Analogues of GLP-1

ANALOGUES OF GLP-1

Background of the Invention

The present invention is directed to a peptide analogue of glucagon-like peptide-1, and pharmaceutically-acceptable salts thereof, to methods of using such analogue to treat mammals and to pharmaceutical compositions useful therefor comprising said analogue.

Glucagon-like peptide-1 (7-36) amide (GLP-1) is synthesized in the intestinal L-cells by tissue-spedfic post-translational processing of the glucagon precursor preproglucagon (Vamdell, J.M., et al., J. Histochem Cytochem, 1985:33:1080-6) and is released into the circulation in response to a meal. The plasma concentration of GLP-1 rises from a fasting level of approximately 15 pmol/L to a peak postprandial level of 40 pmol/L. It has been demonstrated that, for a given rise in plasma glucose concentration, the increase in plasma insulin is approximately threefold greater when glucose is administered orally compared with intravenously (Kreymann, B., et al., Lancet 1987:2, 1300-4). This alimentary enhancement of insulin release, known as the incretin effect, is primarily humoral and GLP-1 is now thought to be the most potent physiological incretiri in humans.

In addition to the insulinotropic effect, GLP-1 suppresses glucagon secretion, delays gastric emptying (Wettergren A., et al., Dig Dis Sd 1993:38:665-73) and may enhance peripheral glucose disposal (D’Alessio, DA et al., J. Clin Invest 1994:93:2293-6).

In 1994, the therapeutic potential of GLP-1 was suggested following the observation that a single subcutaneous (s/c) dose of GLP-1 could completely normalize postprandial glucose levels in patients with non-insulin-dependent diabetes mellitus (NIDDM) (Gutniak, M.K., et al., Diabetes Care 1994:17:1039-44). This effect was thought to be mediated both by increased insulin release and by a reduction in glucagon secretion. Furthermore, an intravenous infusion of GLP-1 has been shown to delay postprandial gastric emptying in patients with NIDDM (Williams, B., et al., J. Clin Endo Metab 1996:81:327-32). Unlike sulphonylureas. the insulinotropic action of GLP-1 is dependent on plasma glucose concentration (Holz. G.G. 4^m, et al.. Nature 1993:361:362-5). Thus, the loss of GLP-1-mediated insulin release at low plasma glucose concentration protects against severe

-2hypoglycemia. This combination of actions gives GLP-1 unique potential therapeutic advantages over other agents currently used to treat NIDDM.

Numerous studies have shown that when given to healthy subjects, GLP-1 potently influences glycemic levels as well as insulin and glucagon concentrations (Orskov, C, Diabetologia 35:701-711, 1992; Holst, J.J., et al., Potential of GLP-1 in diabetes management in Glucagon 111, Handbook of Experimental Pharmacology, Lefevbre PJ, Ed. Berlin, Springer Veriag, 1996, p. 311-326), effects which are glucose dependent (Kreymann, B., et al.. Lancet ii:' 1300-1304, 1987; Weir, G.C., et al., Diabetes 38:338-342, 1989). Moreover, it is also effective in patients with diabetes (Gutniak, Μ., N. Engl J Med 226:1316-1322, 1992; Nathan, D.M., et al., Diabetes Care 15:270-276, 1992), normalizing blood glucose levels in type 2 diabetic subjects (Nauck, M.A., et al., Diagbetologia 36:741-744, 1993), and improving glycemic control in type 1 patients (Creutzfeldt, W.O., et al., Diabetes . Care 19:580-586,1996), raising the possibility of its use as a therapeutic agent.

GLP-1 is, however, metabolically unstable, having a plasma half-life (t_1/2) of only 1-2 min in vivo. Exogenously administered GLP-1 is also rapidly degraded (Deacon, C.F., et al., Diabetes 44:1126-1131, 1995). This metabolic instability limits the therapeutic potential of native GLP-1. Hence, there is a need for GLP-1 analogues that are more active or are more metabolically stable than native GLP-1.

Summary of the Invention

In one aspect, the present invention is directed to a compound of the formula (Aib⁸'³⁵)hGLP-1(7-36)NH₂,or a pharmaceutically acceptable salt thereof.

-3In another aspect, the present invention provides a pharmaceutical composition comprising an effective amount of the compound of the invention, or a pharmaceutically acceptable salt thereof and a pharmaceutically acceptable carrier or diluent.

₅ In yet another aspect, the present invention provides a method of eliciting an agonist effect from a GLP-1 receptor in a subject in need thereof which comprises administering to said subject an effective amount of the compound of the invention or a pharmaceutically acceptable salt thereof.

In a further aspect, the present invention provides a method of treating a disease selected from the group consisting of Type I diabetes, Type II diabetes.

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obesity, glucagonomas, secretory disorders of the airway, metabolic disorder, arthritis, osteoporosis, central nervous system disease, restenosis, neurodegenerative disease, renal failure, congestive heart failure, nephrotic syndrome, cirrhosis, pulmonary edema, hypertension, and disorders wherein the 5 reduction of food intake is desired, in a subject in need thereof which comprises administering to said subject an effective amount of the compound of the invention or a pharmaceutically acceptable salt thereof. A preferred method of the immediately foregoing method is where the disease being treated is Type 1 diabetes or Type II diabetes.

In a still further aspect, the present invention provides the use of the compound of the invention, or a pharmaceutically acceptable salt thereof, in the preparation of a medicament for the treatment of disease selected from the group consisting of Type 1 diabetes, Type II diabetes, obesity, glucagonomas, secretory disorders of the airway, metabolic disorder, arthritis, osteoporosis, central nervous ₁₅ system disease, restenosis and neurodegenerative disease.

With the exception of the N-terminal amino acid, all abbreviations (e.g. Ala) of amino acids in this disclosure stand for the structure of -NH-CH(R)-CO-, wherein R is the side chain of an amino acid (e.g., CH₃ for Ala). For the N-terminal amino acid, the abbreviation stands for the structure of (R²R³)-N-CH(R)-CO-₁ wherein R is 20 a side chain of an amino acid and R² and R³ are as defined above, except when A⁷is lira, Paa or Pta, in which case R² and R³ are not present since lira, Paa and Pta are considered here as des-amino amino acids. Amp, β-Nal, Nle, Cha, 3-Pal, 4-Pal and Aib are the abbreviations of the following α-amino acids: 4-aminophenylalanine, E-(2-naphthyl)alanine, norleucine, cyclohexylalanine, β-(325 pyridinyl)alanine, fi-(4-pyridinyl)alanine and α-aminoisobutyric acid, respectively.

Other amino acid definitions are: Ura is urocanic acid; Pta is (4-pyridylthio) acetic acid; Paa is frans-3-(3-pyridyl) acrylic acid; Tma-His is N,N-tetramethylamidinohistidine; N-Me-Ala is N-methyl-alanine; N-Me-Gly is N-methyl-glycine; N-Me-Glu is N-methyl-glutamic acid; Tie is fert-butylglycine; Abu is α-aminobutyric acid; Tba is fert-butylalanine; Orn is ornithine; Aib is α-aminoisobutyric acid; β-Ala is β-alanine; Gaba is γ-aminobutyric acid; Ava is 5-aminovaleric acid; Ado is 12aminododecanoic acid, Aic is 2-aminoindane-2-carboxylic acid; Aun is 11aminoundecanoic acid; and Aec is 4-(2-aminoethyl)-1-carboxymethyl-piperazine,

-5represented by the structure:

<img file="AU762012B2_D0004.tif" />

What is meant by Acc is an amino acid selected from the group of 1 -amino1-cyclopropanecarboxylic acid (A3c); 1-amino-1-cyclobutanecarboxylic acid (A4c);

1-amino-1 -cyclopentanecarboxylic acid (A5c); 1-amino-1-cyclohexanecarboxylic acid (A6c); 1-amino-1 -cycloheptanecarboxylic acid (A7c); 1-amino-1-

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-6cyclooctanecarboxylic acid (A8c); and 1-amino-1-cyclononanecarboxylic acid (A9c). In the above formula, hydroxyalkyl, hydroxyphenylalkyl, and hydroxynaphthylalkyl may contain 1-4 hydroxy substituents. COX⁵ stands for -C=O X⁵. Examples of C=O-X⁵ include, but are not limited to, acetyl and phenylpropionyl.

What is meant by Lys(N.-alkanoyl) is represented by the following structure:

<img file="AU762012B2_D0007.tif" />

ch₃

<img file="AU762012B2_D0008.tif" />

. What is meant

<img file="AU762012B2_D0009.tif" />

by Lys(Nc-alkylsulfonyl) is

<img file="AU762012B2_D0010.tif" />

<img file="AU762012B2_D0011.tif" />

. What represented by the following structure:

is meant by Lys(N.-(2-(4-alkyl-1-piperazine)-acetyl)) is represented by the following

<img file="AU762012B2_D0012.tif" />

represented . What is meant by the following

A

<img file="AU762012B2_D0013.tif" />

structure:

Asp(1-(4-alkyl-piperazine)) structure:

<img file="AU762012B2_D0014.tif" />

'3 meant by Asp(1 -alkylamino)

<img file="AU762012B2_D0015.tif" />

. What is structure:

. What is

<img file="AU762012B2_D0016.tif" />

is represented by meant by Lys(Nc-Aec-alkanoyl) is

-Ί-

<img file="AU762012B2_D0017.tif" />

in the foregoing structures is 1-30. What is meant by Lys (Νε-ace-alkanoyl) is represented by the structure:

<img file="AU762012B2_D0018.tif" />

The full names for other abbreviations used herein are as follows: Boc for tbutyloxycarbonyl, HF for hydrogen fluoride, Fm for formyl, Xan for xanthyl, Bzl for benzyl, Tos for tosyl, DNP for 2,4-dinitrophenyl, DMF for dimethylformamide, DCM for dichloromethane, HBTU for 2-(1H-Benzotriazol-1-yl)-1,1,3,3-tetramethyl 10 uranium hexafluorophosphate, DIEA for diisopropylethylamine, HOAc for acetic acid, TFA for trifluoroacetic acid, 2CIZ for 2-chlorobenzyloxycarbonyl, 2BrZ for 2bromobenzyloxycarbonyl, OcHex for O-cyclohexyl, Fmoc for 9fluorenylmethoxycarbonyl, HOBt for N-hydroxybenzotriazole and PAM resin for 4hydroxymethylphenylacetamidomethyl resin.

The term “halo encompasses fluoro, chloro, bromo and iodo.

The term “(CpCjoJhydrocarbon moiety” encompasses alkyl, alkenyl and alkynyl, and in the case of alkenyl and alkynyl there are C₂-C_M.

A peptide of this invention is also denoted herein by another format, e.g.. (A5c⁸)hGLP-1(7-36)NH₂, with the substituted amino acids from the natural 20 sequence placed between the first set of parentheses (e.g., A5c⁸ for Ala⁸ in hGLP1). The abbreviation GLP-1 means glucagon-like peptide-1; hGLP-1 means human glucagon-like peptide-1. The numbers between the parentheses refer to the number of amino acids present in the peptide (e.g., hGLP-1 (7-36) is amino acids 7 through 36 of the peptide sequence for human GLP-1). The sequence for hGLP

-81(7-37) is listed in Mojsov, S., Int. J. Peptide Protein Res,. 40, 1992, pp. 333-342 and, in any event is well known in the art. The amino acid sequence represented by hGLP1(7-36) is presented below as a convenience to the reader: His⁷-Ala-Glu-Gly¹⁰-ThrPhe-Thr-Ser-Asp¹⁵-Val-Ser-Ser-Tyr-Leu²⁰-Glu-Gly-Gln-Ala-Ala²⁵-Lys-Glu-Phe-lle-Ala³⁰T rp-Leu-Val-Lys-Gly³⁵-Arg-NH₂.

The designation NH₂ in hGLP-1(7-36)NH₂ indicates that the C-terminus of the peptide is amidated. hGLP-1(7-36) means that the C-terminus is the free acid. In hGLP-1(7-38), residues in positions 37 and 38 are Gly and Arg, respectively.

Detailed Description

The peptides of this invention can be prepared by standard solid phase peptide synthesis. See, e.g., Stewart. J.M., et al.. Solid Phase Synthesis (Pierce Chemical Co., 2d ed. 1984). The substituents R² and R³ of the above generic formula may be attached to the free amine of the N-terminal amino acid by standard methods known in the art. For example, alkyl groups, e.g., (CrCjJalkyl, may be attached using reductive alkylation. Hydroxyalkyl groups, e.g., (C,15 CjJhydroxyalkyl, may also be attached using reductive alkylation wherein the free hydroxy group is protected with a t-butyl ester. Acyl groups, e.g., COE’, may be attached by coupling the free add, e.g., E’COOH, to the free amine of the Nterminal amino add by mixing the completed resin with 3 molar equivalents of both the free add and diisopropylcarbodiimide in methylene chloride for one hour. If the free add contains a free hydroxy group, e.g., p-hydroxyphenyfpropionic add, then the coupling should be performed with an additional 3 molar equivalents of HOBT.

When R’ is NH-X²-CH2-CONH2, (i.e., Z°=CONH2), the synthesis of the peptide starts with BocHN-X²-CH2-COOH which is coupled to the MBHA resin. If R¹ is NH-X²rCH₂-COOH, (i.e., Z°=COOH) the synthesis of the peptide starts with

Boc-HN-X²-CH₂-COOH which is coupled to PAM resin. For this particular step, 4 molar equivalents of Boc-HN-X²-COOH, HBTU and HOBt and 10 molar equivalents of DIEA are used. The coupling time is about 8 hours.

-9The protected amino acid 1-(N-tert-butoxycarbonyl-amino)-1-cyclohexanecarboxylic acid (Boc-A6c-OH) was synthesized as follows. 19.1 g (0.133 mol) of 1amino-1 -cyclohexanecarboxylic acid (Acros Organics, Fisher Scientific. Pittsburgh, PA) was dissolved in. 200 ml of dioxane and 100 ml of water. To it was added 67 ml of 2N NaOH. The solution was cooled in an ice-water bath. 32.0 g (0.147 mol) of di-tert-butyl-dicarbonate was added to this solution. The reaction mixture was stirred overnight at room temperature. Dioxane was then removed under reduced pressure. 200 ml of ethyl acetate was added to the remaining aqueous solution. The mixture was cooled in an ice-water bath. The pH of the aqueous layer was adjusted to about 3 by adding 4N HCI. The organic layer was separated. The

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aqueous layer was extracted with ethyl acetate (1 x 100 ml). The two organic layers were combined and washed with water (2 x 150 ml), dried over anhydrous MgSO₄, filtered, and concentrated to dryness under reduced pressure. The residue was recrystallized in ethyl acetate/hexanes. 9.2 g of the pure product was 5 obtained. 29% yield.

Boc-A5c-OH was synthesized in an analogous manner to that of Boc-A6cOH. Other protected Acc amino acids can be prepared in an analogous manner by a person of ordinary skill in the art as enabled by the teachings herein.

In the synthesis of a GLP-1 analogue of this invention containing A5c, A6c 10 and/or Aib, the coupling time is 2 hrs. for these residues and the residue immediately following them. For the synthesis of (Tma-His⁷)hGLP-1(7-36)NH₂, HBTU (2 mmol) and DIEA (1.0 ml) in 4 ml DMF are used to react with the Nterminal free amine of the peptide-resin in the last coupling reaction; the coupling time is about 2 hours.

The substituents R² and R³ of the above generic formula can be attached to the free amine of the N-terminal amino acid by standard methods known in the art. For example, alkyl groups, e.g., (CrC^alkyl, can be attached using reductive alkylation. Hydroxyalkyl groups, e.g., (C,-C;jo)hydroxyalkyl, can also be attached using reductive alkylation wherein the free hydroxy group is protected with a t-butyl 20 ester. Acyl groups, e.g., COX¹, can be attached by coupling the free acid, e.g., X’COOH, to the free amine of the N-terminal amino add by mixing the completed resin with 3 molar equivalents of both the free add and diisopropylcarbodiimide in methylene chloride for about one hour. If the free add contains a free hydroxy group, e.g., p-hydroxyphenylpropionic acid, then the coupling should be performed 25 with an additional 3 molar equivalents of HOBT.

A compound of the present invention can be tested for activity as a GLP-1 binding compound according to the following procedure.

Cell Culture:

RIN 5F rat insulinoma cells (ATCC-# CRL-2058, American Type Culture

Collection, Manassas, VA), expressing the GLP-1 receptor, were cultured in Dulbecco's modified Eagle's medium (DMEM) containing 10% fetal calf serum, and maintained at about 37 °C in a humidifed atmosphere of 5% COz/95% air. Radioligand Binding:

Membranes were prepared for radioligand binding studies by

-11homogenization of the RIN cells in 20 ml of ice-cold 50 mM Tris-HCI with a Brinkman Polytron (Westbury, NY) (setting 6, 15 sec). The homogenates were washed twice by centrifugation (39,000 g / 10 min), and the final pellets were resuspended in 50 mM Tris-HCI, containing 2.5 mM MgCI₂, 0.1 mg/ml bacitracin 5 (Sigma Chemical, St. Louis, MO), and 0.1% BSA. For assay, aliquots (0.4 ml) were incubated with 0.05 nM (^,25l)GLP-1(7-36) (-2200 Ci/mmol, New England Nuclear, Boston, MA), with and without 0.05 ml of unlabeled competing test peptides. After a 100 min incubation (25 °C), the bound (¹²⁵l)GLP-1(7-36) was separated from the free by rapid filtration through GF/C filters (Brandel, 10 Gaithersburg, MD), which had been previously soaked in 0.5% polyethyleneimine.

The filters were then washed three times with 5 ml aliquots of ice-cold 50 mM Tris···

HCI, and the bound radioactivity trapped on the filters was counted by gamma spectrometry (Wallac LKB, Gaithersburg, MD). Specific binding was defined as the total (¹²⁵l)GLP-1(7-36) bound minus that bound in the presence of 1000 nM 15 GLP1(7-36) (Bachem, Torrence, CA).

The peptides of this invention can be provided in the form of pharmaceutically acceptable salts. Examples of such salts include, but are not limited to, those formed with organic adds (e.g., acetic, lactic, maleic, dtric, malic, ascorbic, sucdnic, benzoic, methanesulfonic, toluenesulfonic, or pamoic acid), 20 inorganic adds (e.g., hydrochloric add, sulfuric add, or phosphoric acid), and polymeric adds (e.g., tannic add, carboxymethyl cellulose, polylactic, polyglycolic, or copolymers of polylactic-glycolic adds). A typical method of making a salt of a peptide of the present invention is well known in the art and can be accomplished by standard methods of salt exchange. Accordingly, the TFA salt of a peptide of the 25 present invention (the TFA salt results from the purification of the peptide by using preparative HPLC, eluting with TFA containing buffer solutions) can be converted into another salt, such as an acetate salt by dissolving the peptide in a small amount of 0.25 N aceti£ acid aqueous solution. The resulting solution is applied to a semi-prep HPLC column (Zorbax, 300 SB, C-8). The column is eluted with (1) 30 0.1N ammonium acetate aqueous solution for 0.5 hrs., (2) 0.25N acetic acid aqueous solution for 0.5 hrs. and (3) a linear gradient (20% to 100% of solution B over 30 min.) at a flow rate of 4 ml/min (solution A is 0.25N acetic acid aqueous solution; solution B is 0.25N acetic acid in acetonitrile/water, 80:20). The fractions containing the peptide are collected and lyophilized to dryness.

-12As is well known to those skilled in the art. the known and potential uses of GLP-1 is varied and multitudinous (See, Todd, J.F., et al„ Clinical Science, 1998, 95, pp. 325-329; and Todd, J.F. et al., European Journal of Clinical Investigation, 1997, 27, pp.533-536). Thus, the administration of the compounds of this invention 5 for purposes of eliciting an agonist effect can have the same effects and uses as GLP-1 itself. These varied uses of GLP-1 may be summarized as follows, treatment of: Type I diabetes, Type II diabetes, obesity, glucagonomas, secretory disorders of the airway, metabolic disorder, arthritis, osteoporosis, central nervous system diseases, restenosis, neurodegenerative diseases, renal failure, congestive 10 heart failure, nephrotic syndrome, cirrhosis, pulmonary edema, hypertension, and disorders wherein the reduction of food intake is desired. GLP-1 analogues of the present invention that elicit an antagonist effect from a subject can be used for treating the following: hypoglycemia and malabsorption syndrome associated with gastroectomy or small bowel resection.

Accordingly, the present invention includes within its scope pharmaceutical compositions comprising, as an active ingredient, at least one of the compounds of formula (I) in association with a pharmaceutically acceptable carrier.

The dosage of active ingredient in the compositions of this invention may be varied; however, it is necessary that the amount of the active ingredient be such 20 that a suitable dosage form is obtained. The selected dosage depends upon the desired therapeutic effect, on the route of administration, and on the duration of the treatment. In general, an effective dosage for the activities of this invention is in the range of 1x1 O'⁷ to 200 mg/kg/day, preferably 1x1 O'⁴ to 100 mg/kg/day, which can be administered as a single dose or divided into multiple doses.

The compounds of this invention can be administered by oral, parenteral (e.g., intramuscular, intraperitoneal, intravenous or subcutaneous injection, or implant), nasal, vaginal, rectal, sublingual or topical routes of administration and can be formulated with pharmaceutically acceptable carriers to provide dosage forms appropriate for each route of administration.

Solid dosage forms for oral administration include capsules, tablets, pills, powders and granules. In such solid dosage forms, the active compound is admixed with at least one inert pharmaceutically acceptable carrier such as sucrose, lactose, or starch. Such dosage forms can also comprise, as is normal practice, additional substances other than such inert diluents, e.g., lubricating

-13agents such as magnesium stearate. In the case of capsules, tablets and pills, the dosage forms may also comprise buffering agents. Tablets and pills can additionally be prepared with enteric coatings.

Liquid dosage forms for oral administration include pharmaceutically 5 acceptable emulsions, solutions, suspensions, syrups, the elixirs containing inert diluents commonly used in the art, such as water. Besides such inert diluents, compositions can also include adjuvants, such as wetting agents, emulsifying and suspending agents, and sweetening, flavoring and perfuming agents.

Preparations according to this invention for parenteral administration include 10 sterile aqueous or non-aqueous solutions, suspensions, or emulsions. Examples of non-aqueous solvents or vehicles are propylene glycol, polyethylene glycol, vegetable oils, such as olive oil and com oil, gelatin, and injectable organic esters such as ethyl oleate. Such dosage forms may also contain adjuvants such as preserving, wetting, emulsifying, and dispersing agents. They may be sterilized by, 15 for example, filtration through a bacteria-retaining filter, by incorporating sterilizing agents into the compositions, by irradiating the compositions, or by heating the compositions. They can also be manufactured in the form of sterile solid compositions which can be dissolved in sterile water, or some other sterile injectable medium immediately before use.

Compositions for rectal or vaginal administration are preferably suppositories which may contain, in addition to the active substance, excipients such as coca butter or a suppository wax.

Compositions for nasal or sublingual administration are also prepared with standard excipients well known in the art.

Further, a compound of this invention can be administered in a sustained release composition such as those described in the following patents and patent applications. U.S. Patent No. 5,672,659 teaches sustained release compositions comprising a bioactive^agent and a polyester. U.S. Patent No. 5,595,760 teaches sustained release compositions comprising a bioactive agent in a gelable form.

U.S. Application No. 08/929,363 filed September 9, 1997, teaches polymeric sustained release compositions comprising a bioactive agent and chitosan. U.S Application No. 08/740,778 filed November 1, 1996, teaches sustained release compositions comprising a bioactive agent and cyclodextrin. U.S. Application No 09/015,394 filed January 29, 1998, teaches absorbable sustained release

-14compositions of a bioactive agent. U.S. Application No. 09/121.653 filed July 23.

1998, teaches a process for making microparticles comprising a therapeutic agent such as a peptide in an oil-in-water process. U.S. Application No. 09/131,472 filed

August 10, 1998, teaches complexes comprising a therapeutic agent such as a peptide and a phosphorylated polymer. U.S. Application No. 09/184,413 filed November 2, 1998, teaches complexes comprising a therapeutic agent such as a peptide and a polymer bearing a non-polymerizable lactone. The teachings of the foregoing patents and applications are incorporated herein by reference.

Unless defined otherwise, all technical and scientific terms used herein have.

the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Also, all publications, patent applications, patents and other references mentioned herein are incorporated by reference.

The following example describes a synthetic method for making the peptide of this invention, which methods are well-known to those skilled in the art. Other methods io are also known to those skilled in the art. The example is provided for the purpose of illustration and is not meant to limit the scope of the present invention in any manner.

Boc-fiAla-OH, Boc-D-Arg(Tos)-OH and Boc-D-Asp(OcHex) were purchased from Nova Biochem, San Diego, California. Boc-Aun-OH was purchased from 20 Bachem, King of Prussia, PA. Boo-Ava-OH and Boc-Ado-OH were purchased from Chem-lmpex International, Wood Dale, IL. Boc-Nal-OH was purchased from Synthetech, Inc. Albany, OR.

‘ Example 1 (Aib’-^M)hGLP-1(7-36)NH₂

The title peptide was synthesized on an Applied Biosysterns (Foster City.

CA) model 430A peptide synthesizer which was modified to do accelerated Bocchemistry solid phase peptide synthesis. See Schnolzer, et al., Int. J. Peptide Protein Res., 90:180 (Ϊ992). 4-methylbenzhydrylamine (MBHA) resin (Peninsula, Belmont, CA) with the substitution of 0.91 mmol/g was used. The Boc amino acids 30 (Bachem, CA. Torrance, CA; Nova Biochem., LaJolla, CA) were used with the following side chain protection: Boc-Ala-OH, Boc-Arg(Tos)-OH, Boc-Asp(OcHex)OH. Boc-Tyr(2BrZ)-OH. Boc-His(DNP)-OH. Boc-Val-OH, Boc-Leu-OH, Boc-GlyOH. Boc-GIn-OH, Boc-lle-OH. Boc-Lys(2CIZ)-OH, Boc-Thr(Bzl)-OH. Boc-Ser(Bzl)OH. Boc-Phe-OH. Boc-Aib-OH. Boc-Glu(OcHex)-OH and Boc-Trp(Fm)-OH The

-15synthesis was carried out on a 0.20 mmol scale. The Boc groups were removed by treatment with 100% TFA for 2 x 1 min. Boc amino acids (2.5 mmol) were preactivated with HBTU (2.0 mmol) and DIEA (1.0 mL) in 4 mL of DMF and were coupled without prior neutralization of the peptide-resin TFA salt. Coupling times were 5 min. except for the Boc-Aib-OH residues and the following residues. BocLys(2CIZ)-OH and Boc-His(DNP)-OH wherein the coupling times were 2 hours.

-At the end of the assembly of the peptide chain, the resin was treated with a solution of 20% mercaptoethanol/10% DIEA in DMF for 2 x 30 min. to remove the DNP group on the His side chain. The N-terminal Boc group was then removed by 10 treatment with 100% TFA for 2 x 2 min. After neutralization of the peptide-resin with 10% DIEA in DMF (1x1 min), the formyl group on the side chain of Trp was removed by treatment with a solution of 15% ethanolamine/15% water/ 70% DMF for 2 x 30 min. The peptide-resin was washed with DMF and DCM and dried under

<img file="AU762012B2_D0021.tif" />

reduced pressure. The final cleavage was done by stirring the peptide-resin in 10 15 mL of HF containing 1 mL of anisole and dithiothreitol (24 mg) at 0°C for 75 min.

HF was removed by a flow of nitrogen. The residue was washed with ether (6x10 mL) and extracted with 4N HOAc (6x10 mL).

The peptide mixture in the aqueous extract was purified on reverse-phase preparative high pressure liquid chromatography (HPLC) using a reverse phase 20 VYDAC® C,_e column (Nest Group, Southborough, MA). The column was eluted with a linear gradient (20% to 50% of solution B over 105 min.) at a flow rate of 10 mL/min (Solution A = water containing 0.1% TFA; Solution B = acetonitrile containing 0.1% of TFA). Fractions were collected and checked on analytical HPLC. Those containing pure product were combined and lyophilized to dryness.

135 mg of a white solid was obtained. Purity was 98.6% based on analytical HPLC analysis. Electro-spray mass spectrometer (MS(ES))S analysis gave the molecular weight at 3339.7 (in agreement with the calculated molecular weight of 3339.7).

-16The words comprising, having, including should be interpreted in an inclusive sense meaning that additional features may also be added.

It is to be understood that, if any prior art publication is referred to herein, such reference does not constitute an admission that the publication forms a part of the common general knowledge in the art, in Australia or in any other country.

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