Université catholique de Louvain, Louvain Drug Research Institute, Brussels, Belgium.
Phytomedicine. 2013 Feb 15;20(3-4):270-4. doi: 10.1016/j.phymed.2012.10.010. Epub 2013 Jan 11.
Keetia leucantha is a West African tree used in traditional medicine to treat several diseases among which parasitic infections. The dichloromethane extract of leaves was previously shown to possess growth-inhibitory activities on Plasmodium falciparum, Trypanosoma brucei brucei and Leishmania mexicana mexicana with low or no cytotoxicity (>100 μg/ml on human normal fibroblasts) (Bero et al. 2009, 2011). In continuation of our investigations on the antitrypanosomal compounds from this dichloromethane extract, we analyzed by GC-FID and GC-MS the essential oil of its leaves obtained by hydrodistillation and the major triterpenic acids in this extract by LC-MS. Twenty-seven compounds were identified in the oil whose percentages were calculated using the normalization method. The essential oil, seven of its constituents and the three triterpenic acids were evaluated for their antitrypanosomal activity on Trypanosoma brucei brucei bloodstream forms (Tbb BSF) and procyclic forms (Tbb PF) to identify an activity on the glycolytic process of trypanosomes. The oil showed an IC(50) of 20.9 μg/ml on Tbb BSF and no activity was observed on Tbb PF. The best antitrypanosomal activity was observed for ursolic acid with IC(50) of 2.5 and 6.5 μg/ml respectively on Tbb BSF and Tbb PF. The inhibitory activity on a glycolytic enzyme of T. brucei, glyceraldehyde-3-phosphate dehydrogenase (GAPDH), was also evaluated for betulinic acid, olenaolic acid, ursolic acid, phytol, α-ionone and β-ionone. The three triterpenic acids and β-ionone showed inhibitory activities on GAPDH with oleanolic acid being the most active with an inhibition of 72.63% at 20 μg/ml. This paper reports for the first time the composition and antitrypanosomal activity of the essential oil of Keetia leucantha. Several of its constituents and three triterpenic acids present in the dichloromethane leaves extract showed a higher antitrypanosomal activity on bloodstream forms of Tbb as compared to procyclic forms, namely geranyl acetone, phytol, α-ionone, β-ionone, ursolic acid, oleanolic acid and betulinic acid. The four last compounds were proven to be inhibitors of trypanosomal GAPDH, which may in part explain these antitrypanosomal activities.
金叶安息香是一种西非树木，在传统医学中用于治疗多种疾病，包括寄生虫感染。先前的研究表明，其叶片的二氯甲烷提取物对恶性疟原虫、布氏冈比亚锥虫和墨西哥利什曼原虫具有生长抑制活性，且细胞毒性低或无（对人正常成纤维细胞 >100μg/ml）（Bero 等人，2009 年，2011 年）。为了继续研究该二氯甲烷提取物中的抗锥虫化合物，我们通过 GC-FID 和 GC-MS 分析了其叶片用水蒸馏法获得的精油，通过 LC-MS 分析了该提取物中的主要三萜酸。在油中鉴定出 27 种化合物，并用归一化法计算其百分比。评估了精油、其七种成分和三种三萜酸对布氏冈比亚锥虫血腔形式（Tbb BSF）和前鞭毛形式（Tbb PF）的抗锥虫活性，以确定其对锥虫糖酵解过程的活性。该油对 Tbb BSF 的 IC50 为 20.9μg/ml，对 Tbb PF 无活性。对 Ursolic acid 的最佳抗锥虫活性观察到，其对 Tbb BSF 和 Tbb PF 的 IC50 分别为 2.5 和 6.5μg/ml。还评估了桦木酸、齐墩果酸、熊果酸、叶绿醇、α-紫罗兰酮和β-紫罗兰酮对锥虫甘油醛-3-磷酸脱氢酶（GAPDH）的抑制活性。三种三萜酸和β-紫罗兰酮对 GAPDH 均具有抑制活性，齐墩果酸的活性最强，在 20μg/ml 时抑制率为 72.63%。本文首次报道了金叶安息香精油的组成和抗锥虫活性。二氯甲烷叶片提取物中的几种成分和三种三萜酸对 Tbb 的血腔形式表现出比前鞭毛形式更高的抗锥虫活性，即：叶醇、α-紫罗兰酮、β-紫罗兰酮、熊果酸、齐墩果酸和桦木酸。后四种化合物被证明是锥虫 GAPDH 的抑制剂，这可能部分解释了这些抗锥虫活性。
