somatostatiri

The solution of reduced D-Val-somatostatin (374 ml, theoretical 175 mg) was diluted with 147 ml of 0.2 M acetic acid and 2967 ml of distilled water to a concentration of 50 µg / ml. Concentrated ammonium hydroxide was added to adjust the pH of the mixture to 6.7. The solution was stirred at room temperature in the dark for 64 hours and then determined by Ellman titration that oxidation was complete.

The mixture was concentrated in vacuo to a volume of about 10 mL and 10 mL of glacial acetic acid was added. The mixture was desalted on a Sephadex G-25F column. Chromatography is performed under the following conditions:

<td>solvent:</td><td>degassed 50% acetic acid,</td>

<td>column size:</td><td>50 x 900 mm</td>

<td>temperature:</td><td>26 ° C</td>

<td>flow rate: fraction volume:</td><td>246 ml / ha and 16.4 ml.</td>

The absorbance at 280 nm of each fraction is plotted against the fraction order. The obtained curve contains two large maxima. The first maximum is formed by aggregated product forms and the second maximum is a monomeric product. The material corresponding to the second maximum was collected [(fractions 49-64 (787-1.050 mL)], and the solution was lyophilized to dryness in the dark, and the resulting solid was dissolved in 15 mL of degassed 0.2 M acetic acid and applied to a Sephadex column. G-25F Chromatography is performed under the following conditions:

<td>solvent:</td><td>degassed 0,2 M acetic acid,</td>

<td>Column dimensions:</td><td>50 x 1500 mm,</td>

<td>temperature:</td><td>26 ° C</td>

<td>flow rate:</td><td>475 ml / ha</td>

<td>Fraction volume:</td><td>16.6 ml.</td>

Absorbance at 280 nm of each fraction is plotted against fraction order. The curve obtained contains one large maximum. The spectroscopy indicates that the major part of the maximum is constituted by the product. Fractions 157-172 (from 2,590 to 2,855 mL of eluate, peaks equal to 2,667 mL of eluent) were pooled and lyophilized to dryness in the dark. UV-spectroscopy shows that the yield is 95 mg of the desired (54.3% yield based on reduced form).

A portion of the resulting product was dissolved in 5 mL of 50% acetic acid and re-chromatographed on a Sephadex G-25F column. 0hrommtoggrfie is performed under the following conditions:

Lo: degassed 50% acetic acid, column dimensions: 25, _x , 800 mm ,.

temperature: 26 ⁰C, flow rate: 53.2 ml / h and ...

Fraction volume: 8.77 ml.

Absorbance at 280 nm of each fraction is plotted against fraction order. The curve obtained contains one large maximum. UV-spectroscopy shows that the major part of the maximum is formed by the product. Fractions 56 to 60 (488 to 532 m., Maximum = 505 ml) are pooled and lyophilized to dryness in the dark.

Oppic rotation [11 ^ 2⁶ = -42^,1 ⁽¹% acetic acid). '

Analysis of aminnkkУskin:.

Val 0.98, Gly 1.01, 20ys 1.81, 2Lys 1.99, Asn 0.95, 3Phe 2.94, Trp · 0.80, 2Thr 1.91, Ser · 0.85.

The above results are expressed as ratios with respect to (Gly + Lys) / 3 = 1.0. Three 21-hour hydrolyses are performed:

1. in the direct oxidation of cysteic acid to oxidize cysteine ​​to cysteic acid,

2. using thioglycolic acid as an acceptor,

3 · without acceptor and without oxidizing agent.

All values ​​given are the averages of these three hydrolyses except

0ys and Ser - average of hydrolysis only 1 and 3 ·

Trp - value only from hydrolysis 2.

Phe - average from hydrolyses 2 and 3 only.

'

D-Val spomattoPQtin has been tested with a pseudo-agent for the in vivo inhibition of gastric acid secretion. Six dogs with a chronic fistula and Heidenhain's pouch were induced by gastric acid secretion by infusing the O-terminal tetrapeptide of gastrin at a dosage of 0.5, Α / kg.h. Each dog also serves to control itself. In the control experiment, only tetrapeptide was administered for one day. On another day, six dogs were given tetrapeptide and after one hour of secretion of hydrochloric acid at steady state, an infusion of D-SVal-somatostatin at a dose of 0.75 µgkg.h was administered for 1 hour. Sampling of gastric acid is continued for a further 1.5 hours at a sampling interval of 15 minutes.

The samples are titrated to an pH of 7 in an automatic titrator. The inhibitory effect of D-Waterspattoo Satin is extrapolated against the sommacosatin dose-response curve, and the relative potency of the analog to that of sometGatatin is expressed as% activity. D-Vat'spomatcoPatkn inhibits the steady-state gastric acid secretion induced by G-tectappeptide gastrin by · 85.1 Λ 6.0% (standard mean error of measurement). This effect is equivalent to the effect of 0.935 of sommaGosatin. Thus, the relative activity of this substance towards · sommaGosatin is 125%.

D-Vel'-somaú ^ atin was equal^ěž longed for ^pin reducing the intestinal intestines ^pconscious. As test animals, three dogs with intralimeneal catheters placed in the antrum, duodenum and pylor are used. Pressure changes in the lumen of the intestine were recorded in a Visicorder using voltage meters and miniature light beam galvanometers.

After the steady-state has been established, the test compound is administered by intravenous infusion over 10 minutes. · The test compound initially raises and then decreases the intraumenary pressure in the pylorus, while the pressure in the duodenum and anthra remains reduced during the test. The lowest effective dose required to increase pyloric pressure and to reduce duodenal and anthraous pressure is less than 0.129 - // k / .10 min. The corresponding value for somatootatin alone is 0.129-0.25 -A / kg. 10 min.

D-Val¹-soaajoosat^andIt was also tested^Ce je^hon the effect of inhibiting pancreatic secretion. The experiment was carried out as follows: Three dogs who mm;]! both an oesthetic and a complete gastric fist with an infusion of secretion at a dose of 2 units (k / h) and cholecystokinin at a dose of 0.45 units (k / h) induces secretion of α: chicrease and a small amount of teto (asthma at a dose of 0.5). * // k / .h induces secretion of gastric hydrochloric acid. After the response is steady state, each psu is formed^pO ^dobu 1 ^hO^din^y D-Vvl¹-toaa^tooSatii v ^dávce ^O,753*^//to^/.h. · ^^ j ^^χ^ I ^^aáThe inhibition effect, expressed as a percentage change from the control for all protein, is -51%. .

D-Val ^ somatoototto was equal^ěž Zkou^withen_?^peye^d it relates to the activity of releasing growth hormone. The procedure was carried out using standard male Sprt / ue-Dawley rats weighing 100-120 / (Laboratory Supply Compotiy, IpapanOit, Indiana). The assay is a moodfication method of P. Brazeau, W. Vale and R. Guuileman, Enádorinolo / y, 94, 184 (1974).

A total of five groups of eight rats were used in the test to test each compound. To stimulate the growth hormone secretion, all rats were treated with sodium phosphate. One group serves as a control and receives only a salt solution. Animals from two groups were injected subcutaneously with animals, i.e. animals from one group at a dose of 2 µg / animal and animals from the other group at a dose of 50 µg / animal. Animals from the remaining two groups were injected subcutaneously with the test compound, to animals from one group at a dose of 2 µg / ml and animals from the other group at a dose of 50 µl / ml. ,

Serum growth hormone co-immunization was measured 20 minutes after the simultaneous administration of sodium foothaxate and the test compound. The degree of inhibition of serum growth hormone concentration relative to the control group and the relative activity of D-Val are determined^--somatostattou with respect to TomaoSatiiu himself.

^Při ^d2&gt;^//tor^ywith D-Vvl¹-tomajoo^withatii increased growth hormone secretion by 2% compared to control, while tomatooSatii caused 44% inhibition. At a dose of 50 µl D-Vaa rat¹-somatoosatin inhibits the increase in growth hormone secretion by 73% compared to the control, whereas tomatooSatii alone causes 79% inhibition.

D-Val^L-It has got^joo^tAtii was equ^ěž in vivo efficacy in inhibiting secretion ^/luka / on and insulin after stimulation with L-alamin. Ordinary purebred dogs of both sexes do not feed overnight. Blood samples are taken and then started on the blood. infusing a saline solution containing tomajosatin or a test compound. After 30 minutes, L-allanto is also administered intravenously over 15 minutes. The fusion of a saline solution containing somato? 1? Or the test compound is continued for 15 minutes after the end of administration of the L-alanine tofusion.

Injection of L-alanine-induced increase in serum / luka / on and insulin concentration, which returns to control concen- tration after L-alanine is complete. This procedure found that^ofThe minimum D-Val I-somatoattaatt to the target is ^0,06 · A^of · 0,^{11 /}G / k // miiu, and for inhibiting insulin 0.006 to 0.03 z / kg / min, while the minimum dose of tInIntooSatiiu for inhibition / luka / on is 0.10 to 0.12 k / min min and for inhibition of insulin, 0.03 · 0.10X4 / kg / min.