Electrochemical study of bergenin on a poly(4-(2-pyridylazo)-resorcinol) modified glassy carbon electrode and its determination in tablets and urine

A very sensitive electroanalytical method was employed to determine bergenin in phosphate buffer with a pH of 6.0, bergenin was accumulated at a 4-(2-pyridylazo)-resorcinol (PAR) polymer film modified glassy carbon electrode (GCE) surface under the condition of open-circuit. In the following anodic sweep from −0.4 to 0.8 V, bergenin adsorbed at the PAR polymer film modified electrode surface, was oxidized and yielded a sensitive oxidation peak at 0.595 V. Due to its unique structure and extraordinary properties, the PAR polymer film shows higher accumulation efficiency toward bergenin compared with a bare GCE. Hence, the amount of bergenin at the PAR polymer film modified GCE surface increases significantly, and finally the oxidation peak current improves greatly. The experimental conditions, such as supporting electrolyte, pH value, accumulation time and scan rate, were optimized for the measurement of bergenin, and a sensitive electroanalytical method was proposed for bergenin determination. The oxidation peak current varies linearly with the concentration of bergenin over the range of 2.0 × 10⁻⁷ to 1.2 × 10⁻⁵ mol/L, and the detection limit is 2.0 × 10⁻⁸ mol/L after 3 min open-circuit accumulation. The relative standard deviation of the same electrode in 10 successive scans is 1.8% for 1.0 × 10⁻⁶ mol/L bergenin and 2.1% for interelectrodes, indicating excellent reproducibility. This new method was successfully demonstrated with bergenin tablets and diluted urine.     

Integrating approach to discover novel bergenin derivatives and phenolics with antioxidant and anti-inflammatory activities from bio-active fraction of Syzygium brachythyrsum

Syzygium brachythyrsum is an important folk medicinal and edible plant in Yunnan ethnic minority community of China, however, little is known about the chemical and bio-active properties. The present study is aimed to identify the bioactive constituents with antioxidant and anti-inflammatory properties by an integrating approach. First, two new bergenin derivatives, brachythol A (1) and brachythol B (2), together with eleven known phenolic compounds (3–13) were isolated from bioactive fractions by phytochemical method. Among these isolated chemicals, five bergenin derivatives, along with 3 phenolics were found in Syzygium genus for the first time. Then, a further chemical investigation based on ultra-high-performance liquid chromatography-Q Exactive Orbitrap mass spectrometry resulted in a total of 107 compounds characterized in the bio-active fractions, including 50 bergenin derivatives, among which 14 bergenin derivatives and 14 phenolics were potential new natural chemicals. Most of the isolated compounds showed obvious antioxidant activities, while compounds 11, 12, and 13 had favorable performance. Eight compounds (2–5, 7, and 9–11) showed good inhibitory activity on nitric oxide (NO) production in macrophage RAW 264.7 cells. The structure–activity correlation analysis indicated that the antioxidation and anti-inflammatory activities enhanced when bergenin was esterified with gallic acid, caffeic acid or ferulic acid. This is the first report of bergenins in Syzygium genus and the richness in new bio-active bergenins and gallic acid derivatives indicated that Syzygium brachythyrsum is a promising functional and medicinal resource.     

岩白菜素的电化学行为及其测定

采用循环伏安法研究岩白菜素在电极上的电化学行为并建立了差示脉冲伏安法对其测定的电化学分析方法。在pH 6.0 PBS缓冲液中,氧化峰电流与岩白菜素的浓度在2.0×10-7~1.2×10-6mol/L范围内呈良好的线性关系,检出限为2.0×10-8mol/L。玻碳电极可有效消除样品中其它组分对岩白菜素测定的干扰,已用于实际样品中岩白菜素的直接测定。     

盘龙七的提取工艺

将盘龙七粉碎除去泥沙,以饱和的石灰水为溶剂,加热回流提取3次,每次4h、合并提取液,常压浓缩至溶液密度为1.15-1.20g/cm<'3>.冷至室温调pH为2-3.70℃保温结晶得岩白菜素粗品.后用95%乙醇加活性炭煮沸脱色,趁热过滤,得精品.     

流动注射-抑制化学发光法测定岩白菜素

本文基于岩白菜素对鲁米诺-牛血清白蛋白体系化学发光信号显著的抑制作用,建立了快速灵敏测定岩白菜素的流动注射-化学发光分析新方法。实验发现,化学发光强度的降低值与岩白菜素质量浓度对数值呈良好的线性关系,方法的线性范围为3.0~5.0×10~5 pg/mL,检出限(3σ)为1.0pg/mL。当溶液流速为2.0mL/min时,完成一次分析过程仅需30s,采样频率120/h。本法用于片剂、人血清和尿液中岩白菜素的含量测定,回收率为98.1%~102.7%,相对标准偏差小于2.0%(n=7)。同时对化学发光反应机理进行了探讨。     

氮杂岩白菜素衍生物的合成及其初步抗肿瘤活性

岩白菜素因其广泛的生理活性而备受关注。本文通过Mannich和Mitsunobu反应,合成了8个氮杂岩白菜素衍生物,其结构经1H NMR、13C NMR及质谱确证。采用MTT法初步测试了目标化合物体外抗肿瘤活性,结果表明,化合物3c和3d对细胞株A549均表现出优于岩白菜素的抑制活性(IC50分别为3.74μmol/L和5.05μmol/L),可做进一步研究。     

Total Synthesis of the Proposed Structure of Ardimerin,and Proposal for its Structural Revision

We report the first total synthesis of the proposed structure of ardimerin, which was achieved in 14 steps starting from 2,3,4‐trimethoxybenzoic acid. The key steps include the β‐selective formation of the crucial C‐glycoside linkage and stepwise construction of the strained eight‐membered salicylide core. The synthesis revealed that the proposed structure 1 does not match the natural product. A proposal is made for reassigning the isolated natural product to the already known structure of bergenin. Interesting properties of the synthetic eight‐membered salicylides are documented, including their susceptibility toward nucleophilic ring opening and the bowl chirality.     

Improving Activity of Salt-Lyophilized Enzymes in Organic Media

Lyophilization with salts has been identified as an important method of activating enzymes in organic media. Using salt-activated enzymes to transform molecules tethered to solid surfaces in organic phase requires solubilization of enzymes in the solvents. Methods of improving performance of salt-lyophilized enzymes, further, via chemical modification, and use of surfactants and surfactants to create fine emulsions prior to lyophilization are investigated. The reaction system used is transesterification of N-acetyl phenylalanine ethyl ester with methanol or propanol. Initial rate of formation of amino acid esters by subtilisin Carlsberg (SC) was studied and found to increase two to sevenfold by either chemical modification or addition of surfactants in certain solvents, relative to the salt (only)-lyophilized enzyme. The method to prepare highly dispersed enzymes in a salt-surfactant milieu also improved activity by two to threefold. To test the effect of chemical modification on derivatization of drug molecules, acylation of bergenin was investigated using chemically modified SC.     

氯过氧化物酶修饰电极用于岩白菜素的电催化氯化

将氯过氧化物酶(CPO)与双十二烷基二甲基溴化铵(DDAB)混合后滴涂于玻碳(GC)电极表面, 制得CPO-DDAB/GC修饰电极. 循环伏安结果显示, 固定在电极表面的CPO可与电极之间发生直接的电子传递作用. 利用高效液相色谱-质谱联用技术对反应产物进行表征, 结果显示, 以该CPO修饰电极为工作电极, 在氧气饱和的氯化钾-岩白菜素溶液中, 利用CPO催化氧还原生成的过氧化氢可进一步驱动CPO对岩白菜素的催化氯化反应. 经估算总转化数(TTN)达到13600, 即1 mol CPO可催化13600 mol岩白菜素.     

4R-岩白菜素的合成

岩白菜素为碳苷类化合物,具有广泛的生理活性。本文通过一系列反应,将岩白菜素分子中4位羟基的构型由S转化为R,合成得到其非对映异构体4(R)-岩白菜素,为岩白菜素的衍生化研究提供了新的思路。