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991.
Euphorbia helioscopia L is widespread in China and has a large number of flavonoids. Quercetin glycosides, having useful biological activities,
are abundant in this plant, and no validated analytical method has so far been developed for their determination. We, therefore,
standardized a reversed-phase high-performance liquid chromatography (RP-HPLC) assay for quercetin detection. For this, the
plant was locally procured and identification was confirmed based on its morpho-histological characteristics. Ethyl acetate
extracts of leaves, stems, and roots were analyzed by RP-HPLC using Agilent 1120 HPLC TC-C18 column (250 × 4.6 mm; 5 μm) with UV-detector system. The mobile phase of methanol-0.2% phosphoric acid (65:35) solution was
used with the flow rate of 1.0 ml min−1 at 30°C, and the detection was performed at 360 nm wavelength. Our data show that the linear range of quercetin was 0.025–0.150 mg.ml−1 (r = 0.9995; n = 6) with the recovery rate of 97.50–103.30% (average 100.40%; RSD = 2.28%). The target component was baseline separated
during only the period of 9 min. The repeatability of RP-HPLC analysis was demonstrated with an RSD of 1.77% (n = 6), and the highest quercetin content (average 1.42 mg g−1dry-weight) was present in leaves. It was, therefore, concluded that RP-HPLC is a simple, rapid, accurate, and sensitive method
for the detection of quercetin from Euphorbia helioscopia L. 相似文献
992.
Emergy evaluations of three aquaculture systems on wetlands surrounding the Pearl River Estuary,China 总被引:1,自引:0,他引:1
Emergy and economic analysis, accompanied by sensitivity analysis, were used to evaluate the ecological economic characteristics of three fish aquaculture systems on wetlands surrounding the Pearl River Estuary in China. The sustainability of these systems was compared to two aquaculture systems and two wetland systems, to provide reference conditions for the best use of limited wetland areas. We found that the three systems studied had similar emergy characteristics, despite their very different economic characteristics. Counter intuitively, the high economic input and output mode did not have higher environmental impact or lower sustainability compared with low economic input and output mode. Apparently, the sustainability of an intensive aquaculture system is determined mainly by how many natural renewable resources are exploited. The large differences in economic benefit and environmental impacts between the mangrove reserve and the aquaculture systems demonstrated the important role of nature reserves on preserving the sustainability of an estuary. Transformity (TR) and Emergy Yield Ratio (EYR) are both indicators of system efficiency, but from different points of view, and they produced opposite results in assessing the efficiency of the same system in this study. The ratio of EYR to TR might be used in addition to the EYR and transformity as a discreet perspective on overall system production efficiency. 相似文献
993.
运用生物信息学的方法,对已在GenBank数据库中注册的大豆、海红豆、凤凰木、象耳豆及洋紫荆等植物Kunitz蛋白酶抑制剂的氨基酸序列进行分析.结果显示,这些植物的Kunitz蛋白酶抑制剂中甘氨酸、谷氨酸、亮氨酸、丝氨酸、天冬氨酸及缬氨酸含量较丰富;不同植物Kunitz蛋白酶抑制剂的氨基酸序列具有较高的同源性,其中P1位点的氨基酸残基序度保守;分子进化研究表明Kunitz蛋白酶抑制剂可作为植物遗传分化和分子进化研究的重要依据;部分序列中存在信号肽;分子中不存在跨膜结构域,可能受蛋白激酶C的磷酸化;无规卷曲是多肽链中的主要结构元件;分子中包含典型的STI功能结构域. 相似文献
994.
紫茎泽兰9-羰基-10,11-去氢泽兰酮分布积累动态 总被引:1,自引:0,他引:1
9-羰基-10,11-去氢泽兰酮为紫茎泽兰(Eupatorium adenophorum)的主要致肝脏毒性成分及杀虫的生物活性成分。从紫茎泽兰叶片中分离提纯得到9-羰基-10,11-去氢泽兰酮(Euptox A)标准品,建立了高效液相色谱法测定紫茎泽兰中Euptox A含量的分析方法。采用C18反相色谱柱,柱温30°C,以甲醇-水(60:40,v/v)为流动相、流速为0.8 mL.min–1、检测波长为255 nm进行测定。Euptox A在紫茎泽兰中的添加回收率为97.3%–103.7%,检测限为0.4μg.g–1。利用建立的方法测定Euptox A在紫茎泽兰体内分布与积累的动态变化规律。结果表明,Euptox A主要分布在紫茎泽兰的叶片中,且在营养生长期积累量高,生殖生长期积累量低。该方法快速、简捷,可用于紫茎泽兰原料及其产品中Euptox A成分的测定。 相似文献
995.
996.
Liu SG Wang BS Jiang YY Zhang TT Shi ZZ Yang Y Yang YL Wang XC Lin DC Zhang Y Yang H Cai Y Zhan QM Wang MR 《Molecular cancer research : MCR》2011,9(4):390-402
Protein kinase Cι (PKCι) is an atypical PKC isoform and participates in multiple aspects of the transformed phenotype in human cancer cells. We previously reported that frequent amplification and overexpression of PKCι were correlated with lymph node metastasis in primary esophageal squamous cell carcinomas (ESCC). In the present study, short interfering RNA-mediated silencing of PKCι revealed that this enzyme was required for cell migration, invasion, and resistance to anoikis. In vivo experiments showed that PKCι suppression decreased tumor growth in esophageal cancer xenografts and lung metastases in nude mice. At the molecular level, knockdown of PKCι in suspended ESCC cells caused a decrease in S-phase kinase-associated protein 2 (SKP2) that had been reported to promote resistance to anoikis via the PI3K/AKT pathway. AKT phosphorylation was abolished after PKCι suppression, but AKT activation could be refreshed by PKCι upregulation, suggesting that PKCι enhanced cell resistance to anoikis via the PKCι-SKP2-PI3K/AKT pathway. Addition of the proteasome inhibitor MG132 prevented the decrease of SKP2 in PKCι silenced cells, and polyubiquitin-SKP2 was elevated after PKCι depletion, showing that PKCι might regulate the expression of SKP2 through the ubiquitin-proteasome pathway in suspended cells. Furthermore, overexpression of SKP2 in PKCι-downregulated cells restored cell resistance to anoikis. Most importantly, PKCι expression significantly correlated with SKP2 in 133 ESCC tissues (P = 0.031). Taken together, our data show that PKCι promotes tumorigenicity and metastasis of human esophageal cancer and that SKP2 is a candidate downstream effector of PKCι signaling in ESCC. 相似文献
997.
Won KJ Lee P Jung SH Jiang X Lee CK Lin HY Kang H Lee HM Kim J Toyokuni S Kim B 《Proteomics》2011,11(2):193-201
3-Morpholinosydnonimine (SIN-1) affects vascular smooth muscle cell migration and proliferation, processes essential for atherosclerosis. However, the mechanism by which SIN-1 exerts these effects has not been elucidated. We used 2-DE followed by MALDI-TOF/TOF MS to identify responses in protein expression to SIN-1 in rat aortic smooth muscle. Platelet-derived growth factor-BB increased cell migration and proliferation in rat aortic smooth muscle cells, and subsequent SIN-1 treatment inhibited it. Administration of SIN-1 in vivo attenuated neointima formation in balloon-injured rat carotid arteries. Proteomic analysis showed that glutathione peroxidase and 40S ribosomal protein S12 were differentially expressed in aortic strips exposed to SIN-1. Expression of annexin A2 was decreased by SIN-1. Platelet-derived growth factor-BB-induced cell migration was increased and inhibited in rat aortic smooth muscle cells with overexpression and knockdown of annexin A2 gene, respectively. The expression of annexin A2 was increased in vascular neointima compared with the intact control, which was inhibited by SIN-1 treatment. These results demonstrate that SIN-1 may attenuate vascular neointima formation by inhibiting annexin A2-mediated migration. Therefore, annexin A2 may be a potential target for therapeutic strategies for atherosclerosis. 相似文献
998.
Han H Miyoshi Y Ueno K Okamura C Tojo Y Mita M Lindner W Zaitsu K Hamase K 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2011,879(29):3196-3202
For a metabolomics study focusing on the analysis of aspartic and glutamic acid enantiomers, a fully automated two-dimensional HPLC system employing a microbore-ODS column and a narrowbore-enantioselective column was developed. By using this system, a detailed distribution of D-Asp and D-Glu besides L-Asp and L-Glu in mammals was elucidated. For the total analysis concept, the amino acids were first pre-column derivatized with 4-fluoro-7-nitro-2,1,3-benzoxadiazole (NBD-F) to be sensitively and fluorometrically detected. For the non-stereoselective separation of the analytes in the first dimension a monolithic ODS column (750 mm × 0.53 mm i.d.) was adopted, and a self-packed narrowbore-Pirkle type enantioselective column (Sumichiral OA-2500S, 250 mm × 1.5 mm i.d.) was selected for the second dimension. In the rat plasma, RSD values for intra-day and inter-day precision were less than 6.8%, and the accuracy ranged between 96.1% and 105.8%. The values of LOQ of D-Asp and D-Glu were 5 fmol/injection (0.625 nmol/g tissue). The present method was successfully applied to the simultaneous determination of free aspartic acid and glutamic acid enantiomers in 7 brain areas, 11 peripheral tissues, plasma and urine of Wistar rats. Biologically significant D-Asp values were found in various tissue samples whereas for D-Glu the values were very low possibly indicating less significance. 相似文献
999.
Liu C Wang H Jiang Y Du Z 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2011,879(7-8):533-540
A rapid, sensitive, and specific method for the determination of amoxicillin (AMO), amoxicilloic acid (AMA), amoxicillin diketopiperazine-2′,5′-dione (DIKETO), penicillin G (PEN G), benzylpenicilloic acid (BPA-1), benzylpenilloic acid (BPA-2), and benzylpenillic acid (BPA-3) in bovine milk using ultra-high-performance liquid chromatography–tandem mass spectrometry (UHPLC–MS/MS) was developed and validated. The method used penicillin V (PEN V) as the internal standard and ethanol for the deproteinisation of bovine milk. Chromatographic separation of the components was performed on a Waters Acquity UPLC® HSS T3 column (100 mm × 2.1 mm, 1.8 μm) using a mixture of 0.15% formic acid in water with 5 mM ammonium acetate and acetonitrile as the mobile phase. Gradient elution was performed at a flow rate of 0.25 mL min?1. The mass spectrometer was operated in the positive electrospray ionisation MS/MS mode. The method was fully validated according to EU requirements, including linearity, precision, trueness, limit of quantification, limit of detection, and specificity. The results were within the ranges specified. The established method was successfully applied in the determination of AMO, PEN G, and their major metabolites in 40 commercial bovine milk samples. The results showed that 8 samples were contaminated with BPA-1 or BPA-2. The mean levels (occurrence) of BPA-1 and BPA-2 in positive samples were 287 (50%) and 320 (100%) ng mL?1, respectively. No sample was found to be contaminated with AMO, AMA, DIKETO, PEN G, and BPA-3. These findings could play an important role in food safety, because BPA-1 and BPA-2 metabolites pose possible health risks, although they are not included in the maximum residue limit legislation. 相似文献
1000.
Hai Yu Shaowei Li Chunyan Yang Minxi Wei Cuiling Song Zizheng Zheng Ying Gu Hailian Du Jun Zhang Ningshao Xia 《Journal of molecular modeling》2011,17(5):987-995
P239, a truncated construct of the hepatitis E virus (HEV) ORF2 protein, has been proven able to bind with a chaperone, Grp78,
in both an in vitro co-immune precipitation test and an in vivo cell model. We previously solved the crystal structure of
E2s—the C-terminal domain of p239 involved in host interactions. In the present study, we built a 3D structure of Grp78 using
homology modeling methods, and docked this molecule with E2s using the Zdockpro module of the InsightII software package.
The modeled Grp78 structure was deemed feasible by profile 3D evaluation and molecular dynamic simulations. The docking result
consists of six clusters of distinct complexes and C035 was selected as the most reasonable. The interacting interface of
the predicted complex is comprised of the Grp78 linker region and nucleotide binding domain along with the E2s groove region
and surrounding loops. Using energy, hydrogen bond and solvent accessible surface analyses, we identified a series of key
residues that may be involved in the Grp78:E2s interaction. By comparing with the known structure of the Hsp70:J complex,
we further concluded that the interaction of Grp78 and E2s could interrupt binding of Grp78 with the J domain, and in turn
diminish or even eliminate the binding ability of the Grp78 substrate binding domain. The predicted series of key residues
also provides clues for further research that should improve our understanding of the fundamental molecular mechanisms of
HEV infection. 相似文献