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.