Detail chemical investigations on the stem bark of Mesua daphnifolia gave three triterpenoids and four xanthones. They are friedelin (1), friedelan-1,3-dione (2), lup-20(29)-
en-3β-ol (3), cudraxanthone G (4), ananixanthone (5), 1,3,5-trihydroxy-4-methoxyxanthone
(6) and euxanthone (7). These chemical constituents were tested in vitro for their cytotoxic
activities against four cell lines, MDA-MB-231 (human estrogen receptor negative breast
cancer), HeLa (cervical carcinoma), CEM-SS (T-lymphoblastic leukemia) and CaOV3 (human
ovarian cancer). Compound 4 showed a broad spectrum of activity against the MDA-MB-231,
HeLa and CEM-SS cell lines with IC50 values of 1.3, 4.0 and 6.7 μg/ml respectively. Meanwhile, the other compounds 1, 2, 3, 5, 6 and 7 gave only selective activities against the cell lines.