Wiley Acta Medica Okayama 0022-1147 85 9 2020 A comparative study of the antioxidant profiles of olive fruit and leaf extracts against five reactive oxygen species as measured with a multiple free‐radical scavenging method 2737 2744 EN Yoshimi Sueishi Department of Chemistry, Faculty of Science, Okayama University Risako Nii Department of Chemistry, Faculty of Science, Okayama University Olive fruits and leaves are recognized to have great potential as natural sources of antioxidants. The major phenolic antioxidant component in these plant tissues is oleuropein. The antioxidant activity of olive fruits and leaves was evaluated in this study using multiple free‐radical scavenging (MULTIS) methods, wherein we determined the scavenging abilities of different extracts against five reactive oxygen species (ROS; HO·, O2－·, RO·, t‐BuOO·, and 1O2). Raw olive fruits taste bitter and are inedible without undergoing a debittering treatment. Following the NaOH‐debittering process, the radical scavenging activity of olives decreased by 90%. The MULTIS measurements indicated that oleuropein and hydroxytyrosol are responsible for the radical scavenging activity of olive fruits. Furthermore, we evaluated the radical scavenging profiles of olive leaf extracts against five ROS and found significant seasonal variations in their antioxidant activities. Leaves picked in August possessed greater radical scavenging abilities (180% to 410% for different ROS) than those picked in the cold season (December and February). In roasted olive leaves, we found marked increases (230% to 300% and 180% to 220%) in the antioxidant activities of Maillard reaction products against RO· and t‐BuOO·, respectively. This study presented a useful comparative analysis of the antioxidant capacities of food against various types of ROS. No potential conflict of interest relevant to this article was reported.

The Society for Free Radical Research Japan Acta Medica Okayama 0912-0009 64 2 2019 Heat Treatments of Ginger Root Modify but Not Diminish Its Antioxidant Activity as Measured With Multiple Free Radical Scavenging (MULTIS) Method 143 147 EN Yoshimi Sueishi Department of Chemistry, Faculty of Science, Okayama University Hiroaki Masamoto Department of Chemistry, Faculty of Science, Okayama University Yashige Kotake RRINC-USA Ginger (Zingiber officinale Rosc.) root (or rhizome) has been reported to have antioxidant properties such as reactive oxygen species scavenging activities. Using multiple free-radical scavenging method, we have newly determined the scavenging abilities of ginger roots against five reactive oxygen species, i.e., HO•, O2 -•, RO•, tert-BuOO•, and 1O2. After heating grated ginger roots at 80°C for 2 h, nearly 50% decrease in scavenging ability was recorded against 1O2 and tert-BuOO•. Conversely, the O2 -• scavenging ability increased by about 56% after heat treatment. Based on the antioxidant activity measurement of the ginger's components, i.e., 6-gingerol, 6-shogaol, and zingerone, active species acting as antioxidant capacity of ginger was shown. Additionally, ginger's antioxidant capacity was quantitatively compared with that of rosemary extract, indicating that rosemary is peroxyl specific scavenger while ginger has higher scavenging ability against HO• and 1O2. No potential conflict of interest relevant to this article was reported.

Acta Medica Okayama 0008-6223 49 12 2011 Analysis of bis(trifluoromethylsulfonyl)imide-doped paramagnetic graphite intercalation compound using F-19 very fast magic angle spinning nuclear magnetic resonance 4064 4066 EN Kazuma Gotoh Kazuyuki Takeda Michael M. Lerner Yoshimi Sueishi Shinpei Maruyama Atsushi Goto Masataka Tansho Shinobu Ohki Kenjiro Hashi Tadashi Shimizu Hiroyuki Ishida F atoms bonding to paramagnetic/conductive graphene layers in accepter-type graphite intercalation compounds (GICs) are analyzed using very fast magic angle spinning nuclear magnetic resonance, which is applied for the first time on F-19 nuclei to investigate paramagnetic materials. In the bis(trifluoromethylsulfonyl)imide(TFSI)-doped GIC, C-F bonds between fluorine atoms and graphene layers conform to a weak bonding of F to the graphene sheets. TFSI anions intercalated in the GIC do not show overall molecular motion; even at room temperature only the CF3 groups rotate. No potential conflict of interest relevant to this article was reported.

Acta Medica Okayama 54 3-4 2006 Elucidation of the role of the complex in hydride transfer reaction between methylene blue and 1-benzyl-1,4-dihydronictinamide by effect of γ-cyclodextrin 233 239 EN Yingin Liu Naoto Hotouchi Yoshimi Sueishi Shunzo Yamamoto The kinetics of the hydride transfer reaction between Methylene Blue (MB+) and　1-benzyl-1,4-dihydronicotinamide (BNAH) were studied in 10 % ethanol-90 % water mixed solvents containing β- and γ-cyclodextrins (β-CD and γ-CD). The pseudo-first order rate constant shows kinetic saturation at high initial concentration of BNAH. This indicates the formation of a complex between MB+ and BNAH. The reaction was suppressed by addition of β-CD, but enhanced by addition of γ-CD. MB+ and BNAH were separately accommodated within the β-CD cavity and the cavity walls may protect the activity site of the reactants. On the other hand, in the MB+-BNAH-γ-CD system, the inclusion of the complex between MB+ and BNAH with γ-CD occurred. This effect of γ-CD can distinguish between the productive and non-productive nature of the complex. No potential conflict of interest relevant to this article was reported.

Acta Medica Okayama 162 1 2004 Separation into polar and hydrogen-bonding factors of the effects of alcohols on the emission spectrum of 4-phenyl-1-N,N-dimethylaminobutane in THF 73 79 EN Xie Guobin Mayuko Nakamura Yoshimi Sueishi Shunzo Yamamoto The effects of the additions of protic and aprotic polar solvents on the emission spectrum of 4-phenyl-1-N,N-dimethylaminobutane (PDAB) in THF have been studied under conditions of steady-state illumination. The fluorescence spectrum of PDAB in THF was reported to consist of three component bands (band A at 285 nm (fluorescence of the phenyl group), band B at 343 nm (fluorescence of the amino group) and band C at 385 nm (emission from an intramolecular exciplex)). The intensities of bands B and C decreased with increasing solvent polarity. They also decreased owing to the hydrogen-bonding interaction between the amino group in PDAB and protic solvents, but in this case the intensity of band A was found to increase. Acetonitrile has only a polar effect and trichloroacetic acid only a hydrogen-bonding (or protonation) effect, while alcohols have both effects. The equilibrium constants for the formation of intermolecular hydrogen-bonded complexes of the amino group with alcohols were estimated from the intensity change of band A. The hydrogen-bonding and polar effects of alcohols on the intensities of bands B and C could be separately evaluated. The decrease in the intensities of bands B and C with increasing solvent polarity in THF-AN and THF-alcohol mixtures is considered to be caused by the conversion of the exciplex to an ion-pair enhanced by the increase in solvent polarity. No potential conflict of interest relevant to this article was reported.

Acta Medica Okayama 162 2-3 2004 Effects of alcohols on emission spectra of toluene-triethylamine mixtures in THF: separation into polar and hydrogen-bonding interactions 449 456 EN Guobin Xie Yoshimi Sueishi Shunzo Yamamoto The emission spectra of toluene (T)–triethylamine (TEA) systems were measured under conditions of steady-state illumination in some protic and aprotic solvent–THF mixtures. The fluorescence spectrum of the T–TEA system in THF could be separated into three component bands (band A at 279 nm (fluorescence of T), band B at 336 nm (fluorescence of TEA) and band C at 373 nm (emission from an intermolecular exciplex)). The intensities of bands B and C decreased with increasing solvent polarity. The decrease in the intensities of bands B and C is considered to be caused by the enhanced conversion of the exciplex to an ion-pair with increase in solvent polarity. The intensities of bands B and C also decreased owing to the hydrogen-bonding interaction between TEA and protic solvents, but in this case the intensity of band A increased. Acetonitrile only has a polar effect and trichloroacetic acid only has a hydrogen-bonding (or protonation) effect, while alcohols have both effects. The equilibrium constants for the formation of intermolecular hydrogen-bonded complexes of TEA with alcohols were estimated from the changes in the intensity of band A. The hydrogen-bonding and polar effects of alcohols on the intensities of bands B and C could be evaluated separately. The ratio of the hydrogen-bonding effect to the polar effect of alcohols was observed to increase with increasing vol.% of alcohol. No potential conflict of interest relevant to this article was reported.

Acta Medica Okayama 37 7 2008 Kinetic study of the reaction of leuco methylene blue with 2,6-dimethyl-p-benzoquinone in a reverse micellar system 1005 1014 EN Daisuke Usui Yoshimi Sueishi Shunzo Yamamoto The kinetics of the reaction of leuco methylene blue (MBH) with 2,6-dimethyl-p-benzoquinone (DMBQ) were studied in a heptane/bis(2-ethylhexyl)-sulfosuccinate (AOT)/water reverse micellar system. The pseudo-first-order rate constant (k (obsd)) obtained in the presence of excess of DMBQ was found to be proportional to the initial concentration of DMBQ for W (0)=3, 5, 10, 15 and 20 (W (0)=[H2O]/[AOT]). The second-order rate constant (k (2)=k (obsd)/[DMBQ](0)) increased with an increase in the W (0) value, but was almost independent of the concentration of the water pool. A mechanism involving the distribution of DMBQ between the reverse micellar interface and bulk organic solvent was proposed to explain these findings. No potential conflict of interest relevant to this article was reported.