Vlasouliodes A-D, four new C₃₀ dimeric sesquiterpenes exhibiting potential inhibition of MCF-7 cells from Vladimiria souliei

As our ongoing interest to search bioactive dimeric sesquiterpenes from the genus Vladimiria (Asteraceae), the plant of Vladimiria souliei was studied. Based on the repetitive chromatographic fractionation, a chemical investigation on the roots of Vladimiria souliei led to the isolation and the identification of four previously undescribed sesquiterpene dimers, vlasouliodes A-D (1-4). Their chemical structures were elucidated by comprehensive analysis of spectroscopic data, including HRESIMS, 1D and 2D NMR spectroscopic data. The absolute configurations of them were unambiguously established by the experimental and calculated ECD data. In the in vitro biological activity evaluation, 1 and 3 displayed pronounced inhibitory activity against human breast adenocarcinoma cell lines (MCF-7) with IC₅₀ values of 17.12 ± 0.42 μM and 13.12 ± 0.10 μM, respectively. Additionally, treatment with 1 and 3 induced cell apoptosis in MCF-7 cells, down-regulated the expression of Caspase-3 and up-regulated the expression of Cleaved-caspase-3.