OLIGOPEPTIDE COMPOUNDS CONTAINING D-2-ALKYLTRYPTOPHAN CAPABLE OF PROMOTING THE RELEASE OF GROWTH HORMONE

Abstract: A peptide of formula: A-D-X-D-Mrp-B wherein A is hydrogen, 2-aminoisobutyryl, 4-aminobutyryl, D relates to the dextro isomer, X is Mrp, wherein Mrp means 2-alkyltryptophan or X is a residue of protected serine, Ser (Y), wherein Y can be benzyl, p-chlorobenzyl, 4-methoxybenzyl, 2,4,6-trimethoxybenzyl, tert-butyl; B is NR2R3, wherein R2 and R3, which can be the same or different, are hydrogen or a C1-C3 alkyl group; an OR4 group, wherein R4 is hydrogen or a C1-C3 alkyl C-Lys-NH2 group, wherein C is Phe or Mrp, and the addition salts with pharmaceutically acceptable organic or inorganic acids of anyone of said polipeptides; these compounds are capable of promoting the release of growth hormone and they are active by the oral route.

Description: OLIGOPEPTIDE COMPOUNDS CONTAINING D-2-ALKYLTRYPTOPHAN CAPABLE OF PROMOTING THE RELEASE OF GROWTH HORMONE The present invention relates to oligopeptide compounds containing a D-2-alkyltryptophan ammo acid and having and which are capable of releasing growth hormone (GH) from somatotropes , and are active by oral route . Background of the invention The increase of growth hormone (GH ) levels in mammals after the administration of compounds inducing GH release can yield to growth acceleration and muscular mass increase and enhanced production of milk, if sufficiently high GH levels are obtained after the administration. Moreover, it is known that the increase of growth hormone levels in mammals can be achieved by administering known growth hormone release agents, such as growth hormone release hormones (GHRH). The increase of growth hormone levels in mammals can also be obtained by administering growth hormone release peptides, some of them having previously been described, for example in US 4,223,019, US 4,223,020, US 4,223,021, US 4,224,316, US 4,226,857, US 4,228,155, US 4,228,156, US 4,228,157, US 4,228,158, US 4,410,512, US 4,410,513, US 4,411,890 and US 4,839,344. Therefore, rather simple short cham-oligopeptides , capable of promoting growth hormone release on condition that they are easily and conveniently preparable, as well as of easy purification and formulation and active when administered by the oral route, are presently desired. Summary of the invention In a completely surprising manner it has now been found that very short oligopeptides, having at least one D-2-alkyltryptophan (2-Mrp) residue, have activity releasing growth hormone (GH} from somatotropes. Another unexpected distinctive feature of the present invention is the very high potency and the favourable oral activity oral/potency ratio that even the smallest tripept des of the series exhibit. The oligopeptides of the present invention have the formula: A-D-X-D-Mrp-B wherein A is hydrogen, 2-amιnoιsobutyryl, 4- ammobutyryl, D relates to the dextro isomer, X is Mrp, wherein Mrp means 2-alkyltryptophan of formula: wherein R is hydrogen, CHO, S0 2 CH 3 , mesitylene-2- sulfonyl, P0 3 (CH 3 ) 2 , P0 3 H 2 ; R 1 is a alkyl group; or X is a residue of protected seπne , Ser (Y), wherein Y can be benzyl, p-chlorobenzyl , 4-methoxybenzyl , 2,4,6- trimethoxybenzyl, tert-butyl; B is NR 2 R 3 , wherein R 2 e R 3 , which can be the same or different, are hydrogen or a C- ^ -^ alkyl group; a 0R 4 group, wherein R 4 is hydrogen or a alkyl C-Lys-NH 2 group, wherein C is Phe or Mrp. Detailed Disclosure of the Invention The present invention lies on the discovery that different short-chain oligopeptides which promote the release and increase of growth hormone levels in blood of animals are characterized in that all of them comprise in the peptide chain a D-isomer of 2- alkyltryptophan (D-2-Me-Trρ or D-Mrp). The oligopeptides comprised in the scope of the present invention are defined by the following formula A-D-X-D-Mrp-B wherein A is hydrogen, 2-amιnoιsobutyryl , 4- ammobutyryl , D relates to the dextro isomer, X is Mrp, wherein Mrp means 2-alkyltryptophan of formula: wherein R is hydrogen, CHO, S0 2 CH 3 , mesιtylene-2- sulfonyl, P0 3 (CH 3 ) 2 , P0 3 H 2 ; R^ is a C^-C 3 alkyl group; or X is a residue of protected serine, Ser (Y), wherein Y can be benzyl, p-chlorobenzyl , 4-methoxybenzyl , 2,4,6- trimethoxybenzyl , tert-butyl; B is NR- > R 3 , wherein R- > and R 3 , which can be the same or different, are hydrogen or a C«-C 3 alkyl group; a 0R 4 group, wherein R 4 is hydrogen or a C^-C- j alkyl C- ys-NH 2 group, wherein C is Phe or Mrp, and the addition salts with pharmaceutically acceptable organic or inorganic acids of any one of said polipeptides . The abbreviations for the residues of ammo acids herein used are agreement with the standard nomenclature for the peptides: Lys = L-Lysme. Moreover , Alb = 2-ammoιsobutyryl ; GAB = 4-ammobutyryl ; Mrp = 2-alkyltryptophan ; Bz l = benzyl ; p-Cl-Bzl = p-chlorobenzyl; Mob = 4-methoxybenzyl; Tmob = 2 ,4 ,6-trιmethoxybenzyl; tbu = tert-butyl; For = formyl; Mts = mesιtylene-2-εulfonyl . According to the present invention, alk 1 means lower alkyl, comprising from 1 to 3 carbon atoms. Examples of lower alkyl are methyl, ethyl, propyl, isopropyl. Among these, the methyl group is most preferred. All the three letter-abbreviations of the am o acids preceded by a "D" indicate the D-configuiation of the ammo acid residue When the ammo acid is referred to with the only three-letter abbreviation, _t has L configuration The preferred growth hormone-release compounds of the present invention are: (a) GAB-D-Mrp-D-Mrp-Phe-Lys-NH 2 ; (b) GAB-D-Mrp-D-Mrp-Mrp-Lys-NH 2 ; ( c ) Aιb-D-Mrp-D-Mrp-NH 2 ; ( d ) Aιb-D-Mrp-Mrp-NH 2 ; ( e ) Aιb-D-Ser ( Bzl ) -D-Mrp-NH 2 ; wherein Mrp is 2-methyltryptophan, GAB and Aib are as defined above, and the addition salts with pharmaceutically acceptable organic or inorganic acids of anyone of said oligopeptides. These compounds are preferably administered by the oral route, but they also can be administered tranasally or parenterally, or they can be formulated in controlled release systems, such as biodegradable microcapsules , microspheres , subcutaneous implants and the like. The oligopeptide compounds according to the present invention can be synthesized accordmg to the usual methods of peptide chemistry, both solid-phase and solution, or by means of the classical methods known in the art. The solid-phase synthesis starts from C- term al end of peptide. A suitable starting material can be prepared, for example attaching the required protected alpha-ammo acid to a chloromethylated resm, a hydroxymethylated resm, a benzhydryla ine resm (BHA), or to a para-methylbenzhydrylamme resm (p-Me- BHA) As example, a chloromethylated resm is sold with the Trade Mark BIOBEADS ( R ) SX 1 by BioRad Laboratories, Richmond, California. The preparation of the hydroxymethyl resm is described by Bodansky et al . , Chem Ind (London) 38, 15997, (1966). The BHA resm is described by Pietta and Marshall, Chem. Comm. , 650 (1970) „ and is commercially available by Peninsula Laboratories Inc. , Belmont, California. After the starting attachment , the alpha-ammo acid-protectmg group can be removed by means of different acid reagents, comprising trifluoroacetic ac d (TFA) or hydrochloric acid (HCI) dissolved in organic solvents at room temperature. After the removal of the alpha-ammo acid-protectmg group, the remaining protected ammo acids can be coupled step by steo m the desired order. Each protected ammo acid can generally be reacted in excess of about three times using a suitable carboxyl activating group, such as dicyclohexylcarbodiimide (DCC) or dusopropylcarbodi- lmide (DIC) dissolved, for example, in methylene chloride (CH 2 C1 2 ) or dimethylformamide (DMF) and their mixtures. After the desired ammo acid sequence las been completed, the desired peptide can be cleaved rom the supporting resin by treatment with a reagent such as hydrogen fluoride (HF), which not only cleaves the peptide from the resm, but also the more common protecting groups of the lateral chains. When a chloromethylated resin or a hydroxymethylated resm is used, the treatment with HF leads to the formation of the acid peptide in free form. When a BHA or p-Me-BHA resin is used, the treatment with HF directly Leads to the formation of the amide peptide in free form. The above discussed solid-phase procedure LS known m the art and was described by Atherton and Sheppard, Solid Phase Peptide Synthesis (IRL Press, Oxford, 1989). Some methods in solution, which can be used to synthesize the peptide moieties of the present invention are detailed in Bodansky et al., Peptide Synthesis, 2 nd edition, John Wiley & Sons, New York, N.Y. 1976 and from Jones, The Chemical Synthesis of Peptides, (Clarendon Press, Oxford, 1994). These compounds can be administered to animals and humans at an effective dose which can be easily determined by the expert in the field and which can vary accordmg to the specie, age, sex and weight of the treated subject . For example, in humans, when intravenously administered, the preferred dose falls in the range from about 0.1 μg to 10 μg of total peptide per kg of body weight. When orally administered, typically higher amounts are necessary. For example, m humans for the oral administration, the dosage level is typically from about 30 μg to about 1000 μg of polypeptide per kg of body weight. The exact level can be easily determined empirically based on the above disclosure. Compositions, which comprise as active ingredient the organic and inorganic addition salts of the above described oligopeptides and their combinations, optionally, in admixture with a vehicle, diluent, matrix or delayed release coating, are also comprised in the scope of the present invention. The delayed release pharmaceutical forms, comprising bioerodible matrixes, suitable for subcutaneous implant are particularly interesting. Examples of these matrices are described m WO9222600 and W09512629. Biological activity In vivo activity of these compounds was determined in ten day-rats, which were subcutaneously injected (s.c. ) ^ wιth a dose of 300 μg/kg or with different doses in dose-response studies, according to what described m detail by R. Deghenghi et. al, Life Sciences 54, 1321, (1994). The results are resumed in the Table below, the released GH was measured after 15 minutes from the treatment . IAE E Peptide of example Dose μg/kg s.c. released GH (ng/ml ) 1 300 155.4 + 19.7 2 300 165.4 + 18.5 3 300 174.2 + 25.9 4 300 64.2 + 12.6 5 1.2 mg/kg 59.4 + 12.3 Controls - 7 - 23 The following examples further illustrate the invention: Example 1 Making use of the solid-phase peptide synthesis technique as described in "Solid phase peptide synthesis" by E.Atherton and R.C. Sheppard, IRL Press, Oxford University Press, 1984, using fluorenylmethoxycarbonyl (Fmoc) as the protecting group, the peptide: GAB-D-2-Mrp-D-2-Mrp-Phe-Lys-NH 2 , was prepared, wherein Mrp is 2-methyltryptophan, M.W. 779.9, found 778.4; purity (HPLC) 98.0%. Example 2 Analogously to Example 1, the following peptide was prepared: GAB-D-2-Mrp-D-2-Mrp-2-Mrp-Lyε-NH 2 , wherein Mrp is 2-methyltrγptophan, M.W. 830.8, found 831.3; purity (HPLC) 98.0%. Analogously to Example 1, the following peptide was prepared: Aιb-D-2-Mrp-D-2-Mrp-NH 2 , wherein Mrp is 2-methyltryptophan, M.W. 502.6, found 503.3; purity (HPLC) 99.0%. Example 4 Analogously to Example 1, the following peptide was prepared: Aιb-D-2-Mrp-2-Mrp-NH 2 _ wherein Mrp is 2-methyltryptophan, M.W. 502.6, found 503.3; purity (HPLC) 99.0%. Example 5 Analogously to Example 1, the following peptide was prepared: Aib-D-Ser(Bzl)-D-Mrp-NH 2 wherein Mrp is 2-methyltryptophan, M.W. 479.6, found 480.5; purity (HPLC) 99.0%.

Claims: CLAIMS 1. A peptide of formula: A-D-X-D-Mrp-B wherein A is hydrogen, 2-aminoisobutyryl , 4- aminobutyryl , D relates to dextro isomer, X is Mrp, wherein Mrp means 2-alkyltryptophan of formula: wherein R is hydrogen, CHO, S0 CH , mesιtylene-2- sulfonyl, P0 3 (CH 3 ) 2 , P0 3 H 2 ; R^ is a C-_-C 3 alkyl group; or X is a residue of protected serine, Ser (Y), wherein Y can be benzyl, p-chlorobenzyl , 4-methoxybenzyl, 2,4,6- tri ethoxybenzyl, tert-butyl; B is NR 2 R 3 , wherein R e R 3 , which can be the same or different, are hydrogen or a 1 -C 3 alkyl group; a 0R 4 group, wherein R 4 is hydrogen or a ^-C- q alkyl C-Lys-NH 2 group, wherein C i s Phe or Mrp, and the addition salts with pharmaceutically acceptable organic or inorganic acids of anyone of said polipeptides . 2. The peptide according to claim 1, wherein Mrp is selected from 2-methyltryptophan, 2-ethyltryptophan, 2- propyltryptophan, 2-isopropyltryptophan. 3. A peptide accordmg to claim 1, wherein Mrp is 2- methyl-trryptophan. 4. The peptide according to claim 1, wherein A is 2- ammoisobutyryl , 4-amιnobutyryl . 5. The peptide accordmg to claim 1, wherein B is C- LysNH 2 wherein C is as defined above. 6. The peptide accordmg to claim 1, having formula: GAB-D-Mrp-D-Mrp-Phe-Lys-NH 2 . 7. The peptide accordmg to claim 1, having formula: GAB-D-Mrp-D-Mrp-Mrp-Lys-NH 2 . 8. The peptide according to claim 1, having formula: Aib-D-Mrp-D-Mrp-NH 2 . 9. The peptide according to claim 1, having formula: Aib-D-Mrp-Mrp-NH 2 . 10. The peptide accordmg to claim 1, having formula: Aιb-D-Ser(Bzl )-D-Mrp-NH 2 . 11. A peptide according to claims 6-10, wherein Mrp is 2-methyltryptophan. 12. The use of the peptides of claims 1-11 for the manufacturing of a medicament useful for promoting the release of growth hormone in an animal. 13. The use according to claim 12, wherein the medicament is useful in human medicine. 14. Pharmaceutical compositions comprising an effective amount of at least one peptide of claims 1-11 as active ingredient, optionally in admixture with carriers and excipients . 15. Pharmaceutical compositions according to claim 14 in the form of compositions for parenteral, intranasal, oral, controlled release administrations, subcutaneous implants. 16. Compositions according to claim 14 in the form of compositions for the oral administration.

Inventors: DEGHENGHI ROMANO, DEGHENGHI, ROMANO
Applicants: DEGHENGHI ROMANO, DEGHENGHI, ROMANO
Application year: 1996
Main classification: C07K5
IPC codes: A61K31, A61K38, A61P5, A61P43, C07K5, C07K7, C07K14