Synthesis,cytotoxicity and topoisomerase II inhibitory activity of lomefloxacin derivatives

A novel series of amide derivatives of lomefloxacin were synthesized and evaluated for their topoisomerase I and II inhibitory activity as well as cytotoxicity against a panel of five human cancer cell lines. Of the compounds prepared compounds 9d and 9g exhibited strong inhibition against topoisomerase II at 100 μM. In addition, docking studies were performed to predict the inhibition mode.     

<i>In vitro</i> Antibacterial Activity of <i>Moringa oleifera</i> Ethanolic Extract against Tomato Phytopathogenic Bacteria

The tomato (Solanum lycopersicum L.) is one of the world’s most important vegetable crops. Still, phytopathogenic bacteria affect the yield and quality of tomato cultivation, like Agrobacterium tumefeciens (At), Clavibacter michiganensis subsp. michiganensis (Cmm), Pseudomonas syringae pv. tomato (Pst), Ralstonia solanacearum (Rs), and Xanthomonas axonopodis (Xa). Synthetic chemical products are used mostly on disease plant control, but overuse generates resistance to bacterial control. This study aimed to evaluate the in vitro antibacterial activity of the ethanolic extract of Moringa oleifera Lam. leaves against At, Cmm, Pst, Rs, and Xa, as well as information about this plant species’ chemical composition. Antibacterial activity against pathogens observed by microplate technique, phytochemical screening, and FTIR analysis revealed different bio-active compounds on ethanolic extracts with antibacterial activity. The growth inhibition rate ranged between 0.08% and 99.94%. The inhibitory concentration, IC50, required to inhibit 50% of At, Cmm, Pst, Rs, and Xa bacterial growth, was 276.67, 350.48, 277.85, 351.49, and 283.22 mg/L, respectively. Inhibition of phytopathogen bacteria’s growth increased as the concentrations of the extract also increased. Moringa oleifera extract can be recommended as a potent bio-bactericide.     

普生轮藻浸提液对两种淡水藻类的化感抑制作用及其数学模型

利用大型水生植物的化感作用抑制水华藻类是水域生态学研究的热点课题之一。探讨了不同浓度普生轮藻浸提液对产毒铜绿微囊藻和斜生栅藻(单纯以及混合藻类)的抑制作用,并根据实验过程中得到的数据和数据特征,在传统的Logistic模型和Lotka-Volterra模型基础上,通过微元法建立了普生轮藻浸提液对单纯产毒铜绿微囊藻、单纯斜生栅藻抑制的数学模型以及两藻混合时抑制的数学模型。结果表明,(1)普生轮藻浸提液无论对单独的毒性铜绿微囊藻或斜生栅藻还是共生状态的毒性铜绿微囊藻和斜生栅藻均有很强抑制作用,且对毒性铜绿微囊藻的抑制作用要显著高于对斜生栅藻;(2)所建立的抑藻模型可有效表征和预测在一定范围内的产毒铜绿微囊藻、斜生栅藻及其混合藻在普生轮藻浸提液胁迫下藻密度随时间变化的规律;通过这些模型可方便地计算出实验期间任何时间节点上普生轮藻浸提液的半抑制浓度(EC50)、最小有效浓度(MIC)等指标的预测值、混合藻在小生境中相对稳定时的预测值等等。该研究可为实际抑藻的方案制定和实施提供有价值的数据支撑和参考,具有一定的理论与应用意义。     

小花杜鹃中两个新的木脂素

研究小花杜鹃(Rhododendron minutiflorum)的化学成分及其α-葡萄糖苷酶抑制活性。采用正相硅胶、ODS、Sephadex LH-20和HPLC等多种色谱技术,从小花杜鹃的95%乙醇提取物中分离得到9个化合物,通过波谱分析和文献数据对比,鉴定其结构分别为rhodominutinan A(1)、rhodominutinan B(2)、3,4-di(4-hydroxy-3-methoxybenzyl)tetrahydrofuran(3)、venkatasin(4)、苔色酸甲酯(5)、苔黑酚羧酸乙酯(6)、2,4-二羟基-3,6-二甲基苯甲酸甲酯(7)、芹菜素(8)、山奈酚(9)。其中化合物1和2为新的木脂素,化合物3~9为首次从小花杜鹃中分离得到。通过α-葡萄糖苷酶抑制剂体外筛选模型评价化合物的潜在降血糖活性,结果表明化合物8和9具有较好的α-葡萄糖苷酶抑制活性,IC₅₀值分别为57.51±6.35、54.70±3.67μM。     

曲酸对台湾乳白蚁纤维素酶活的抑制与应用研究

为了探究有害白蚁的安全防控新技术,本文研究了生物源活性物质曲酸对建筑结构主要害虫台湾乳白蚁纤维素酶活性的抑制效果。在室内条件下选择1%曲酸溶液滤纸饲喂白蚁,分别于饲喂6 h、12 h、1 d、3 d、5 d、7 d时收集白蚁消化道,采用还原糖法测定了白蚁消化道的滤纸酶活性(FPA)及内切β-1,4-葡聚糖酶(EG)、β-葡萄糖苷酶(BG)和纤维二糖水解酶(CBH)的比活力,并观测记录供试白蚁的体重与死亡率变化。结果显示,除6 h处理样的FPA和CBH活性影响不显著外,其余处理对白蚁纤维素酶活性均有显著的抑制作用,且随处理时间的延长曲酸对台湾乳白蚁纤维素酶活抑制率增强,抑制率显示FPAEG≥BGCBH。曲酸处理7d后,白蚁活动能力明显减弱,工蚁体重显著降低且死亡率显著升高。曲酸与氟虫脲联合喂食处理对台湾乳白蚁FPA和EG活性的抑制效果高于氟虫脲单独饲喂台湾乳白蚁,而且白蚁死亡率也显著提高。研究表明曲酸对于白蚁纤维素酶活性具有抑制效果,对于氟虫脲具增效作用,可为白蚁治理新技术的研究提供参考。     

The role of short-chain fatty acids in the interplay between diet,gut microbiota,and host energy metabolism

Short-chain fatty acids (SCFAs), the end products of fermentation of dietary fibers by the anaerobic intestinal microbiota, have been shown to exert multiple beneficial effects on mammalian energy metabolism. The mechanisms underlying these effects are the subject of intensive research and encompass the complex interplay between diet, gut microbiota, and host energy metabolism. This review summarizes the role of SCFAs in host energy metabolism, starting from the production by the gut microbiota to the uptake by the host and ending with the effects on host metabolism. There are interesting leads on the underlying molecular mechanisms, but there are also many apparently contradictory results. A coherent understanding of the multilevel network in which SCFAs exert their effects is hampered by the lack of quantitative data on actual fluxes of SCFAs and metabolic processes regulated by SCFAs. In this review we address questions that, when answered, will bring us a great step forward in elucidating the role of SCFAs in mammalian energy metabolism.     

北京城市与西北远郊地表臭氧浓度梯度移动监测研究

北京城市与区域臭氧浓度逐年升高,对自然生态系统已经构成影响。但地表臭氧在北京城市与远郊梯度空间上的连续递变特征机制尚不清楚。采用移动监测车,搭载臭氧分析仪,选择夏季典型臭氧污染天气,以北京教学植物园为对照点,从北京城市中心向西北远郊方向,多点位连续测定地表臭氧浓度。通过分析臭氧浓度和采样点周围归一化植被指数(NDVI)的关系以及典型臭氧污染情况下的天气形势和气团轨迹,探讨北京城市和区域臭氧浓度连续空间变化特征及机制。结果表明:(1)北京西北山区森林区域臭氧浓度显著高于"城市区域",约为城市区域的2.00倍。十三陵是地表臭氧浓度的分界点,从十三陵开始臭氧浓度陡然升高,在西北山区方向保持在高水平。空间上从高到低的顺序是西北山区(254.68μg/m~3)对照点教学植物园(220.89μg/m~3)城市支路(162.84μg/m~3)城市快速路和高速路(103.24μg/m~3);(2)植被分布影响臭氧空间格局。在相同时间范围内,臭氧浓度和NDVI正相关,随NDVI增加臭氧浓度呈Logistic增长;(3)西北山区地表臭氧空间变异系数为0.11,城市支路上平均为0.28,城市快速路上为0.26,高速公路上为0.36。山区地表臭氧浓度的空间变异系数最小,高速公路最大,城市快速路、城市支路空间变异较大;(4)大范围均压场、高压后部、低压前部等稳定型天气型易造成南向弱气流,能够把空气污染物输送到西北远郊,但本研究中监测到的西北山区高浓度臭氧并非当天从城区输送而来。北京城市与区域臭氧格局与植被的关系及成因需要深入研究。     

QTL detection on porcine chromosome 12 for fatty-acid composition and association analyses of the fatty acid synthase, gastric inhibitory polypeptide and acetyl-coenzyme A carboxylase alpha genes

Refinement of previous QTL on porcine chromosome 12 for fatty-acid composition and a candidate gene association analysis were conducted using an Iberian × Landrace cross. The concentrations of ten fatty acids were assayed in backfat tissue from which four metabolic ratios were calculated for 403 F₂ animals. Linkage analysis identified two significant QTL. The first QTL was associated with the average chain length ratio and the percentages of myristic, palmitic and gadoleic acids. The second QTL was associated with percentages of palmitoleic, stearic and vaccenic acids. Based upon its position on SSC12, fatty acid synthase was tested as a candidate gene for the first QTL and no significant effects were found. Similarly, gastric inhibitory polypeptide ( GIP ) and acetyl-coenzyme A carboxylase alpha ( ACACA ) were tested as candidate genes for the second QTL using three SNPs in GIP and 15 synonymous SNPs in ACACA cDNA sequences. Two missense SNPs in GIP showed significant effects with palmitoleic and stearic fatty-acid concentration. Highly significant associations were found for two SNPs in ACACA with stearic, palmitoleic and vaccenic fatty-acid concentrations. These associations could be due to linkage disequilibrium with the causal mutations.     

Regulation of nitrate reductase in detached oat leaves by light and oxygen

Regulation of nitrate reductase (NR, EC 1.6.6.1) by oxygen concentration and light was studied in segments of oat ( Avena sativa L. cv. Suregrain) leaves, using the in vivo nitrate reductase assay. The activity of NR decreased after excision in either light or darkness; the addition of cycloheximide prevented this decrease. Treatments that increased tissue permeability (anoxia, Triton X-100) also increased NR activity. There was in general less NR activity in the light than in the dark and also less under aerobic (21–100% O₂) than under anaerobic (0.3% O₂) conditions. Treatments with antioxidants improved the activity in the light, but only at high O₂ levels (21–100% O₂).
The results suggest that NR may be regulated by inhibitory proteins synthesized in either light or darkness, by permeability changes and by light-induced oxidations that occur when O₂ is present. Oxygen may control the activity by stimulating the synthesis of inhibitory proteins in the light and in the dark and by promoting oxidation of SH-groups in the light.     

Molecular basis of guanine nucleotide dissociation inhibitor activity of human neuroglobin by chemical cross-linking and mass spectrometry

Oxidized human neuroglobin (Ngb), a heme protein expressed in the brain, has been proposed to act as a guanine nucleotide dissociation inhibitor (GDI) for the GDP-bound form of the heterotrimeric G protein alpha-subunit (Galpha(i)). Here, to elucidate the molecular mechanism underlying the GDI activity of Ngb, we used an glutathione-S-transferase pull-down assay to confirm that Ngb competes with G-protein betagamma-subunits (Gbetagamma) for binding to Galpha(i), and identified the Galpha(i)-binding site in Ngb by chemical cross-linking with 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride and sulfo-N-hydroxysuccinimide, coupled with mass spectrometry (MS). Matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) MS analysis for tryptic peptides derived from the cross-linked Ngb-Galpha(i) complex revealed several binding regions in Ngb. Furthermore, MALDI-TOF/TOF MS analysis of the cross-linked Ngb and Galpha(i) peptides, together with the MS/MS scoring method, predicted cross-linking between Glu60 (Ngb) and Ser206 (Galpha(i)), and between Glu53 (Ngb) and Ser44 (Galpha(i)). Because Ser206 of Galpha(i) is located in the region that contacts Gbetagamma, binding of Ngb could facilitate the release of Gbetagamma from Galpha(i). Binding of Ngb to Galpha(i) would also inhibit the exchange of GDP for GTP, because Ser44 (Galpha(i)) is adjacent to the GDP-binding site and Glu53 (Ngb), which is cross-linked to Ser44 (Galpha(i)), could be located close to GDP. Thus, we have identified, for the first time, the sites of interaction between Ngb and Galpha(i), enabling us to discuss the functional significance of this binding on the GDI activity of Ngb.