10596-22-2Relevant articles and documents
Ratiometric pH Imaging with a CoII2 MRI Probe via CEST Effects of Opposing pH Dependences
Thorarinsdottir, Agnes E.,Du, Kang,Collins, James H. P.,Harris, T. David
, p. 15836 - 15847 (2017)
We report a Co2-based magnetic resonance (MR) probe that enables the ratiometric quantitation and imaging of pH through chemical exchange saturation transfer (CEST). This approach is illustrated in a series of air- and water-stable CoII2 complexes featuring CEST-active tetra(carboxamide) and/or hydroxyl-substituted bisphosphonate ligands. For the complex bearing both ligands, variable-pH CEST and NMR analyses reveal highly shifted carboxamide and hydroxyl peaks with intensities that increase and decrease with increasing pH, respectively. The ratios of CEST peak intensities at 104 and 64 ppm are correlated with solution pH in the physiological range 6.5-7.6 to construct a linear calibration curve of log(CEST104 ppm/CEST64 ppm) versus pH, which exhibits a remarkably high pH sensitivity of 0.99(7) pH unit-1 at 37 °C. In contrast, the analogous CoII2 complex with a CEST-inactive bisphosphonate ligand exhibits no such pH response, confirming that the pH sensitivity stems from the integration of amide and hydroxyl CEST effects that show base- and acid-catalyzed proton exchange, respectively. Importantly, the pH calibration curve is independent of the probe concentration and is identical in aqueous buffer and fetal bovine serum. Furthermore, phantom images reveal analogous linear pH behavior. The CoII2 probe is stable toward millimolar concentrations of H2PO4-/HPO42-, CO32-, SO42-, CH3COO-, and Ca2+ ions, and more than 50% of melanoma cells remain viable in the presence of millimolar concentrations of the complex. The stability of the probe in physiological environments suggests that it may be suitable for in vivo studies. Together, these results highlight the ability of dinuclear transition metal PARACEST probes to provide a concentration-independent measure of pH, and they provide a potential design strategy toward the development of MR probes for ratiometric pH imaging.
Bisphosphonate-Generated ATP-Analogs Inhibit Cell Signaling Pathways
Malwal, Satish R.,O'Dowd, Bing,Feng, Xinxin,Turhanen, Petri,Shin, Christopher,Yao, Jiaqi,Kim, Boo Kyung,Baig, Noman,Zhou, Tianhui,Bansal, Sandhya,Khade, Rahul L.,Zhang, Yong,Oldfield, Eric
supporting information, p. 7568 - 7578 (2018/05/31)
Bisphosphonates are a major class of drugs used to treat osteoporosis, Paget's disease, and cancer. They have been proposed to act by inhibiting one or more targets including protein prenylation, the epidermal growth factor receptor, or the adenine nucleotide translocase. Inhibition of the latter is due to formation in cells of analogs of ATP: the isopentenyl ester of ATP (ApppI) or an AppXp-type analog of ATP, such as AMP-clodronate (AppCCl2p). We screened both ApppI as well as AppCCl2p against a panel of 369 kinases finding potent inhibition of some tyrosine kinases by AppCCl2p, attributable to formation of a strong hydrogen bond between tyrosine and the terminal phosphonate. We then synthesized bisphosphonate preprodrugs that are converted in cells to other ATP-analogs, finding low nM kinase inhibitors that inhibited cell signaling pathways. These results help clarify our understanding of the mechanisms of action of bisphosphonates, potentially opening up new routes to the development of bone resorption, anticancer, and anti-inflammatory drug leads.
SYNTHESIS AND HIV-1 REVERSE TRANSCRIPTASE INHIBITION ACTIVITY OF FUNCTIONALIZED PYROPHOSPHATE ANALOGUES
McKenna, Charles E.,Khare, Anil,Ju, Jing-Yue,Li, Zeng-Min,Duncan, Greg,et al.
, p. 139 - 142 (2007/10/02)
A new approach, ketone derivatization, for introducing desired functionality into the α-keto pyrophosphate analogues oxophosphonoacetic acid (COPAA) and oxomethanediphosphonic acid (COMDP) is exemplified in the synthesis of several COPAA and COMDP hydrazones with specific functional groups.The preparation of tetraalkyl COMDP esters is also described.Inhibition of HIV-1 reverse transcriptase (isolated enzyme) and of p24 production by HIV-1 (virus-infected H9 cells) by hydrazone derivatives of COPAA and COMDP is briefly discussed.
