Bradykinin receptor antagonists containing N-substituted amino acids: in vitro and in vivo B(2) and B(1) receptor antagonist activity.
We report a systematic probing of the structural requirements of the bradykinin (BK) type 2 (B(2)) receptor for antagonist activity by incorporating N-alkyl-amino acid residues at positions 7 and 8 of a potent antagonist sequence. Compound 1 (D-Arg(0)-Arg(1)-Pro(2)-Hyp(3)-Gly(4)-Thi(5)-Ser(6)-D-Tic(7)-N-Chg (8)-Arg(9), CP-0597)(1,2) is a potent (pA(2) = 9.3, rat uterus; pK(i) = 9.62, binding, human receptor clone) B(2) receptor antagonist devoid of in vitro B(1) antagonist activity (rabbit aorta). Compound 1 exhibits high potency (ED(50) = 29.2 pmol/kg/min, iv, rabbit) and duration of action when tested in models for in vivo B(2) antagonist activity. Although devoid of activity in a classic B(1) isolated tissue assay, B(1) antagonist activity for 1 was demonstrated in vivo, in a LPS-treated, inducible BK(1) receptor rabbit blood pressure model (ED(50) = 1.7 nmol/kg/min). D-Arg(0) of 1 can be formally replaced by an achiral arginine surrogate, without significant loss in antagonist potency on rat uterus (compound 11, B(2) pA(2) = 9.1). Antagonist 13 (Hyp(2), Nchg(8)), pK(i) = 10.2, and agonist 4 (N-methylcyclohexyl-Gly(8)), pK(i) = 10.1, also exhibited substantial binding to guinea pig ileum membrane receptors as well as a human B(2) receptor clone. Very minor structural changes in the N-alkyl amino acid residues in positions 7 and 8 can modify the activity of this class of compounds from being extremely potent antagonists to tight binding partial or full agonists. These studies have resulted in a series of compounds containing inexpensive amino acid residues but which produce broad spectrum BK receptor blocking potency and exceptional in vivo duration of action.
Goodfellow
V S
VS
Department of New Leads Discovery, Cortech, Inc., Denver, Colorado 80221, USA.
Marathe
M V
MV
Kuhlman
K G
KG
Fitzpatrick
T D
TD
Cuadrado
D
D
Hanson
W
W
Zuzack
J S
JS
Ross
S E
SE
Wieczorek
M
M
Burkard
M
M
Whalley
E T
ET
D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D001011:Aorta / Q000187:drug effects; D001667:Binding, Competitive; D001794:Blood Pressure / Q000187:drug effects; D065168:Bradykinin Receptor Antagonists; D005260:Female; D006168:Guinea Pigs; D006801:Humans; D007082:Ileum / Q000187:drug effects / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D015394:Molecular Structure; D009842:Oligopeptides / Q000138:chemical synthesis* / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D011485:Protein Binding; D011817:Rabbits; D051381:Rats; D043783:Receptor, Bradykinin B1; D043782:Receptor, Bradykinin B2; D018002:Receptors, Bradykinin / Q000378:metabolism; D013329:Structure-Activity Relationship; D014599:Uterus / Q000187:drug effects
D000596:Amino Acids; D065168:Bradykinin Receptor Antagonists; D009842:Oligopeptides; D043783:Receptor, Bradykinin B1; D043782:Receptor, Bradykinin B2; D018002:Receptors, Bradykinin