(抗酸化化合物のモデル生体反応中間体に関する研究)

Antioxidants are useful not only for preserving foods but also for preventing free radical-induced damage in the field of medicine. Short-lived free radicals (e.g. oxygen radicals) are involved in various diseases such as coronary disease, oxidative stress, etc. Antioxidants react with short-lived free radicals and become the corresponding intermediates (free radicals) as shown below. If the intermediate is stable or less reactive, damage induced by the short-lived radical can be minimized. However, the antioxidant intermediates are not yet well understood.

(K. Nakagawa: Analytical Biochem., 1997; J. Am. Oil Chem. Soc., 2000; Cell. Mol. Biol., 2000)

(脂質二分子膜の動的構造に関するEPR/ESR研究)

The EPR (electron paramagnetic resonance, ESR, electron spin resonance) spin probe method has been employed to considerable advantage in the study of membranes. The macroscopic and local viscosities of the environment profoundly influence the rate of molecular reorientation; changes in viscosity are reflected in the EPR linewidth as well as lineshape because of anisotropy in the g-value and in the nitrogen hyperfine structure. The lineshape of the EPR signal can be analyzed to determine the probe dynamics.

(K. Nakagawa: Langmuir, 2003; Bull. Chem. Soc. Jpn., 2004; Lipids, 2005; Lipids, 2007; Bull. Chem. Soc. Jpn., 2008; J. Am. Oil Chem. Soc., 2009; Colloids and Surfaces: A, 2012)

(電子スピン共鳴法による皮膚角層脂質の状態構造に関する研究、共同研究)

The skin barrier against chemicals, surfactants, and UV irradiation is its outermost layer, the stratum corneum (SC). Stratum corneum has a heterogeneous structure composed of corneocytes embedded in the intercellar lipid lamellae. Ordering of the lipid bilayer is associated with the main epidermal barrier. Knowledge of the lipid structure is important in understanding the mechanism of irritant dermatitis and other SC diseases. The ordering (or fluidity) change of the lipid bilayer is obtained by the analyses of aliphatic spin probes incorporated into intercellar lamella lipids using EPR. The EPR spin probe method measures non-distractively the ordering of the lipid bilayer of SC.

(K. Nakagawa, et al.: Spectrochim. Acta Part (A); Mol. & Biomol. Spectroscopy, 2005; Cosmetic Sci. and Technol., 2006; J. Invest. Dermatology, 2007; Textbook of Aging Skin, Chapter 70, 2009; Oleoscience, 2010: Lipids, 2010; Skin Research & Technology, 2011; Appl. Magn. Reson., 2011; J. Dermatological Science, 2012)

(電子スピン共鳴イメージング法による薄膜に関する研究、共同研究)

A 9 GHz EPR imager that is capable of the imaging surface area of thin materials has been built. The EPR imager resolved samples spaced 1 mm apart. The developed TE₁₁₁ cavity was able to detect easily ~1.0 mM aqueous TEMPOL solution in ~1.0 mm (i.d.) glass capillary placed just above the cavity. The relatively low measured sensitivity of the TE₁₁₁ cavity is due to utilization of the microwave field from ~3 mm aperture (hole) in the cavity wall. More importantly, the TE₁₁₁ cavity does not require inserting the sample into the cavity and placing samples into EPR tubes.

(K. Nakagawa, et al.: Oleoscience, 2010; J. Oleo Science, 2012)

(粒子線照射で生ずるモノ、ジ-サッカライドのラジカルに関するEPR/ESR研究、共同研究)

Irradiation effects induced by various irradiations on materials are important subjects of radiation research. The results will lead to a wide range of applications, such as clinical usage, nuclear wastes, a dosimeter for cosmic rays, etc. Especially, effects caused by heavy ion particles are of interest. Heavy ion particles exert much larger impulses on the orbital electrons of molecules of a material, causing excitations and ionizations. Free radical production could be used as an indicator of heavy ion exposure.

(K. Nakagawa, et al.: Radiat Research, 2000; Spectrochim. Acta Part A, Mol. & Biomol. Spectroscopy, 2004; Radiat. Research, 2005; Spectrochim. Acta Part A, Mol. & Biomol. Spectroscopy, 2007; Appl. Magn. Reson., 2008; Karakirova Y, et al., Radiation Measurements, 2010; Appl. Magn. Reson., 2010)