2-Deoxy derivative is a partial agonist of the intracellular messenger inositol 3,4,5,6-tetrakisphosphate in the epithelial cell line T84.
We have synthesized the first deoxy analogues of myo-inositol 3,4,5, 6-tetrakisphosphate (1) [Ins(3,4,5,6)P4], rac-2-deoxy-myo-inositol 3, 4,5,6-tetrakisphosphate (rac-2), 2-deoxy-myo-inositol 1,4,5, 6-tetrakisphosphate (ent-2), and rac-1-deoxy-myo-inositol 3,4,5, 6-tetrakisphosphate (rac-3). In order to evaluate the binding properties of the three derivatives to the yet unidentified intracellular binding sites for Ins(3,4,5,6)P4, the analogues were converted to membrane-permeant derivatives. Starting with common inositol precursors, various forms of Barton-McCombie deoxygenation and classical protection/deprotection procedures yielded the desired precursors rac-1-O-butyryl-2-deoxy-myo-inositol (rac-12), ent-3-O-butyryl-2-deoxy-myo-inositol (ent-12), and rac-2-O-butyryl-1-deoxy-myo-inositol (rac-19), respectively. Phosphorylation and subsequent deprotection yielded rac-2, ent-2, and rac-3. Alternatively, phosphorylation followed by alkylation with acetoxymethyl bromide gave the membrane-permeant derivatives 1-O-butyryl-2-deoxy-myo-inositol 3,4,5,6-tetrakisphosphate octakis(acetoxymethyl) ester (rac-5), 3-O-butyryl-2-deoxy-myo-inositol 1,4,5,6-tetrakisphosphate octakis(acetoxymethyl) ester (ent-5), and 2-O-butyryl-1-deoxy-myo-inositol 3,4,5,6-tetrakisphosphate octakis(acetoxymethyl) ester (rac-6), respectively. We examined the potency of the membrane-permeant deoxy derivatives in inhibition of calcium-mediated chloride secretion (CaMCS) in intact T84 cells. Compared to the 1,2-di-O-butyryl-myo-inositol 3,4,5, 6-tetrakisphosphate octakis(acetoxymethyl) ester (4), the membrane-permeant derivative of Ins(3,4,5,6)P4 (1), the 2-deoxy derivative (rac-5) exhibited a slightly weaker inhibitory effect, while the enantiomerically pure 2-deoxy-Ins(1,4,5,6)P4 (ent-5) and the 1-deoxy derivative (rac-6) were inactive. As expected, the effect was stereoselective. Thus, the 1-hydroxyl group is apparently essential for binding and the inhibitory effect of Ins(3,4,5,6)P4 on chloride secretion, whereas the 2-hydroxyl group plays a less important role.
Rudolf
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MT
Institut für Organische Chemie, Abt. Bioorganische Chemie, Universität Bremen UFT, Leobener Strasse, 28359 Bremen, Germany.
Li
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WH
Wolfson
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Traynor-Kaplan
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AE
Schultz
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C
D002118:Calcium / Q000378:metabolism; D002460:Cell Line; D002463:Cell Membrane Permeability; D002712:Chlorides / Q000378:metabolism; D004847:Epithelial Cells / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D007295:Inositol Phosphates / Q000819:agonists* / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D015398:Signal Transduction / Q000502:physiology*; D013237:Stereoisomerism
C114595:1-O-butyryl-2-deoxy-myo-inositol 3,4,5,6-tetrakisphosphate octakis(acetoxymethyl) ester; C114608:2-O-butyryl-1-deoxy-myo-inositol 3,4,5,6-tetrakisphosphate octakis(acetoxymethyl) ester; C114596:3-O-butyryl-2-deoxy-myo-inositol 1,4,5,6-tetrakisphosphate octakis(acetoxymethyl) ester; D002712:Chlorides; D007295:Inositol Phosphates; C081652:inositol-3,4,5,6-tetrakisphosphate; D002118:Calcium