Enhanced Catalytic Four-Electron Dioxygen (O₂) and Two-Electron Hydrogen Peroxide (H₂O₂) Reduction with a Copper(II) Complex Possessing a Pendant Ligand Pivalamido Group

Kakuda, Saya,Peterson, Ryan L.,Ohkubo, Kei,Karlin, Kenneth D.,Fukuzumi, Shunichi American Chemical Society 2013 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.135 No.17

<P>A copper complex, [(PV-tmpa)Cu<SUP>II</SUP>](ClO<SUB>4</SUB>)<SUB>2</SUB> (<B>1</B>) [PV-tmpa = bis(pyrid-2-ylmethyl){[6-(pivalamido)pyrid-2-yl]methyl}amine], acts as a more efficient catalyst for the four-electron reduction of O<SUB>2</SUB> by decamethylferrocene (Fc*) in the presence of trifluoroacetic acid (CF<SUB>3</SUB>COOH) in acetone as compared with the corresponding copper complex without a pivalamido group, [(tmpa)Cu<SUP>II</SUP>](ClO<SUB>4</SUB>)<SUB>2</SUB> (<B>2</B>) (tmpa = tris(2-pyridylmethyl)amine). The rate constant (<I>k</I><SUB>obs</SUB>) of formation of decamethylferrocenium ion (Fc*<SUP>+</SUP>) in the catalytic four-electron reduction of O<SUB>2</SUB> by Fc* in the presence of a large excess CF<SUB>3</SUB>COOH and O<SUB>2</SUB> obeyed first-order kinetics. The <I>k</I><SUB>obs</SUB> value was proportional to the concentration of catalyst <B>1</B> or <B>2</B>, whereas the <I>k</I><SUB>obs</SUB> value remained constant irrespective of the concentration of CF<SUB>3</SUB>COOH or O<SUB>2</SUB>. This indicates that electron transfer from Fc* to <B>1</B> or <B>2</B> is the rate-determining step in the catalytic cycle of the four-electron reduction of O<SUB>2</SUB> by Fc* in the presence of CF<SUB>3</SUB>COOH. The second-order catalytic rate constant (<I>k</I><SUB>cat</SUB>) for <B>1</B> is 4 times larger than the corresponding value determined for <B>2</B>. With the pivalamido group in <B>1</B> compared to <B>2</B>, the Cu<SUP>II</SUP>/Cu<SUP>I</SUP> potentials are –0.23 and –0.05 V vs SCE, respectively. However, during catalytic turnover, the CF<SUB>3</SUB>COO<SUP>–</SUP> anion present readily binds to <B>2</B> shifting the resulting complex’s redox potential to –0.35 V. The pivalamido group in <B>1</B> is found to inhibit anion binding. The overall effect is to make <B>1</B> easier to reduce (relative to <B>2</B>) during catalysis, accounting for the relative <I>k</I><SUB>cat</SUB> values observed. <B>1</B> is also an excellent catalyst for the two-electron two-proton reduction of H<SUB>2</SUB>O<SUB>2</SUB> to water and is also more efficient than is <B>2</B>. For both complexes, reaction rates are greater than for the overall four-electron O<SUB>2</SUB>-reduction to water, an important asset in the design of catalysts for the latter.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jacsat/2013/jacsat.2013.135.issue-17/ja3125977/production/images/medium/ja-2012-125977_0017.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ja3125977'>ACS Electronic Supporting Info</A></P>

Trajectory Formation of Arm Movement using Genetic Algorithm

Tadashi TSUBONE,Hisami KAKUDA,Yasuhiro WADA 제어로봇시스템학회 2006 제어로봇시스템학회 국제학술대회 논문집 Vol.2006 No.10

Green Tea Extract Thermogenesis-Induced Weight Loss by Epigallocatechin Gallate Inhibition of Catechol-O-Methyltransferase

J. Shi,Y. Kakuda,Y. Jiang,Q. Shixian,B. VanCrey 한국식품영양과학회 2006 Journal of medicinal food Vol.9 No.4

Epidemiological studies have shown that intake of tea catechins is associated with a lower risk of cardiovas-cular disease. The antioxidative activity of tea-derived catechins has been extensively studied. Reports have shown that greentea extract intake is associated with increased weight loss due to diet-induced thermogenesis, which is generally attributed tothe catechin epigallocatechin gallate. That catechin-polyphenols are known to be capable of inhibiting catechol-O-methyl-transferase (the enzyme that degrades norepinephrine) is a possible explanation for why the green tea extract is effective instimulating thermogenesis by epigallocatechin gallate to augment and prolong sympathetic stimulation of thermogenesis.Knowledge about thermogenesis-induced weight loss produced by green tea’s epigallocatechin gallate and its ability to in-hibit catechol-O-methyltransferase is important for health benefits and for prolonging the action of norepinephrine in the synap-tic cleft.

Synergistic Antioxidant Effects of Lycopene and Other Antioxidants on Methyl Linoleate Autooxidation

Youn Young Shim,Yukio Kakuda,John Shi 한국식품과학회 2009 Food Science and Biotechnology Vol.18 No.4

The beneficial effects derived from consuming natural antioxidants may not depend on the action of an individual antioxidant, but rather on the concerted action of several antioxidants naturally present. The aim of this study was to determine the concentrations and combinations of antioxidants that can produce synergistic effects (SyEs). Quantification of the lipoperoxyl radical scavenging capacity of antioxidants was carried out in a homogeneous model system where the free radicals were produced by the oxidation of methyl linoleate, initiated by the 2,2’-azobis (2,4-dimethylvaleronitrile). The greatest SyE (2.21, p<0.05) was seen in mixtures of all 4 antioxidants when used with concentrations of 15 μM lycopene, 2.5 μM vitamin E, 0.16 μM vitamin C, and 10 μM β-carotene. Doubling the vitamin E concentration from 2.5 to 5.0 μM in the mixture with all 4 antioxidant reduced the SyE to 1.69 (p<0.05). Other combinations produced synergistic effects that ranged from 1.28 to 1.41.

Characterization of Intraductal Papillary Neoplasm of the Bile Duct with Respect to the Histopathologic Similarities to Pancreatic Intraductal Papillary Mucinous Neoplasm

Yasuni Nakanuma,Yuko Kakuda,Katsuhiko Uesaka 거트앤리버 소화기연관학회협의회 2019 Gut and Liver Vol.13 No.6

Intraductal papillary neoplasms of the bile duct (IPNBs) are known to show various pathologic features and biological behaviors. Recently, two categories of IPNBs have been proposed based on their histologic similarities to pancreatic intraductal papillary mucinous neoplasms (IPMNs): type 1 IPNBs, which share many features with IPMNs; and type 2 IPNBs, which are variably different from IPMNs. The four IPNB subtypes were re-evaluated with respect to these two categories. Intestinal IPNBs showing a predominantly villous growth may correspond to type 1, while those showing papillay-tubular or papillay-villous growth correspond to type 2. Regarding gastric IPNB, those with regular foveolar structures with varying numbers of pyloric glands may correspond to type 1, while those with papillary-foveolar structures with gastric immunophenotypes and complicated structures may correspond to type 2. Pancreatobiliary IPNBs that show fine ramifying branching may be categorized as type 1, while others containing many complicated structures may be categorized as type 2. Oncocytic type, which displays solid growth or irregular papillary structures, may correspond to type 2, while papillary configurations with pseudostratified oncocytic lining cells correspond to type 1. Generally, type 1 IPNBs of any subtype develop in the intrahepatic bile ducts, while type 2 IPNBs develop in the extrahepatic bile duct. These findings suggest that IPNBs arising in the intrahepatic ducts are biliary counterparts of IPMNs, while those arising in the extrahepatic ducts display differences from prototypical IPMNs. The recognition of these two categories of IPNBs with reference to IPMNs and their anatomical location along the biliary tree may deepen our understanding of IPNBs.

Saponins from Edible Legumes: Chemistry, Processing, and Health Benefits

John Shi,Konesh Arunasalam,David Yeung,Yukio Kakuda,Gauri Mittal,Yueming Jiang 한국식품영양과학회 2004 Journal of medicinal food Vol.7 No.1

Demand for bean products is growing because of the presence of several health-promoting components in edible bean products such as saponins. Saponins are naturally occurring compound, which are widely distributed in all cells of legume plants. Saponins, which derive their name from their ability to form stable, soaplike foams in aqueous solutions, constitute a complex and chemically diverse group of compounds. In chemical terms, saponins contain a carbohydrate moiety attached to a triterpenoid or steroids. Saponins are attracting considerable interest as a result of their diverse properties, both deleterious and beneficial. Clinical studies have suggested that these health-promoting components, saponins, affect the immune system in ways that help to protect the human body against cancers, and also lower cholesterol levels. Saponins decrease blood lipids, lower cancer risks and lower blood glucose response. A high saponin diet can be used in the inhibition of dental caries and platelet aggregation, in the treatment of hypercalciuria in humans, and as an antidote against acute lead poisoning. In epidemiological studies, saponins have been shown to have an inverse relationship with the incidence of renal stones. Thermal processing such as canning is the typical method to process beans. The study reviews the effect of thermal processing on the characteristics and stability of saponins in canned bean products. Saponins are thermal sensitive. During soaking and blanching, portions of saponins are dissolved in water and lost in the soaking, washing and blanching liquors. An optimum thermal process can increase the stability and maintain the saponins in canned bean products, which is useful for assisting the food industry to improve thermal processing technology and enhance bean product quality.

Stability of Lycopene During Food Processing and Storage

J. Shi,S. Xianquan,Y. Kakuda,J. Yueming 한국식품영양과학회 2005 Journal of medicinal food Vol.8 No.4

With an increasing understanding of the health benefit of lycopene, how to preserve lycopene during food pro-cessing and storage has caused much attention. Lycopene belongs to the carotenoid family and mostly exists in nature as theall-transform. Heat, light, oxygen, and different food matrices are factors that have an effect on lycopene isomerization andautooxidation. Lycopene may isomerize to mono- or poly-cisforms with the presence of heat or oil or during dehydration.Reisomerization takes place during storage. After oxidation, the lycopene molecule split, which causes loss of color and off-flavor. The effects of heat, oxygen, light, and the presence of oil on the stability of lycopene are uniform in much of the lit-erature; however, controversy still exists on some details, such as the conditions causing the occurrence of isomerization, theoptimal moisture, and temperature for storage.

Study on dynamic behavior of a new type of two-way single layer lattice dome with nodal eccentricity

Eka Satria,Shiro Kato,Shoji Nakazawa,Daisuke Kakuda 국제구조공학회 2008 Steel and Composite Structures, An International J Vol.8 No.6

This paper discusses a feasibility of a new type of two-way system for single layer lattice domes with nodal eccentricity by investigating the dynamic behavior under earthquake motions. The proposed dome is composed of two main arches, intersecting each other with T-joint struts to provide space for tensioning membranes. The main purposes of this study are to calculate the nonlinear dynamic response under severe earthquake motions and to see the possibility of using this new type of two-way system for single layer lattice domes against earthquake motions. The results show that the main arches remain elastic except yielding of the joints of strut members that can be used to absorb some amount of strain energy at strong earthquake motion. Consequently, deformation of the main arches can be reduced and any heavy damages on the main arches can be minimized. A kind of damage-control characteristic appeared in this system may be utilized against severe earthquake motions, showing a possibility of designing a new type of single layer lattice dome.

Bioavailability of Lycopene from Tomato Products

John Shi,Laura MacNaughton,Yukio Kakuda,William Bettger,David Yeung,Yueming Jiang 한국식품영양과학회 2004 Preventive Nutrition and Food Science Vol.9 No.1

Tomatoes and tomato products are the major source of lycopene in the diet. The bioavailability of lycopene is different in raw tomatoes compared to processed tomato products. This is due to the chemical and physical properties of the different lycopene isomers. All-trans-lycopene is found in raw tomatoes and is a poor bioavailable source, whereas, processed tomato products are more bioavailable because they contain more cis-isomers. Heat and mechanical processing of tomatoes induces rupture of the cell walls, thereby releasing lycopene from its food matrix. Heat processing also induces cis-trans isomerization and disrupts protein-carotenoid complexes. Many dietary components also impact lycopene bioavailability, like the amount and type of fat present with the intake and processing of tomato products, the amount and type of fiber present, and the interaction between carotenoids. Fundamentally, anything that enhances formation and incorporation of lycopene in bile acid micelles increases bioavailability, and the opposite is true in that anything that interferes with micelle formation decreases bioavailability.

Bioavailability of Lycopene from Tomato Products

Shi, John,Naughton, Laura-Mac,Kakuda, Yukio,Bettger, William,Yeung, David,Jiang, Yueming The Korean Society of Food Science and Nutrition 2004 Preventive Nutrition and Food Science Vol.9 No.1

Tomatoes and tomato products are the major source of lycopene in the diet. The bioavailability of lycopene is different in raw tomatoes compared to processed tomato products. This is due to the chemical and physical properties of the different lycopene isomers. All-trans-lycopene is found in raw tomatoes and is a poor bioavailable source, whereas, processed tomato products are more bioavailable because they contain more cis-isomers. Heat and mechanical processing of tomatoes induces rupture of the cell walls, thereby releasing lycopene from its food matrix. Heat processing also induces cis-trans isomerization and disrupts protein-carotenoid complexes. Many dietary components also impact lycopene bioavailability, like the amount and type of fat present with the intake and processing of tomato products, the amount and type of fiber present, and the interaction between carotenoids. Fundamentally, anything that enhances formation and incorporation of lycopene in bile acid micelles increases bioavailability, and the opposite is true in that anything that interferes with micelle formation decreases bioavailability.