Structure determination of oleanolic and ursolic acids: a combined DFT/vibrational spectroscopy methodology

Raw samples of oleanolic and ursolic acids, a class of terpenoid acids mainly found in the leaf and fruit cuticles of some plant species, can be defined as a blend of clusters of different conformers aggregated in dimers and tetramers by means of hydrogen bonds and stabilized by non-electrostatic interactions.齐墩果酸（oleanolic acid）与熊果酸（ursolic acid）属于一类萜类酸，主要存在于部分植物的叶与果实角质层中；其原始样品可被界定为由不同构象体簇构成的混合物，该类簇通过氢键聚集形成二聚体与四聚体，并由非静电相互作用维持稳定。