Vesicular and Fibrillar Gels by Self-Assembly of Nanosized Oleanolic Acid
Vesicular and Fibrillar Gels by Self-Assembly of Nanosized Oleanolic Acid
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DOI：
10.1002/ajoc.201200032
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发表时间：
2012-10-01
影响因子：
2.7
通讯作者：
Paul, Koushik
中科院分区：
文献类型：
--
作者：
Bag, Braja Gopal;Paul, Koushik
近年来，研究分子在水和非水介质中的自组装，形成纳米到微米尺寸的超分子结构和凝胶已经成为一个非常感兴趣的领域。受到各种类型分子自组装自发形成的启发，研究人员的目标是提高对给定介质中自组装过程的理解，并开发其巨大的技术应用潜力。[1-3]在本文中，我们报告了在不同溶剂中的油酸（1，图1）的自组装，这是一种医学上重要的三萜类化合物。的三萜类化合物的形式主要是泡状凝胶在溶剂中的研究，即使没有功能的修改。形成的囊泡能够包封荧光团，包括药物分子，如阿霉素。三萜类化合物是由常见的前体角鲨烯生物合成的历史建议[4]已经被许多酶学实验，机理研究[5]和计算研究所证实。[6]我们小组对这些C30植物代谢物进行的计算确定，所有三萜类化合物的长度都在纳米量级，这使得它们即使没有结构修饰也可用作可再生功能纳米实体。[7，8]文献中很少有关于分子自组装而不进行功能修饰的例子[9]，并且超分子囊泡凝胶也很少见。[10最近，我们报道了桦木酸，一种6-6- 6 -6-5五环三萜酸，在各种不同的溶剂中自组装形成纤维状凝胶。[12]三萜类化合物的结构变化以及功能基团的空间分布可能对自组装性质产生重要影响。因此，为了研究具有微小结构变化和不同官能团的三萜类化合物自组装过程中的结构-性质关系，我们想到油酸（1，图1）将是用于此类研究的合适分子。油酸可从不同的植物中提取[13]，是一种纳米级的6-6- 6 - 6 -6五环三萜类化合物，具有巨大的药用价值，包括抗癌活性[14]（参见支持信息）。
The study of the self-assembly of molecules in aqueous and non-aqueous media leading to supramolecular architectures of nano to micrometer dimensions and gels has become an area of immense interest in recent years. Inspired by the spontaneous formation of various types of molecular self-assemblies, researchers are aiming to improve the understanding of the self-assembly process in a given medium, and exploit their tremendous potential for technological applications.[1–3] Herein, we report the self-assembly of oleanolic acid (1, Figure 1), which is a medicinally important triterpenoid, in different solvents. The triterpenoid forms mostly vesicular gels in the solvents studied, even without functional modifications. The vesicles formed are capable of encapsulating fluorophores, including drug molecules such as doxorubicin. The historical proposal that the triterpenoids are biosynthesized from the common precursor squalene [4] has been confirmed by numerous enzymological experiments, mechanistic investigations,[5] and computational studies.[6] Calculations carried out by our group on these C30 plant metabolites established that all the triterpenoids have lengths in the order of nanometers, which renders them useful as renewable functional nanoentities, even without structural modifications.[7, 8] There are very few examples in the literature on the self-assembly of molecules without functional modifications [9] and supramolecular vesicular gels are rare.[10, 11] Recently, we have reported that betulinic acid, a 6-6-6-6-5 pentacyclic triterpenic acid, self-assembles in a variety of different solvents to form fibrillar gels.[12] Variations in the triterpenoid frameworks as well as the spatial dispositions of the functional groups may have significant effects on the self-assembly properties of the triterpenoids. Hence, to investigate the structure–property relationships during self-assembly of triterpenoids with minute structural variation and different functional groups, it occurred to us that oleanolic acid (1, Figure 1) would be a suitable molecule for such investigations. Oleanolic acid is extractable from different plants [13] and is a nanosized, 6-6-6-6-6 pentacyclic triterpenoid with tremendous medicinal importance, which includes anticancer activities [14](see the Supporting Information).