Bioactive Phenolic Components from the Twigs of Atalantia buxifolia

Five new compounds named buxifoximes A–C (1–3), buxifobenzoate (4), and 7-O-(7′-peroxygeranyl) coumarin (5), together with 25 known compounds, were identified from the twigs of Atalantia buxifolia. Compounds 1–3 are unique secondary metabolites with the aldoxime functionality. The structures of the isolates were determined on the basis of spectroscopic data analyses, and the structure of 1 was confirmed by an X-ray single-crystallographic analysis. With respect to bioactivity, antidengue virus, anti-inflammatory, and cytotoxic activities of all purified compounds were tested and evaluated. Compound 1 showed a significant anti-inflammatory effect by inhibiting superoxide anion generation with an IC50 value of 4.8 ± 0.7 μM. Among the acridone alkaloids, 5-hydroxy-N-methylseverifoline (23) exhibited antidengue activity (IC50 = 5.3 ± 0.4 μM), and atalaphyllinine (20) demonstrated cytotoxicity (IC50 = 6.5 ± 0.0 μM) against the human liver cancer cell line, HepG2.