<jats:title>Abstract</jats:title><jats:p>During investigation of cell suspension cultures of <jats:italic>Brucea javanica (L.) Merr</jats:italic>., the canthin‐6‐one alkaloid 5,11‐dimethoxycanthin‐6‐one (1) was isolated. The structural determination is based on spectral analysis. Five other alkaloids, canthin‐6‐one‐3‐<jats:italic>N</jats:italic>‐oxide (2), 11‐hydroxycanthin‐6‐one (3), canthin‐6‐one (4), 5‐methoxycanthin‐6‐one (5), and 11‐methoxycanthin‐6‐one (6), were also identified.