title: Synthesis of pyridoxal phosphate derivatives with antagonist activity at the P2Y13 receptor.
abstract: We have synthesized a series of derivatives of the known P2 receptor antagonist PPADS (pyridoxal-5'-phosphate-6-azo-phenyl-2,4-disulfonate) and examined their ability to inhibit functional activity of the recombinant human P2Y13 nucleotide receptor expressed in 1321N1 human astrocytoma cells co-expressing G(alpha)16 protein (AG32). Analogues of PPADS modified through substitution of the phenylazo ring, including halo and nitro substitution, and 5'-alkyl phosphonate analogues were synthesized and tested. A 6-benzyl-5'-methyl phosphonate analogue was prepared to examine the effect of stable replacement of the azo linkage. The highest antagonistic potency was observed for 6-(3-nitrophenylazo) derivatives of pyridoxal-5'-phosphate. The 2-chloro-5-nitro analogue (MRS 2211) and 4-chloro-3-nitro analogue (MRS 2603) inhibited ADP (100 nM)-induced inositol trisphosphate (IP3) formation with pIC50 values of 5.97 and 6.18, respectively, being 45- and 74-fold more potent than PPADS. The antagonism of MRS 2211 was competitive with a pA2 value of 6.3. MRS2211 and MRS2603 inhibited phospholipase C (PLC) responses to 30 nM 2-methylthio-ADP in human P2Y1 receptor-mediated 1321N1 astrocytoma cells with IC50 values of >10 and 0.245 microM, respectively. Both analogues were inactive (IC50>10 microM) as antagonists of human P2Y12 receptor-mediated PLC responses in 1321N1 astrocytoma cells. Thus, MRS2211 displayed >20-fold selectivity as antagonist of the P2Y13 receptor in comparison to P2Y1 and P2Y12 receptors, while MRS2603 antagonized both P2Y1 and P2Y13 receptors.
authors.affiliation: Laboratory of Drug Discovery, Department of Life Science, Gwangju Institute of Science and Technology, 1 Oryong-dong, Buk-gu, Gwangju 500-712, Republic of Korea.
authors.forename: Yong-Chul
authors.initials: YC
authors.lastname: Kim
authors.forename: Jung-Sun
authors.initials: JS
authors.lastname: Lee
authors.forename: Katrin
authors.initials: K
authors.lastname: Sak
authors.forename: Frederic
authors.initials: F
authors.lastname: Marteau
authors.forename: Liaman
authors.initials: L
authors.lastname: Mamedova
authors.forename: Jean-Marie
authors.initials: JM
authors.lastname: Boeynaems
authors.forename: Kenneth A
authors.initials: KA
authors.lastname: Jacobson
mesh_terms: D045744:Cell Line, Tumor; D004305:Dose-Response Relationship, Drug; D006801:Humans; D058919:Purinergic P2 Receptor Antagonists; D011732:Pyridoxal Phosphate / Q000031:analogs & derivatives* / Q000138:chemical synthesis* / Q000494:pharmacology; D018048:Receptors, Purinergic P2 / Q000502:physiology; D013329:Structure-Activity Relationship
chemical_list: C440036:P2RY13 protein, human; D058919:Purinergic P2 Receptor Antagonists; D018048:Receptors, Purinergic P2; D011732:Pyridoxal Phosphate