胡芦巴中总皂苷的含量测定

选用薯蓣皂苷元为对照品,以高氯酸显色,分光光度法测定胡芦巴总皂苷含量。薯蓣皂苷元在410nm处有最大吸收,在0.0163—0.0357mg.mL-1范围内吸光度与薯蓣皂苷元浓度呈良好的线性关系(r=0.9996),方法的平均回收率为98.0%(n=9),RSD为0.6%。该方法简便、准确、稳定,是一种快速测定胡芦巴总皂苷的有效方法。     

Systematically Exploring the Chemical Ingredients and Absorbed Constituents of Polygonum capitatum in Hyperuricemia Rat Plasma Using UHPLC-Q-Orbitrap HRMS

Polygonum capitatum as an ethnic medicine has been used to treat urinary tract infections, pyelonephritis and urinary calculi. In our previous study, P. capitatum was found to have anti-hyperuricemia effects. Nevertheless, the active constituents of P. capitatum for treating hyperuricemia were still unclear. In this study, an ultra-high-performance liquid chromatography coupled to quadrupole/orbitrap high-resolution mass spectrometry (UHPLC-Q-Orbitrap HRMS) was used to comprehensively detect the chemical ingredients of P. capitatum and its absorbed constituents in the plasma of hyperuricemia rats for the first time. Xcalibur 3.0 and Compound Discoverer 2.0 software coupled to mzCloud and ChemSpider databases were utilized for qualitative analysis. A total of 114 chemical components including phenolics, flavonoids, tannins, phenylpropanoids, amino acids, amides and others were identified or tentatively characterized based on the exact mass, retention time and structural information. Compared to the previous P. capitatum study, an additional 66 different components were detected. Moreover, 68 related xenobiotics including 16 prototype components and 52 metabolites were found in the plasma of hyperuricemia rats. The metabolic pathways included ring fission, hydrolysis, decarboxylation, dehydroxylation, methylation, glucuronidation and sulfation. This work may provide important information for further investigation on the active constituents of P. capitatum and their action mechanisms for anti-hyperuricemia effects.     

Decomposition of [NiRR′L2] complexes induced by bromine or anodic oxidation

A study has been made of the decomposition of the compounds t-[NiRR′L₂] (L = PMe₂Ph and PEt₃; R = aryl or vinyl groups) and [Ni(mes)(o-tol)bipy] (mes = mesityl) oxidatively induced either by electrochemical means or by bromine. No organometallic compound of Ni^III was isolated in the above reactions, but a pentacoordinate intermediate of Ni^III is postulated. Breakdown takes place readily after the Ni^III intermediate is formed. If the decomposition is induced electrochemically, the intermediate decomposes giving only the coupling product R-R′. When bromine is used as the oxidizing agent, the Ni^III intermediate is only formed if coordination to the central atom is allowed by the volume of the ligands. Thus, [Ni(C₂Cl₃)(mes)(PMe₂Ph)₂] does not decompose at all, and only [Ni(C₂Cl₃)(mesBr₂)(PMe₂Ph)₂] is obtained. The intermediate “Ni^IIIRR′BrL₂” undergoes reductive elimination to give R-R′, RBr and R′Br. The formation of the products R-R′ is increasingly favoured the greater the electronegativity of the organic ligands. The reductive elimination giving RBr takes place more readily the greater the electronegativity of the organic ligand R. The product of the reductive elimination reaction is “Ni^IBr”, “Ni^IR”, or “Ni^IR′”, which in the presence of bromine give Ni²⁺, [NiBr(RBr)L₂], phosphonium salts, RBr, and R′Br.     

Ab initio study of the effect of side-chain reactions on the electronic structure of proteins

The effect of side-chain protonation and tautomerization of histidine on the electronic structure of proteins is investigated. Ab initio band structure results for protonated polyhistidine, polyhistidine in both tautomeric forms, polyglycine and polyalanine are reported. The density of states of the corresponding composite aperiodic polypeptides is studied using the simple negative factor counting method. It is shown how these side-chain reactions reduce the fundamental gap in aperiodic proteins, thereby modifying their conduction properties.     

乌骨鸡脂肪油中脂肪酸组成的气相色谱-质谱分析

乌骨鸡脂肪油是乌骨鸡重要的营养成份之一,其脂肪酸组成更是影响肉质风味的重要化学成分。以氯仿:甲醇(2:1)超声提取乌骨鸡中脂肪油,皂化后,用三氟化硼-甲醇法甲酯化,应用气相色谱-质谱联用技术对乌骨鸡脂肪酸组成进行了分析,分离和鉴定了22种脂肪酸,并以面积归一法,计算各脂肪酸的相对百分含量。结果表明,乌骨鸡脂肪油中含有饱和脂肪酸:棕榈酸、硬脂酸、豆蔻酸、十七烷酸、花生酸、山嵛酸、十五烷酸、十九烷酸,其含量分别为22.02%、12.89%、0.80%、0.36%、0.33%、0.16%、0.14%、0.13%,占总脂肪酸的36.83%;不饱和脂肪酸含量占总脂肪酸的63.17%,其中油酸29.18%、亚油酸21.19%、棕榈油酸4.82%、花生四烯酸3.86%、11-二十碳烯酸0.82%、EPA 0.75%、DHA 0.69%、10,13-二十碳二烯酸0.63%、7,10,13-二十碳三烯酸0.55%、γ-亚麻酸0.18%、7,10-十六碳二烯酸0.17%、15-甲基-11-十六碳烯酸0.12%、11-十四碳烯酸0.12%、10-十九碳烯酸0.09%。多不饱和脂肪酸占总脂肪酸含量的28.02%。