Acetogenins from the Stem of Uvaria rufa and Their Cytotoxic Activity.

Four new adjacent bis-tetrahydrofuran acetogenins, bullacin C ( 7 ), uvarirufin ( 9 ), and uvariasolins III ( 12 ) and IV ( 13 ), along with 11 known acetogenins, were isolated from the stem of Uvaria rufa . Their structures were elucidated based on spectroscopic data analysis, including 1D and 2D NMR, HRESIMS, and MALDI-MS/MS of the lithium adducts. Absolute configurations were assigned using Mosher ester analysis and ECD measurements. Uvarirufin ( 9 ) possesses a unique C-39 skeleton among acetogenins. Most tested acetogenins exhibited cytotoxicity against human cancer cell lines (HCT 116, 22Rv1, MDA-MB-435, OVCAR3). Squamocin ( 8 ) and uvarirufin ( 9 ) were found to be the most potent, with an IC ₅₀ value of 1.2 μM for both in HCT 116 colon cancer cells. Additionally, a new application of Dragendorff's reagent is proposed herein for the TLC detection of acetogenins.