James G. Douglass

Synthesis and P2Y receptor activity of a series of uridine dinucleoside 5′-polyphosphates

A series of dinucleoside 5-polyphosphates UpnU (n = 2-7) was synthesized. Their relative potencies as agonists at the G-protein-coupled receptors P2Y1, P2Y2, P2Y4, and P2Y6 were determined by intracellular calcium measurements using fluorescent imaging techniques. The correlation of phosphate chain length to activities at these receptors is discussed.

Structure–activity relationships of dinucleotides: Potent and selective agonists of P2Y receptors

Dinucleoside polyphosphates act as agonists on purinergic P2Y receptors to mediate a variety of cellular processes. Symmetrical, naturally occurring purine dinucleotides are found in most living cells and their actions are generally known. Unsymmetrical purine dinucleotides and all pyrimidine containing dinucleotides, however, are not as common and therefore their actions are not well understood. To carry out a thorough examination of the activities and specificities of these dinucleotides, a robust method of synthesis was developed to allow manipulation of either nucleoside of the dinucleotide as well as the phosphate chain lengths. Adenosine containing dinucleotides exhibit some level of activity on P2Y1 while uridine containing dinucleotides have some level of agonist response on P2Y2 and P2Y6. The length of the linking phosphate chain determines a different specificity; diphosphates are most accurately mimicked by dinucleoside triphosphates and triphosphates most resemble dinucleoside tetraphosphates. The pharmacological activities and relative metabolic stabilities of these dinucleotides are reported with their potential therapeutic applications being discussed.

Lipophilic Modifications to Dinucleoside Polyphosphates and Nucleotides that Confer Antagonist Properties at the Platelet P2Y12 Receptor

Platelet P2Y12 receptors play a central role in the regulation of platelet function and inhibition of this receptor by treatment with drugs such as clopidogrel results in a reduction of atherothrombotic events. We discovered that modification of natural and synthetic dinucleoside polyphosphates and nucleotides with lipophilic substituents on the ribose and base conferred P2Y12 receptor antagonist properties to these molecules producing potent inhibitors of ADP-mediated platelet aggregation. We describe methods for the preparation of these functionalized dinucleoside polyphosphates and nucleotides and report their associated activities. By analysis of these results and by deconstruction of the necessary structural elements through selected syntheses, we prepared a series of highly functionalized nucleotides, resulting in the selection of an adenosine monophosphate derivative (62) for further clinical development.

Potency and Duration of Action of Synthetic P2Y2 Receptor Agonists on Schirmer Scores in Rabbits

P2Y2 receptors belong to the family of G-protein coupled receptors and are activated by nucleotides such as ATP and UTP.1,2 Activation of P2Y2 receptors (P2Y2-Rs) on various epithelial cell types enhances chloride, fluid and mucin secretion and thereby stimulates the body’s natural mucosal lubrication and clearance mechanisms.3,4 On the ocular surface, P2Y2-R mRNA is localized in various epithelial cells in the eyelid, cornea and conjunctiva. Previous work using conventional non-isotopic in situ hybridization techniques demonstrated localization of P2Y2-R mRNA in the palpebral conjunctiva of the eyelid, the epithelium of the lid margin and the meibomian gland; the corneal epithelium and adjacent bulbar conjunctiva, particularly the conjunctival goblet cells.5