OCTAPEPTIDE ANALOGS OF SOMATOSTATIN HAVING THREONINE AT THE SIXTH POSITION

Abstract: A compound of formula (I), wherein each A1 and A2, independently, is H C1-12 alkyl, C7-10 phenylalkyl, R1CO (where R1 is C1-20 alkyl, C3-20 alkenyl, C3-20 alkenyl, phenyl, naphthyl, or C7-10 phenylalkyl), or R2OCO (where R is C1-10 alkyl or C7-10 phenylalkyl), provided that when one of A1 or A2 is R1CO or R2OCO, the other must be H; each X1 and X2, indepently, is H, F, Cl, Br, OH, CH3, or CF3, provided that at least one of X1 and X2 must be H; A3 is Phe or Tyr; and A4 is OH, NH2, or NH-R3 (wherein R3 is a saturated aliphatic C1-8 alkyl): or a pharmaceutically acceptable salt thereof; a therapeutic composition comprising such compound; and a method of using such compound.

Description: OCTAPEPTIDE ANALOGS OF SO ATOSTATIN HAVING THREONINE AT THE SIXTH POSITION Background of the Invention This invention relates to therapeutic peptides. A number of somatostatin analogs exhibiting growth hormone-release-inhibitirig activity have been described in the literature, including analogs containing fewer than the naturally-occurring fourteen amino acids. For example, Coy et al., U.S. Patent No. 4,485,101, hereby incorporated by reference, describes dodecapeptides having an amino-terminal acetyl group, a carboxy-terminal amino group, D-Trp at position 6, and p-Cl-Phe at position 4. (The name of each amino acid is herein designated by its standard three-letter abbreviation; the stereoisomeric designation of each amino acid is L unless otherwise specified.) Summary of the Invention In general, the invention features a compound of the formula: wherein each A χ and A 2 , independently, is H C 1 _ 12 alkyl, C 7 - i o Phenylalkyl, I^CO (where R χ is C 1 _ 20 alkyl, C 3 _ 20 alkenyl, C 3 _ 2Q alkenyl, phenyl, naphthyl, or C 7 _ 10 phenylalkyl) , or R 2 OCO (where R is C 1 _ 10 alkyl or C ? _ 10 phenylalkyl) , provided that when one of A χ or -A 2 is R χ C0 or R 2 0C0, the other must be H; each X χ and X 2 , independently, is H, F, Cl, Br, OH, CH-, or CF 3 , provided that at least one of X χ and X 2 must by H; A 3 is Phe or Tyr; and A 4 is OH, NH 2 , or NH-R 3 (wherein 3 is a saturated aliphatic C 1 _ 8 alkyl) : or a pharmaceutically acceptable salt thereof. The naturally-occurring amino acids are indicated by their generally-accepted three-letter symbols; unless the D- stereoisomer of an amino acid (other than jSNal) is specified, the L-form is assumed. "SNal" denotes D- or L-/3-naphthylalanine, unless the D- or L- stereoisomer is specified. In preferred embodiments, each A χ and A 2 , independently, is H or a saturated aliphatic C 1 _ 3 alkyl; each X and X 2 , independently, is H, F, Cl, or OH, provided that at least one of X χ and X 2 must be H; and R 3 is saturated aliphatic C _ 3 alkyl; more preferably, the compound has the formula: D-Phe-Cys-Phe-D-Trp-Lys-Thr-Cys-/3Nal-NH 2 or D-Phe-Cys-Tyr-D-Trp-Lys-Thr-Cys-^Nal-NH 2 In another aspect, the invention features compounds of the formula: D-βNal-Cys-Phe-D-Trp-Lys-Thr-Cys-Thr-NH 2 . and D-jSNal-Cys-Tyr-D-Trp-Lys-Thr-Cys-Thr-NH 2 or a pharmaceutically acceptable salt thereof. Also featured is a combination of one of the above compounds and a pharmaceutically acceptable carrier - 3 - substance in a therapeutic composition capable of inhibiting the release of growth hormone ("GH") , epidermal growth factor, insulin, glucagon, pancreatic exocrine secretions, or substance P, and preferably of GH. In preferred embodiments, the composition is in the form of a pill, tablet, capsule, or liquid for oral administration; a cream, gel, lotion, spray or ointment for application to the skin of a patient; a liquid capable of being administered nasally as drops or spray; or a liquid capable of intravenous, subcutaneous, parenteral, or intraperitoneal administration. The therapeutic composition can also be in the form of an oil emulsion or dispersion in conjunction with a lipophilic salt such as a pamoic acid, or in the form of a biodegradable sustained-release formulation for subcutaneous or intramuscular administration. For maximum efficacy, zero-order release is desired. Zero- order release can be obtained using an implantable or external pump to administer the therapeutic composition. The compounds of the invention exhibit a broad range of biological activities related to their antisecretory and antiproliferative properties. The compounds suppress the secretion of several endocrine hormones, including insulin, glucagon, and, in particular, growth hormone (GH) . The compounds of the invention also suppress pancreatic and gastric exocrine secretions, and suppress or modulate the release of some neurotransmitters, including substance P and acetylcholine. The somatostatin analogs can effect tumor cell multiplication by preventing the release of mitotic factors (such as insulin-like growth factor 1 (IGF-1) , gastrin-releasing peptides, etc.), and may interfere with the intracellular transduction mechanism, as, for - 4 - example, in the case of epidermal growth factor (EGF)- induced cell proliferation. The aromatic lipophilic N-terradnal end can provide long-lasting in vivo activity. Other features and advantages of the invention will be apparent from the following description of the preferred embodiments thereof, and from the claims. Description of the Preferred Embodiments Structure The compounds of the invention, which are peptide analogs of somatostatin, have the general formula recited in the Summary of the Invention, above. The compounds can be provided in the form of pharmaceutically acceptable salts or complexes. As used herein, the term "pharmaceutically acceptable salts or complexes" refers to salts or complexes that retain the desired biological activity of the parent compound and do not impart any undesired toxicological effects. Examples of such salts are (a) acid addition salts formed with inorganic acids (for example, hydrochloric acid, hydrobro ic acid, sulfuric acid, phosphoric acid, nitric acid, and the like) , and slats formed with organic acids such as acetic acid, oxalic acid, tartaric acid, succinic acid, malic acid, ascorbic acid, benzoic acid, tannic acid, pamoic acid, alginic acid, polyglutamic acid, naphthalenesulfonic acids, naphthalenedisulfonic acids, and polygalacturonic acid; (b) base addition salts formed with polyvalent metal cations such as zinc, calcium, bismuth, barium, magnesium, aluminum, copper, cobalt, nickel, cadmium, and the like, or with an organic cation formed from N,N-dibenzylethylene-diamine or ethylenediamine; or (c) combinations of (a) and (b) : e.g., a zinc tannate salt or the like. - 5 - . Synthesis The synthesis of one octapeptide follows. Other compounds of the invention can be prepared by making appropriate modifications, within the ability of someone or ordinary skill, in this field, or the following synthetic method. The first step in the preparation of D-Phe-Cys-Phe-D-Trp-Lys-Val-Cys-βNal-NH 2 was the preparation of the intermediate tert-butyloxycarbonyl-D- Phe-S-methylbenzyl-Cys-Phe-D-Trp-N e -benzyloxycarbonyl- Lys-Thr-S-methylbenzyl-Cys-?Nal-NH 2 -benzyhydrylamine resin, as follows. Methyl-benzyhydrylamine-polystyrene resin (Advanced Chem-Tech, Inc.) in the chloride ion form was placed in the reaction vessel of a Beckman 990B peptide synthesizer programmed to perform the following reaction cycle: (a) methylene chloride; (b) 33% trifluoroacetic acid in methylene chloride (2 times for 1 and 25 min each) ; (c) methylene chloride; (d) ethanol; (e) methylene chloride; (f) 10% triethylamine in chloroform. The neutralized resin was stirred with Boc-?Nal and diisopropylcarbodiimide (1.5 mmole each) in methylene chloride for 1 h and the resulting amino acid resin was then cycled through steps (a) to (f) in the above wash program. The following amino acids (1.5 mmole) were then coupled successively by the same procedure: Boc-S- methylbenzyl-Cys, Boc-Thr, Boc-N e -benzyloxycarbonyl- Lysine, Boc-D-trp, Boc-Phe, Boc-S-methylbenzol-Cys, Boc- D-Phe. The resin was washed and dried and then mixed with anisole (4 ml) and anhydrous hydrogen fluoride (36 ml) at 0°C and stirred for 45 min. (one can also use thioanisole, trifluoroacetic acid, and trifluoromethane sulfonic acid at a ration of 1:90:9, for 6 h) . Excess hydrogen fluoride was evaporated rapidly under a stream S U BSTITUTESHEET of dry nitrogen and free peptide precipitated and washed with ether. The crude peptide was then dissolved in 800 ml or 90% acetic acid., to which was added I 2 in methanol until a permanent brown color was present. The solution was then stirred for 1 h before removing the solvent in vacuo. The resulting oil was dissolved in a minimum volume of 50% ' acetic acid and eluted on a column (2.5 X 100 mm) of Sephadex G-25. Fractions containing a major component by UV absorption and thin-layer chromatography were then pooled, evaporated to a small volume, and applied to a column (2.5 X 50 cm) or Vydac octadecylsilane (10-15 μM) . The column was eluted with a linear gradient of 1 0 -50% acetonitrile in 0.1% trifluoroacetic acid in water. Fractions were examined by thin-layer chromatography and analytical high-performance liquid chromatography, pooled to give maximum purity, and, if desired, a different salt prepared, e.g., acetate or phosphate. Repeated lyophilization of the solution from water gave 120 mg of the product as white, fluffy powder. The product was found to be homogeneous by high- performance liquid chromatography and thin-layer chromatography. Amino acid analysis of an acid hydrolysate confirmed the composition of the octapeptide. Compounds of the invention having the formulas D-Phe- C ys-Tyr-D-Trp-Lys-Thr-Cys-/3Nal-NH, D-,9Nal-Cys-Phe-D-Trp-Lys-Thr-Cys-Thr-NH 2i and D-JNal-Cys-Tyr-D-Trp-Lys-Thr-Cys-Thr-NH 2 were made according to methods analogous to those described above. 4 - 7 - Use When administered to mammals, particularly humans (e.g. orally; topically; intravenously; parenterally in a sustained release, biodegradable form; nasally; or 'by suppository) , the compounds can be e fective to ' inhibit the secretion of 'various hormones and trophic factors. They may be used to suppress certain endocrine secretions, such as GH, insulin, glucagon and prolactin, the treatment of, for example, acromegaly; endocrine tumors such as carcinoids, vipomas, insulinomas, and glucagonomas; or diabetes and diabetes-related pathologies, including retinopathy, nephropathy, dawn syndrome and type 2 diabetes. The compounds may also be used to suppress exocrine secretions in the pancreas, stomach and intestines, for treatment of, for example, pancreatitis, fistulas, bleeding ulcers, and diarrhea associated with such diseases as AIDS of cholera. Disorders involving autocrine or paracrine secretions of trophic factors such as IGF-1 (as well as some endocrine factors) which may be treated by administration of these compounds include cancers of the breast, prostate, and lung (both small cell and non-small cell epidermoids) as well as hepatomas, neuroblastomas, colon and pancreatic adenocarcinomas (ductal type) , chondrosarcomas, and melanomas, and also atherosclerosis associated with vascular grafts and restenosis following angioplasty. The compounds of the invention also are useful to suppress the mediators of neurogenic inflammation (e.g., substance P or the tachykinins) , and thus may be used in the treatment of such pathologies as the rheumatoid arthritis; psoriasis; topical inflammation such as is associated with sunburn, eczema, or other sources of itching; arid allergies, including asthma. The compounds also can function as neuromodulators in the central nervous system, with useful applications in the treatment of Alzheimer's disease and other forms of dementia, pain (as a spinal analgesic) , and headaches. Furthermore, in disorders involving the splanchnic blood flow, including cirrhosis, oesophageal varices, and certain cases of mushroom poisoning, the compounds of the invention can provide cytoprotection. The compounds can be administered to a mammal, e.g., a human, in a dosage of 0.01 to 50 mg/kg/day, preferably 0.1 to 5 mg/kg/day. Other embodiments are within the following claims.

Claims: - 9 - Claims 1. A compound of the formula ; wherein each A χ and A 2 , independently, is H C χ _ 12 alkyl, C 7-ιo Phenylalkyl, R^O (where R χ is C 1 _ 20 alkyl, C 3 _ 20 alkenyl, C 3 _ 20 alkenyl, phenyl, naphytyl, or C ? _ 10 phenylalkyl) , or R 2 OCO (where R is alkyl or C 7 _ 10 phenylalkyl) , provided that when one of A χ or A 2 is R χ CO or R 2 OCO, the other must by H; each X 1 and X 2 , independently, is H, F, Cl, Br, OH, CH 3 , or CF 3 , provided that at least one of X^ ^ and X 2 must be H; A 3 is Phe or Tyr; and A 4 is OH, NH 2 , or NH-R 3 (wherein R 3 is a saturated aliphatic C 1 _ 8 alkyl) : or a pharmaceutically acceptable salt thereof. 2. The compound of claim 1, wherein each A χ and A 2 , independently, is H of a saturated aliphatic C 1-3 alkyl: each X 1 and X 2 , independently, is H, F, Cl, or OH, provided ' that at least one of X. and X 2 must by H; and R 3 is a saturated aliphatic C- - alkyl; or a pharmaceutically acceptable salt thereof. 3. The compound of claim 2, wherein said compound has the formula: D-Phe-Cys-Phe-D-Trp-Lys-Thr-Cys-?Nal-NH 2 , or a pharmaceutically acceptable salt thereof. 4. The compound of claim 2 wherein said compound has the formula: D-Phe-Cys-Tyr-D-Trp-Lys-Thr-Cys-/3Nal-NH 2 , or a pharmaceutically acceptable salt thereof. 5. A compound of the formula: D-SNal-Cys-Phe-D-Trp-Lys-Thr-Cys-Thr-NH- or D-/?Nal-Cys-Tyr-D-Trp-Lys-Thr-Cys-Thr-NH 2 , or a pharmaceutically acceptable salt thereof. 6. A therapeutic composition capable of inhibiting the release of GH; epidermal growth factor; insulin; glucagon; prolactin; exocrine secretions from the pancreas, stomach or intestines; the tachykining and substance P, said composition comprising a therapeutically effective amount of the compound of claim 1 or claim 5, together with a pharmaceutically acceptable carrier substance. 7. The therapeutic composition of claim 6, wherein said composition is capable of inhibiting the release of GH. 8. The therapeutic composition of claim 6, wherein said composition is in the form of a liquid, - 11 - . pill, tablet, or capsule for oral administration to a human patient in need of said composition. 9. The therapeutic composition of claim 6, said composition being in the form of a cream, gel, lotion, spray, or ointment for application to the skin of a human patient in need of said composition. 10. The therapeutic composition of claim 6, said composition being in the form of a liquid capable of being administered nasally as drops or spray to a human patient in need of said composition. 11. The therapeutic composition of claim 6, said composition being in the form of a liquid for intravenous, subcutaneous, parenteral, or intraperitoneal administration to a human patient in need of said composition. 12. The therapeutic composition of claim 6, said composition being in the form of a biodegradable sustained-release composition for intramuscular administration to a human patient in need of said composition. 13. The therapeutic composition of clai 6, wherein said composition includes a lipophilic salt and is suitable for administration in the form of an oil emulsion or dispersion to a human patient in need of said composition. 14. A method of treating a mammal in need of reduction of GH; epidermal growth factor; insulin; glucagon; prolactin; exocrine secretions from the pancreas, stomach or intestines; the tachykining and substance P, said method comprising administering to said mammal a therapeutically effective amount of the compound of claim 1 or claim 5..

Inventors: COY DAVID H, MURPHY WILLIAM A, COY, DAVID, H., MURPHY, WILLIAM, A.
Applicants: UNIV TULANE, THE ADMINISTRATORS OF THE TULANE EDUCATIONAL FUND
Application year: 1990
Main classification: C07K7
IPC codes: A61K31, A61K38, A61P5, C07K14