Department of Chemical Technology of Drugs, Poznan University of Medical Sciences, Grunwaldzka 6, 60-780 Poznan, Poland.
Department of Organic Chemistry, Poznan University of Medical Sciences, Grunwaldzka 6, 60-780 Poznan, Poland.
Int J Mol Sci. 2023 Mar 31;24(7):6572. doi: 10.3390/ijms24076572.
Oleanolic (OA) and glycyrrhetinic acids (GE), as well as their derivatives, show a variety of pharmacological properties. Their crystal structures provide valuable information related to the assembly modes of these biologically active compounds. In the known-to-date crystals of OA esters, their 11-oxo derivatives, and GE ester crystals, triterpenes associate, forming different types of ribbons and layers whose construction is based mainly on van der Waals forces and weak C-H···O interactions. New crystal structures of 11-oxo OA methyl ester and the polymorph of OA butyl ester reveal an alternative aggregation mode. Supramolecular architectures consist of helical chains which are stabilized by hydrogen bonds of O-H···O type. It was found that two polymorphic forms of butyl OA ester (layered and helical) are related monotropically. In a structure of metastable form, O-H···O hydrogen bonds occur, while the thermodynamically preferred phase is governed mainly by van der Waals interactions. The intermolecular interaction energies calculated using CrystalExplorer, PIXEL, and Psi4 programs showed that even in motifs formed through O-H···O hydrogen bonds, the dispersive forces have a significant impact.
齐墩果酸（OA）和甘草次酸（GE）及其衍生物表现出多种药理学特性。它们的晶体结构提供了与这些生物活性化合物组装模式相关的有价值的信息。在迄今为止已知的 OA 酯、其 11-酮衍生物和 GE 酯晶体中，三萜类化合物相互关联，形成不同类型的带状物和层状物，其结构主要基于范德华力和弱 C-H···O 相互作用。11-酮 OA 甲酯和 OA 丁酯的新晶体结构揭示了一种替代的聚集模式。超分子结构由氢键稳定的螺旋链组成，氢键类型为 O-H···O。发现丁基 OA 酯的两种多晶型形式（层状和螺旋状）是单斜相关的。在亚稳形式的结构中，发生 O-H···O 氢键，而热力学上更有利的相主要由范德华相互作用控制。使用 CrystalExplorer、PIXEL 和 Psi4 程序计算的分子间相互作用能表明，即使在通过 O-H···O 氢键形成的基元中，色散力也有显著影响。
