Synthesis and pharmacological activities of xanthone derivatives as alpha-glucosidase inhibitors

Considerable interest has been attracted in xanthone and its derivatives because of their large variety of pharmacological activities. In this project, a series of hydroxylxanthones and their acetoxy and alkoxy derivatives were synthesized and evaluated as alpha-glucosidase inhibitors, aimed at clarifying the structure-activity correlation. The results indicated that these xanthone derivatives were capable of inhibiting in vitro alpha-glucosidase with moderate to good activities. Among them, polyhydroxylxanthones exhibited the highest activities and thus may be exploitable as a lead compound for the development of potent alpha-glucosidase inhibitors.     

Arabidopsis thaliana wild type, pho1, and pho2 mutant plants show different responses to exogenous cytokinins.

Despite the involvement of cytokinins in phosphate (Pi) signaling being highlighted, the physiological processes involved remain unclear. In this study, we have evaluated the effect of cytokinins on different physiological responses using wild type (wt) and two Arabidopsis mutants with altered shoot Pi content (pho1 and pho2). Physiological studies were related with those previously described as cytokinin-regulated: including hypocotyl elongation, root growth, anthocyanin accumulation, senescence and relative gene expression. Generally, pho1 mutants showed decreased sensitivity to cytokinin, whereas pho2 mutants showed increased sensitivity to the hormone. This observation applies to inhibition of hypocotyls and root growth and anthocyanin accumulation. However, this effect was not shown during senescence or in the expression of ARR6 (Arabidopsis response regulator, ARR). Interestingly, Pi content in shoot of pho1 mutants increased to wt levels after treatment with cytokinins. These results suggest that the interaction between phosphate signaling and cytokinin signaling may be bidirectional while the differential behavior in response to cytokinin is discussed further.     

一种新型的琼脂糖疏水层析介质开发及其在重组乙肝表面抗原(CHO-HBsAg)分离纯化中的应用

以粒径均一的国产高交联度快速流琼脂糖为基质,采用活化、交联等步骤合成了针对分离纯化CHO-HBsAg的3C间臂的丁基琼脂糖疏水介质,通过控制丁基配基密度提高分离HBsAg的纯化倍数和回收率,获得了纯化倍数约20、HBsAg回收率约80%的介质。评估了合成介质的理化性质,流速为500cm/h时柱压力小于0.06MPa,表明介质具有较高的机械强度和良好的流动性能,介质经过酸、碱、变性剂等处理后化学性质稳定。将介质合成工艺进一步放大到2L介质/批,应用到HBsAg分离纯化的三步层析整和工艺中,结果表明,批量合成的疏水介质,HBsAg回收率与进口介质相当,HBsAg终产品纯度在95%以上,符合国家药典要求。最后考察了介质合成批次间的配基密度的可控性和单批次合成介质的重复使用性,结果表明,合成工艺和介质的重复性能满足产业化要求,这种成本低的介质有望替代目前工业生产广泛使用的进口疏水介质。     

Reovirus mu1 structural rearrangements that mediate membrane penetration

Membrane penetration by nonenveloped reoviruses is mediated by the outer-capsid protein, mu1 (76 kDa). Previous evidence has suggested that an autolytic cleavage in mu1 allows the release of its N-terminally myristoylated peptide, mu1N (4 kDa), which probably then interacts with the target-cell membrane. A substantial rearrangement of the remaining portion of mu1, mu1C (72 kDa), must also have occurred for mu1N to be released, and some regions in mu1C may make additional contacts with the membrane. We describe here a particle-free system to study conformational rearrangements of mu1. We show that removal of the protector protein sigma3 is not sufficient to trigger rearrangement of free mu1 trimer and that free mu1 trimer undergoes conformational changes similar to those of particle-associated mu1 when induced by similar conditions. The mu1 rearrangements require separation of the mu1 trimer head domains but not the mu1N/C autocleavage. We have also obtained a relatively homogeneous form of the structurally rearranged mu1 (mu1*) in solution. It is an elongated monomer and retains substantial alpha-helix content. We have identified a protease-resistant approximately 23-kDa fragment of mu1*, which contains the largely alpha-helical regions designated domains I and II in the conformation of mu1 prior to rearrangement. We propose that the mu1 conformational changes preceding membrane penetration or disruption during cell entry involve (i) separation of the beta-barrel head domains in the mu1 trimer, (ii) autolytic cleavage at the mu1N/C junction, associated with partial unfolding of mu1C and release of mu1N, and (iii) refolding of the N-terminal helical domains of mu1C, with which mu1N was previously complexed, accompanied by dissociation of the mu1 trimer.     

Catalpol protects dopaminergic neurons from LPS-induced neurotoxicity in mesencephalic neuron-glia cultures

Inflammation plays an important role in the pathogenesis of Parkinson's disease (PD). Microglia, the resident immune cells in the central nervous system, are pivotal in the inflammatory reaction. Activated microglia can induce expression of inducible nitric-oxide synthase (iNOS) and release significant amounts of nitric oxide (NO) and TNF-alpha, which can damage the dopaminergic neurons. Catalpol, an iridoid glycoside, contained richly in the roots of Rehmannia glutinosa, was found to be neuroprotective in gerbils subjected to transient global cerebral ischemia. But the effect of catalpol on inflammation-mediated neurodegeneration has not been examined. In this study, microglia in mesencephalic neuron-glia cultures were activated with lipopolysaccharide (LPS) and the aim of the study was to examine whether catalpol could protect dopaminergic neurons from LPS-induced neurotoxicity. The results showed that catalpol significantly reduced the release of reactive oxygen species (ROS), TNF-alpha and NO after LPS-induced microglial activation. Further, catalpol attenuated LPS-induced the expression of iNOS. As determined by immunocytochemical analysis, pretreatment by catalpol dose-dependently protected dopaminergic neurons against LPS-induced neurotoxicity. These results suggest that catalpol exerts its protective effect on dopaminergic neurons by inhibiting microglial activation and reducing the production of proinflammatory factors. Thus, catalpol may possess therapeutic potential against inflammation-related neurodegenerative diseases.     

Development of rabbit monoclonal and polyclonal antibodies for detection of site-specific histone modifications and their application in analyzing overall modification levels

In addition to DNA sequence information,site-specific histone modifications are another important determinant ofgene expression in a eukaryotic organism.We selected four modification sites in common histones that are known tosignificantly impact chromatin function and generated monoclonal or polyclonal antibodies that recognize each of thosesite-specific modifications.We used these antibodies to demonstrate that the site-specific histone modification levelsremain relatively constant in different organs of the same organism.We also compared the levels of selected histonemodifications among several representative organisms and found that site-specific modifications are highly variable amongdifferent organisms,providing new insight into the evolutionary divergence of specific histone modifications.     

用超声法从花锚中提取(口山)酮类化合物

用超声法从高原植物椭圆叶花锚的全草中,提取并分离出2种针状结晶化合物;采用元素分析(EA)、核磁共振波谱(NMR)、质谱(MS)、红外光谱(IR)、紫外光谱(UV)、熔点测定等分析方法,对其化学结构进行表征;产物分别为1,3-二羟基-4,5,8-三甲氧基酮和1-羟基-2,3,4,8-四甲氧基酮。     

滇西北香格里拉县大型真菌资源及其利用现状

香格里拉县（中旬县）位于云南省西北部,该区域内地形地貌复杂,海拔高差悬殊,兼有温带和寒温带高山气候类型。该区具有典型的温性、寒温性针叶林和寒温性常绿阔叶林以及针阔混交林,其中有不少是能与大型真菌形成共生关系的树种,如云南松（Pinus yunnanensis Franch．）、高山松（P．densata Mast．）、川滇高山栎（Quercus aquifolioides Rehd．etWils．）、灰背栎（Q．senescens Hand．-Mazz．）以及高山桦（Betula delavayi Franch．）和白桦（B．platyphylla Suk．）等。     

反义CD151基因转染对大鼠血管平滑肌细胞迁移的影响

目的观察pcDNA3.1真核表达载体介导的反义CD151基因转染对培养的大鼠动脉平滑肌细胞(VSMCs)迁移的影响。方法构建携带全长正义和反义CD151的真核表达载体pcDNA3.1-CD151和pcDNA3.1-anti-CD151重组质粒,转染体外培养的VSMCs,以RT-PCR和Western blot方法检测CD151的表达,用Boyden趋化小室方法观察细胞迁移。结果与载体对照组、脂质体对照组和空白对照组3组均值比较,转染48h后,反义CD151组mRNA表达降低58%,蛋白表达降低51%,正义CD151组的VSMCs CD151mRNA表达增加171%,蛋白表达增加133%;趋化迁移的细胞数,反义CD151组为37.9±6.3,正义CD151组为86.5±12.4;载体对照组、脂质体对照组和空白对照组分别为60.3±7.1、61.8±7.6和67.3±9.6。反义CD151组显著低于其余各组(P<0.01),正义CD151组显著高于其余各组(P<0.01)。结论pcDNA3.1真核表达载体介导的反义CD151转染,通过抑制CD151的表达,能够显著抑制大鼠VSMCs的迁移。     

TBa多克隆抗体的制备及其重组蛋白免疫活性的鉴定

目的:TBa(tartary buckwheat allergen)是苦荞麦中的主要过敏原。为了研究TBa的结构与功能关系并鉴定其重组蛋白的特异性免疫活性。方法:采用之前从种子中分离纯化的天然TBa作为抗原免疫小鼠,制备抗血清,建立了类似竞争酶联免疫吸附检测TBa的分析方法。结果:对重组TBa的免疫活性鉴定表明,采用该方法制备的多克隆抗体能满足重组TBa的免疫活性鉴定,这为下一步研究其免疫学功能奠定了基础。