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1.
Kashima M 《Chemical & pharmaceutical bulletin》1999,47(2):279-283
Superoxide (O2-.) was reduced by the addition of superoxide dismutase (SOD: O2-. scavenger) and catechins. In competitive reactions utilizing different concentrations of spin-trap agent, the IC50 values of each sample were changed. With regard to the Cu2+/H2O2 and Fe2+/H2O2 reaction systems, metal chelater, hydroxyl radical (.OH) scavenger and catechins eliminated the levels of .OH. For the Cu2+/H2O2 reaction systems, the IC50 for .OH scavenger changed, but that for metal chelater and catechins did not. However, for the Fe2+/H2O2 reaction system, the IC50 for .OH scavenger and catechins changed, whereas that for metal chelater did not. The ESR signal for free Cu2+ was changed by addition of metal chelater and catechins. In the spectrophotometer experiments, it was confirmed that the CuCl2 spectrum was changed by addition of metal chelater and catechins but not by .OH scavenger. Conversely, the FeSO4 spectrum was not changed by addition of .OH scavenger or catechins, but was altered by metal chelater. Lipid peroxidation was inhibited by catechins in a concentration-dependent manner. Therefore, it was suggested that the catechins did not scavenge directly the generated .OH from the Cu2+/H2O2 reaction system, but inhibited the generation of .OH by acting on the Cu2+/H2O2 reaction system. On the other hand, with respect to the .OH generated from the Fe2+/H2O2 reaction system, it was suggested that the catechins had a direct scavenging capacity of the .OH, but had little chelating activity of iron. It was confirmed that catechins have the ability to scavenge for O2-. as well as .OH and to inhibit the generation of .OH by chelation with metal ions. 相似文献
2.
3.
Choji Kashima Tadakuni Tajima And Yoshimori Omote 《Journal of heterocyclic chemistry》1984,21(1):133-137
2-Alken-1-ones, 3,3-di-(1-azolyl)-2-alken-1-ones and related compounds were prepared by two methods. These compounds were found to be the useful precursors for acylketene derivatives such as ketene dithioacetals and diaminals by treatment with various nucleophiles. 相似文献
4.
The proposed structures of patellamides B and C, cytotoxic lipophilic cyclic peptides from a marine tunicate, have been revised on the basis of the spectral data of their partial hydrolysates, and their revised structures have been synthetically confirmed by the use of diphenyl phosphorazidate(DPPA) and diethyl phosphorocyanidate(DEPC). 相似文献
5.
Diethyl phosphorocyanidate (DEPC) can be efficiently used for the synthesis of α-amino nitriles from carbonyl compounds and amines. The reaction may be called a modified Strecker synthesis. 相似文献
6.
Choji Kashima Shigeki Hibi Tatsuya Maruyama Kazuo Harada Yoshimori Omote 《Journal of heterocyclic chemistry》1987,24(3):637-639
The relative reaction rate of five-membered heterocycles with ozone was evaluated. These relative rates were correlated to the highest bond order value in the corresponding ring, calculated by the convenient HMO method. From this correlation, the reactivity of heterocycles with ozone was able to be predicted. Also it was concluded that the predominant product in the ozonolysis of five-membered heterocycles containing an oxygen atom was the corresponding carboxylic acid, while nitrogen heterocycles gave the corresponding amide. 相似文献
7.
Choji Kashima Yumiko Konno Nobutoshi Yoshiwara Tadakuni Tajima 《Journal of heterocyclic chemistry》1982,19(6):1535-1536
The regioselective synthesis of 3-hydroxyisoxazoles and 5-isoxazolones is accomplished by the reaction of β-amino α,β-unsaturated esters with hydroxylamine hydrochloride in the presence of appropriate bases. The total yield of isoxazole derivatives is sensitively influenced on the β-substituent group of the esters. 相似文献
8.
Choji Kashima Katsumi Takahashi Kiyoshi Fukusaka Akira Hosomi 《Journal of heterocyclic chemistry》1998,35(3):503-511
The conjugate additions of N-(α,β-unsaturated)acylpyrazoles were carried out by the treatment with Grignard reagents in the presence of cuprous halides. The reaction of 2-(α,β-unsaturated)acyl-3-phenyl-l-menthopyrazoles 3a-h occurred in higher chemical yields and with asymmetric inductions on β-position, where the addition of magnesium bromide as a Lewis acid influenced to the yields and the diastereoselectivities. In the case of α-methylated 2-(α,β-unsaturated)acyl-3-phenyl-l-menthopyrazoles 3i-n , the excellent asymmetric induction on the α-position was also observed through the diastereofacial protonation. 相似文献
9.
Takeo Kawashiro Fumihiro Yamasawa Yasumasa Okada Hirosuke Kobayashi Kunio Tanabe 《Mathematical Programming》1991,52(1-3):1-9
The uneven distribution of ventilation—perfusion ratios (
) in diseased lungs is the major cause of arterial hypoxemia. Farhi and Yokoyama (1967) and Yokoyama and Farhi (1967) were the first who used physiologically inert gases as indicator gases to assess the uneven distribution of
Wagner and his coworkers in San Diego (1977b) extended the method and elaborated the multiple inert gas elimination technique in which blood flows in 50 compartments with different
were estimated based on data for 6 indicator gases. They analyzed the indicator gas data through an enforced smoothing technique with the ridge regression. To get smooth distributions, they introduced a weighting function for
compartments and an additional treatment for the non-negativity of the blood flow. The weighting function was empirically obtained. We analyzed the data without putting any weights on
compartments nor any additional treatment for non-negativity of blood flow. The analytical method in the present study was a modified Newton method, which is one of the enforced smoothing method. Our method was capable of recovering all distribution patterns that were found through the method reported by Wagner et al. (1977b). 相似文献