Cytotoxic dimeric sesquiterpenoids from Curcuma parviflora: isolation of three new parviflorenes and absolute stereochemistry of parviflorenes A, B, D, F, and G

Three novel dimeric sesquiterpenoids, named parviflorenes G–I (), have been isolated from Curcuma parviflora (Zingiberaceae), and their structures were elucidated by means of spectroscopic studies. Absolute stereochemistry of parviflorene G () as well as previously isolated related compounds, parviflorenes A (), B (), D (), and F (), was revealed by CD spectral data and chemical means. Parviflorenes G () and I () were cytotoxic against HeLa cells, while parviflorenes A () and F () were cytotoxic against all tested tumor cell lines in the human cancer cell line panel assay.