Development of novel 19F NMR pH indicators: Synthesis and evaluation of a series of fluorinated vitamin B6 analogues

Sha He, Ralph P. Mason, Sandeep Hunjan, Vimal D. Mehta, Veera Arora, Revathi Katipally, Padmakar V. Kulkarni, Peter P. Antich

Research output: Contribution to journalArticlepeer-review

37 Scopus citations


We have synthesized a series of novel fluorinated vitamin B6 analogues (6-fluoropyridoxol derivatives) as potential 19F NMR pH indicators for use in vivo. Modifications included addition of aldehyde, carboxyl or aminomethyl groups at the 4- or 5-ring position, and examination of a trifluoromethyl moiety as an internal chemical shift standard. The variation in chemical shift with respect to acid-base titration showed pK(a) values in the range 7.05-9.5 with a chemical shift sensitivity in the range 7.4-12ppm. Several of the molecules readily cross cell membranes providing estimates of both intra- and extra-cellular pH in whole blood. 6-Fluoropyridoxamine (6-FPAM) exhibits a pK(a)=7.05, which is closer to normal physiological pH than the parent molecule 6-fluoropyridoxol (6-FPOL) (pK(a)=8.2), and should thus, be useful for precise and accurate measurements of pH in vivo. Enhanced spectral resolution for 6-FPAM over 6-FPOL is demonstrated in whole blood and the perfused rat heart. Copyright (C) 1998 Elsevier Science Ltd.

Original languageEnglish (US)
Pages (from-to)1631-1639
Number of pages9
JournalBioorganic and Medicinal Chemistry
Issue number9
StatePublished - Sep 1998


  • F NMR
  • Fluoropyridoxamine
  • Fluoropyridoxol
  • Vitamin B
  • pH

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Medicine
  • Molecular Biology
  • Pharmaceutical Science
  • Drug Discovery
  • Clinical Biochemistry
  • Organic Chemistry


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