Seven undescribed tirucallane-type triterpenoids, kumunorquassins A‒E and kumuquassins K and L, along with nine known analogues, have been isolated from the leaves of Picrasma quassioides (D. Don) Benn. Their structures and absolute configurations were elucidated based on comprehensive spectroscopic analyses, single-crystal X-ray diffraction analysis and electronic circular dichroism (ECD). The absolute configuration of cornusalterin J was unequivocally determined by X-ray diffraction based on its p-bromobenzoate derivative. A brief approach was presented in our study, which could rapidly and conveniently determine the relative and absolute configurations of OCH₃-23 of kumuquassin L and cornusalterins J, H and G depending on the chemical shift differences (Δδ) of C-24 and C-25 and the chemical shifts of C-23, H-23 and H-24. In addition, the cytotoxicities of these compounds against two human tumour cell lines (HepG2 and Hep3B) were evaluated.

从九头Picrasma quassioides（D. Don）Benn的叶子中分离出了七个未描述的四氢呋喃型三萜，kumunorquassins A ‒ E和kumuquassins K和L，以及九种已知类似物。根据全面的光谱分析，单晶X射线衍射分析和电子圆二色性（ECD），阐明了它们的结构和绝对构型。基于其对-溴苯甲酸酯衍生物，通过X-射线衍射明确地确定了角膜沙特林J的绝对构型。我们的研究提出了一种简短的方法，该方法可以快速方便地确定OCH ₃的相对和绝对构型kumuquassin L和Ĵ，H和G取决于化学位移差（Δcornusalterins -23 δ C-24和C-25）和C-23，H-23和H-24的化学位移。此外，评估了这些化合物对两种人类肿瘤细胞系（HepG2和Hep3B）的细胞毒性。