Synthesis and pharmacology of benzoxazines as highly selective antagonists at M(4) muscarinic receptors.
Previously, we reported on PD 102807 (41) as being the most selective synthetic M(4) muscarinic antagonist identified to date. Synthesized analogues of 41 showed no improvement in affinity and selectivity at that time. However, several newly synthesized compounds exhibit a 7-fold higher affinity at M(4) receptors and demonstrate a selectivity of at least 100-fold over all other muscarinic receptor subtypes. For example, compound 28 showed an affinity of pK(i) = 9.00 at M(4) receptors and a selectivity of M(1)/M(4) = 13 183-fold, M(2)/M(4) = 339-fold, M(3)/M(4) = 151-fold, and M(5)/M(4) = 11 220-fold. This high selectivity along with high affinity has not been reported for any synthetic muscarinic antagonist, nor for natural occurring M(4) antagonists such as the M(4) selective Eastern Green Mamba venom MT3 (M(4) pK(b) = 8.7, M(1)/M(4) = 40-fold, M(2)/M(4) > or = 500-fold, M(3)/M(4) > or = 500-fold, and M(5)/M(4) > or = 500-fold). Derivative 24, a compound with a high selectivity pattern as well, has been tested for in vivo efficacy. It was able to block the L-3,4-dihydroxyphenylalanine accumulation produced by CI-1017, an M(1)/M(4) selective muscarinic agonist, in the mesolimbic region and striatum, which suggests that 24 is capable of crossing the blood-brain barrier and confirms the pharmacokinetic data obtained on this compound. This is evidence that suggests that agonist-induced increase in catecholamine synthesis observed in these regions is mediated by M(4) receptors.
Böhme
Thomas M
TM
Department of Medicinal Chemistry, Pfizer Global Research and Development, Ann Arbor Laboratories, 2800 Plymouth Road, Ann Arbor, MI 48105, USA. thomas.boehme@aventis.com
Augelli-Szafran
Corinne E
CE
Hallak
Hussein
H
Pugsley
Thomas
T
Serpa
Kevin
K
Schwarz
Roy D
RD
D000818:Animals; D000873:Anthracenes / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D001667:Binding, Competitive; D001682:Biological Availability; D001812:Blood-Brain Barrier; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000494:pharmacology; D016466:CHO Cells; D006224:Cricetinae; D004295:Dihydroxyphenylalanine / Q000096:biosynthesis; D006801:Humans; D008297:Male; D009043:Motor Activity / Q000187:drug effects; D018721:Muscarinic Agonists / Q000494:pharmacology; D018727:Muscarinic Antagonists / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D010078:Oxazines / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D010091:Oximes / Q000494:pharmacology; D051381:Rats; D020318:Rats, Long-Evans; D017207:Rats, Sprague-Dawley; D017208:Rats, Wistar; D043643:Receptor, Muscarinic M1; D043588:Receptor, Muscarinic M4; D011976:Receptors, Muscarinic / Q000187:drug effects*; D013329:Structure-Activity Relationship
C461206:9-methoxy-2-propyl-11,12-dihydro-3H,6aH,13H-6-oxa-3,12a-diazabenzo(a)cyclopent(h)anthracene-1-carboxylic acid ethyl ester; D000873:Anthracenes; D019086:Bridged Bicyclo Compounds, Heterocyclic; D018721:Muscarinic Agonists; D018727:Muscarinic Antagonists; D010078:Oxazines; D010091:Oximes; D043643:Receptor, Muscarinic M1; D043588:Receptor, Muscarinic M4; D011976:Receptors, Muscarinic; C096405:PD 142505-0028; D004295:Dihydroxyphenylalanine