Abstract Three stigmastane steroids: 6-hydroxystigmast-4-en-3-one (1), stigmast-4-en-3-one (2), and 3-hydroxystigmast-5-en-7-one (3) were successfully isolated from the acetone extract of Dryobalanps oblongifolia stem bark. The structural determination of isolated compounds was carried out on the basis of data analysis of NMR and MS spectra. In order to identify the antiplasmodial activity, the isolated compound was put to test against Plasmodium falciparum 3D7. Antiplasmodial activity of the isolated compounds showed that the IC50 values of 6-hydroxystigmast-4-en-3-one were 37.29 μg/mL while the IC50 values of stigmast-4-en-3-one were 43.54 μg/mL and the IC50 values of 3-hydroxystigmast-5-en-7-one were 13.34 μg/mL (chloroquine phosphate was used as a positive control, IC50 0.006 μg/mL). Judging from the results, the isolated compounds were proven to demonstrate mediocre antiplasmodial activity. Compound (3) indicated a better antimalarial activity than compound (1) and (2), even though there was no satisfactory activity that indicated its ability to combat chloroquine. Therefore, it might not be developed as an antimalarial drug.

中文翻译：

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来自Dryobalanops oblongifolia 茎皮的柱头烷类固醇的抗疟原虫活性

摘要 三种柱头甾醇：6-hydroxystigmast-4-en-3-one (1)、stigmast-4-en-3-one (2) 和 3-hydroxystigmast-5-en-7-one (3)从 Dryobalanps oblongifolia 茎皮的丙酮提取物中分离。分离化合物的结构测定是在核磁共振和质谱数据分析的基础上进行的。为了鉴定抗疟原虫活性，将分离的化合物用于抗恶性疟原虫 3D7 的测试。分离化合物的抗疟原虫活性表明 6-hydroxystigmast-4-en-3-one 的 IC50 值为 37.29 μg/mL，而 stigmast-4-en-3-one 的 IC50 值为 43.54 μg/mL 和 IC50 3-hydroxystigmast-5-en-7-one 的值为 13.34 μg/mL（磷酸氯喹用作阳性对照，IC50 0.006 μg/mL）。从结果来看，经证实，分离的化合物表现出中等的抗疟原虫活性。化合物(3)显示出比化合物(1)和(2)更好的抗疟活性，尽管没有令人满意的活性表明其具有对抗氯喹的能力。因此，它可能不会被开发为抗疟药。