WO1992004371A1

WO1992004371A1 - Kininogenase inhibitors

Info

Publication number: WO1992004371A1
Application number: PCT/GB1991/001479
Authority: WO
Inventors: Michael Szelke; David Michael Evans; David Michael Jones
Original assignee: Ferring Peptide Research Partnership Kb
Priority date: 1990-09-07
Filing date: 1991-09-02
Publication date: 1992-03-19
Also published as: GB9019558D0; NO930731D0; FI930946A; ZA917096B; EP0652893A1; AU8438791A; HU9300610D0; FI930946A0; IE913120A1; CA2090858A1; NO930731L; MC2313A1; JPH06501461A; HUT64084A; PT98885A

Abstract

Kininogenase inhibitors, optimally not exceeding the size of a hexapeptide, represented by (II), wherein A and B = amino acyl (including amino acyl analogue) the same or different forming a dipeptide group the amino acid of A carrying a terminal group and being any amino or imino-acid residue (but preferably of D-configuration) and of B being a lipophilic amino-acid residue of D- or L-configuration but not proline or a proline analogue, or a conformational analogue of said dipeptide group wherein the peptide link is replaced by -CH2-NH- ('reduced'), -CH(OH)-CH2- ('hydroxy'), -CO-CH2 ('keto'), -CH2-CH2- ('hydrocarbon') or other conformational mimic of the peptide bond and in (III) the side chain R1 is that of a basic amino acid or amino acid analogue (preferably of L-configuration), and R is H or lower alkyl(C¿1?-C4) or C?α¿ or the peptide link comprising -N(R)- is replaced leading to a conformational mimic as above; Y = a binding enhancing or carbonyl activating group preferably selected from H (when A or B must be cyclohexylalanine, preferably D if at A or L if at B) or alkyl (C¿1?-C20) or fluoroalkyl (C2-C12); substituted oxymethylene; thiomethylene; sulphoxymethylene; sulphonylmethylene; aminomethylene; hydrazino-methylene; -CH2-Het (where Het = a substituted or unsubstituted heterocycle); substituted amino (but when the resulting compound is a secondary alkylamide B must not be phenylalanine); an amino-acid group or its ester or amide; a carboxylic secondary amide or primary amide, when B must be cyclohexylalanine or adamantylalanine or other bulky lipophilic, non-aromatic amino-acid (not Ala Leu Ile Val Nva Met Nle Phe Tyr Trp Nal (1)); tertiary-carboxamide; carboxy-alkyl group or its ester or amide or amino acyl derivative.

Description

KININOGENASE INHIBITORS

FIELD OF INVENTION

The invention relates to enzyme inhibition and to treatment of disease.

BACKGROUND - KININS

Kinins are natural vasoactive peptides liberated in the body from high molecular weight precursors (kininogens) by the action of selective proteases known as kininogenases.

There is evidence for the involvement of kinins in the following pathological states:

(a) Conditions associated with vasodilatation and hypotension, e.g. septic, anaphylactic and hypovolaemic shock; carcinoid syndrome and dumping syndrome

(b) Conditions involving inflammation, e.g. acute arthritis, pancreatitis, local thermal injury, crush injury and brain oedema

(C) Conditions involving bronchoconstriction, especially for example the initial, acute allergic reaction in asthma

(d) Allergic inflammation, particularly allergic rhinitis and conjunctivitis, together generally known as hay fever, and the bronchial inflammation and consequent occlusion found in the non-acute but serious and even fatal inflammatory phase of asthma.

The kinins (bradykinin, kallidin and Met-Lys-bra kinin) are potent medi

rs of inflammation. Their actions are

as follows:

(a) They increase capillary permeability which leads to exudate formation and oedema

(b) They are potent vasodilators in arterioles and therefore reduce blood pressure and increase blood flow (c) They induce pain

(d) They contract bronchial smooth muscle

(e) They activate phospholipase A₂ and thus stimulate the biosynthesis of prostaglandins ( PG's) which mediate some of their actions.

In regard to prostaglandins, it may be noted that certain actions of kinins, particularly pain and vascular permeability above, are potentiated by PG's, although PG's themselves do not cause pain nor do they induce vascular permeability at the concentrations found in inflamed tissue. PG's therefore act as either mediators or potentiators of kinins.

In spite of the above knowledge of kinins and their actions, relatively little attention has been paid to reduction of their action. In asthma treatment for example clinical attention is primarily directed to the acute bronchoconstrictive reaction, for which there are effective drugs. Deaths continue to occur from the gradually developing bronchial occlusion, and at present not only are there no clinically effective inhibitors of kinin release available but the concept of kinin release inhibition, at least in treating allergic inflammation, appears to be new. The only substance that is in fact a kinin release inhibitor and has attained clinical significance is aprotinin ('Trasylol', Bayer, trade mark), a proteinase inhibitor isolated from bovine tissues

(lungs, lymph nodes and pancreas). It is a strongly basic protein (pl = 10.5) of MW = 6,500 comprising a single peptide chain of 58 residues. However, aprotinin is primarily a trypsin inhibitor (Ki = 10^-13M) and is some 10⁶-times less active against kinin release. It has been found marginally beneficial in acute pancreatitis, a serious condition, where it inhibits the activation by trypsin of zymogens of pancreatic serine proteinases, and in traumatic - haemorrhagic shock. Aprotinin has to be administered parenterally, and it frequently produces a painful reaction at the injection site. BACKGROUND - KININOGENASES

The kininogenases are serine proteinases, that is to say proteinases in which the hydroxy group of a serine residue is the nucleophile involved in forming the substrate transition state. They liberate the kinins (bradykinin, kallidin) from the kininogens by limited proteolysis. There are several kinds of kininogenase:-

(a) Tissue kallikrein (TK, also called glandular kallikrein GT or urinary kallikrein UK) which is found in the pancreas, salivary glands, intestines, kidney and urine. It has MW = 30,000 and acts preferentially on low molecular weight kininogen (LMWK) to release the kinin kallidin (KD). Tissue kallikrein has no potent and fast acting endogenous inhibitor present in plasma.

(b) Plasma kallikrein (PK) occurs in plasma as an inactive zymogen which is activated by Factor Xlla, and is part of the intrinsic coagulation cascade. It has MW = 100,000 and its preferred substrate is high molecular weight kininogen (HMWK) from which it releases bradykinin (BK). Plasma kallikrein is rapidly and effectively inhibited in plasma, by endogenous inhibitors known as cl-inactivator and α₂-macroglobulin.

(c) Mast cell tryptase which, while not as active as the kallikreins in kinin release, we have found to occur in large amounts in the mast cells of the lung tissue of asthmatics.

BACKGROUND - KININOGENS

The kininogens which are the natural substrates for the kininogenases (they act also as potent inhibitors, Ki approx. 10 ^{- 11} , of cysteine proteinases such as cathepsins B, H and L, calpain and papain) occur in two types: (a) Low molecular weight kininogen (LMWK) with molecular weight in the range 50,000 - 70,000 depending on species of origin and degree of glycosylation.

(b) High molecular weight kininogen (HMWK) with molecular weight in the range 88,000 - 114,000 which, in addition to serving as an alternative precursor of kinins and a cysteine proteinase inhibitor, also plays an obligatory role with plasma kallikrein in the initiation of the intrinisic coagulation cascade.

The two kininogens, whose mRNA's are transcribed from the same gene, have identical primary sequences throughout the N- terminal or heavy chain (H-chain) region, the kinin region and the first twelve amino acids of the C-terminal or light chain ( L-chain ). At this point their structures diverge, HMWK having a longer L-chain (MW approximately 45K) than LMWK (4.8K).

The cleavage of human HMWK by plasma kallikrein is for example shown schematically in Fig. 1, with details of the sequence at the cleavage sites in Fig. 2 and a more detailed sequence in Fig. 3 where the conventional numbering of residues adajcent to a cleavage site is shown for cleavage site I. After excision of one or other kinin sequence, the H- and L-Chains are held together by a single disulphide bridge:-

As shown, plasma kallikrein and tissue kallikrein act at a single site to free the kinin C-terminal site, cleaving between residues 389 and 390, but at sites one residue apart, either side of residue 380, to free the N-terminal of bradykinin (by PK) or kallidin (by TK).

The role of PK and HMWK as clotting factors in the intrinsic cascade does not involve the enzymatic release of kinins. However many of the effects of PK and all those of TK do involve such release, being mediated by the kinins released from the respective substrates HMWK and LMWK through selective proteolysis.

INDICATIONS

The main clinical indications for kininogenase inhibitors are inflammatory conditions, particularly aller g i c inflammation ( e . g . asthma and hay fever ) . A fuller list of indications is given below:

(1) Allergic inflammation (e.g. asthma, rhino-conjunctivitis [hay fever], rhinorrhoea, urticaria

(2) Inflammation (e.g. arthritis, pancreatitis, gastritis, inflammatory bowel disease, thermal injury, crush injury, conjunctivitis)

(3) Smooth muscle spasm (e.g. asthma, angina)

(4) Hypotension (e.g. shock due to haemorrhage, septicaemia or anaphylaxis, carcinoid syndrome, dumping syndrome)

(5) Oedema (e.g. burns, brain trauma, angioneurotic oedema whether or not as a result of treatment with inhibitors of angiotensin converting enzyme) (6) Pain and irritation (e.g. burns, wounds, cuts, rashes, stings, insect bites)

STATEMENT OF INVENTION

In one aspect the invention provides a method of treatment (including prophylactic treatment) of an inflammatory or other condition set out in the indications above, particularly, an allergic inflammatory condition, wherein an effective amount of a peptide or peptide-analogue kininogenase inhibitor is administered topically or systemically to a patient suffering from or at risk of the condition. It is believed that for optimum activity, administrability and stability in the body the compounds should not exceed the size of a hexapeptide, that is to say should not comprise more than six amino acid or amino acid analogue residues; the presence of further residues, particularly in a pro-drug from which residues are cleaved in the body to give the compound primarily exerting the desired effect, is however not excluded.

Particularly, the invention provides a method of treatment of the allergic inflammatory phase of asthma, wherein an effective amount of a kininogenase inhibitor such as a mast cell tryptase inhibitor is administered topically or systemically to a patient suffering from or at risk of the condition.

The invention extends further to a method of preparation of a medicament for the topical or systemic treatment (including prophylactic treatment) of conditions as above particularly for allergic inflammatory conditions and especially for asthma as above, wherein a kininogenase inhibitor is associated with a pharmaceutically acceptable diluent or carrier to constitute said medicament.

In the above, the kininogenase inhibitor is conveniently but not essentially of the novel kind now described in which in another aspect, without limitation to any particular clinical indication, the invention provides synthetic, low molecular weight compounds that selectively inhibit kininogenases and thus block the release of kinins from kininogens. The inhibitors are peptide analogues, desirably (as above) not exceeding the size of a hexapeptide in terms of amino acid or analogue residues, based on the known amino acid sequence of the kininogens at cleavage site I, which analogues have sufficient similarity to the cleavage site sequence to bind to the active site of the kininogenase but are not hydrolysable and therefore remain bound, inactivating the enzyme.

The inhibitors are essentially of the structure below, in which A represents the P₃ residue, B the P₂ residue, C the P₁ residue and Y a carbonyl-activating or binding group the structure being:-

A - B - C - Y I where A, B and C are amino acyl or amino acyl analogue groups linked by peptide bonds or conformational analogues thereof giving a peptide mimic. Other residues in addition to these essential ones may of course be present, including amino acyl or amino acyl analogue residues.

In more definitive terms the compounds are represented by

wherein

A and B = amino acyl (including amino acyl analogue) the same or different forming a dipeptide group the amino acid of A optionally carrying a terminal group (other than hydrogen) and being any amino or imino-acid residue (but preferably of D- configuration) and of B being a lipophilic amino-acid residue of D- or L-configuration but not proline or a proline analogue, or a conformational analogue of said dipeptide group wherein the peptide link is replaced by -CH₂-NH- ('reduced'), -CH(OH)-CH₂- ('hydroxy'), -CO-CH₂- ('keto'), -CH₂-CH₂- ('hydrocarbon') or other conformational mimic of the peptide link and in:-

0

the side chain R¹ is that of a basic amino acid or amino acid analogue (preferably of L- configuration) and R is H or lower alkyl ( C₁ - C₄) or C^α or the peptide link comprising -N(R)- is replaced leading to a conformational mimic as above. For example C^α may be replaced by nitrogen. Y = a binding enhancing or carbonyl activating group for example selected from H (but only if A or B is cyclohexylalanine, preferably D if at A or L if at B) or alkyl ( C₁ - C₂₀) or fluoroalkyl (C₂ - C₁₂); substituted

oxymethylene; thiomethylene; sulphoxy- methylene; sulphonylmethylene; aminomethylene; hydrazino-methylene; -CH₂-Het (where Het = a substituted or unsubstituted heterocycle);

substituted amino (but when the resulting compound is a secondary alkylamide B must not be phenyl-alanine); an amino-acid group or its ester or amide; a carboxylic secondary amide or primary amide, when B must be a bulky lipophilic, non-aromatic amino-acid e.g.

cyclohexylalanine, adamantylalanine (not Ala Leu lle Val Nva Met Nle Phe Tyr Trp Nal (1)); tertiary-carboxamide; carboxy-alkyl group or its ester or amide.

In the above context substituents are suitably common functional groups that increase binding affinity to the enzyme and/or improve pharmacological properties. Further in considering conformational analogues or mimics a dipeptide mimic is a structure containing non-natural amino acid (amino acid analogue) residues or which is non-peptidic and which in I holds the side-chains of A and B or B and C or all of them in a conformation similar to that present in the parent peptide when bound to the active site of the enzyme. It may also contain features favourable for other interactions with the enzyme, e.g. hydrogen bonding. A mimic may be chosen from the published work on such analogues.

For example, the following are mimics of the dipeptide DPro-Phe (Ph may be replaced by -CH₂Ph):-

( i ) ' Reduced ' mimic ( ii) ' Hydroxy ' or ( iii) ' Keto ' or

hydroxyethylene mimic ketomethylene mimic

The preferred compounds represented by the above general formula are now considered.

Preferred residues for A are imino-acids, (e.g. D-proline or an analogue of proline e.g. pipecolinic acid, azetidine carboxylic acid etc.); lipophilic amino acids (e.g. DPhe, DCha, DChg); strongly basic amino acids (e.g. D-Arg or a guanidinophenylalanine) and for B they are L-Phe, L-Cha, L-αNal, L-Tal, L-(4F)Phe L-(NMe)Phe or other substituted phenylalanines. A and B may also be the N-alkyl (C₁-C₄) or Cα-alkyl ( C₁-C₇ e.g. methyl, benzyl) analogues of these amino acids. Suitable terminal groups for A include lower alkyl (preferred) or acyl (not excluding amino acyl), alkyl sulphonyl (straight chain or branched or cyclic), amino-alkyl, carboxy alkyl, hydroxy alkyl or any other common protecting group encountered in peptide chemistry.

Groups suitable as group Y are specific to the present invention in that they are part of the structure giving the required binding to the active site and are not merely non- interfering end groups. They form a binding group which increases affinity to the enzyme and/or a group which activates the adjacent carbonyl by rendering it more electrophilic. Specific groups are included in the following formula:

where in a peptide link to residue B the α-nitrogen may be free or substituted for example by methyl or other C₁-C₄ alkyl and thus R¹ and R are as before but particularly R¹ =

3-guanidinopropyl or other guanidinoalkyl group or an amidino- alkyl or aminoalkyl group, also para- or meta substituted guanidino or amidino-benzyl or protected forms of the above (the basic nitrogens may also be alkylated e.g. with Me, Et), and where

Y = groups as given below, first in more general terras and then in terms of more detailed preferences, subject in both cases to the provisos expressed in defining the compounds of the invention earlier. The detailed preferences are given in groups under roman numerals, which are also indicated, in brackets, with the first listing which is:-

(I) Y = H (representing aldehydes) or alkyl including fluoroalkyl (representing ketones)

(II-III-IV) Y = -CH₂Q where Q = -OR² or -SR² or -SOR² or -SO₂R² or

-NHR² or -

(note that -D] represents a ring in which D is an atom of that ring)

wherein R² , R⁴ and R⁵ are as below ⁴

( V-VI ) ₂ ⁶

-CH₂ CHR⁶ CO-D] wherein R⁴, R⁵ and R⁶ are as below

(VII-VIII) Y = amino acyl or a group forming a substituted amide or hydrazide

(IX-X-XI) Y = a group forming an α-keto amide e.g.

- COR ⁹ or -CO-D or

and in which further:-

R² = alkyl or substituted alkyl including aarryyll or aryl alkyl and -CH₂R³ where R^{3 =} fluoroalkyl

R⁴ and R⁵ the same or different but not both hydrogen = H or C₁-C₂₀ alkyl (which may be further substituted), acyl or alkyl sulphonyl

-D] is a heterocyclic ring (D = nitrogen or carbon in Group IV and N in Groups VI and X) optionally unsaturated and optionally with further hetero atoms and substituents R⁶ = hydrogen, alkyl, hydroxyalkyl, aminoalkyl, alkylaminocarbonyl

R⁹ = -NH₂ as such or alkylated, or amino acyl

The listing of more detailed preferences, again within the provisos expressed earlier, is:-

Group I

Y = H; alkyl including branched alkyl (C₁-C₂₀); aryl alkyl; or cycloalkyl (C₁-C₂₀); perfluoroalkyl or partially fluorinated alkyl (C₂-C₁₂); [e.g. Y = Me;

-CH(CH₂CH₂CH₂CH₃)₂; -CH(CH₂CH₂CH₂CH₃)CH₂-cyclohexyl;

—CH₂CF₂CF₂CF₃; -CF₂CH₂CH₂CH₃].

Group II

Y = -CH₂QR² where Q = O, S, SO, SO₂, NH and where R² = Alkyl, branched alkyl or acyl (C₁-C₁₂); or

cycloalkyl (C₁-C₁₂); or aryl or aryl alkyl; or -CH₂-R³ where R³ = perfluoroalkyl or partially fluorinated alkyl, branched or not (C₁-C₁₂).

Group III

R⁴, R⁵ the same or different = alkyl, branched alkyl, cycloalkyl, acyl, alkylsulphonyl, carboxyalkyl (the carboxyl group may be further derivatized to form an ester or amide with an amino-acid or dipeptide), carbamoyl, suiphamoyl, N-dialkylamino-, arylalkyl, haloalkyl including fluoroalkyl, cyanoalkyl, alkoxyalkyl. hydroxyalkyl, mercaptoalkyl, aminoalkyl and derivatives thereof e.g. esters, amides and thioesters; or one of R⁴ or R⁵ = hydrogen

Group IV

Y = -CH - D] where D = nitrogen or carbon and -D] is a saturated or unsaturated heterocyclic ring or a bicyclic ring system, each is 5 - 8 membered, where there may be other hetero- atoms (N, S, O) and carbons or nitrogens may optionally be substituted by alkyl, branched alkyl, cycloalkyl, carboxyalkyl, carboxy (attached to carbon), amino, alkoxy, alkoxymethyl or (carbon) as carbonyl or other groups beneficial for interaction with the enzyme.

Group V

Y = -CH₇CH(R⁶)CONR⁴R⁵

R⁴, R⁵ as defined in Group III

R⁶ = hydrogen lower alkyl, branched alkyl, cycloalkyl, hydroxyalkyl, amino-alkyl, alkylaminocarbonyl.

Group VI

Y = -CH₂CH(R⁶)COD]

R⁶ as defined in Group V and - D]

as defined in Group IV ( but with D = N) Group VII

Y = an amino-acid residue or any amide (secondary or tertiary) or ester of that residue, L or D configuration. Preferred residues are of lipophilic amino-acids e.g. norleucine, cyclohexylalanine, homocyclohexylalanine, cyclohexylglycine, ^tertbutylglycine.

Group VIII

R⁷ = H (when however B is not phenylalanine unless R⁸ is carboxylalkyl or derivatized carboxylalkyl); or alkyl, branched alkyl (C₁ - C₁₂) , cycloalkyl (C₁-C₂₀) carboxyalkyl or bis (carboxyl) alkyl, which may be derivatized at the carboxyl group to form an amide e.g. with an amino-acid (preferred is arginine) or a substituted amine; N'-dialkylamino; N'-alkylamino-;

R⁸ = R⁷ the same or different but excluding H.

Group IX

Y = -CO-R⁹ but only if B is a bulky non-aromatic lipophilic amino acid or its N^α alkyl (C₁ - C₄) derivative (e.g. cyclohexylalanine but excluding Ala, Leu, lie, Val, Nva, Met, Nle, Phe, Tyr, Trp, Nal(l) and their N-methyl derivatives) where R⁹ = NH₂,

N'-alkylamino (where the alkyl groups include branched and/or cycloalkyl); an amino-acid residue. Group X

Y = -CO-D]

-D] as defined in Group IV (but D = N) Group XI

Y = -CO-NR⁴R⁵

R⁴,R⁵ as defined in Group III, but not H

The following examples illustrate the invention. They are given in the form of:- - Nine tables of compounds with reference number, structure, molecular ion as determined by FAB (fast atom bombardment) spectrometrv and class of compound (the same as the 'groups' referred to earlier herein) - Eight detailed examples of synthesis - Twelve synthesis schemes, as referred to in the detailed examples - Table of abbreviations - Description of in vitro tests of inhibition of kininogenases and in vivo tests of efficacy against asthma

All structures of intermediates were verified by NMR.

EXAMPLE I

5 Me-DPhe-Cha-Arg-H

The synthesis of 5 was carried out according to Scheme I. Arabic numerals underlined e.g. 1 refer to structures in these schemes. Roman numerals in parentheses e.g. (i) refer to reaction steps.

(i) Isobutyl chloroformate (10.2 mmol) was added to a solution of

Boc-Arg(Z₂)OH (9.23 mmol) and N-methylmorpholine (11.08 mmol) in dry THF (25 cm³) at -20°C After 20 mins the solid was filtered off and the filtrate added to a solution of sodium borohydride (10.3 mmol) in water (10 cm³) at 0°C After 3 hours 0.3 M KHSO₄ was added, the crude product extracted with EtOAc and purified by flash chromatography on silica with EtOAc - petrol (4:6). The alcohol 1 was isolated as a white solid (97%).

(ii) The Boc group of 1 (4.75 mmol) was removed with sat. HCl/Dioxan and the product acylated with Boc-Cha-ONSu (9.5 mmol) in CH₂CI₂ (20 cm³) at 0°C in the presence of N-methylmorpholine. After two hours the reaction was worked up using standard procedures and the crude product purified by flash chromatography on silica with EtOAc - petrol (4:6). The pure alcohol 2 was isolated as a colourless oil (90%).

(iii) The Boc group of 2 (4.27 mmol) was removed with sat HCl/Dioxan and the product reacted with Z(NMe)DPhe-OH (5.12 mmol) in the presence of HOBt (10.2 mmol), water soluble carbodiimide (6.1 mmol) and N-methylmorpholine in DMF (20 cm³) at 0°C. After 18 hours the reaction was worked up using standard procedures and the product purified by flash chromatography on silica with EtOAc - petrol (1:1). The pure alconol 3 was isolated as a colourless oil (52%). (iv) The alcohol 3 (2.22 mmol) was dissolved in CH₂Cl₂/AcOH (30:1) and Dεss-Martin Periodinane (4.5 mmol) added. After 2½ hours at room temperature the reaction mixture was diluted with EtOAc and poured into a solution of sodium thiosulphate (32 mmol) and sat. NaHCO₃. The crude product was purified by flash chromatography on silica with EtOAc-petrol (3:7). The pure aldehyde 4 was isolated as a colourless oil (75%).

(v) The aldehyde 4 (1.65 mmol) was dissolved in MeOH/H₂O/AcOH

(90:9:1, 50 cm³) and hydrogenated over 5% Pd/C. The crude material was purified by mplc on *Vydac C₁₈ (15-25 μ) using MeCN/H₂O/TFA to give pure 5 (CH-851) as a white solid (780 mg). Tlc, EtOAc-Py-AcOH-H₂O (30:20:6:11), R_F 0.66 on silica. After hydrolysis at 110°C/22 hrs with 6N HCI peptide content based on Cha was 40%. FAB mass spec [M+H]⁺ = 473 (Calc. ^m/z = 472).

EXAMPLE ll

11 H-DPro-Phe-Lys-CONⁿBu₂ (see Scheme II)

(i) TcbocONSu (14.8 mmol) was added to a solution of

H-Lys(Z)-OMe. HCI (12.2 mmol) and triethylamine (14.8 mmol) in CH₂Cl₂ (50 cm³). After 3 hours at room temperature the reaction was worked up using standard procedures and the product purified by flash chromatography on silica using EtOAc - petrol (7:13). The pure ester 6 was isolated as a colourless oil (100%).

(ii) Diisobutylaluminium hydride (1.5 M solution in toluene, 50 mmol) was added to a solution of 6 (12.2 mmol) in dry toluene (100 cm³) at -78°C over a period of 20 minutes. After a further 15 minutes methanol (10 cm³) was added followed by a saturated solution of Rochelle's salt (100 cm³). After 2½ hours the reaction was worked up using standard procedures and the product purified by flash chromatography on silica using EtOAc - petrol (3:7). The pure aldehyde 7 was isolated as a colourless oil (49%).

* Trade name (iii) Potassium cyanide (18 mmol) and 1 M hydrochloric acid (30 cm³) were added to a solution of 7 (5.98 mmol) in ethyl acetate (30 cm³). After 18 hours at room temperature the reaction was worked up using standard procedures and the product purified by flash chromatography on silica using EtOAc - petrol (4:6). The pure cyanohydrin 8 was isolated as a colourless oil (88%).

(iv) A 4 M solution of HCI in dioxan (50 cm³) was added to a solution of 8 (5.28 mmol) in dry methanol (15 cm³) at 0°C. After 18 hours at room temperature an ice/water mixture (15 cm³) was added. After 3 days at 4°C solid KHCO₃ was added. The reaction was worked up using standard procedures and the product purified by flash chromatography on silica using EtOAc - petrol (11:9). The pure ester 8b was isolated as a yellow oil (59%).

(v) Activated zinc dust was added in small portions to a solution of 8b

(3.1 mmol) in AcOH/H₂O (9:1, 25 cm³). After 1½ hours at room temperature the zinc was filtered off, the filtrate evaporated in vacuo and the residue was taken up in EtOAc. This solution was washed with sat. NaHCO₃, water, brine, dried (Na₂SO₄) and evaporated in vacuo. The amine 9 was isolated as a colourless oil (85%).

(vi) The amine 9 (2.63 mmol) was acylated with Boc-Phe-ONSu (3.04 mmol) in CH₂Cl₂ (30 cm³) at 0°C in the presence of N-methyl morpholine. After 3 hours the reaction was worked using standard procedures and the crude product purified by flash chromatography on silica with EtOAc/Pet Ether (6:4). The pure ester 10a was isolated as a colourless oil (92%). (vii) The Boc group of 10a (2.41 mmol) was removed using sat. HCl/Dioxan and the product acylated with Boc-DPro-ONSu (2.92 mmol) in CH₂Cl₂ (30 cm³) at 0°C in the presence of N-methyl-morpholine. After 3 hours the reaction was worked up using standard procedures and the product purified by flash chromatography on silica using EtOAc/Petrol (3:1). The pure ester 10b was isolated as a colourless oil (64%).

(viii) Lithium hydroxide (1.6 mmol) and water (3 cm³) were added to a solution of 10b (1.54 mmol) in THF (30 cm³). After 4 hours at room temperature the THF was removed in vacuo, the pH of the residue adjusted to pH 4 with 1 M citric acid and extracted with CHCI₃. The organic extracts were washed with brine, dried (Na₂SO₄) and evaporated in vacuo. The pure acid 10c was isolated as a colourless oil (70%).

(ix) Pentafluorophenol (1.3 mmol) and water soluble carbodiimide (1.3 mmol) were added to a solution of 10c (1.07 mmol) in CH₂Cl₂ (20 cm³) at 0°C. After 2½ hours dibutylamine (2.1 mmol) was added to this solution at 0°C and the pH adjusted to pH 9 with DIEA. After 18 hours at room temperature the reaction was worked up using standard procedures and the product purified by flash chromatography on silica using EtOAc/Petrol (7:3). The pure amide 10d was isolated as a colourless oil (48%).

(x) Dess-Martin Periodinane (0.97 mmol) was added to a solution of

10d (0.52 mmol) in CH₂Cl₂ (100:1, 40 cm³). After 2 hours at room temperature further Dess-Martin Periodinane (0.52 mmol) was added. After a further 3 hours the reaction mixture was diluted with EtOAc and poured into a solution of sodium thiosulphate (7.3 mmol) in water and sat NaHCO₃ were added. The crude product was purified by flash chromatography on silica with EtOAc/petrol (9:11). The pure keto amide 10e was isolated as a colourless oil (57%). (xi) The Boc group of 10e (0.24 mmol) was removed using sat. H Cl/Dioxan. The resultant product was dissolved in AcOH/H₂O (9:1) and hydrogenated over 5% Pd/C. The crude material was purified by mplc on *Vydac C₁₈ (15 - 25 μ) using MeCN/H₂O/TFA to give 11 (CH-1463 89.7 mg). Hplc, *Novapak C₁₈, 4 μ (8 x 100 mm), linear gradient 20→ 80% 0.1% TFA/MeCN into 0.1% TFA/H₂O over 25 min at 1.5 ml min^-1 indicates th presence of two epimers D-Arg (40%) at 11.2 min and L-Arg (60%) at 12.6 min. After hydrolysis at 110°C/22 h with 6N HCI, amino acid analysis Phe 0.93, Pro 1.07.

EXAMPLE lll

17 H-DPro-Phe-Arg-CH₂S(CH₂)₄CH₃ (see Scheme lll)

(i) Boc-Arg(Z₂)OH (46.1 mmol) was dissolved in dry THF (200 cm³).

N-methylmorpholine (50.85 mmol) and isobutyl chloroformate (50.73 mmol) were added at -20°C. After 20 min. this mixture vas added to a solution of diazomethane (0.1 mole) in Et₂O at -5°C. After 2 hours the diazoketone 12 was isolated as a yellow solid.

(ii) The diazoketone 12 (46.1 mmol) in dry THF was treated with HBr

(69.15 mmol) in EtOAc at -20°C followed by addition of sat. NaHCO₃ after 45 mins. The crude product was extracted with EtOAc and crystallised from EtOH to give pure Boc-Arg(Z₂)CH₂Br, 13, (85%).

(iii) 1-Pentanethiol (1.27 mmol) in dry DMF (5 cm³) was treated with sodium hydride (1.4 mmol). After 30 mins Boc-Arg(Z₂)CH₂B

3 (1.27 mmol) was added-40°C for 20 mins and -5°C for 2½ hours. After addition of 0.3 M KHSO₄ and extraction of the crude product with EtOAc, flash chromatograpy on silica with EtOAc - petrol (15:85) yielded the pure thiometnylene compound 14 as a colourless oil (74%).

* Trade name (iv) The Boc protecting group of 14 (0.94 mmol) was removed using sat. HCl/Dioxan and the resulting product was acylated with Boc-Phe-OPfp (1.13 mmol) in CH₂Cl₂ at 0°C in the presence of DIEA. The crude product was purified by flash chromatography on silica with EtOAc - petrol (3:7) yielding the pure thiomethylene analogue 15 as a colourless oil (55%).

(v) The Boc protecting group of i5 (0.52 mmol) was removed using sat.

HCl/Dioxan. The resulting product was dissolved in DMF and treated with Boc-DPro-OH (0.63 mmol) in the presence of HOBt (1.05 mmol), water soluble carbodiimide (0.76 mmol) and N-methylmorpholine. After a standard work-up the crude material was purified by flash chromatography on silica with EtOAc - petrol (4:6) yielding the pure thiomethylene compound 1 6 as a colourless oil (74%).

(vi) The Boc protecting group of 16 (0.38 mmol) was removed using sat.

HCl/Dioxan. The resultant product was dissolved in AcOH/H₂O (9:1) and hydrogenated over 5% Pd/C. The crude material was purified by mplc on *Vydac C₁₈ (15-25 μ), using MeCN/H₂O/TFA to give pure 17 (CH-574, 41 mg). Hplc, *Novapak C₁₈, 4μ (8 x 100 mm), Unear gradient 20→ 80% 0.1% TFA/MeCN into 0.1% TFA/H₂O over 25 min at 1.5 ml min^-1 indicates the presence of two epimers D-Arg (<5%) at 9.8 min and L-Arg (>95%) at 11.1 min. After hydrolysis at 150°C/1.5 h with 6N HCI, amino acid analysis Phe, 0.80; Pro, 1.00.

All analogues in Table 2 were synthesised by the described method. 61 was synthesised by the oxidation of 60 with meta- chloroperoxybenzoic acid.

* Trade name EXAMPLE IV

23 H-DPro-Phe-Arg-CH₂OCH₂(CF₂)₃CHCF₂ (see Scheme IV)

(i) IH, IH, 5H-Octafluoro-1-pentanol (2.45 mmol) in dry DMF (8 cm³) was treated with sodium hydride (1.83 mmol). After 30 mins the bromoketone 13 (1.65 mmol) was added at -40°C and left at this temperature for 30 mins and -5°C for 2½ hours. Addition of 0.3 M KHSO₄ and extraction with EtOAc gave the crude product which was purified by flash chromatography on silica using EtOAc - petrol (15:85). The pure fluoroether 18 was isolated as a colourless oil (69%).

(ii) The fluoroether 18 (1.13 mmol) was dissolved in MeOH (40 cm³), sodium borohydride (1.18 mmol) was added to this solution at 0°C. After 15 min 0.3 M KHSO₄ was added and the mixture extracted with EtOAc giving the pure compound 19 as a colourless oil (88%).

(iii) The Boc protecting group of 19 (1.0 mmol) was removed with sat.

HCl/Dioxan. The resulting product was dissolved in CH₂CI₂ and acylated with Boc-Phe-OPfp (1.2 mmol) in the presence of DEEA at 0°C. After a standard work up the crude product was purified by flash chromatography on silica with EtOAc - petrol (3:7) yielding the pure product 20 as a colourless oil (55%).

(iv) 20 (0.55 mmol) wa s deprotected with sat. HCl/Dioxan and acylated with Boc-DPro-OPr p (1.63 mmol) in CH₂Cl₂ at 0°C in the presence of DIEA. After a standard work up the crude product was purified by flash chromatography on silica with EtOAc - petrol (4:6) yielding the pure product 21 as a colourless oil (48%). (v) 21 (0.24 mmol) was dissolved in CH₂Cl₂/ AcOH (30:1) and

Dess-Martin Periodinane (0.48 mmol) was added. After 2 hours at room temperature the reaction mixture was diluted with EtOAc and poured into a solution of sodium thiosuiphate (3.5 mmol) in water and sat. NaHCO₃. The crude product was purified by flash chromatography on silica with EtoAc - petrol (7:13) yielding the pure fluoroether 22 as a colourless oil (64%).

(vi) The fluoroether 22 (0.16 mmol) was deprotected and purified as described in Example in (vi). Pure 23 (CH-619) was isolated as a white solid (50.9 mg). Hplc, *Novapak C₁₈ 4μ (8 x 100 mm), linear gradient 20→ 80% 0.1% TWMeCN into 0.1% TFA/H₂O over 25 mins at 1.5 ml min^-1 indicated a single product (TR = 11.5 min). After hydrolysis at 150°C/1.5 hr with 6N HCI, amino acid analysis Phe, 1.00; Pro, 1.2.

All analogues in Table 3 were synthesised by the described method except 54 and 55 which were synthesised by methods outlined in Schemes XIII and XlV respectively.

EXAMPLE V

31 H-DPro-Phe-Arg-CH₂N[(CH₂)₅CH₃]₂ (see Scheme V)

DL

(i) Boc-Arg(Z₂)OH (18.5 mmol) was dissolved in CH₂Cl₂ (50 cm³).

To this solution at 0°C was added trichloroethanol (20.35 mmol), water soluble carbodϋmide (22.2 mmol) and dimethylaminopyridine (0.93 mmol). After 3 hours the reaction was worked up using standard procedures giving the pure trichloroethyl derivative 24 as a colourless oil (100%).

* Trade name (ii) 24 (18.1 mmol) was deprotected with sat. HCl/Dioxan and acylated with Boc-Phe-ONSu (27.2 mmol) in CH₂Cl₂ at 0°C in the presence of N-methylmorpholine. After 3 hours the reaction mixture was worked up using standard procedures and the crude product was purified by flash chromatography on silica with EtOAc - petrol (2:8) yielding the pure product 25 as a white solid (97%).

(iii) 25 (17.4 mmol) was deprotected with sat. HCl/Dioxan and acylated with Boc-DPro-ONSu (26.2 mmol) in CH₂Cl₂ at 0°C in the presence of N-methylmorpholine. After 3 hours the reaction was worked up using standard procedures and the crude product purified by flash chromatography on silica with EtOAc - petrol (35:65) giving the pure protected tripeptide 26 as a colourless oil (94%).

(iv) Activated zinc powder was added to a solution of 26 (16.47 mmol) in glacial acetic acid. After 3 hours at room temperature the zinc was filtered off, the filtrate evaporated and the crude product purified by flash chromatography on silica with EtOAc - petrol -

cOH (74:25:1) giving the pure tripeptide 27 as a white solid (91%).

(v) The protected tripeptide 27 (15 mmol) was dissolved in dry THF

(40 cm³), N-methylmorpholine (18 mmol) and isobutyl- chloroformate (16.6 mmol) were added at -20°C. After 20 mins the mixture was added to a solution of diazomethane (35 mmol) in Et₂O at -5°C. After 2½ hours the diazoketone 28 was isolated as a yellow oil.

(vi) The diazoketone 28 (15 mmol) in dry THF was treated with HBr

(22.5 mmol) in EtOAc at -20°C followed by addition of sat. NaHCO₃ after 45 mins. The crude product was extracted with EtOAc and purified by flash chromatography on silica with EtOAc - petrol (1:1). The pure bromoketone 29 was isolated as a white solid (72%). (vii) Dihexyiamine (1.25 mmol) and NaHCO₃ (0.8 mmol) were added to a solution of bromoketone 29 (0.23 mmol) in dry THF (5 cm³). After 18 hrs at room temperature 0.3 M KHSO₄ was added to the reaction mixture and the crude product was purified by flash chromatography on silica with EtOAc - petrol (35:65). The protected aminomethylene ketone 30 was isolated as a yellow oil (54%).

(viii) The aminomethylene ketone 30 (0.12 mmol) was deprotected and purified as described in Example lll (vi). Pure 31 (CH-694) was isolated as a white solid (41 mg). Hplc, linear gradient 20→ 80% 0.1% TFA/MeCN into 0.1% TFA/H₂O over 25 mins at 1.5 ml min^-1 indicated the presence of two epimers D-Arg (50%) at 11.2 min and L-Arg (50%) at 12.5 mins. After hydrolysis at 110°C/22 hrs with 6N HCI, amino acid analysis Phe, 0.91; Pro, 1.09.

All analogues in Table 4 were synthesised by the described method. The required amines were synthesised by standard synthetic methods such as reductive amination and the Curtius rearrangement.

EXAMPLE VI

40 H-DPro-Phe-Arg^kGly-Pro-NHEt (see Scheme VI)

DL

(i) H₂C(CO₂Tce)₂ (6.81 mmol) was treated with sodium hydride (5.67 mmol) in dry THF (30 cm³). After 45 mins the bromoketone 13 (4.52 mmol) was added at -5°C. After 2½ hours 0.3 M KHSO₄ was added, the crude product extracted with EtOAc and purified by flash chromatography on silica with EtOAc - petrol (2:8). The pure Boc-Arg(Z₂)CH₂CH(CO₂Tce)₂ 32 was isolated as a colourless oil (83%).

(ii) Activated zinc was added to a solution of 32 (3.65 mmol) in glacial acetic acid. After 2½ hours at room temperature the zinc was filtered off, the filtrate evaporated and the diacid 33 isolated (iii) A solution of the diacid 33 in toluene was heated at reflux for 45 mins. The solvent was evaporated and the crude product purified by flash chromatography on silica with EtOAc - petrol - AcOH (60:39:1). The Boc-Arg(Z₂) ^kGly-OH 34 was isolated as a colourless oil (70% from 32).

(iv) Trichloroethanol (2.82 mmol), water soluble carbodiimide (2.81 mmol) and dimethylaminopyridine (0.117 mmol) were added to a solution of 34 (2.34 mmol) in CH₂Cl₂ (50 cm³) at 0°C. After 2½ hours the reaction was worked up using standard procedures and the crude product purified by flash chromatography on silica with EtOAc - petrol (85:15). The trichloroethyl derivative 35 was isolated as a colourless oil (83%).

(v) The Boc protecting group of 35 ( 1.85 mmol) was removed using sat.

HCl/Dioxan and the resulting product acylated with Boc-Phe-OPfp (6.04 mmol) in CH₂Cl ₂ in the presence of DlEA. After 2 hours the reaction was worked up using standard procedures and the crude product purified by flash chromatography on silica with EtOAc - petrol (2:8). The pure product 36 was isolated as a colourless oil (85%).

(vi) The Boc protecting group of 36 (1.58 mmol) was removed using sat.

HCl/Dioxan and the resulting product acylated with Boc-DPro-OPfp (5.12 mmol) in CH₂Cl₂ in the presence of DIEA. After 2 hours the reaction was worked up using standard procedures and the crude product purified by flash chromatography on silica with EtOAc - petrol (35:65). The pure product 32 was isolated as a colourless oil (79%).

(vii) Activated zinc dust was added to a solution of 37 (1.13 mmol) in glacial acetic acid. After 2½ hours at room temperature the zinc was filtered off, the filtrate evaporated and the crude product purified by flash chromatography on silica with EtOAc - petrol - AcOH (70:29:1). The product 38 was isolated as a colourless oil (76%). (viii) The protected keto isostere 38 (0.26 mmol) was convened to its Pfp ester by treatment with Pfp-OH (0.29 mmol) and water soluble carbodiimide (0.31 mmol) in CH₂Cl₂ (8 cm³) at 0°C for 2½ hours. This Pfp ester was coupled at 0°C to H-Pro-NHEt . HCI salt (0.78 mmol) in the presence of DIEA. After 18 hours the reaction was worked up using standard procedures and the product purified by flash chromatography on silica with CHCl₃-MeOH-AcOH (97:2:1). The product 39 was isolated as a colourless oil (91%).

(ix) The protected keto isostere containing analogue 39 (0.23 mmol) was deprotected as described in Example llI (vi). Pure 40 (CH-595) was isolated as a white solid (40 mg). Hplc, linear gradient 10→ 50% 0.1% TFA/MeCN into 0.1% TFA/H₂O over 25 mins at 1.5 ml min^-1 indicated the presence of two epimers D-Arg (46%) at 10.1 min and L-Arg (54%) at 11.7 min. After hydrolysis at 150°C/1.5 hrs with 6N HCI amino acid analysis Phe, 0.91; Pro, 1.09.

All analogues in Table 5 were synthesised by the described method.

EXAMPLE VII

45 H-DPro-Phe-Arg-Chg-NH₂ (see Scheme Vll)

(i) Boc-Phg-OH (19.9 mmol) was dissolved in AcOH/H₂O (9:1, 100 cm³) and hydrogenated over Rh/C at 60 p.s.i. for 3 days. The catalyst was filtered off and the solvent removed to give Boc-Chg-OH 41 (100%).

(ii) Water soluble carbodiimide (4.1 mmol) and HOBt (4.3 mmol) were added to a solution of 41 (3.9 mmol) in CH₂Cl₂/DMF (2:1, 60 cm³) at room temperature. After 30 mins 35% ammonia solution (0.8 cm³) was added. After a further 3 hours at room temperature the reaction was worked up using standard procedures and the product recrystallised from EtOH to give the pure amide 42 as a white solid (60%). (iii) The Boc group of 42 (0.77 mmol) was removed with sat. HCl/Dioxan to give the amide 43 as a white solid (100%).

(iv) The protected tripeptide 27 (0.38 mmol) was dissolved in DMF (5 cm³). 43 (0.76 mmol), HOBt (0.76 mmol) water soluble carbodiimide (0.46 mmol), and N-methylmorpholine were added at 0°C. After 18 hours at room temperature the reaction was worked up using standard procedures and the product purified by flash chromatography on silica with CHCl₃/MeOH (99:1). The pure protected tetrapeptide 44 was isolated as a white solid (69%).

(v) The protected tetrapeptide 44 (0.27 mmol) was deprotected and purified as described in Example Ill (vi). Pure 45 (CH-640) was isolated as a white solid (58 mg). Hplc, linear gradient 10→ 50% 0.1% TFA/MeCN into 0.1% TFA/H₂O over 25 min at 1.5 ml min^-1, single peak detected at 14.2 min. After hydrolysis at 110°C/22 hrs with 6N HCI, amino acid analysis, Arg, 0.96; Phe, 1.00; Pro, 0.95.

All analogues in Table 6 were synthesised by the described method or by other standard peptide coupling methodology. (M. Bodansky & A. Bodansky, The Practice of Peptide Synthesis, Springer- Verlag, 1984)

EXAMPLE Vlll

47 H-DPro-Phe-Arg-N[(CH₂)₅CH₃](CH₂)₃Ch (see Scheme VllI)(i) The protected tripeptide 27 (0.32 mmol) was dissolved in DMF (5 cm³), HN[(CH₂)₅CH₃](CH₂)₃Ch (0.96 mmol), HOBt (0.64 mmol), water soluble carbodiimide (0.38 mmol) and N-methylmorpholine were added at 0°C. After 18 hours at room temperature the reaction was worked up using standard procedures and the product purified by flash chromatography on silica using EtOAc/Hexane (4:6). The amide 46 was isolated as a colourless oil (32%). (ii) The protected tripeptide amide 46 (0.1 mmol) was deprotected and purified as described in Example Ill (vi). Pure 47 (CH-985) was isolated as a white solid (17 mg). Hplc, linear gradient 40→ 90% 0.1% TFA/MeCN into 0.1% TFA/H₂O over 25 min at 1.5 ml min^-1, single peak detected at 10.7 min. After hydrolysis at 110°C for 22 hrs with 6N HCI, amino acid analysis Phe, 1.01; Pro, 0.99.

All analogues in Table 7 were synthesised by the described method. The required tripeptide presursors were synthesised in a similar manner to 27 or by standard peptide coupling methodology. (M. Bodansky & A. Bodansky, The Practice of Peptide Synthesis, Springer- Verlag, 1984.) Required amines were either commercially available or synthesised via the Curtius rearrangement. nBu-DPro-OH for 181 was synthesised by reductive amination.

Sch

S

II

Sch XI

III

ABBREVIATIONS USED

Abn 3-Azabicyclo[3.2.2]-nonane

Ac Acetyl

AcOH Acetic acid

Ada Adamantylalanine

Aha 2-Aminohexanoic acid (Norieucine )

Boc tert-Butyloxycarbonyl

Bu Butyl

Ch Cyclohexyl

Cha Cyclohexylalanine

Chg Cyclohexylglycine

Cpr Cyclopropyl

DIEA Diisopropylethylamine

DMAP 4-Dimethylamino-pyridine

DMF Dimemylformamide

EtOAc Ethyl acetate

FAB Fast Atom Bombardment

4-Fph 4-Fluorophenylalanine

Hch Homocyclohexylalanine

HOBt 1-Hydroxybenzoniazole

hplc high performance liquid chromatography

Hyp 4-Hydroxyproline

'Hyp trans-4-Hydroxyproline K keto isostere -COCH₂-

Me Methyl

MeCN Acetonitrile

MeOH Methanol

mplc medium pressure (preparative) liquid chromatography

Nal Naphthylalanine

NMM N-Methylmorpholine

Npg Neopentylglycine

Oc Octyl

OH Hydroxy isostere -CHOH-

ONSu hydroxysuccinimide

Petrol Petroleum ether 60 - 80°C

Pfp Pentafluorophenyl

Phe-4NO₂ 4-Nitrophenylalanine

Phg Phenylglycine

Pic Pipecolinic acid

Pip Piperidyl

Py Pyridine

R Reduced isostere -CH₂-

Sar Sarcosine (N-methylglycine)

TBAF Tetrabutylammonium fluoride

TBDMS tert-B utyldimethylsilyl

Tcboc (1-Dimethyl-1-trichloromethyl)ethoxy carbonyl

Tce 2,2,2-Trichloroethyl Tha 3,3,5-Trimethylhexahydroazepyl

THF Tetrahydrofuran

Thi Thienylalanine

Tic 1 ,2,3,4-Tetrahydroisoquinoline-3-carboxylic acid tlc thin iayer chromatography

wscd water soluble carbodiimide

Z B enzy loxycarbonyl

Nor Norarginine

BIOLOGICAL ACTIVITY; MEDICAL USE

Compounds were tested in vitro for the following activities using standard procedures:

(a) Inhibition of human tissue kallikrein, plasma kallikrein and mast cell tryptase hydrolysing the chromogenic substrates S-2266, S-2302 and S-2266 respectively (method is adapted from that of Johansen, H.T., et al., Int. J. Tiss. Reac, 1986, a, 185-192). A series of measurements were carried out using a number of different; inhibitor concentrations and at least two different substrate concentrations. The inhibitory constant Ki was determined graphically, using a Dixon plor (M. Dixon, Biochem. J., 1953, 55, 170).

(b) Inhibition of kinin release from low and high molecular weight kininogens by tissue and plasma kallikrein respectively. A series of measurements were carried out using two substrate concentrations. The activity is calculated as the amount of kinen released per minute, this being determined by radioimmunoassay using polyclonal antibodies. The inhibitory constant Ki was determined graphically using a Dixon plot.

All the examples in Tables 1 - 9 have Ki values in the range 10^{- 3} - 10^-9 M against one or all of the enzymes in the chromogenic assay,

In vivo activity has been tested in well-established pharmacology models of asthma based on the sensitised guinea pig. A selection of these inhibitors representing the different chemical types proved to be highly effective in blocking both the acute phase response and the late phase reaction, their efficacy being comparable or superior to those of the topical steroids and β₂-agonist currently used in asthma therapy. When the compounds of the present invention are used as a medicine, there are no critical limitations to the administration methods. The present enzyme inhibitor can be formulated by any conventional method in pharmaceutics. For example, the present enzyme inhibitor may be applied in any conventional manner including intravenous injection, intramuscular injection, instillation, oral administration, respiratory inhalation, instillation, rhinenchysis, and external skin treatment. Although there are no critical limitations to the administration dosage, the suitable dosage is 1 to 1000 mg/day/person.

Claims

C L A I M S

1. Kininogenase inhibitors, optimally not exceeding the size of a hexapeptide, represented by:-

wherein

A and B = amino acyl (including amino acyl analogue) the same or different forming a dipeptide group the amino acid of A carrying a terminal group and being any amino or imino-acid residue (but preferably of D-configuration) and of B being a lipophilic amino-acid residue of D- or L- configuration but not proline or a proline analogue, or a conformational analogue of said dipeptide group wherein the peptide link is replaced by -CH₂-NH- ('reduced'), -CH(OH)-CH₂- ('hydroxy'), -CO-CH₂- ('keto'), -CH₂-CH₂- ('hydrocarbon') or other conformational mimic of the peptide bond and in:-

the side chain R¹ is that of a basic amino acid or amino acid analogue (preferably of L- configuration) and R is H or lower alkyl (C₁ - C₄) or C^α or the peptide link comprising -N(R)- is replaced leading to a conformational mimic as above Y = a binding enhancing or carbonyl activating group preferably selected from H (when A or B must be cyclohexylalanine, preferably D if ar A or L if at B) or alkyl (C₁ - C₂₀) or fluoroalkyl (C₂ - C₁₂); substituted

substituted amino (but when the resulting compound is a secondary alkylamide B must not be phenylalanine); an amino-acid group or its ester or amide; a carboxylic secondary amide or primary amide, when B must be cyclohexylalanine or adamantylalanine or other bulky lipophilic, non-aromatic amino-acid (not Ala Leu lie Val Nva Met Nle Phe Tyr Trp Nal (1)); tertiary-carboxamide; carboxy-alkyl group or its ester or amide or amino acyl derivative.

2. Compounds according to claim 1 wherein A is selected from imino-acids, (e.g. D-proline or an analogue of proline e.g. pipecolinic acid, azetidine carboxylic acid); lipophilic amino acids (e.g. DPhe, DCha, DChg); strongly basic amino acids (e.g. D-Arg or a homologue or analogue of Arg, e.g. amidino- or guanidinophenylalanine); or N-alkyl or C_α-alkyl (including benzyl) derivatives thereof.

3. Compounds according to claim 1 or 2 wherein B is selected from L-Phe, L-Cha, L-αNal, L-Tal, L-(4F)Phe L-(NMe)Phe or other substituted phenyialanines; or N-alkyl or C_α-alkyl (including benzyl) derivatives thereof.

4. Compounds according to claim 1, 2, or 3 wherein R¹ is selected from 3-guanidinopropyl or other guanidinoalkyl group, (or an amidinoalkyl or aminoalkyl group), also para- or meta substituted guanidino or amidino-benzyl or protected forms of the above; optionally basic nitrogens are alkylated (Me, Et or other).

5. Compounds according to any preceding claim wherein subject to the provisos in regard to the nature of Y expressed in claim 1, selection for Y is from:-

Y = H or alkyl including fluoroalkyl

Y = -CH₂Q where Q = -OR² or -SR² or -SOR² or -SO₂R² or

wherein R ², R⁴ and R⁵ are as below

-CH₂ CHR⁶ CO-D] wherein R⁴, R⁵ and R⁶ are as below

Y = amino acyl or a group forming a substituted amide or hydrazide

Y = a group forming an α-keto amide - COR ⁹ or -CO-D] or

and in which further:-

R² = alkyl or substituted alkyl including aryl or aryl alkyl or -CH₂R³ where R³ = fluoroalkyl

-D] is a heterocyclic ring (D = nitrogen or carbon in Group IV and N in Groups VI and X) optionally unsaturated and optionally with further hetero atoms and substituents

R⁶ = hydrogen, alkyl, hydroxyalkyl, aminoalkyl, alkylaminocarbonyl

R⁹ = -NH₂ as such or alkylated, or ammo acyl.

6. Compounds according to any claim 1 to 4 wherein subject to the provisos in regard to the nature of Y expressed in claim 1, selection for Y is from:-

Group I

-CH(CH₂CH₂CH₂CH₃)₂; -CH(CH₂CH₂CH₂CH₃) CH₂-cvclohexyl;

-CH₂CF₂CF₂ CF₃ ; -CF₂CH₂CH₂CH₃].

Group II

Y = -CH₂QR² where Q = O, S, SO, SO₂, NH and where R ² = Alkyl, branched alkyl or acyl (C₁-C₁₂); or

cycloalkyl (C₁-C₂₀); or aryl or aryl alkyl; or -CH₂-R³ where R³ = perfluoroalkyl or partially fluorinated alkyl, branched or not (C₁-C₁₂).

Group III

R⁴, R⁵ the same or different = alkyl, branched alkyl, cycloalkyl, acyl, alkylsulphonyl, carboxyalkyl (the carboxyl group may be further derivatized to form an ester or amide with an amino-acid or dipeptide), carbamoyl, sulphamoyl, N-dialkylamino-, arylalkyl, haloalkyl including fluoroalkyl, cyanoalkyl, alkoxyalkyl, hydroxyalkyl, mercaptoalkyl, aminoalkyl and derivatives thereof e.g. esters, amides and thioesters; or one of R⁴ or R⁵ = hydrogen

Group IV

Y = -CH₂ - D] where D = nitrogen or carbon and -D ] is a saturated or unsaturated heterocyclic ring or a bicyclic ring system, each is 5 - 8 membered, where there may be other hetero- atoms (N, S, O) and carbons or nitrogens may optionally be substituted by alkyl, branched alkyl, cycloalkyl, carboxyalkyl, carboxy (attached to carbon), amino, alkoxy, alkoxymethyl or (carbon) as carbonyl or other groups beneficial for interaction with the enzyme.

Grouo V

Y = -CH₂CH(R⁶)CONR⁴R⁵

R⁴, R⁵ as defined in Group III.

Group VI

Y = -CH₂CH(R⁶)COD]

R⁶ as defined in Group V and - D]

as defined in Group IV (but with D = N) Group VII

Y = an amino-acid residue or any amide (secondary or tertiary) or ester of that residue, L or D configuration. Preferred residues are of lipophilic amino-acids e.g. norleucine, cyclohexylalanine, homocyclohexylalanine,cyclohexylglycine, ^tert:butylglycine.

Group Vlll

R⁷ = H (when however B is not phenylalanine unless R⁸ is carboxylalkyl or derivatized carboxylalkyl); or alkyl, branched alkyl (C₁ - C₁₂) , cycloalkyl (C₁,-C₂₀) carboxyalkyl or bis (carboxyl)alkyl, which may b derivatized at the carboxyl group to form an amide e.g. with an amino-acid (preferred is arginine) or substituted amine; N'-dialkylamino; N'-alkylamino-;

R⁸ = R⁷ the same or different but excluding H.

Group IX

Y = -CO-R⁹ but only if B is a bulky non-aromati lipophilic amino acid or its N^α alkyl (C₁ - C₄) derivative (e.g. cyclohexylalanine but excluding Ala, Leu, lie, Val, Nva, Met, Nle, Phe, Tyr, Trp, Nal(l) an their N-methyl derivatives) where R⁹ = NH₂,

N'-alkylamino (where the alkyl groups include branche and/or cycloalkyl); an amino-acid residue. Group X

Y = -CO-D]

-D] as defined in Group IV (but D = N)

Group XI

Y = -CO-NR⁴R⁵

R⁴,R⁵ as defined in Group III, but not H.

7. Any one of the compounds specifically listed in Tables 1 to 9 herein.

8. A method of treatment (including prophylactic treatment) of an inflammatory or other condition as set out in the indications (1) to (6) herein, particularly an allergic inflammatory condition, wherein an effective amount of a peptide or peptide-analogue kininogenase inhibitor is administered topically or systemically to a patient suffering from or at risk of the condition, the peptide or peptide analogue used being optimally of hexapeptide or smaller size.

9. A method of treatment of the allergic inflammatory phase of asthma, wherein an effective amount of a kininogenase inhibitor e.g. a mast cell tryptase inhibitor is administered topically or systemically to a patient suffering from or at risk of the condition.

10. A method of preparation of a medicament for the topical or systemic treatment (including prophylactic treatment) of conditions as in claim 8 particularly for allergic inflammatory conditions and especially for asthma as in claim 9, wherein a kininogenase inhibitor is associated in effective amounts with a pharmaceutically acceptable diluent or carrier to constitute said medicament.

11. A method of treatment or of preparation of a medicament as above wherein the inhibitor is a compound as claimed in any of claims 1 to 7.