2002 Fiscal Year Final Research Report Summary
Investigation of MRI contrast media and free radical analysis
| Project/Area Number |
12670876
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Radiation science
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| Research Institution | Kagawa Medical University |
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Principal Investigator |
MORI yasutane Kagawa Medical University, Research Associates, 医学部, 助手 (50253282)
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| Co-Investigator(Kenkyū-buntansha) |
TAKASHIMA hitoshi Kagawa Medical University, Assistant Professor, 医学部, 助教授 (10116402)
OHKAWA motoomi Kagawa Medical University, Professor, 医学部, 教授 (70028629)
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| Project Period (FY) |
2000 – 2002
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| Keywords | Free radical / Contrast media / MRI / Hydroxyl radical / ESR / EPR |
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| Research Abstract |
Gd-DTPA, GdHP-D03A and Gd-DTPA-BMA are Gd-complexes, and the contrast media approved for magnetic resonance imaging (MRI). The lanthanide Gd^<3+> has the strongest magnetic moment of all paramagnetic elements owing to its 7 unpaired electrons. But, the chelation of the Gd^<3+> ion resulted in the very stable metal chelate Gd-complexes. The chelation of DTPA, DTPA-BMA and HP-D03A, to Gd^<3+> ion resulted in formation of stable Gd^<3+> complexes.
In the present study, we examined the free radical scavenging activity of these complexes by means of electron paramagnetic resonance spectroscopy (EPR) coupled with DMPO spin-trapping method.
MRI contrast media (Gd-DTPA, GdHP-D03A, Gd-DTPA-BMA) were used as samples (0mM-10mM).
The hydroxy radical was generated by exposure of diluted hydrogen peroxide solution (3.3mM, Ph7.4 phosphate buffer) to UV irradiation (500W Hg-Xe lump) for about 20 sec. EPR signal intensity due to the DMPO-OH radical adducts was monitored by JEOL TE-300 X-band spectrometer at room temperature. The dose dependent radical scavenging activity of these Gd^<3+> complexes were estimated by comparison of the EPR signal intensity due to the DMPO-hydroxy radical adduct.
All MRI contrast media showed dose-dependent radical scavenging effects. As compared three contrast media, the radical scavenging system of GdHP-D03A is slightly stronger than that of Gd-DTPA-BMA.
In this study, MRI contrast media showed dose-dependent radical scavenging activity. We suggest that this reaction was caused by the reaction occurring between hydroxy radical and water molecule ligated to the Gd^<3+> complex.
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