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871.
Tanabe T Ogamino T Shimizu Y Imoto M Nishiyama S 《Bioorganic & medicinal chemistry》2006,14(8):2753-2762
Synthesis of the verbenachalcone derivatives 3-5 involving littorachalcone 2 from diaryl ether 7 enabled an SAR study of enhancement activity against the NGF-mediated neurite outgrowth from PC12D cells. Littorachalcone 2 and o-deoxyverbenachalcone 5 showed similar activity to that of verbenachalcone 1. 相似文献
872.
Isolation of a new anti-allergic phlorotannin, phlorofucofuroeckol-B, from an edible brown alga, Eisenia arborea 总被引:1,自引:0,他引:1
Sugiura Y Matsuda K Yamada Y Nishikawa M Shioya K Katsuzaki H Imai K Amano H 《Bioscience, biotechnology, and biochemistry》2006,70(11):2807-2811
Eisenia arborea is an edible brown alga occasionally used as a folk medicine in gynecopathy in Japan. A new phlorotannin was isolated from the alga during our search for naturally occurring anti-allergic compounds from edible algae guided by the inhibitory effect on histamine release from rat basophile leukemia (RBL)-2H3 cells. The phlorotannin was called "phlorofucofuroeckol-B." Its structure was determined by spectral analysis and chemical conversion. This paper describes the isolation, structure elucidation, and inhibitory effect of phlorofucofuroeckol-B on histamine release. 相似文献
873.
Abe M Ozawa Y Uda Y Morimitsu Y Nakamura Y Osawa T 《Bioscience, biotechnology, and biochemistry》2006,70(10):2494-2500
We screened myoga extracts for inhibitors of human platelet aggregation and human 5-lipoxygenase. We identified a novel labdane type of diterpene, together with three known diterpenes (miogadial and galanals A and B) from the flower buds of myoga. Spectroscopic data indicated the structure of the new compound to be 12(E)-labdene-15,16,(8beta)17-trial (miogatrial). Miogatrial and miogadial were potent inhibitors of human platelet aggregation and human 5-lipoxygenase (5-LOX). The sesquiterpene, polygodial, also exhibited strong inhibitory activity against human platelet aggregation and 5-LOX. On the other hand, galanals A and B did not have inhibitory activity in either experimental system. It thus appears that a 3-formyl-3-butenal structure was essential for the potent inhibition of human platelet aggregation and human 5-LOX. 相似文献
874.
An important and promising group of compounds that have a chemopreventive property are organosulfur compounds, such as isothiocyanates (ITCs). In recent years, it has been shown that ITCs induce apoptosis in various cancer cell lines and experimental rodents. During the course of apoptosis induction by ITC, multiple signal-transduction pathways and apoptosis intermediates are modulated. We have also clarified the molecular mechanism underlying the relationship between cell cycle arrest and apoptosis induced by benzyl isothiocyanate (BITC), a major ITC compound isolated from papaya. The exposure of cells to BITC resulted in the inhibition of the G2/M progression that coincided with not only the up-regulated expression of the G2/M cell cycle arrest-regulating genes but also the apoptosis induction. The experiment using the phase-specific synchronized cells demonstrated that the G2/M phase-arrested cells are more sensitive to undergoing apoptotic stimulation by BITC than the cells in other phases. We identified the phosphorylated Bcl-2 as a key molecule linking the p38 MAPK-dependent cell cycle arrest with the JNK activation by BITC. We also found that BITC induced the cytotoxic effect more preferentially in the proliferating normal human colon epithelial cells than in the quiescent cells. Conversely, treatment with an excessive concentration of BITC resulted in necrotic cell death without DNA ladder formation. This review addresses the biological impact of cell death induction by BITC as well as other ITCs and the involved signal transduction pathways. 相似文献
875.
Nakamura U Iwase M Uchizono Y Sonoki K Sasaki N Imoto H Goto D Iida M 《Free radical biology & medicine》2006,40(11):2047-2055
Pancreatic beta-cell death induced by oxidative stress plays an important role in the pathogenesis of diabetes mellitus. We studied the relation between rapid intracellular acidification and cell death of pancreatic beta-cell line NIT-1 cells exposed to H2O2 or alloxan. Intracellular pH was measured by a pH-sensitive dye, and cell damage by double staining with Annexin-V and propidium iodide using flow cytometry. H2O2 and alloxan caused a rapid fall in intracellular pH and suppressed Na+/H+ exchanger activity in the NH4Cl prepulse method. H2O2 induced necrotic cell death, which shifted to apoptotic cell death when initial acidification was prevented by pH clamping to 7.4 using nigericin (unclamped cells vs clamped cells, necrosis 43.8 +/- 5.8% vs 21.1 +/- 10.6%, P < 0.05; apoptosis 8.0 +/- 1.9% vs 44.5 +/- 5.0%, P < 0.01). pH-clamped cells showed enhanced caspase 3 activity and proapoptotic Bax expression. On the other hand, NIT-1 cells were resistant to alloxan toxicity, but treatment with alloxan and nigericin strikingly enhanced the cytotoxicity. Antioxidants partly prevented cell death, although intracellular pH remained similarly acidic. The rapid intracellular acidification was not the cause of cell death but a significant determinant of the mode of death of H2O2 -treated beta cells, whereas no link between cell death and acidification was demonstrated in alloxan toxicity. 相似文献
876.
Khokon MA Uraji M Munemasa S Okuma E Nakamura Y Mori IC Murata Y 《Bioscience, biotechnology, and biochemistry》2010,74(11):2313-2315
Chitosan induced stomatal closure in wild type-plants and NADPH oxidase knock-out mutants (atrbohD atrbohF), and reactive oxygen species (ROS) production in wild-type guard cells. Closure and production were completely abolished by catalase and a peroxidase inhibitor. These results indicate that chitosan induces ROS production mediated by peroxidase, resulting in stomatal closure. 相似文献
877.
Mori T Ishii T Akagawa M Nakamura Y Nakayama T 《Bioscience, biotechnology, and biochemistry》2010,74(12):2451-2456
In this study, we investigated the relationship between the stability of catechins and their electrophilic reactivity with proteins. The stability of catechins was evaluated by HPLC analysis. Catechol-type catechins were stable in a neutral buffer, but pyrogallol-type catechins, such as (-)-epigallocatechin gallate (EGCg), were unstable. The electrophilic reactivity of catechins with thiol groups in a model peptide and a protein was confirmed by both mass spectrometry and electrophoresis/blotting with redox-cycling staining. In a comparison of several catechins, pyrogallol-type catechins had higher reactivity with protein thiols than catechol-type catechins. The instability and reactivity of EGCg were enhanced in an alkaline pH buffer. The reactivity of EGCg was reduced by antioxidants due to their ability to prevent EGCg autoxidation. These results indicate that the instability against oxidation of catechins is profoundly related to their electrophilic reactivity. Consequently, the difference in these properties of tea catechins can contribute to the magnitude of their biological activities. 相似文献
878.
Hoque MA Uraji M Banu MN Mori IC Nakamura Y Murata Y 《Bioscience, biotechnology, and biochemistry》2010,74(10):2124-2126
Methylglyoxal (MG) is one of the aldehydes that accumulate in plants under environmental stress. Glutathione S-transferases (GSTs) play important roles, including detoxification, in the stress tolerance systems of plants. To determine the effects of MG, we characterized recombinant GST. MG decreased GST activity and thiol contents with increasing K(m). GST can serve as a target of MG modification, which is suppressed by application of reduced glutathione. 相似文献
879.
Takako Ishida Yoshimasa Takizawa Takashi Kainuma Jin Inoue Tsutomu Mikawa Takehiko Shibata Hidekazu Suzuki Satoshi Tashiro Hitoshi Kurumizaka 《Nucleic acids research》2009,37(10):3367-3376
RAD51, an essential eukaryotic DNA recombinase, promotes homologous pairing and strand exchange during homologous recombination and the recombinational repair of double strand breaks. Mutations that up- or down-regulate RAD51 gene expression have been identified in several tumors, suggesting that inappropriate expression of the RAD51 activity may cause tumorigenesis. To identify chemical compounds that affect the RAD51 activity, in the present study, we performed the RAD51-mediated strand exchange assay in the presence of 185 chemical compounds. We found that 4,4′-diisothiocyanostilbene-2,2′-disulfonic acid (DIDS) efficiently inhibited the RAD51-mediated strand exchange. DIDS also inhibited the RAD51-mediated homologous pairing in the absence of RPA. A surface plasmon resonance analysis revealed that DIDS directly binds to RAD51. A gel mobility shift assay showed that DIDS significantly inhibited the DNA-binding activity of RAD51. Therefore, DIDS may bind near the DNA binding site(s) of RAD51 and compete with DNA for RAD51 binding. 相似文献
880.
Haitao Wu Hang Qi Dai Iwasaki Beiwei Zhu Yasuaki Shimoishi Yoshiyuki Murata Yoshimasa Nakamura 《Free radical biology & medicine》2009,47(7):1028-1038
(–)-Epigallocatechin-3-gallate (EGCG) has been reported to possess a wide range of biological and pharmacological properties. In this study, we investigated the effects of EGCG on IL-13 gene expression in human basophilic KU812 cells. The IL-13 mRNA expression level was dose-dependently increased by treatment with EGCG (5–20 μM) for 1 h and additional incubation in a medium for 23 h. EGCG significantly increased the intracellular peroxide level as detected by the peroxide-sensitive probe 2′,7′-dichlorodihydrofluorescein diacetate. A pharmacological experiment using catalase and a structure–activity relationship study revealed that the exogenously produced H2O2 significantly, but partially, contributed to the IL-13 expression as well as the intracellular oxidative status. Furthermore, EGCG at the concentration required for IL-13 up-regulation activated c-Jun NH2-terminal kinase (JNK), but not extracellular signal-regulated protein kinase or p38 mitogen-activated protein kinase in KU812 cells. Transfection of a JNK-specific siRNA as well as treatment with a JNK-specific inhibitor, SP600125, significantly reduced the EGCG-induced IL-13 mRNA expression, by 47.1 and 44.6%, respectively. In addition, we observed the nuclear translocation, mRNA up-regulation, and activation of DNA binding with the IL-13 promoter of nuclear factor of activated T cells (NFATc1) in the EGCG-treated cells. These data provide biological evidence that EGCG induces IL-13 mRNA expression via the JNK-dependent NFATc1 pathway in KU812 cells. 相似文献