Abstract A phytochemical investigation of the stem bark of Calophyllum canum resulted in the isolation of a new xanthone dimer identified as biscaloxanthone (1), together with four compounds; trapezifoliaxanthone (2), trapezifolixanthone A (3), taraxerone (4) and taraxerol (5). The structures of these compounds were determined via spectroscopic methods of IR, UV, MS and NMR (1D and 2D). The cytotoxicity of compounds 1–3 were screened against A549, MCF-7, C33A and 3T3L1 cell lines, wherein weak cytotoxic activities were observed (IC50 > 50 μm).

中文翻译：

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来自Calophyllum canum茎皮的一种新的呫吨酮二聚体和细胞毒性

摘要 对 Calophyllum canum 茎皮的植物化学研究导致分离出一种新的呫吨酮二聚体，被鉴定为双氯氧杂蒽酮 (1)，以及四种化合物；梯形叶黄酮 (2)、梯形叶黄酮 A (3)、蒲公英 (4) 和蒲公英 (5)。这些化合物的结构是通过 IR、UV、MS 和 NMR（1D 和 2D）光谱方法确定的。针对 A549、MCF-7、C33A 和 3T3L1 细胞系筛选了化合物 1-3 的细胞毒性，其中观察到微弱的细胞毒性活性（IC50 > 50 μm）。