MOLECULAR BASIS OF DRUG PHOTOTOXICITY: PHOTOSENSITIZED CELL DAMAGE BY THE MAJOR PHOTOPRODUCT OF TIAPROFENIC ACID

Abstract Tiaprofenic acid is a photosensitizing nonsteroidal anti-inflammatory drug, whose major photoproduct (decarboxytiaprofenic acid) is also a potent photosensitizer. Because of the lack of the carboxylate moiety, this photoproduct is more lipophilic and might bind more efficiently to cell membranes, thereby causing phototoxic damage. To verify the feasibility of this hypothesis, we have prepared the ³H-labeled analogs of tiaprofenic acid and its photoproduct and examined the binding, persistence and phototoxicity of the photoproduct using poorly metabolizing (fibroblasts) and actively metabolizing cells (hepatocytes). The photoproduct of tiaprofenic acid accumulates in both cell types as it is formed. Upon removal of the photoproduct from the culture medium, it rapidly disappears from hepatocytes but not from fibroblasts. Consequently, irradiation of fibroblasts previously incubated with the photoproduct and kept in culture in the dark for 20 h results in generalized cell damage while this effect is not observed in hepatocytes. Because of its long persistence in poorly metabolizing skin cells and its reluctance to photobleaching, the formation of this photoproduct in skin may be of relevance to explain the in vivo phototoxicity of tiaprofenic acid.     

“分子钳”人工受体的研究进展

本文综述了分子钳人工受体近年来在分子识别领域中的新进展     

分子力学和分子动力学方法研究不同变质程度烟煤的分子结构

采用分子力学和分子动力学模拟方法 ,研究了不同变质程度烟煤的三维分子构型和能量参数。结果表明 :随变质程度的增加 ,煤分子内平行的芳香片层结构增大。不同变质程度烟煤分子在团聚前后的成键相互作用能仅略有变化 ,其中扭转能Et 的变化相对较为显著 ,并且扭转能随煤阶的增加呈逐渐减小的趋势。非成键作用能 ,特别是超过三个原子的范德华作用能 ,是煤中的重要相互作用能 ,是模型分子团聚的重要驱动力 ,对于烟煤分子聚集状态的形成起着决定性的作用。同时随煤阶的升高 ,超过三个原子的范德华作用能逐渐增加。模型分子的总势能随煤阶的变化呈两头高、中间低的趋势 ,与煤的一些宏观物理性质有一定的相一致性。     

金属卟啉配合物的分子识别研究进展

综述了金属卟啉配合物的分子识别研究进展。介绍了金属卟啉配合物在分子形状与大小识别、官能团识别和手性识别方面的研究概况。     

黄原胶的分子量

黄原胶是一种具有超高分子量的细菌胞外多糖,只溶于水中,作为增粘剂而得到广泛的应用。由于其侧链上含有可电离的三糖基团,表现出很强的聚电解质行为,因而给分子量及分子量分布的测定带来许多困难。 许多学者对黄原胶的分子量进行了研究。但由于测试方法和实验条件以及样品的差异,     

《分子科学学报》总目次

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晶区分子链构象及拉伸取向对聚酰胺-6分子运动的影响

用声频共振法在-150°—170℃范围内测定了晶区构象为α、γ、γ+α型以及经不同拉体程度的聚酰胺-6单纤维的动态力学性质的温度谱。除三个已知的内耗峯—— -110℃(β_a),-40℃(β’_a),50℃(α_a)以外,对晶区为γ构象且含有单体及低聚体的聚酰胶-6观察到一个新的内耗峯,130℃(α’_a)。具有α构象的试样,其α_a内耗峯出现的温度较具有γ构象的试样为高。 经碘处理而未脱碘的聚酰胺-6,(β’_a)内耗峯高度显著增加,进一步证实β’_a内耗峯与自由酰胺基的运动有关。β’_a内耗峯的高度亦随拉伸比的增加而增高,说明在拉伸过程中,酰胺基之间的氢键有破坏的可能性。 出现在130℃处的α’_c内耗峯随拉伸比的增加其高度显著地下降,当拉伸到3.8倍时不再出现α’_c内耗峯。结合晶区分子链构象及碘处理对α’_c内耗峯的影响,我们认力α’_c内耗峯应为γ构象部分的松弛运动。     

钩吻素子的晶体及分子结构

钩吻素子(Koumine)是钧吻生物碱(Kou-Wen Alkaloids)中的单体之一,其分子式为C_(20)H_(22)N_2O。它的晶体属单斜晶系,空间群为P2_1,晶胞参数为:α=8.422(0),b=13.209(1),c=7.881(1)A,β=108.201(9)°,V=834.995A~3;Z=2;D_c=1.29g/cm~3。 本文报道的钩吻素子是1981年Khuong-Huu F等人报导的钩吻素子的一个立体异构体,它们是钩吻素子的两个非对映体旋光异构体。     

CRYSTAL AND MOLECULAR STRUCTURE OF RABDOSERRIN-B

<正> INTRODUCTION. Four compounds of diterpenoids that have in vitro cytotoxity against cultured Hala cells have been obtained by means of extraction from Rabdosia serra(Maxim) Hara, a chinese medical herb. They are Rabdoserrin A (Rab A), Rabdoserrin B (Rab B), Excisanin A and Kamebakaurin (Kam). Among them, Rab A and Rab B are new compounds. Crystal structures of Rab A and Kam have been solved. The chemical structure of Rab B has been     

醇的链长对微乳状液形成的影响

本文研究了醇对非离子型表面活性剂ＡＥＯ９［Ｃ１２Ｈ２５Ｏ（Ｃ２Ｈ４Ｏ）９ＯＨ］、正庚烷、水体系形成微乳液的影响。通过四组分的拟三元相图，得到各体系的微乳区。结果表明，当醇的链长不同时，体系的微乳区的类型及面积均不同。其中，丁醇体系的微乳区面积最大，它比Ｂａｎｓａｌ－Ｓｈａｈ－Ｏ＇ｃｏｎｎｅｌ相关方程的结果少一个碳原子。     

CRYSTAL AND MOLECULAR STRUCTURE OF TETRAPHENYLDIARSINE

<正> The title compound, C24H20As2(Mr=458.24), crystallizes in mono-clinic with space group P21/n and a=6.268(2), b=7.494(2), c=21.340(7)A, β= 91.027(3)°, V=1002.6 A3, Z=2, D.x=1.518gcm-3. The final value of R is 0.059 for 1619 observed reflections. The four phenyls arrange in a staggered trans-conformation around the As-As' bond.     

ABSOLUTE MOLECULAR WEIGHT DISTRIBUTION OF NITROCELLULOSE

Abstract

Being one of the oldest known polymers, nitrocellulose has been the subject of study for over a century. It was initially used solely for military purposes; however, since the end of World War I its usage has expanded into the fiber and coatings industries where it has been a mainstay to the present day [1, 2]. General interest in the molecular weight characterization of nitrocellulose may be classified into two categories. The firstand more obvious reason for the relevance of this parameter is that the molecular weight and molecular weight distribution profoundly influence the properties of the product and affect the processability of the material, For instance, the molecular weight (hence, the viscosity of this material) is one of the most important factors that needs to be considered in the determination of the nonvolatile content in lacquers [21]. The second reason is that it is a soluble derivative of cellulose, for which direct molecular weight determination is problematic due to solubility difficulties. Thus, nitrocellulose, barring degradation during nitration, has been utilized as a practical means of indirectly arriving at the molecular weight distribution of the starting cellulose. Very closely tied with this second interest is the focus on the conformation of nitrocelluloses with different degrees of substitution. This piece of information has been a major source of questions related to the methodology of calibration when gel permeation chromatography (GPC) was chosen for molecular weight determination.