Chromatographic analysis of salicylic compounds in different species of the genus Salix

The separation of nine phenol glycosides--salicin, salicortin, 2'-acetylsalicortin, populin, tremulacin, salidroside, triandrin, picein and helicin--by normal phase (NP), reversed phase (RP) HPLC techniques and a coupling of NP and RP monolithic silica columns was studied. Among the above nine compounds only five--salicin, populin, tremulacin, salidroside and triandrin--were resolved in an NP system with a mobile phase comprising hexane/isopropanol/methanol (87:12:1, v/v/v). Optimized separation was performed with two coupled monolithic silica columns of different polarity (bare silica and RP-18). The method was applied to verify the presence of salicylic compounds and other phenolic derivatives in the bark of six species from the genus Salix, namely S. purpurea, S. daphnoides clone 1095, S. alba clone 1100, S. triandra, S. viminalis, and S. herbacea. Gradient elution with a mobile phase composed of acetonitrile and water containing 0.05% of trifluoroacetic acid, with increasing acetonitrile concentration from 3% to 48%, was chosen as optimal. For the selective detection of the salicylic compounds, an evaporative light scattering detector was employed along with a UV detector. The differences in the composition of phenols in the different plant materials were confirmed. Additionally, it must be emphasized that for the first time the presence of 2'-acetylsalicortin was revealed in S. alba clone 1100. Furthermore, an SPE-HPLC method was developed for the rapid analysis of the salicin content, analyzed as free and total fraction, in willow barks. The determined concentrations of total salicin varied from 25.4 mg/g in S. alba clone 1100 to 96.47 mg/g in S. daphnoides clone 1095.     

A new total antioxidant potential measurements using RP-HPLC assay with fluorescence detection

In this paper, an improved total antioxidant potential (TAP) estimation using high-performance liquid chromatographic (HPLC) assay with fluorometric detection has been described. The principle of this method is based on the hydroxyl radicals generated in the Fenton-like reaction and subsequently detected using hydroxyterephthalic acid (HTPA), which is a reaction product of hydroxyl radicals and terephthalic acid (TPA), working as a sensing compound. HTPA quantity in the samples was measured by fluorescence detector working at excitation and emission wavelengths equal to 312 and 428 nm, respectively. A number of key experimental conditions including the influence of the reaction (incubation) time on the surface areas of HTPA peaks, concentration of Fe(II) ions as well as the influence of concentration of TPA on the surface area of the chromatographic peak of HTPA were optimized to the characteristic feature of TAP measurements. The elaborated assay has been used to evaluate TAP values of selected low-molecular mass compounds like pyrogallol, tryptamine, and n-alcohols (methanol, ethanol, and n-propanol) as well as chlorogenic and ascorbic acids and benzoic acid derivatives, which are commonly present in the food samples.     

Ground state and excited state dipole moments of 6,8-diphenylimidazo[1,2-α]pyrazine determined from solvatochromic shifts of absorption and fluorescence spectra

Electronic absorption and dual fluorescence spectra of 6,8-diphenylimidazo[1,2-α]pyrazine (68DIP) was recorded in various solvents with different polarity at room temperature. The ground state (μg) and the excited state (μg) dipole moments of 68DIP were estimated from solvatochromic shifts of absorption and fluorescence spectra as a function of the dielectric constant (?) and refractive index (n). The results show that the value of excited state dipole moment in SE: μeSE=2.8772 D and twisted intramolecular charge transfer (TICT) excited equilibrated state dipole moment value of μeLE=2.9744 D was found. The solvent dependent spectral shifts in absorption and fluorescence spectra were analyzed by the polarizability-polarity and Kamlet-Taft parameters.     

Distribution and chemical polymorphism of the essential oils of Achillea cartilaginea growing wild in Lithuania

The essential oils from 14 Achillea cartilaginea samples (leaves and flowers) collected from natural habitats in Lithuania were analysed by GC-MS. In total, 97 compounds were identified, 69 of which have not been reported previously in this species. In general, the essential oils of A. cartilaginea were rich in oxygenated monoterpenes. Remarkable chemical polymorphism was observed within the population of A. cartilaginea in Lithuania. It was observed that 1,8-cineole, camphor, cis-chrysanthenol, β-thujone, sabinol, chrysanthenone, terpinen-4-ol, bornyl acetate and β-sesquiphellandrene were the major constituents in the oils of the analysed plants. Hierarchical cluster analysis, which was based on the 19 major components exceeding 5% in the total oil, indicates the presence of several main chemical groups in the analysed plant populations.     

Ardisikivuoside, a new triterpenoid saponin from Ardisia kivuensis (Myrsinaceae)

Column chromatography of the n-butanol extract of the stem of Ardisia kivuensis (Myrsinaceae) led to the isolation of a new triterpenoid saponin, ardisikivuoside (1) {3-O-beta-D-xylopyranosyl-(1 --> 3)-beta-D-glucopyranosyl-(1 --> 4)-beta-D-xylopyranosyl-3beta-hydroxy-13beta,28-epoxyoleanan-16-oxo-30-al}. The structure was elucidated on the basis of spectral studies.     

Quest for quantum superpositions of a mirror: High and moderately low temperatures

The Born-Markov master equation analysis of the vibrating mirror and photon experiment proposed by Marshall, Simon, Penrose, and Bouwmeester is completed by including the important issues of temperature and friction. We find that at the level of cooling available to date, visibility revivals are purely classical, and no quantum effect can be detected by the setup, no matter how strong the photon-mirror coupling is. Checking proposals of universal nonenvironmental decoherence is ruled out by dominating thermal decoherence; a conjectured coordinate-diffusion contribution to decoherence may become observable on reaching moderately low temperatures.     

OH抽提1-戊醇分子中α-H和β-H引发的大气反应机理的理论研究

采用量子化学密度泛函理论研究了OH抽提1-戊醇分子中α-H和β-H引发的大气反应的机理. 在B3LYP/6-311＋G(3df,2p)//B3LYP/6-31G(d)水平上对该反应体系的反应物、中间体、过渡态及产物进行了几何构型优化和频率计算, 给出了各反应通道的自由能剖面图. 计算结果表明: OH抽提1-戊醇分子中α-H和β-H引发的反应通道的主要产物分别为1-戊醛和1-丁醛; 生成的产物极性和水溶性增强, 易通过成核、水合或吸附反应形成二次有机气溶胶.     

新型α1受体拮抗剂先导化合物的寻找(I): 5-氯-2-(4-(芳氧烷基)哌嗪-1-基)苯并噁唑类化合物的设计、合成及生物活性研究

为寻找用于治疗良性前列腺增生的新型α1受体拮抗剂, 以本研究组发现的2-[(4-(2-(2-氯苯氧基)乙基)哌嗪-1-基)甲基]-5-甲基苯并噁唑(wb5c)为先导化合物, 结合已构建的α1-AR拮抗剂药效团模型, 通过骨架改造, 设计出以苯并噁唑-2-基哌嗪为母核的目标物, 然后以5-氯-2-氨基酚和取代苯酚为原料, 经缩合、卤代、氨化、Williamson醚合成、取代等反应共合成11个新目标化合物, 结构经ESI-MS, 1H NMR, IR及HRMS确证. 初步药理活性实验表明, 目标物具有中等强度α1受体拮抗活性, 符合我们提出的三元素药效团模型. 5-氯-2-[4-(芳氧烷基)哌嗪-1-基]类化合物是一类新的具有潜在开发价值的α1受体拮抗剂.     

Multiple Effective Two-photon Correlated-emission Optical Bistability with Injected Squeezed Vacuum

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