Callintegers A and B, Unusual Tricyclo[4.4.0.0<sup>9,10</sup>]tetradecane Clerodane Diterpenoids from <i>Callicarpa integerrima</i> with Inhibitory Effects on NLRP3 Inflammasome Activation
De‐Wen Bi, Feng Xiong, Bin Cheng, Ya‐Ling Zhou, Muhammad Aurang Zeb, Peng Tang, Wen‐Hui Pang, Ruihan Zhang, Xiao‐Li Li, Xing‐Jie Zhang, Wei‐Lie Xiao
Abstract
Callintegers A (1) and B (2), unprecedented clerodane norditerpenoids based on a novel carbon skeleton, were isolated from Callicarpa integerrima. Compounds 1 and 2 possess a novel 6/6/6-fused tricyclic ring system. Their structures and absolute configurations were determined by quantum chemical calculations, spectroscopic analysis, and single-crystal X-ray diffraction methods. Biological evaluation showed that compound 2 inhibited IL-1β secretion in a dose-dependent manner with an IC50 value of 5.5 ± 3.2 μM. Caspase-1 maturation and IL-1β secretion were also reduced, indicating that compound 2 impaired NLRP3 inflammasome activation.