Sesquiterpenoids isolated from the root bark of Lycium chinense

This study reports the isolation of 11 previously undescribed sesquiterpenoids from the root bark of Lycium chinense Mill, including a 1,10-secoeudesmane-type sesquiterpene (1), a 9,10-secoeudesmane-type sesquiterpene (2) and nine rearranged eudesmane sesquiterpenes (3-11). Structures elucidation of these compounds was established using 1D/2D NMR, electronic circular dichroism calculations along with DP4⁺ probability analysis, and X-ray diffraction analysis of single crystals. Lyciiterpenoid E (1), a eudesmane sesquiterpenoid, is characterised by a bond cleavage between C-1 and C-10 while, lyciiterpenoid F (2) exhibits a bond cleavage between C-9 and C-10. All compounds (1-11) were evaluated for neuroinflammatory inhibitory activity in LPS-induced BV-2 cells. Among them, compound 5 exhibited potent anti-neuroinflammatory effects, with an EC₅₀ of 2.1 ± 0.07 μM, exceeding the effectiveness of curcumin, a standard positive control. Furthermore, compound 5 may inhibit the synthesis of LPS-induced TNF-α and IL-1β/6 in BV-2 cells while downregulating iNOS and COX-2 gene and protein expression in a dose-dependent manner. This study provides the first evidence of natural anti-neuroinflammatory agents from the root bark of L. chinense for the treatment of neurodegenerative disorders.