应用SDSL-EPR技术研究溶液中牛血清白蛋白的运动性及构象变化

应用位置定向自旋标记-电子顺磁共振(SDSL-EPR)技术研究牛血清白蛋白(BSA)的运动性、构象特征及其加入芹菜素(Apigenin)后的变化.采用MTSL对BSA的第34位半胱氨酸(Cys)进行标记;通过EPR检测计算旋转相关时间τc及强弱固定化之比S/W研究运动性的变化;通过功率饱和实验检测该位点的易趋性,研究构象特点及其变化.在BSA溶液中加入Apigenin后,τc及S/W值明显降低,说明其Cys位点运动性变快;易趋性检测结果显示,34位Cys位点位于蛋白质表面,加入Apigenin后,该位点构象发生改变,且微环境由亲水性变为疏水性.实验揭示BSA同Apigenin能够相互结合,且引起BSA自由Cys位点的运动性和构象的改变.     

Synthesis and characterization of a new water-soluble sodium 5, 7, 4＇-trihydroxyflavone-6, 3＇-disulfonate

Aim To synthesize a new water-soluble Na 2(C15H8O5)(SO3) 2 and determine its structure.Method The new water-soluble apigenin sulfonated derivative was synthesized by sulfonation with concentrated sulfuric acid at 40℃for half an hour and the products were obtained in ethanol-water(V∶V =1∶1).The structure of the product was identified by IR,NMR spectrum and elemental analysis.Results and Conclusion After highly selective introduced two - SO 3 groups at C3′and C6of the substrate,the new water-soluble apigenin sulfonated derivative,sodium 5,7,4 '-trihydroxyflavone-6,3′-sulfonate was obtained in good yield(78%) at moderate conditions.This method is an ideal synthesis way because of its simple operation,mild reaction conditions,high selectivity,easy separation of the product and higher yield.     

Inhibition of PKB/Akt activity involved in apigenininduced apoptosis in human gastric carcinoma cells

Apigenin is a flavonoid widely distributed in fruits and vegetables. It possesses growth inhibitory properties against numerous cancer cell lines. However,the molecular mechanism(s) by which api-genin elicits its effects have not been fully elucidated. Here we studied whether apigenin inhibits growth and induces apoptosis in human gastric carcinoma cells. We showed that the flavonoid inhibited growth of the cells and caused apoptosis,as evidenced by DNA Ladder,cleavage of pro-caspase-3 in a time-dependent manner. Induction of apoptosis was dependent on inhibition of the PKB/Akt activity. We found that while apigenin had no effect on the expression of Akt and Bad,it inhibited specific phosphorylation of the two proteins that are associated with pro-survival mechanisms. We propose that this important flavonoid induces apoptosis in gastric cancer cells by inhibiting Akt activity. Since Akt is often activated in cancers,our findings may have clinical implications.     

山楂根的化学成分分离和结构鉴定

研究中药山楂根中的化学成分.利用硅胶柱、聚酰胺柱、葡聚糖LH-20柱色谱技术进行分离和纯化,根据理化性质以及UV,IR,ESI-MS,1H-NMR,13CNMR等波谱数据分析鉴定结构.从山楂根中分离鉴定了4种化合物,分别为化合物(Ⅰ)5,7,4'-三羟基黄酮(芹菜素)、化合物(Ⅱ)2,3,4,6-四甲氧基-7-羟基二苯并呋喃、化合物(Ⅲ)β-胡萝卜苷、化合物(Ⅳ)β-谷甾醇.     

丹酰氯荧光猝灭法测定芹菜中芹菜素含量

在pH 7~8的弱碱性条件下,丹酰氯可与芹菜素反应生成一种酚酯化合物,使丹酰氯的内源性荧光发生猝灭,其猝灭程度(ΔF=F0-F)与加入芹菜素的量在一定范围内呈良好的线性关系.在优化的条件下,体系ΔF与芹菜素的浓度在6.40×10-7mol/L~5.92×10-5mol/L范围内线性关系良好,线性回归方程为ΔF=112.18CAp(×10-5mol/L)-1.25,相关系数r=0.9989.检出限为1.92×10-7mol/L,RSD为2.6%~4.1%,加标回收率为98.1%~101.5%.本方法简便、快速,用于芹菜中芹菜素的含量测定结果满意.