New cytotoxic phloroglucinols, baeckenones D–F, from the leaves of Indonesian Baeckea frutescens

Three new phloroglucinols, baeckenones D–F (1–3), were obtained from the leaves of Indonesian Baeckea frutescens, along with the known unusual endoperoxide, phloroglucinol (4). The structures of the isolated compounds were elucidated by 1D and 2D NMR and HREIMS spectra. Furthermore, the stereochemistry of baeckenone D (1) was established by an X-ray diffraction analysis. Among the isolated compounds 1–4, baeckenone F (3) showed moderate cytotoxic activities against human pancreatic (PSN-1), lung (A549), and breast (MDA-MB-231) cancer cell lines, with IC50 values of 33.3 μM, 34 μM, and 39.3 μM, respectively.

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