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31.
The binding of amines to artificial zinc-porphyrin receptors 1-4 was examined in basic aqueous solutions. For nicotinic acid and 3,5-dicarboxypyridine, substantial binding enhancements were observed compared to other amines with no pi system or carboxyl group. This observation suggested that interligand attractions of Coulomb and CH-pi interactions in addition to N-atom coordination can act effectively as recognition factors. The differences in the Coulomb interaction between carboxylate and sulfonate anions were also discussed. 相似文献
32.
Yoshikawa M Morikawa T Asao Y Fujiwara E Nakamura S Matsuda H 《Chemical & pharmaceutical bulletin》2007,55(4):606-612
The methanolic extract from the flowers buds of Camellia japonica L. (Theaceae) were found to exhibit potent inhibitory activities on ethanol- or indomethacin-induced gastric mucosal lesions in rats. Through bioassay-guided separation, 28-noroleanane-type triterpene oligoglycosides, camelliosides A, B, and C, and an oleanane-type triterpene oligoglycoside, camellioside D, were isolated from the methanolic extract together with five known compounds. The absolute stereostructures of camelliosides were determined on the basis of chemical and physicochemical evidence, which included the structure revision of the nortriterpene aglycons (camellenodiol and camelledionol). The principal oligoglycosides, camelliosides A and B, showed platelet aggregation activity in addition to the gastroprotective effects on ethanol- or indomethacin-induced gastric mucosal lesions in rats. 相似文献
33.
Four new aromatic constituents, rhododendroketoside, (-)-sakuraresinoside, acernikol, and nikoenoside, were isolated from a Japanese folk medicine, the stem bark of Acer nikoense MAXIM. The structures of the new constituents were determined on the basis of chemical and physicochemical evidence. The principle cyclic diarylheptanoids were found to show inhibitory effects on the release of beta-hexosaminidase in RBL-2H3 cells. 相似文献
34.
Y. Saito-Kokubu K. Yasuda M. Magara Y. Miyamoto S. Sakurai S. Usuda H. Yamazaki S. Yoshikawa 《Journal of Radioanalytical and Nuclear Chemistry》2007,273(1):183-186
In order to know the distribution of plutonium derived from the Nagasaki atomic bomb, soil samples were measured to determine
the 240Pu/239Pu isotope ratio of and concentrations of 239+240Pu and 137Cs. The 239+240Pu concentrations in soils, except for Nishiyama area, were close to the average concentration of soil collected in Japan.
In soils collected at the Nishiyama area and at the eastern area of Nagasaki Prefecture and at part of northern area in Kumamoto
Prefecture, the 240Pu/239Pu ratios were lower than the global fallout values. This suggests that plutonium from the atomic bomb was deposited in the
eastern area from the hypocenter reaching up to 100 km eastwards. 相似文献
35.
Makoto Ojika Hideo Kigoshi Kiyotake Suenaga Yoshifumi Imamura Kohji Yoshikawa Takeshi Ishigaki Akira Sakakura Tsuyoshi Mutou Kiyoyuki Yamada 《Tetrahedron》2012,68(4):982-987
Five cytotoxic macrolides, aplyronines D–H (4–8), were isolated from the Japanese sea hare Aplysia kurodai. They are new congeners of the antitumor compound aplyronine A (1), which was previously isolated from the same organism. Their structures were determined by spectroscopic analysis (NMR and MS). The cytotoxicity of these new compounds was evaluated in comparison with that of aplyronines A–C (1–3), suggesting the importance of the 7-O-seryl ester group for mediating the potent cytotoxicity of aplyronines. 相似文献
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39.
Mizooku Y Yoshikawa M Tsuneyoshi T Arakawa R 《Rapid communications in mass spectrometry : RCM》2003,17(16):1915-1918
(-)-Epigallocatechin gallate (EGCG) of catechins changes from non-colored at around neutral pH to yellow at higher pH region in aqueous solution. The pH-dependent oxidation of EGCG was analyzed by liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS). LC/MS/MS analysis of EGCG and its related compounds, (-)-epicatechin gallate (ECG) and (-)-epigallocatechin (EGC), successfully elucidated the structure relationship of EGCG solution involving the color change reaction at different pH conditions. The oxidation species produced at alkaline pH was detected at a different retention time from EGCG in the chromatograms of the EGCG sample. The oxidation species was found to correspond to M+14 (where M is the molecular weight of EGCG), which has two hydrogen atoms removed and addition of one oxygen atom to the gallyl moiety in the B-ring of EGCG. 相似文献
40.
Kazuto Takaishi Bikash Dev Nath Yuya Yamada Hiroyasu Kosugi Tadashi Ema 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(29):10089-10093
Unique self‐assembled macrocyclic multinuclear ZnII and NiII complexes with binaphthyl‐bipyridyl ligands (L) were synthesized. X‐ray analysis revealed that these complexes consisted of an outer ring (Zn3L3 or Ni3L3) and an inner core (Zn2 or Ni). In the ZnII complex, the inner Zn2 part rotated rapidly inside the outer ring in solution on an NMR timescale. These complexes exhibited dual catalytic activities for CO2 fixations: synthesis of cyclic carbonates from epoxides and CO2 and temperature‐switched N‐formylation/N‐methylation of amines with CO2 and hydrosilane. 相似文献