顶空-气相色谱-质谱法分析线叶旋覆花不同入药部位中挥发性成分的差异

将线叶旋覆花两个入药部位分开裁剪,用水洗净后干燥、粉碎,过孔径为0.25 mm筛网。分取0.02 g粗粉于20 mL顶空瓶中,于120℃加热30 min。所得挥发性成分进入气相色谱仪,以DB-5色谱柱在程序升温条件下分离,用配电子轰击离子源的质谱仪检测,以保留时间、碎片离子峰定性,以面积归一化法定量。结果显示：从线叶旋覆花中鉴定出的挥发性成分分别有46种(茎叶中)和30种(花中),其峰面积占总挥发性成分峰面积的71.11%,99.98%。花和茎叶中共有挥发性成分有8种,特有挥发性成分有22,38种;茎叶中挥发性成分包括烯烃类、酸类、醇类、醛类、烷烃类、芳香烃类、酯类、酮类和其他类化合物各13,5,4,9,7,2,3,2,1种,相对含量分别为18.11%,17.32%,12.16%,8.76%,4.05%,0.41%,0.80%,0.32%,9.18%;花中挥发性成分包括烯烃类、醇类、醛类、芳香烃类和其他类化合物各18,2,5,2,3种,相对含量分别为52.67%,29.35%,11.50%,2.07%,4.39%。不同入药部位中活性成分烯烃类化合物相对含量均较高,挥发性成分的种类和相对...     

QM/MM Study of the Second Harmonic Generation and Two-photon Absorption Properties of a Fluorescent Proteins-Dreiklang

A new reversibly switchable fluorescent protein(RSFP), namely Dreiklang, exhibits prominent feature that the wavelengths for switching and fluorescence are decoupled due to its great different structures between bright and dark states. This feature might also induce some nonlinear optic(NLO) properties changing as switching between two states, which might promote new method of biological science. We employ the QM/MM method to simulate the structures of different states, and study their second harmonic generation(SHG) and two-photon absorption(TPA) properties. And we found different states of Dreiklang have different SHG and TPA responses. The SHG and TPA properties of Dreiklang are correlated to particularly geometrical structures of different states, especially the centrosymmetric or nocentrosymmetric π-stacking structures which are formed by chromophore and beside residue Tyr203, so the SHG and TPA responses could be changed as the light induces switching among different states of Dreiklang. This work would prospectively guide the application of Dreiklang on the NLO technology, and help the development of new RSFP with special NLO function.     

芳基锡烷的合成研究进展

芳基锡烷化合物是参与构筑功能分子中芳基碳碳键和碳杂原子键的一类重要合成中间体. 其在药物化学、材料科学以及有机合成中都具有重要应用, 因此发展其高效新颖的合成方法具有重要的意义. 根据反应机理的类型, 综述了近些年来合成芳基锡烷的方法, 包括(1)芳香亲核试剂的锡化反应; (2)芳香亲电试剂的锡化反应; (3)过渡金属催化的锡化偶联反应; (4)芳基自由基中间体介导的锡化反应; (5)炔烃的环化和串联的锡化反应. 最后, 进一步分析了未来合成芳基锡烷的研究趋势.     

芳香性氨基酸的二次谐波非线性光学性质

采用密度泛函理论(DFT)-B3LYP方法在6-31G^*基组水平上,对芳香性氨基酸分子体系(Phe, [Phe―H]^-,PheH^*, Tyr, [Tyr―H]^-, TyrH⁺, Trp, [Trp―H]^-和TrpH⁺)进行结构优化. 在优化所得构型的基础上, 利用含时密度泛函理论(TDDFT)-B3LYP在6-31G^*基组上计算了它们的激发态性质,并结合态求和方法研究了它们在二次谐波过程中的二阶极化率值. 同时讨论了二次谐波非线性光学响应的起源及其产生变化的原因. 计算结果表明,相对于中性的氨基酸分子, 去质子化和质子化后的氨基酸分子的二阶极化率值都有明显的增加, 且符合规律Phe < PheH⁺ < [Phe―H]^-和Tyr < TyrH⁺ < [Tyr―H]^-. 通过对它们电极化起源的分析, 我们得到对于中性氨基酸分子, 侧链芳香环上的π→π^*跃迁对二阶极化率起主要贡献; 对去质子化和质子化后的氨基酸分子, 吲哚环上的π→π^*电荷跃迁和α碳原子相连的氨基和羧基基团内电荷跃迁对二阶极化率起到同样重要的贡献.