Constituents of Aegle marmelos from Myanmar.

Five compounds (1-5), including three coumarins (1-3) and two alkaloids (4,5) were isolated during the first investigation of the stem bark of Aegle marmelos (L.) Corrêa. collected in Myanmar. Their structures were determined by NMR spectra analysis. Among them, 7´-O-ethylmarmin (1) and 2-O-ethyltembamide (5) were identified as new compounds. Skimmianine (4) showed moderate cytotoxicity against a HeLa cell line, and 7´-O-ethylmarmin (1), marmin (2), and (+)-epoxyaurapten (3) displayed weak radical scavenging activity according to a DPPH scavenging assay.