Cyclic CRF agonists

Details Cyclic CRF agonists Cyclic CRF agonists

1999-11-29

2001-12-04

Borin, Michael (Department: 1631)

Chemistry: natural resins or derivatives; peptides or proteins;

Peptides of 3 to 100 amino acid residues

Corticotropin ; related peptides

C530S317000, C514S002600, C514S805000, C930S021000, C930S070000, C930S260000

Reexamination Certificate

active

06326463

ABSTRACT:

This invention is generally directed to peptides and to the pharmaceutical treatment of mammals using such peptides. More specifically, the invention relates to cyclic agonists of the hentetracontapeptide CRF which mimic the pharmacological properties thereof and are superior thereto in at least some aspects, to pharmaceutical compositions containing such cyclic CRF agonists, to methods of treatment of mammals using such cyclic CRF agonists, and to methods of screening for new drugs using such peptides.
A physiologic corticotropin releasing factor (CRF) was first characterized from the ovine species (oCRF) in 1981. As disclosed in U.S. Pat. No. 4,415,558, oCRF (SEQ ID NO:1) was found to be a 41-residue amidated peptide which lowers blood pressure in mammals when injected peripherally and stimulates the secretion of ACTH and &bgr;-endorphin.
In about 1981, a 40-residue amidated peptide was isolated from the skin of the South American frog
Phyllomedusa sauvagei
and referred to as sauvagine. Sauvagine (SEQ ID NO:3) has an amino acid sequence homologous to ovine CRF, having been characterized by Erspamer et al. and described in
Regulatoy Peptides
, Vol. 2 (1981), pp. 1-13. When given intravenously (iv), sauvagine and OCRF cause vasodilation of the mesenteric arteries so as to lower blood pressure in mammals and also stimulate the secretion of ACTH and &bgr;-endorphin. However, when administered intracerebroventricularly(icv), there is an elevation of heart rate and mean arterial blood pressure, which are secondary to activation of the sympathetic nervous system.
Rat CRF (rCRF) (SEQ ID NO: 2) was later isolated, purified and characterized; as described in U.S. Pat. No. 4,489,163, it was found to be homologous, having 7 amino acid differences from oCRF. The amino acid sequence of human CRF was determined to be the same as that of rCRF. rCRF and hCRF are used interchangeably, with the designation r/hCRF being frequently used.
Peptides generally homologous to oCRF, i.e. about 54% homology, were isolated from the urophyses of different species of fish and were termed Urotensin I (UI). One is referred to as sucker fish(sf) urotensin, being described in an article by Lederis et al.,
Science
Vol. 218, No. 4568, 162-164 (Oct. 8, 1982). A homolog, carp urotensin, is described in U.S. Pat. No. 4,533,654.
Another urotensin was later isolated from the urophyses of Flathead (Maggy) Sole; it is sometimes referred to as Maggy urotensin and is described in U.S. Pat. No. 4,908,352. Synthetic UIs have been found to also stimulate ACTH and &bgr;-endorphin activities.
Since the original discoveries of CRFs in mammals and urotensins in fish, CRFs have now been shown to exist in other animal species. For example, fish CRF was found to be a 41-residue peptide having high homology to r/hCRF; it is described in an article by Lederis et al. that appears at pages 67-100 in
Fish Physiology
(ed. Farrell), Academic Press, San Diego, 1994). Synthetic fish CRF (fCRF) stimulates ACTH and &bgr;-endorphin activities in vitro and in vivo and has similar biological activities to mammalian CRFs. These various CRFs and urotensins, along with sauvagine are considered to form a larger family of CRF-like peptides and analogs.
One such CRF analog having a high alpha-helical forming potential was developed in about early 1984. This 41-residue amidated peptide is referred to as AHC (alpha-helical CRF) (SEQ ID NO: 4) and is described in U.S. Pat. No. 4,594,329. Other CRF analogs containing D-isomers of &agr;-amino acids were developed, such as those shown in U.S. Pat. No. 5,278,146. Synthetic r/hCRF, oCRF and AHC all stimulate ACTH and &bgr;-endorphin-like activities (&bgr;-END-Li) in vitro and in vivo and substantially lower blood pressure when injected peripherally. Biopotent cyclic CRF analogs are disclosed in U.S. Pat. No. 5,493,006 (Feb. 20, 1996) and in WO 96/18649 which discloses cyclizing the molecule by creating an amide bond between the sidechains of the residues in positions 30 and 33.
During the search for improved analogs of CRF, it was determined that the first three residues at the N-terminus of the native CRF molecule, namely the residues located N-terminally of the Pro-Pro dipeptide, could be deleted without significantly changing the molecule's potency as a CRF agonist. Such analogs are commonly referred to using the shorthand nomenclature CRF(4-41); thereafter, such N-terminally shortened analogs were frequently used to shorten laboratory syntheses. Furthermore, it is indicated in the '329 patent mentioned above that such analogs retain substantial biopotency as a CRF agonist even if one or both of the proline residues were also deleted, although there would be a significant reduction from the potency of the comparable CRF(4-41) analog. At about the same time, it was disclosed in U.S. Pat. No. 4,605,642 that deletion of the first 8 or 9 N-terminal residues created potent CRF antagonists, i.e. CRF(9-41) and CRF(10-41), and it was furthermore disclosed that some antagonistic activity was also shown by CRF(8-41), which is created when only the first 7 residues at the N-terminus are deleted.
The numbering of the individual residues that is used throughout this application is based upon the structure of the native peptide of which the compound in question is an analog. For example, with respect to analogs of the 41-residue peptide rat/human CRF, the numbering of the particular amino acid residues in the native peptide is retained even though the N-terminus of the CRF analog is shortened by elimination of a sequence of residues.
Since the foregoing discoveries, the search for improved CRF agonists has continued.
Cyclic analogs of this CRF family of peptides have now been discovered which exhibit longer lasting and improved biological activity. It is shown that any of the members of the family of CRF-like peptides can be modified to create highly biopotent CRF agonists that bind strongly to the known CRF receptors and activate the CRF receptors.
The CRF family is considered to encompass those peptides which bind to the CRF receptors and have at least about 45% amino acid structural homology with ovine CRF, the first mammalian CRF isolated and characterized. The CRF family includes, but is not limited to, the following known peptides: ovine CRF (SEQ ID NO: 1), rat/human CRF (SEQ ID NO: 2), porcine CRF (SEQ ID NO: 5), bovine CRF (SEQ ID NO: 6), fish CRF (SEQ ID NO: 3), &agr;-helical CRF(AHC) (SEQ ID NO: 4), carp urotensin (SEQ ID NO: 8), sucker urotensin (SEQ ID NO: 9), maggy urotensin (SEQ ID NO: 10), flounder urotensin (SEQ ID NO: 11), and sauvagine (SEQ ID NO: 4). Modifications in these molecules to incorporate a cyclizing bond, preferably a lactam, to join the side chains of the residues that are located as the 8th and 11th residues from the C-terminal residue, e.g. (cyclo 30-33)[Glu
30
, Lys
33
]r/hCRF, and to optionally also incorporate a D-isomer, preferably a residue of a basic or aromatic amino acid, as the residue which is the 9th residue from the C-terminal residue, e.g. (cyclo 30-33)[Glu
30
, D-His
32
, Lys
33
]-r/hCRF, are known to increase biopotency.
It has now surprisingly been found that the synthesis of N-terminally shortened versions of such cyclic CRF analogs which are minus the first six residues (or the equivalent) compared to the respective CRF family member, i.e. creating a CRF(7-41) molecule or the like, results in the creation of unexpectedly potent CRF agonists when such shortened N-terminus is N-acylated. Surprisingly, such acylation of the a-amino group at such a truncated N-terminus i.e. which is now occupied by the 7-position residue of most CRF family members, in combination with the cyclizing linkage between the side chains of the 30 and 33-position residues, creates unexpectedly biopotent CRF agonists, which can be more potent than the comparable cyclic 41-residue analog. This is in dramatic contrast to comparable linear CRF(6-41) analogs which are only very weak agonists and to comparable linear CRF(8-41) analogs which are weak antagonists.
Basi

Affiliated with

Also associated with

Rating

Cyclic CRF agonists does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Cyclic CRF agonists, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Cyclic CRF agonists will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2582779