Structure modification and anti-tumor activity evaluation on sesquiterpene lactones TBA and TBB from Sphagneticola trilobata

Thirteen sesquiterpene lactone derivatives were designed and synthesised using the sesquiterpene lactone epimers TBA and TBB as the parent molecules, isolated from Sphagneticola trilobata. Their structures were elucidated by extensive spectroscopic studies and chemical evidence. Furthermore, the structures of 1a, 4b and 5a were confirmed by X-ray single-crystal diffraction analyses. All of the compounds were further examined for their in vitro antiproliferative activity against human cancer cell lines HeLa and MCF-7. Unfortunately, the activity of all derivatives were weaker than that of the parental compounds.