Peptide compounds analogues of the glucagon-like peptide-1 (7-37)

The present invention relates to new peptide compounds that are analogues of Glucagon-Like Peptide-1 (7-37).

The Glucagon-Like Peptides-1 (7-37) and (7-36) NH 2 ( t GLP-1) are peptides of intestinal origin that are heavily involved in the control of glucidic homeostasis. These peptides are the principal mediators of the “entero-insular axis” and act by bindings to specific receptors.

t GLP-1 is predominantly active in the pancreas where it exerts a powerful stimulating effect on the secretion of insulin by β cells in a glucose-dependent manner (S. Mojsov et al., J. Clin. Invest., 1987, 79, 619; and J. J. Hoist, F.E.B.S. Letters, 1987, 211, 169). That stimulation is accompanied by stimulation of the release of somatostatin and inhibition of the release of glucagon.

In parallel with the above-mentioned effects on the pancreas, t GLP-1 retards gastric emptying, reduces acid secretions and stimulates the peripheral utilisation of glucose in the muscles, liver and adipocytes. (M. L. Villanueva et al., Diabetologia, 1994, 37, 1163; D. J. Drucker, Diabetes, 1998, 47, 159).

Recent studies have also demonstrated that t GLP-1 could have an effect on eating behaviour by inhibiting food and drink intake as a result of action on the satiety centres (M. D. Turton et al., Nature. 1996, 379, 69).

t GLP-1 thus has many potential therapeutic applications, especially in the treatment of non-insulin-dependent type II diabetes, obesity, and type I diabetes. Like many hormonal peptides, however, it has a rather short plasma half-life—less than 2 minutes (T. J. Kieffer et al., Endocrinology, 1995, 136, 3585)—which limits its use.

The use of the natural peptide GLP 1 (7-37) for its insulinotropic properties has been described extensively, whether as the natural peptide GLP 1 (7-37) or GLP 1 (7-36) NH 2 on its own, in the form of salts, esters or amides (U.S. Pat. No. 5,616,492, WO 8706941, WO 9011 296), associated with phospholipids (WO 9318785) or associated with other hypoglycaeinic substances (WO 9318786). Analogues modified at some positions of the natural sequence have also been studied (EP 733 644, EP 708 179, EP 658 568, WO 91 11457) with the aim of devising compounds as potent as GLP 1 (7-37) that are better absorbed.

The compounds of the present invention have a novel structure derived from that of t GLP-1 by modifications to several residues and/or by suppression of arginine at position 36. In addition to the fact that they are new, these compounds have valuable pharmacological properties as a result of their agonist character in relation to t GLP-1 receptors. The modifications have the additional advantage of substantially increasing the metabolic stability of the compounds of the invention, thus giving them a duration of action superior to that of the natural peptide. Those properties make the compounds especially valuable in the treatment of pathologies in which t GLP-1 is involved, especially in the treatment of non-insulin-dependent type II diabetes, obesity, and type I diabetes.

The present invention relates to peptide compounds of the general formula (I):

Z 1 -X 1 -X 2 -X 3 -Gly-Thr-Phe-Thr-Ser-X 4 -X 5 -Ser-X 6 -X 7 -X 8 -Glu-Gly-Gln-Ala-X 9 -Lys-X 10 -X 11 -X 12 -Ala-X 13 -X 14 -Val-Lys-Gly-X 15 -Gly-Z 2 SEQ ID NO: 1  (I)

wherein:

Z 1 , substituent of the terminal amino group of the peptide of formula (I), represents a hydrogen atom, an alkyl group, a linear or branched (C 1 -C 6 )-acyl group, or an optionally substituted arylcarbonyl, optionally substituted heteroarylcarbonyl, optionally substituted arylalkylcarbonyl, optionally substituted heteroarylalkylcarbonyl, optionally substituted aryloxycarbonyl, optionally substituted arylalkoxycarbonyl or optionally substituted alkoxycarbonyl group,

Z 2 , substituent of the terminal carbonyl group of the peptide of formula (I), represents a hydroxy group, a linear or branched (C 1 -C 6 )-alkoxy group, or an amino group optionally substituted by one or two identical or different groups selected from linear or branched (C 1 -C 6 )-alkyl, optionally substituted aryl, optionally substituted heteroaryl, optionally substituted arylcarbonyl, optionally substituted heteroarylcarbonyl, optionally substituted arylalkylcarbonyl and optionally substituted heteroarylalkylcarbonyl, or by two groups that together with the nitrogen atom form a saturated ring having from 5 to 7 ring members),

X 1 to X 14 each represents, independently of the others:

a natural or non-natural amino acid residue, having the D or L configuration, of the formula:

wherein:

R 1 represents a hydrogen atom and R 2 represents a hydrogen atom or an alkyl, aminoalkyl (optionally substituted on the nitrogen atom by one or two alkyl, phenyl, benzyl, cycloalkyl, optionally substituted aryloxycarbonyl, optionally substituted arylalkoxycarbonyl and/or optionally substituted alkoxycarbonyl groups), thioalkyl (optionally substituted on the sulphur atom by an alkyl, phenyl, benzyl or cycloalknyl group), hydroxyalkyl (optionally substituted on the oxygen atom by an alkyl, phenyl, benzyl or cycloalkyl group), carboxyalkyl, carbamoylalkyl, guanidinoalkyl, cycloalkyl, cycloalkylalkyl, optionally substituted fused cycloalkyl, optionally substituted aryl, optionally substituted arylalkyl, optionally substituted heteroaryl or optionally substituted heteroarylalkyl group, or an imidazolyl or imidazolylalkyl group,

or R 1 and R 2 together with the carbon atom carrying them, form a cycloalkyl or fused cycloalkyl group,

or a natural or non-natural cyclic amino acid residue, having the D or L configuration, of the formula:

wherein A, together with the nitrogen and carbon atoms to which it is attached, forms a mono- or bi-cyclic group having from 5 to 11 ring members which is saturated, partially unsaturated or unsaturated, and is optionally substituted,

or a 3-amino-3-(2-furyl)propanoic acid residue, and

X 15 represents a bond or an arginine residue (Arg),

and addition salts thereof with a pharmaceutically acceptable acid or base.

with the proviso that:

X 15 represents a bond:

when X 1 is a residue having the L or D configuration selected from tyrosine (Tyr), arginine (Arg), phenylalanine (Phe), ornithine (Orn), methionine (Met), proline (Pro), leucine (Leu), valine (Val), isoleucine (Ile), alanine (Ala), aspartic acid (Asp), glutamic acid (Glu), asparagine (Asn), glutamine (Gln) and histidine (His),

and/or

when X 2 represents a residue having the L or D configuration selected from serine (Ser), glycine (Gly), cysteine (Cys), sarcosine (Sar), alanine (Ala), proline (Pro), valine (Val), leucine (Leu), isoleucine (Ile) and threonine (Thr),

and/or

when X 3 represents an amino acid residue having the L or D configuration selected from glutamine (Gln), aspartic acid (Asp), threonine (Thr), asparagine (Asn) and glutamic acid (Glu),

and/or

when X 5 represents a tyrosine residue (Tyr),

and/or

when X 6 represents a lysine residue (Lys),

and/or

when X 10 represents an amino acid residue selected from glutamine (Gln), alanine (Ala), threonine (Thr), serine (Ser) and glycine (Gly),

and/or

when X 13 represents an amino acid residue selected from phenylalanine (Phe), valine (Val), leucine (Leu), isoleucine (Ile), alanine (Ala) and tyrosine (Tyr),

it being understood that:

the residues X 1 to X 15 may not be so selected that the peptide obtained is identical to the natural peptide,

the term “alkyl” denotes a linear or branched chain having from 1 to 6 carbon atoms,

the term “cycloalkyl” denotes a saturated cyclic hydrocarbon group having from 3 to 8 ring members,

the expression “fused cycloalkyl” denotes a bicyclic group having from 8 to 11 ring members composed of a saturated carbon-containing rings fused with a saturated or unsaturated ring optionally comprising one or two hetero atoms selected from nitrogen, oxygen and sulphur, for example an indan, tetrahydronaphthalene or tetrahydroquinoline group,

the term “aryl” denotes a phenyl, naphthyl or biphenyl group,

the term “heteroaryl” denotes a mono- or bi-cyclic group having from 5 to 11 ring members and containing from 1 to 4 hetero atoms selected from nitrogen, oxygen and sulphur, for example a furyl, pyridyl, thienyl or indolyl group,

the term “arylcarbonyl” denotes an R a —CO— group, the term “arylalkylcarbonyl” denotes and R a —R b —CO— group, the term “heteroarylcarbonyl” denotes an R c —CO— group and the term “heteroarylalkylcarbonyl” denotes an R c —R b —CO— group, the term “aryloxycarbonyl” denotes an R a —O—CO— group, the term “arylalkoxycarbonyl” denotes an R a —R b —O—CO— group and the term “alkoxycarbonyl” denotes an R b —O—CO— group, in which groups R a represents an aryl group as defined hereinabove, R b represents an alkyl group as defined hereinabove and R c represents a heteroaryl group as defined hereinabove,

the term “substituted” applied to the terms defined above denotes that the groups in question are substituted by one or more halogen atoms or linear or branched (C 1 -C 6 )-alkyl, hydroxy, linear or branched (C 1 -C 6 )-alkoxy, amino, cyano, nitro or linear or branched (C 1 -C 6 )-perhaloalkyl groups,

each peptide bond —CO—NH— may optionally be replaced by a pseudopeptide bond selected from —CH 2 —NH—, —NH—CO—, —CO—N(CH 3 )—, —CH 2 —CH 2 —, —CH 2 —CO—, —CH 2 —S—, —CH 2 —SO—, —CH 2 —SO 2 —, —CH═CH— and —CO—CH 2 —NH—.

Among the pharmaceutically acceptable acids there may be mentioned hydrochloric, hydrobromic, sulphuric, phosphonic, acetic, trifluoroacetic, lactic, pyruvic, malonic, succinic, glutaric, fumaric, tartaric, maleic, citric, ascorbic, methanesulphonic, camphoric acid etc.

Among the pharmaceutically acceptable bases there may be mentioned sodium hydroxide, potassium hydroxide, triethylamine, tert-butylamine etc. The present invention relates especially to peptide compounds of formula (I) wherein the residues X 1 to X 14 are selected as a function of the nature of their side chain, which may be of aromatic character or of aliphatic character, may be capable of establishin interactions of the hydrogen bonding type or capable of establishing ionic interactions, or may be of cyclic nature.

The natural or non-natural amino acid residues having the D or L configuration that have a side chain of aromatic character are represented by the following formula:

wherein:

R 1a represents a hydrogen atom and R 2a represents a cycloalkyl group fused with an unsaturated ring as defined hereinabove, and optionally substituted, or an optionally substituted aryl, optionally substituted arylalkyl, optionally substituted heteroaryl or optionally substituted heteroarylalkyl group, or an imidazolyl or imidazolylalkyl group, among which residues having a side chain of aromatic character there may be mentioned more specifically the phenylalanine (Phe), histidine (His), tyrosine (Tyr), tryptophan (Trp), homophenylalanine (Hof), halophenylalanine (for example 4-chlorophenylalanine (4-Cl-Phe)), dihalophenylalanine (for example 3,4-dichlorophenylalanine (3,4-di-Cl-Phe)), alkylphenylalanine (for example 4-methylphenylalanine (4-Me-Phe)), nitrophenylalanine (for example 4-nitrophenylalanine (4-NO 2 -Phe)), 3-pyridylalanine (3-Pya), 2-thienylalanine (Tha), 2-furylalanine (Fua), 1-naphthylalanine (1-Nal), 2-naphthylalanine (2-Nal), phenylglycine (Phg) and 3-nitrotyrosine (3-NO 2 -Tyr) residues,

The natural or non-natural amino acid residues having the D or L configuration that have a side chain of aliphatic character are represented by the following formula:

wherein:

R 1b represents a hydrogen atom and R 2b represents a hydrogen atom or an alkyl or cycloalkyl group,

among which residues there may be mentioned more specifically the glycine (Gly), alanine (Ala), valine (Val), leucine (Leu), isoleucine (Ile), 2-aminobutyric acid (Abu), 2-aminoisobutyric acid (Aib), β-cyclohexylalanine (Cha), homoleucine (Hol), norleucine (Nle), norvaline (Nva) and tert-leucine (Tle) residues,

The natural or non-natural amino acid residues having the D or L configuration that have a side chain capable of establishing interactions of the hydrogen bonding type are represented by the formula:

wherein:

R 1c represents a hydrogen atom and R 2c represents an aminoalkyl (optionally substituted on the nitrogen atom by an alkyl, phenyl, benzyl or cycloalkyl group), thioalkyl (optionally substituted on the sulphur atom by an alkyl, phenyl, benzyl or cycloalkyl group), hydroxyalkyl (optionally substituted on the oxygen atom by an alkyl, phenyl, benzyl or cycloalkyl group), carboxyalkyl, carbamoylalkyl or guanidinoalkyl group,

among which residues there may be mentioned more specifically the methionine (Met), aspartic acid (Asp), glutamic acid (Glu), lysine (Lys), arginine (Arg), serine (Ser), threonine (Thr), cysteine (Cys), tyrosine (Tyr), asparagine (Asn), glutamine (Gln), tryptophan (Trp), diaminobutyric acid (Dab), diaminopropionic acid (Dapa), ornithine (Orn) and benzylcysteine (Bcy) residues,

The natural or non-natural amino acid residues having the D or L configuration that have a side chain capable of establishing interactions of the ionic type are represented by the formula:

wherein:

R 1d represents a hydrogen atom and R 2d represents an aminoalkyl, thioalkyl, hydroxyalkyl, carboxyalkyl, guanidinoalkyl, imidazolyl or imidazolylalkyl group,

among which residues there may be mentioned more specifically the aspartic acid (Asp), glutamic acid (Glu), lysine (Lys), arginine (Arg), histidine (His), serine (Ser), threonine (Thr), cysteine (Cys), tyrosine (Tyr), diaminoacetic acid (NH-Gly), diaminobutyric acid (Dab), diaminopropionic acid (Dapa), ornithine (Orn) and methionine (Met) residues,

The non-natural amino acid residues having the D or L configuration that have a side chain of cyclic nature are represented by the following formula:

wherein:

R 1c and R 2c together form a cycloalkyl or a fused cycloalkyl group,

among which residues there may be mentioned more specifically the 1-amino-1-cyclohexanecarboxylic acid (Acy), 2-aminoindan-2-carboxylic acid (Aic) and 2-aminotetraline-2-carboxylic acid (Atc) residues,

X 1 preferably represents a natural or non-natural amino acid residue having the D or L configuration that has a side chain of aromatic character, represented by the formula (a),

X 2 preferably represents a natural or non-natural amino acid residue having the D or L configuration that has a side chain of aliphatic character, represented by the formula (b),

X 3 preferably represents a natural or non-natural amino acid residue having the D or L configuration that has a side chain capable of establishing ionic interactions, represented by the formula (d),

X 4 preferably represents a natural or non-natural amino acid residue having the D or L configuration that has a side chain capable of establishing ionic interactions, represented by the formula (d),

or a natural or non-natural amino acid residue having the D or L configuration that has a side chain of aliphatic character, represented by the formula (b),

X 5 preferably represents a natural or non-natural amino acid residue having the D or L configuration that has a side chain of aliphatic character, represented by the formula (b),

X 6 preferably represents a natural or non-natural amino acid residue having the D or L configuration that has a side chain capable of establishing ionic interactions, represented by the formula (d),

X 7 preferably represents a natural or non-natural amino acid residue having the D or L configuration that has a side chain capable of establishing ionic interactions, represented by the formula (d),

or a natural or non-natural amino acid residue having the D or L configuration that has a side chain of aliphatic character, represented by the formula (b),

X 8 preferably represents a natural or non-natural amino acid residue having the D or L configuration that has a side chain of aliphatic character, represented by the formula (b),

X 9 preferably represents a natural or non-natural amino acid residue having the D or L configuration that has a side chain of aliphatic character, represented by the formula (b),

X 10 preferably represents a natural or non-natural amino acid residue having the D or L configuration that has a side chain capable of establishing ionic interactions, represented by the formula (d),

or a natural or non-natural amino acid residue having the D or L configuration that has a side chain of aliphatic character, represented by the formula (b),

X 11 preferably represents a natural or non-natural amino acid residue having the D or L configuration that has a side chain of aromatic character, represented by the formula (a),

X 12 preferably represents a natural or non-natural amino acid residue having the D or L configuration that has a side chain capable of establishing ionic interactions, represented by the formula (d),

or a natural or non-natural amino acid residue having the D or L configuration that has a side chain of aliphatic character, represented by the formula (b),

X 13 preferably represents a natural or non-natural amino acid residue having the D or L configuration that has a side chain of aromatic character, represented by the formula (a),

X 14 preferably represents a natural or non-natural amino acid residue having the D or L configuration that has a side chain of aliphatic character, represented by the formula (b),

X 15 preferably represents a bond.

Preferably, in compounds of formula (I) Z 1 represents a hydrogen atom.

In compounds of formula (I), Z 2 preferably represents a group selected from hydroxy, linear or branched (C 1 -C 6 )-alkoxy, and amino. More specifically, Z 2 represents an amino group.

An advantageous aspect of the invention concerns compounds of formula (I) wherein:

Z 1 represents a hydrogen atom,

Z 2 represents a group selected from hydroxy, linear or branched (C 1 -C 6 )-alkoxy, and amino,

X 1 and X 11 represent a natural or non-natural amino acid residue having the D or L configuration and are independently selected from the amino acid residues having a side chain of aromatic character represented by the following formula:

wherein:

R 1a represents a hydrogen atom and R 2a represents a cycloalkyl group fused with an unsaturated ring as defined hereinabove, and optionally substituted, or an optionally substituted aryl, optionally substituted arylalkyl, optionally substituted heteroaryl or optionally substituted heteroarylalkyl group, or an imidazolyl or imidazolylalkyl group,

among which residues having a side chain of aromatic character there may be mentioned more specifically the phenylalanine (Phe), histidine (His), tyrosine (Tyr), tryptophan (Trp), homophenylalanine (Hof), halophenylalanine (for example 4-chlorophenylalanine (4-Cl-Phe)), dihalophenylalanine (for example 3,4-dichlorophenylalanine (3,4-di-Cl-Phe)), alkylphenylalanine (for example 4-methylphenylalanine (4-Me-Phe)), nitrophenylalanine (for example 4-nitrophenylalanine (4-NO 2 -Phe)), 3-pyridylalanine (3-Pya), 2-thienylalanine (Tha), 2-furylalanine (Fua), 1-naphthylalanine (1-Nal), 2-naphthylalanine (2-Nal), phenylglycine (Phg) and 3-nitrotyrosine (3-NO 2 -Tyr) residues,

X 2 and X 9 represent a natural or non-natural amino acid residue having the D or L configuration and are independently selected from the amino acid residues having a side chain of aliphatic character represented by the following formula:

wherein:

R 1b represents a hydrogen atom and R 2b represents a hydrogen atom or an alkyl or cycloalkyl group,

among which residues there may be mentioned more specifically the glycine (Gly), alanine (Ala), valine (Val), leucine (Leu), isoleucine (Ile), 2-aminobutyric acid (Abu), 2-aminoisobutyric acid (Aib), β-cyclohexylalanine (Cha), homoleucine (Hol), norleucine (Nle), norvaline (Nva) and tert-leucine (Tle) residues,

X 5 and X 6 represent a natural or non-natural amino acid residue having the D or L configuration and are independently selected from the amino acid residues that have a side chain capable of establishing ionic interactions represented by the following formula:

wherein:

R 1d represents a hydrogen atom and R 2d represents an aminoalkyl, thioalkyl, hydroxyalkyl, carboxyalkyl, guanidinoalkyl, imidazolyl or imidazolylalkyl group,

among which residues there may be mentioned more specifically the aspartic acid (Asp), glutamic acid (Glu), lysine (Lys), arginine (Arg), histidine (His), serine (Ser), threonine (Thr), cysteine (Cys), tyrosine (Tyr), diaminoacetic acid (NH-Gly), diaminobutyric acid (Dab), diaminopropionic acid (Dapa), ornithine (Orn) and methionine (Met) residues,

X 4 , X 7 , X 10 and X 12 represent a natural or non-natural amino acid residue having the D or L configuration and are independently selected from the amino acid residues that have a side chain capable of establishing ionic interactions represented by the following formula:

wherein:

R 1d represents a hydrogen atom and R 2d represents an aminoalkyl, thioalkyl, hydroxyalkyl, carboxyalkyl, guanidinoalkyl, imidazolyl or imidazolylalkyl group,

among which residues there may be mentioned more specifically the aspartic acid (Asp), glutamic acid (Glu), lysine (Lys), arginine (Arg), histidine (His), serine (Ser), threonine (Thr), cysteine (Cys), tyrosine (Tyr), diaminoacetic acid (NH-Gly), diaminobutyric acid (Dab), diaminopropionic acid (Dapa), ornithine (Orn) and methionine (Met) residues,

or are independently selected from the natural or non-natural amino acid residues having a side chain of aliphatic character represented by the following formula:

wherein:

R 1b represents a hydrogen atom and R 2b represents a hydrogen atom or an alkyl or cycloalkyl group,

among which residues there may be mentioned more specifically the glycine (Gly), alanine (Ala), valine (Val), leucine (Leu), isoleucine (Ile), 2-aminobutyric acid (Abu), 2-aminoisobutyric acid (Aib), β-cyclohexylalanine (Cha), homoleucine (Hol), norleucine (Nle), norvaline (Nva) and tert-leucine (Tle) residues,

X 5 represents a valine residue (Val),

X 8 and X 14 independently represent a leucine residue (Leu) having the D or L configuration,

X 13 represents a tryptophan residue (Trp), and

X 15 represents a bond or an arginine residue (Arg),

and addition salts thereof with a pharmaceutically acceptable acid or base.

Another advantageous aspect of the invention concerns the compounds of formula (I) wherein:

Z 1 represents a hydrogen atom.

Z 2 represents a group selected from hydroxy, linear or branched (C 1 -C 6 )-alkoxy, and amino,

X 1 and X 11 represent a natural or non-natural amino acid residue having the D or L configuration and are independently selected from the amino acid residues having a side chain of aromatic character represented by the following formula:

wherein:

R 1a represents a hydrogen atom and R 2a represents a cycloalkyl group fused with an unsaturated ring as defined hereinabove, and optionally substituted, or an optionally substituted aryl, optionally substituted arylalkyl, optionally substituted heteroaryl or optionally substituted heteroarylalkyl group, or an imidazolyl or imidazolylalkyl group,

among, which residues having a side chain of aromatic character there may be mentioned more specifically the phenylalanine (Phe), histidine (His), tyrosine (Tyr), trptophan (Trp), homophenylalanine (Hof), halophenylalanine (for example 4-chlorophenylalanine (4-Cl-Phe)), dihalophenylalanine (for example 3,4-dichlorophenylalanine (4-di-Cl-Phe)), alkylphenylalanine (for example 4-methylphenylalanine (4-Me-Phe)), nitrophenylalanine (for example 4-nitrophenylalanine (4-NO-Phe)), 3-pyridylalanine (3-Pya), 2-thienylalanine (Tha), 2-furylalanine (Fua), 1-naphthylalanine (1-Nal), 2-naphthylalanine (2-Nal), phenylglycine (Phg) and 3-nitrotyrosine (3-NO 2 -Tyr) residues,

X 2 and X 9 represent a natural or non-natural amino acid residue having the D or L configuration and are independently selected from the amino acid residues having a side chain of aliphatic character represented by the following formula:

wherein:

R 1b represents a hydrogen atom and R 2b represents a hydrogen atom or an alkyl or cycloalkyl group,

among which residues there may be mentioned more specifically the glycine (Gly), alanine (Ala), valine (Val), leucine (Leu), isoleucine (Ile), 2-aminobutyric acid (Abu), 2-aminoisobutyric acid (Aib), β-cyclohexylalanine (Cha), homoleucine (Hol), norleucine (Nle), norvaline (Nva) and tert-leucine (Tle) residues,

X 3 and X 6 represent a natural or non-natural amino acid residue having the D or L configuration and are independently selected from the amino acid residues that have a side chain capable of establishing ionic interactions represented by the following formula:

wherein:

R 1d represents a hydrogen atom and R 2d represents an aminoalkyl, thioalkyl, hydroxyalkyl, carboxyalkyl, guanidinoalkyl, imidazolyl or imidazolylalkyl group,

among which residues there may be mentioned more specifically the aspartic acid (Asp), glutamic acid (Glu), lysine (Lys), arginine (Arg), histidine (His), serine (Ser), threonine (Thr), cysteine (Cys), tyrosine (Tyr), diaminoacetic acid (NH-Gly), diaminobutyric acid (Dab), diaminopropionic acid (Dapa), ornithine (Orn) and methionine (Met) residues,

X 4 , X 7 and X 10 represent a natural or non-natural amino acid residue having the D or L configuration and are independently selected from the amino acid residues that have a side chain capable of establishing ionic interactions represented by the following formula:

wherein:

R 1d represents a hydrogen atom and R 2d represents an aminoalkyl, thioalkyl, hydroxyalkyl, carboxyalkyl, guanidinoalkyl, imidazolyl or imidazolylalkyl group,

among which residues there may be mentioned more specifically the aspartic acid (Asp), glutamic acid (Glu), lysine (Lys), arginine (Arg), histidine (His), serine (Ser), threonine (Thr), cysteine (Cys), tyrosine (Tyr), diaminoacetic acid (NH-Gly), diaminobutyric acid (Dab), diaminopropionic acid (Dapa), ornithine (Orn) and methionine (Met) residues,

X 5 represents a valine residue (Val),

X 8 and X 14 independently represent a leucine residue (Leu) having the D or L configuration,

X 12 represents a natural or non-natural amino acid residue having the D or L configuration, and is selected from the amino acid residues having a side chain of aliphatic character represented by the following formula:

wherein:

R 1b represents a hydrogen atom and R 2b represents a hydrogen atom or an alkyl or cycloalkyl group,

among which residues there may be mentioned more specifically the glycine (Gly), alanine (Ala), valine (Val), leucine (Leu), isoleucine (Ile), 2-aminobutyric acid (Abu), 2-aminoisobutyric acid (Aib), β-cyclohexylalanine (Cha), homoleucine (Hol), norleucine (Nle), norvaline (Nva) and tert-leucine (Tle) residues,

X 13 represents a tryptophan residue (Trp),

X 15 represents a bond or an arginine residue (Arg),

and addition salts thereof with a pharmaceutically acceptable acid or base.

Another advantageous aspect of the invention concerns the compounds of formula (I) wherein:

Z 1 represents a hydrogen atom,

Z 2 represents a group selected from hydroxy, linear or branched (C 1 -C 6 )-alkoxy, and amino,

X 1 and X 11 represent a natural or non-natural amino acid residue having the D or L configuration and are independently selected from the amino acid residues having a side chain of aromatic character represented by the following formula:

wherein:

R 1a represents a hydrogen atom and R 2 represents a cycloalkyl group fused with an unsaturated ring as defined hereinabove, and optionally substituted, or an optionally substituted aryl, optionally substituted arylalkyl, optionally substituted heteroaryl or optionally substituted heteroarylalkyl group, or an imidazolyl or imidazolylalkyl group,

among which residues having a side chain of aromatic character there may be mentioned more specifically the phenylalanine (Phe), histidine (His), tyrosine (Tyr), tryptophan (Trp), homophenylalanine (Hof), halophenylalanine (for example 4-chlorophenylalanine (4-Cl-Phe)), dihalophenylalanine (for example 3,4-dichlorophenylalanine (3,4-di-Cl-Phe)), alkylphenylalanine (for example 4-methylphenylalanine (4-Me-Phe)), nitrophenylalanine (for example 4-nitrophenylalanine (4-NO 2 -Phe)), 3-pyridylalanine (3-Pya), 2-thienylalanine (Tha), 2-furylalanine (Fua), 1-naphthylalanine (1-Nal), 2-naphthylalanine (2-Nal), phenylglycine (Phg) and 3-nitrotyrosine (3-NO 2 -Tyr) residues,

X 2 and X 9 independently represent an alanine residue (Ala) having the D or L configuration,

X 3 and X 6 represent a natural or non-natural amino acid residue having the D or L configuration and are independently selected from the amino acid residues that have a side chain capable of establishing ionic interactions represented by the following formula:

wherein:

R 1d represents a hydrogen atom and R 2d represents an aminoalkyl, thioalkyl, hydroxyalkyl, carboxyalkyl, guanidinoalkyl, imidazolyl or imidazolylalkyl group,

among which residues there may be mentioned more specifically the aspartic acid (Asp), glutamic acid (Glu), lysine (Lys), arginine (Arg), histidine (His), serine (Ser), threonine (Thr), cysteine (Cys), tyrosine (Tyr), diaminoacetic acid (NH-Gly), diaminobutyric acid (Dab), diaminopropionic acid (Dapa), ornithine (Orn) and methionine (Met) residues,

X 4 represents an aspartic acid residue (Asp),

X 5 represents a valine residue (Val),

X 7 represents a tyrosine residue (Tyr),

X 8 and X 14 independently represent a leucine residue (Leu) having the D or L, configuration,

X 10 represents a glutamine residue (Glu),

X 12 represents an isoleucine residue (Ile),

X 13 represents a tryptophan residue (Trp),

X 15 represents a bond or an arginine residue (Arg),

and addition salts thereof with a pharmaceutically acceptable acid or base.

The present invention relates more especially to the peptide compounds of formula (II):

Z 1 -X 1 -X 2 -X 3 -Gly-Thr-Phe-Thr-Ser-Asp-Val-Ser-Ser-Tyr-Leu-Glu-Gly-Gln-Ala-Ala-Lys-Glu-Phe-Ile-Ala-Trp-Leu-Val-Lys-Gly-X 15 -Gly-Z 2 SEQ ID NO: 2  (II)

wherein:

Z 1 represents a hydrogen atom,

Z 2 represents a group selected from hydroxy, linear or branched (C 1 -C 6 )-alkoxy, and amino,

X 1 represents a natural or non-natural amino acid residue having the D or L configuration that has a side chain of aromatic character and is represented by the following formula:

wherein:

R 1a represents a hydrogen atom and R 2a represents a cycloalkyl group fused with an unsaturated ring as defined hereinabove, and optionally substituted, or an optionally substituted aryl, optionally substituted arylalkyl, optionally substituted heteroaryl or optionally substituted heteroarylalkyl group, or an imidazolyl or imidazolylalkyl group,

among which residues having a side chain of aromatic character there may be mentioned more specifically the phenylalanine (Phe), histidine (His), tyrosine (Tyr), tryptophan (Trp), homophenylalanine (Hof), halophenylalanine (for example 4-chlorophenylalanine (4-Cl-Phe)), dihalophenylalanine (for example 3,4-dichlorophenylalanine (3,4-di-Cl-Phe)), alkylphenylalanine (for example 4-methylphenylalanine (4-Me-Phe)), nitrophenylalanine (for example 4-nitrophenylalanine (4-NO 2 -Phe)), 3-pyridylalanine (3-Pya), 2-thienylalanine (Tha), 2-furylalanine (Fua), 1-naphthylalanine (1-Nal), 2-naphthylalanine (2-Nal), phenylglycine (Phg) and 3-nitrotyrosine (3-NO 2 -Tyr) residues,

X 2 represents a natural or non-natural amino acid residue having the D or L configuration that has a side chain of aliphatic character and is represented by the following formula:

wherein:

R 1b represents a hydrogen atom and R 2b represents a hydrogen atom or an alkyl or cycloalkyl group,

among which residues there may be mentioned more specifically the glycine (Gly), alanine (Ala), valine (Val), leucine (Leu), isoleucine (Ile), 2-aminobutyric acid (Abu), 2-aminoisobutyric acid (Aib), β-cyclohexylalanine (Cha), homoleucine (Hol), norleucine (Nle), norvaline (Nva) and tert-leucine (Tle) residues,

X 3 represents a natural or non-natural amino acid residue having the D or L configuration that has a side chain capable of establishing ionic interactions and is represented by the following formula:

wherein:

R 1d represents a hydrogen atom and R 2d represents an aminoalkyl, thioalkyl, hydroxyalkyl, carboxyalkyl, guanidinoalkyl, imidazolyl or imidazolylalkyl group,

among which residues there may be mentioned more specifically the aspartic acid (Asp), glutamic acid (Glu), lysine (Lys), arginine (Arg), histidine (His), serine (Ser), threonine (Thr), cysteine (Cys), tyrosine (Tyr), diaminoacetic acid (NH-Gly), diaminobutyric acid (Dab), diaminopropionic acid (Dapa), ornithine (Orn) and methionine (Met) residues,

X 15 represents a bond or an arginine residue, it being understood that the restrictions relating to the compounds defined in formula (I) apply to the compounds of formula (II).

More specifically, in the compounds of formula (II) X 15 represents a bond.

Amongst the compounds of formula (II), the compounds wherein X 2 represents an alanine residue (Ala) having the D or L configuration and X 15 represents a bond are preferred.

Amongst the preferred compounds of the invention there may be mentioned more especially the following peptides:

His-Ala-Glu-Gly-Thr-Phe-Thr-Ser-Asp-Val-Ser-Ser-Tyr-(D)-Leu-Glu-Gly-Gln-Ala-Ala-Lys-Glu-Phe-Ile-Ala-Trp-Leu-Val-Lys-Gly-Arg-Gly-NH 2 SEQ ID NO: 3

Trp-Ala-Glu-Gly-Thr-Phe-Thr-Ser-Asp-Val-Ser-Ser-Tyr-Leu-Glu-Gly-Gln-Ala-Ala-Lys-Glu-Phe-Ile-Ala-Trp-(D)-Leu-Val-Lys-Gly-Arg-Gly-NH 2 SEQ ID NO: 4

Trp-Ala-Glu-Gly-Thr-Phe-Thr-Ser-Asp-Val-Ser-Ser-Tyr-Leu-Glu-Gly-Gln-Ala-Ala-Lys-Glu-Phe-Ile-Ala-Trp-Leu-Val-Lys-Gly-Arg-Gly-NH 2 SEQ ID NO: 5

His-Ala-Gln-Gly-Thr-Phe-Thr-Ser-Asp-Val-Ser-Ser-Val-Leu-Glu-Gly-Gln-Ala-Ala-Lys-Glu-Phe-Ile-Ala-Trp-Leu-Val-Lys-Gly-Arg-Gly-NH 2 SEQ ID NO: 6

His-Ala-His-Gly-Thr-Phe-Thr-Ser-Asp-Val-Ser-Ser-Val-Leu-Glu-Gly-Gln-Ala-Ala-Lys-Glu-Phe-Ile-Ala-Trp-Leu-Val-Lys-Gly-Arg-Gly-NH 2 SEQ ID NO: 7

His-Ala-(D)-Glu-Gly-Thr-Phe-Thr-Ser-Asp-Val-Ser-Ser-Tyr-Leu-Glu-Gly-Gln-Ala-Ala-Lys-Glu-Phe-Ile-Ala-Trp-Leu-Val-Lys-Gly-Gly-NH 2 SEQ ID NO: 8

His-(D)-Ala-Glu-Gly-Thr-Phe-Thr-Ser-Asp-Val-Ser-Ser-Tyr-Leu-Glu-Gly-Gln-Ala-Ala-Lys-Glu-Phe-Ile-Ala-Trp-Leu-Val-Lys-Gly-Gly-NH 2 SEQ ID NO: 9

His-Ala-Glu-Gly-Thr-Phe-Thr-Ser-Asp-Val-Ser-Ser-Tyr-Leu-Glu-Gly-Gln-Ala-Ala-Lys-Glu-Phe-Ile-Ala-Trp-Leu-Val-Lys-Gly-Gly-NH 2 SEQ ID NO: 10

His-Leu-Glu-Gly-Thr-Phe-Thr-Ser-Asp-Val-Ser-Ser-Tyr-Leu-Glu-Gly-Gln-Ala-Ala-Lys-Glu-Phe-Ile-Ala-Trp-Leu-Val-Lys-Gly-Gly-NH 2 SEQ ID NO: 11

His-Val-Glu-Gly-Thr-Phe-Thr-Ser-Asp-Val-Ser-Ser-Tyr-Leu-Glu-Gly-Gln-Ala-Ala-Lys-Glu-Phe-Ile-Ala-Trp-Leu-Val-Lys-Gly-Gly-NH 2 SEQ ID NO: 12

Afp-Ala-Glu-Gly-Thr-Phe-Thr-Ser-Asp-Val-Ser-Ser-Tyr-Leu-Glu-Gly-Gln-Ala-Ala-Lys-Glu-Phe-Ile-Ala-Trp-Leu-Val-Lys-Gly-Gly-NH 2 SEQ ID NO: 13

His-Ala-Asp-Gly-Thr-Phe-Thr-Ser-Asp-Val-Ser-Ser-Tyr-Leu-Glu-Gly-Gln-Ala-Ala-Lys-Glu-Phe-Ile-Ala-Trp-Leu-Val-Lys-Gly-Gly-NH 2 SEQ ID NO: 14

His-Ala-Ser-Gly-Thr-Phe-Thr-Ser-Asp-Val-Ser-Ser-Tyr-Leu-Glu-Gly-Gln-Ala-Ala-Lys-Glu-Phe-Ile-Ala-Trp-Leu-Val-Lys-Gly-Gly-NH 2 SEQ ID NO: 15

His-Ala-Lys-Gly-Thr-Phe-Thr-Ser-Asp-Val-Ser-Ser-Tyr-Leu-Glu-Gly-Gln-Ala-Ala-Lys-Glu-Phe-Ile-Ala-Trp-Leu-Val-Lys-Gly-Gly-NH 2 SEQ ID NO: 16

Phe-(D)-Ala-Glu-Gly-Thr-Phe-Thr-Ser-Asp-Val-Ser-Lys-Tyr-Leu-Glu-Gly-Gln-Ala-Val-Lys-Glu-Phe-Ile-Ala-Trp-Leu-Val-Lys-Gly-Gly-NH 2 SEQ ID NO: 17

Phe-(D)-Ala-Gln-Gly-Thr-Phe-Thr-Ser-Asp-Val-Ser-Ser-Val-(D)-Leu-Glu-Gly-Gln-Ala-Ala-Lys-Glu-Phe-Ile-Ala-Trp-Leu-Val-Lys-Gly-Gly-NH 2 SEQ ID NO: 18

His-Ala-Leu-Gly-Thr-Phe-Thr-Ser-Asp-Val-Ser-Ser-Tyr-Leu-Glu-Gly-Gln-Ala-Ala-Lys-Glu-Phe-Ile-Ala-Trp-Leu-Val-Lys-Gly-Gly-NH 2 SEQ ID NO: 19

His-Ala-Met-Gly-Thr-Phe-Thr-Ser-Asp-Val-Ser-Ser-Tyr-Leu-Glu-Gly-Gln-Ala-Ala-Lys-Glu-Phe-Ile-Ala-Trp-Leu-Val-Lys-Gly-Gly-NH 2 SEQ ID NO: 20

His-Ala-Glu-Gly-Thr-Phe-Thr-Ser-Asp-Val-Ser-Ser-Tyr-Leu-Glu-Gly-Gln-Ala-Ala-Lys-Glu-Trp-Ile-Ala-Trp-Leu-Val-Lys-Gly-Gly-NH 2 SEQ ID NO: 21

His-Ala-Glu-Gly-Thr-Phe-Thr-Ser-Asp-Val-Ser-Ser-Tyr-Leu-Glu-Gly-Gln-Ala-Ala-Lys-Glu-Ile-Ile-Ala-Trp-Leu-Val-Lys-Gly-Gly-NH 2 SEQ ID NO: 22

His-Ala-Glu-Gly-Thr-Phe-Thr-Ser-Asp-Val-Ser-Ser-Tyr-Leu-Glu-Gly-Gln-Ala-Ala-Lys-Glu-Val-Ile-Ala-Trp-Leu-Val-Lys-Gly-Gly-NH 2 SEQ ID NO: 23

His-Ala-Glu-Gly-Thr-Phe-Thr-Ser-Asp-Val-Ser-Ser-Tyr-Leu-Glu-Gly-Gln-Ala-Ala-Lys-Glu-His-Ile-Ala-Trp-Leu-Val-Lys-Gly-Gly-NH 2 SEQ ID NO: 24

His-Ala-Glu-Gly-Thr-Phe-Thr-Ser-Asp-Val-Ser-Ser-Tyr-Leu-Glu-Gly-Gln-Ala-Ala-Lys-Glu-Asp-Ile-Ala-Trp-Leu-Val-Lys-Gly-Gly-NH 2 SEQ ID NO: 25

His-Ala-Glu-Gly-Thr-Phe-Thr-Ser-Asp-Val-Ser-Ser-Tyr-Leu-Glu-Gly-Gln-Ala-Ala-Lys-Glu-Phe-Leu-Ala-Trp-Leu-Val-Lys-Gly-Gly-NH 2 SEQ ID NO: 26

His-Ala-Glu-Gly-Thr-Phe-Thr-Ser-Asp-Val-Ser-Ser-Tyr-Leu-Glu-Gly-Gln-Ala-Ala-Lys-Glu-Phe-Val-Ala-Trp-Leu-Val-Lys-Gly-Gly-NH 2 SEQ ID NO: 27

His-Ala-Glu-Gly-Thr-Phe-Thr-Ser-Asp-Val-Ser-Ser-Tyr-Leu-Glu-Gly-Gln-Ala-Ala-Lys-Glu-Phe-Tyr-Ala-Trp-Leu-Val-Lys-Gly-Gly-NH 2 SEQ ID NO: 28

His-Ala-Glu-Gly-Thr-Phe-Thr-Ser-Asp-Val-Ser-Ser-Tyr-Leu-Glu-Gly-Gln-Ala-Ala-Lys-Glu-Phe-Arg-Ala-Trp-Leu-Val-Lys-Gly-Gly-NH 2 SEQ ID NO: 29

His-Ala-Glu-Gly-Thr-Phe-Thr-Ser-Asp-Val-Ser-Ser-Tyr-Leu-Glu-Gly-Gln-Ala-Ala-Lys-Glu-Phe-Glu-Ala-Trp-Leu-Val-Lys-Gly-Gly-NH 2 SEQ ID NO: 30

Phe-Ala-Glu-Gly-Thr-Phe-Thr-Ser-Asp-Val-Ser-Ser-Tyr-Leu-Glu-Gly-Gln-Ala-Ala-Lys-Glu-Phe-Ile-Ala-Trp-Leu-Val-Lys-Gly-Gly-NH 2 SEQ ID NO: 31

His-Ala-Lys-Gly-Thr-Phe-Thr-Ser-Asp-Val-Ser-Ser-Tyr-Leu-Glu-Gly-Gln-Ala-Ala-Lys-Glu-Phe-Ile-Ala-Trp-Leu-Val-Lys-Gly-Arg-Gly-NH 2 SEQ ID NO: 32

His-Ala-Met-Gly-Thr-Phe-Thr-Ser-Asp-Val-Ser-Ser-Tyr-Leu-Glu-Gly-Gln-Ala-Ala-Lys-Glu-Phe-Ile-Ala-Trp-Leu-Val-Lys-Gly-Arg-Gly-NH 2 SEQ ID NO: 33

His-Ala-Leu-Gly-Thr-Phe-Thr-Ser-Asp-Val-Ser-Ser-Tyr-Leu-Glu-Gly-Gln-Ala-Ala-Lys-Glu-Phe-Ile-Ala-Trp-Leu-Val-Lys-Gly-Arg-Gly-NH 2 SEQ ID NO: 34

His-Ala-Ser-Gly-Thr-Phe-Thr-Ser-Asp-Val-Ser-Ser-Tyr-Leu-Glu-Gly-Gln-Ala-Ala-Lys-Glu-Phe-Ile-Ala-Trp-Leu-Val-Lys-Gly-Arg-Gly-NH 2 SEQ ID NO: 35

His-Ala-Glu-Gly-Thr-Phe-Thr-Ser-Asp-Val-Ser-Ser-Tyr-Leu-Glu-Gly-Gln-Ala-Ala-Lys-Glu-Phe-Ile-Ala-Trp-(D)-Leu-Val-Lys-Gly-Arg-Gly-NH 2 SEQ ID NO: 36.

The invention extends also to a process for the preparation of the compounds of formula (I) which may be obtained by various methods, such as solid phase sequential synthesis, synthesis and coupling of fragments in solution, enzymatic synthesis, or by employing molecular biology techniques.

The general methods of solid phase peptide synthesis have been described by, B. W. Erickson and R. B. Merrifield (“The Proteins”, Solid Phase Peptide Synthesis, 3 rd edition, 1976, 257).

Solid phase synthesis is carried out using an automatic device which executes in a repetitive and programmable manner the cycles of deprotection, coupling and washing necessary for the sequential introduction of amino acids into the peptide chain.

The C-terminal amino acid is fixed on a resin conventionally used for the preparation of polypeptides, preferably a polystyrene crosslinked with 0.5 to 3.0% divinylbenzene and provided with activated radicals that enable the first amino acid to be fixed covalently to the resin. Appropriate selection of the resin allows the formation after synthesis of a C-terminal carboxylic acid, amide, alcohol or ester function.

The amino acids are then introduced one by one in the order determined by the operator. Each cycle of synthesis corresponding to the introduction of an amino acid comprises N-terminal deprotection of the peptide chain, successive washings designed to remove the reagents or swell the resin, coupling with activation of the amino acid and further washings. Each of those operations is followed by filtration effected as a result of the presence of a sintered glass filter incorporated in the reactor in which the synthesis is beings carried out.

The couplings reagents used are the conventional reagents for peptide synthesis, such as dicyclohexylcarbodiimide (DCC) and hydroxybenzotriazole (HOBT) or benzotriazol-1-yl-oxytris(dimethylamino)phosphonium hexafluorophosphate (BOP), or also diphenyl-phosphorylazide (DPPA).

Activation by the formation of mixed or symmetrical anhydrides is also possible.

Each amino acid is introduced into the reactor in an approximately 6-fold excess in relation to the degree of substitution of the resin and in an approximately equivalent amount in relation to the coupling agents. The coupling reaction may be confirmed at each stage of the synthesis by the ninhydrin reaction test described by E. KAISER et al. (Anal. Biochem., 34, 595, 1970).

After assembling the peptide chain on the resin, an appropriate treatment, for example using a strong acid such as trifluoroacetic acid, or hydrofluoric acid in the presence of anisole, ethanedithiol or 2-methylindole, is used to separate the peptide from the resin and also to free the peptide of its protecting groups. The compound is then purified by conventional purification techniques, especially chromatography techniques.

The peptides of the present invention may also be obtained by coupling in solution selectively protected peptide fragments which may themselves be prepared either in the solid phase or in solution. The use of protecting groups and the exploitation of their differences in stability is analogous to solid phase methods with the exception of the attachment of the peptide chain to the resin. The C-terminal carboxy group is protected, for example, by a methyl ester or an amide function. The methods of activation during coupling are likewise analogous to those employed in solid phase synthesis.

The peptides of the present invention may also be obtained using molecular biology techniques, employing nucleic acid sequences that encode those peptides. Those sequences may be RNA or DNA and may be associated with control sequences and/or inserted into vectors. The latter are then transfected into host cells, for example bacteria. The preparation of the vectors and their production or expression in a host are carried out by conventional molecular biology and genetic engineering techniques.

The synthesis of peptides containing pseudopeptide bonds is carried out either by methods in solution or in combination with solid phase synthesis using conventional methods of organic chemistry. Thus, for example, the introduction of the —CH 2 —NH bond is effected by preparing Fmoc-NH—CHR—CHO aldehyde in solution according to the technique described by FEHRENTZ and CASTRO (Synthesis, 676-678, 1983) and condensing it with the growing peptide chain either in solid phase according to the technique described by SASAKl and COY (Peptides, 8, 119-121, 1988) or in solution.

The present invention relates also to pharmaceutical compositions comprising as active ingredient at least one compound of the general formula (I) or an addition salt thereof with a pharmaceutically acceptable acid or base, on its own or in combination with one or more inert, non-toxic excipients or carriers.

Amongst the pharmaceutical compositions according to the invention there may be mentioned more especially those which are suitable for oral, parenteral or nasal administration, tablets or dragees, sublingual tablets, sachets, paquets, soft gelatin capsules, suppositories, creams, ointments, dermal gels, transdermal devices, aerosols, drinkable and injectable ampoules.

The dosage varies according to the age and weight of the patient, the nature and severity of the disorder and the route of administration.

The latter may be oral (including the inhalation, gingival and sublingual routes), nasal, rectal, parenteral or transdermal. Generally, the dosage ranges from 10 μg to 500 mg for a treatment of one or more administrations per 24 hours, depending on the administration route and the galenic form used.

The following Examples illustrate the invention without implying any limitation.

By convention, in the Examples below the amino acids in which the abbreviations begin with a capital letter without any other indication, have the L configuration. The amino acids having the D configuration are preceded by the symbol: (D).

GLP-1 Receptor Binding Study

The GLP-1 receptor binding studies were carried out using RIN T3 membranes in a 60 ml Tris-HCl buffer pH 7.5 containing 4% BSA and 750 pg/ml of bacitracin. The membranes (20 to 30 μg) are incubated in a final volume of 500 μl with approximately 15 fmol of [125I]-GLP-1 (50,000 cpm) and the cold competitor for 45 min. at 37° C. The reaction is stopped by the addition of 750 μl of cold KRP buffer, pH 7.5, containing 3% BSA. The mixture is centrifuged at 12,000×g (4° C., 5 min). The residue is resuspended in 1 ml of cold KRP buffer and sedimented by a further centrifugation, and the radioactivity is measured. The results are expressed as IC 50 .

Results:

The results obtained indicate that the compounds of the invention have a very high affinity for GLP-1 receptors.

This is true especially of the compound of Example 7, which has an affinity of 3.3×10 −10 M.

Determination of the Agonist or Antagonist Character

The agonist character of the compounds of the invention was determined by measuring the production of cyclic AMP after activation of the receptor by the different products being tested.

RIN T3 cells are cultured for 6 days and the culture medium is chanced 1 day before the experiment. The cells (3×10 5 per well) are washed twice with DMEM before the addition of 0.5 ml of DMEM containing 1% BSA, 0.2 ml of IBMX and the peptide being tested. After incubation for 20 minutes at 25° C., the intracellular cAMP is extracted, succinylated and quantified by radioimmunoassay.

The reference value of 100% corresponds to the production of cAMP induced by a concentration of 10 −8 M GLP-1 and the value 0% corresponds to the basal production in the absence of GLP-1.

The results are expressed as EC 50 , which is the concentration that induces 50% of the production of cAMP obtained using a concentration of 10 −8 M GLP-1.

Results:

The compounds of the invention present an agonist character. They increase the production of cAMP and have nanomolar or subnanomolar EC 50 values. By way of example, the compound of Example 7 has an EC 50 of 1.02×10 −9 M.

Stimulation of the production of insulin induced by the compounds of the invention is studied using Min6 cells (5×10 5 cells per well in 0.5 ml of culture medium). 18 hours before the experiment, the culture medium is pipetted and the cells are washed twice with DRB, pH 7.5, containing 0.1% BSA. The cells are then pre-incubated for one hour in DRB-BSA containing 1 mM glucose and subsequently incubated in DRB-BSA containing different concentrations of glucose and of the compound to be tested. After incubation the mixture is collected, centrifuged for 5 minutes and stored at −20° C. The secretion of insulin is determined by radioimmunoassay using porcine insulin labelled with iodine 125 and guinea pig Kervran anti-insulin antibody.

Results:

The compounds of the invention are capable of stimulating insulin secretion more substantially than t GLP-1.

Metabolic Stability Study

Each compound is dissolved in 50 mg/ml of BSA in an aqueous 1% trifluoroacetic acid solution to obtain a concentration of 1 mg/ml.

An aliqout of 50 μg/ml of a solution containing the peptide to be studied is incubated in human plasma at 37° C. An HPLC linear analysis method allows measurement of the amount of peptide at time T0, then after incubation for 5, 10, 15, 30 and 60 minutes.

50 μl samples of the above-prepared solution containing 1 mg/ml of the peptide are added to 940 μl of 0.1M TRIS, pH 8.0. After analysis of the solution by HPLC to determine the amount of peptide, 10 μl of an aqueous solution containing 48 milli-units of dipeptidyl peptidase IV (DPP IV) are added, and the samples are analysed by HPLC at time T0 and after incubation for 10 minutes at 37° C.

The measurement results enable evaluation of the amount of peptide remaining and are expressed as a percentage in relation to T0.

Results:

The compounds of the invention appear to exhibit a stability superior to that of the natural peptide.

By way of example, the results obtained with t GLP-1 and with the compound of Example 7 are compiled in the following Table:

Antihyperglycaemic Activity

The antihyperglycaemic activity of the compounds of the invention was investigated in three-month-old normal male Wistar rats weighing approximately 250 g.

The homeostasis was evaluated by a glucose tolerance test.

Intravenous Glucose Tolerance Test (IVGTT)

Glucose is dissolved in an aqueous 0.9% NaCl solution and administered by the saphenous vein route to rats anaesthetised with pentobarbital (60 mg.kg −1 , i.p.). Blood samples are collected sequentially from vessels in the tail before and 2, 5, 10, 15, 20 and 30 minutes after the injection of glucose. They are then centrifuged and the plasma is removed. The plasma glucose concentration is determined immediately in an aliquot of 10 μl and the remaining plasma is kept at −20° C. until the insulin concentration is determined by radioimmunoassay.

A single i.v. injection of the product to be tested is given to fasting rats anaesthetised with pentobarbital immediately after loading with glucose in accordance with the protocol described by Hendrick et al. (Metabolism, 1993, 42, 1).

Analytical Methods

The plasma glucose concentration is determined using a glucose analyser (Beckmann Inc., Fullerton, Calif.). The glucose tolerance is measured in relation to two parameters: ΔG and K. ΔG represents the increase in glycaemia above the base line, integrated over a period of 30 minutes, after overloading with glucose at a dose of 1 g/kg.

K is the rate of glucose disappearance between 5 and 30 minutes after administration of the glucose.

The compounds of the invention appear to have an insulin-secretory and antihyperglycaemic activity equivalent or superior to that of t GLP 1 , and to have a superior duration of action and a greater metabolic stability in vivo.

Pharmaceutical Composition: Injectable Solution