Structurally diverse sesquiterpenoid glucoside esters from Cissampelopsis volubilis suppress triple-negative breast...

Ten previously unreported highly oxygenated sesquiterpenoid glucoside esters (1-10), named cissvolubicins A-J, were isolated from the aerial parts of Cissampelopsis volubilis by bio-guided isolation. All compounds feature a sesquiterpenoid core that is linked to either a disubstituted or monosubstituted glucopyranose moiety, which is rare in Nature. The structures as well as absolute configurations of these compounds were elucidated through a combination of NMR, HRESIMS, chemical methods, single-crystal X-ray diffraction, calculations of ECD and DP4+ technologies. Structurally, the aglycones of 1-5 were identified as cadinane-type sesquiterpenoid class, the aglycone of 6 (5/6-fused ring) was characterized as uncommonly rearranged sesquiterpenoid, and the aglycones of 7-10 were assigned to the eudesmane-type sesquiterpenoid class. Compounds 1-10 were assessed for their cytotoxic effects on TNBC cells, specifically MDA-MB-231 and HCC1806. Among them, compounds 1, 5, and 6 exhibited pronounced anti-TNBC activity, with 50% inhibitory concentration values between 3.5 and 7.6 μM. Evaluation of structure-activity relationships displayed that the absence of oxygenation at C-3 was a key determinant of anti-TNBC potency among cadinane-type sesquiterpenoid glucosides. Additionally, 1 markedly suppressed TNBC cell growth and motility, induced cell cycle arrest and apoptosis, and effectively inhibited tumor growth in both xenograft models in vivo and organoid models in vitro. Mechanistic investigations using molecular docking as well as western blot analyses confirmed that 1 directly interacts with RAS and inhibits ERK activation. Collectively, these findings identify cadinane-type sesquiterpenoid glucoside esters as anti-TNBC agents with therapeutic potential for the first time.