High-performance liquid chromatography/electrospray ionization tandem mass spectrometry of hydroxylated uroporphyrin and urochlorin derivatives formed by photochemical oxidation of uroporphyrinogen I

Hydroxylated uroporphyrin I and urochlorin I derivatives formed by photochemical oxidation of uroporphyrinogen I were separated by high-performance liquid chromatography and fully characterized by electrospray ionization tandem mass spectrometry. The porphyrins and chlorins were identified by analysis of their product ion spectra with each hydroxylated derivative giving a characteristic collision-induced dissociation fragmentation pattern. The porphyrins and chlorins characterized were meso-hydroxyuroporphyrin I, alpha-hydroxypropionic acid uroporphyrin I, beta-hydroxypropionic acid uroporphyrin I, hydroxyacetic acid uroporphyrin I, trans-7-hydroxy-8-spirolactoneurochlorin I, cis-7-hydroxy-8-spirolactoneurochlorin I and trans- and cis-7,8-dihydroxyurochlorins I.     

Complete (1)H and (13)C NMR assignments of two new trans-clerodane diterpenoids from Otostegia limbata

Two new tricyclic trans-clerodane diterpenoids trivially named as ballotenic acid A (1) and ballodiolic acid A (2) have been isolated from ethyl acetate fraction of Otostegia limbata. The structure assignments are based on (1)H and (13)C NMR spectra, 2D NMR (HMQC, HMBC, COSY, NOESY and NOE) techniques and comparison with the literature data.     

羟基喹啉偶氮类化合物的互变异构与顺反异构的研究

本工作合成了数种带不同取代苯基的羟基喹啉偶氮类化合物。对它们在不同溶剂。不同酸碱度溶液中的偶氮式及腙式间互变异构平衡进行了研究。苯环上不同取代基的引入可引起平衡发生变化。拉电子基的引入有利于腙式结构的形成,而推电子基的引入则对偶氮的生成影响不大。此外,工作中还发现:羟基喹啉偶氮化合物在光照下存在着以偶氮顺-反异构化反应为主的变化过程。     

高效液相色谱法对反式-1,2-二取代环丙烷类化合物的手性拆分

在ＣｈｉｒａｌｃｅｌＯＤ和ＣｈｉｒａｌｃｅｌＯＪ柱上,以各种配比的正己烷／异丙醇为洗脱剂,对１３种反式－１,２－二取代环丙烷类化合物的对映体进行了手性拆分。考察了这些外消旋物在这两种柱上的色谱行为。实验表明带芳环的反式－１,２－二取代环丙烷类化合物在ＯＤ及ＯＪ柱上的拆分能力明显地与芳环上取代基的性质和位置有关。另一方面,一些带有脂族取代基的反式－１,２－二取代环丙烷类化合物也能在这两种柱上得到拆分。     

高聚物介质中7-羟基喹啉的光谱特性

通过观测７－羟基喹啉（７ＨＱ）在甲基丙烯酸甲酯（ＭＭＡ）和甲基丙烯酸（ＭＡＡ）以不同配比共聚的基质中的吸收光谱和荧光光谱,研究基质对７ＨＱ各物种相对含量的变化和对７ＨＱ激发态质子转移的影响。结果表明基质中羧基数目增加,可使７ＨＱ各物种的相对含量发生变化,并有利于７ＨＱ发生激发态质子转移。     

Seed Oil Fatty Acids of Mongolian Compositae: The trans‐Fatty Acids of Heteropappus hispidus,Asterothamnus centrali‐asiaticus and Artemisia palustris

Seed oils from the Compositae plant family are known to contain a variety of unusual fatty acids. Subsequent to the recent discovery of γ‐linolenic acid in Saussurea and Youngia, further Mongolian Compositae species were investigated for their seed oil fatty acid composition. A number of δ3trans‐fatty acids (16 : 1δ3t, 18 : 1δ3t and 18 : 3δ3t, 9c, 12c) were found in the seed oils of Heteropappus hispidus and Asterothamnus centrali‐asiaticus. The latter fatty acid, but not the trans‐monoenes, was also found in one species of Artemisia. These unusual fatty acid isomers were characterized by capillary gas‐liquid chromatographic (GLC) separations in combination with other chromatographic techniques (analytical thin layer chromatography, TLC and preparative argentation TLC), and infrared spectrocsopy (IR). Their identity was further confirmed by co‐chromatography with other seed oils known to contain these trans‐fatty acids. The fact that within the Compositae plant family there are apparently two or three distinct groups of genera containing δ3trans‐fatty acids is discussed.