Department of Pharmaceutical Chemistry, Faculty of Pharmacy, University of Ibadan, Nigeria; Department of Pharmacognosy, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria.
Department of Pharmaceutical Chemistry, Faculty of Pharmacy, University of Ibadan, Nigeria.
J Ethnopharmacol. 2020 Jan 30;247:112203. doi: 10.1016/j.jep.2019.112203. Epub 2019 Aug 28.
Combretum racemosum showed activity in previous ethnopharmacological investigations of some Combretum species used in malaria treatment in parts of West Africa.
This study aimed at confirming the antimalarial potential of this plant by an activity-guided isolation of its active principles.
A crude methanolic leaf extract of Combretum racemosum and fractions thereof obtained by partition with chloroform and n-butanol were investigated for antiplasmodial activity against chloroquine-sensitive (D10) and chloroquine-resistant (W2) strains of Plasmodium falciparum. Repeated chromatographic separations were conducted on the chloroform fraction to isolate bioactive compounds for further tests on antiplasmodial activity. The characterization of the isolated substances was performed by applying NMR- and MS-techniques (ESI-MS, HR-ESIMS, 1D and 2D NMR).
The chloroform fraction (D10: IC = 33.8 ± 1.5 μg/mL and W2: IC = 27.8 ± 2.9 μg/mL) exhibited better antiplasmodial activity than the n-butanol fraction (D10: IC = 78.1 ± 7.3 μg/mL and W2: IC = 78 ± 15 μg/mL) as well as the methanolic raw extract (D10: IC = 64.2 ± 2.7 μg/mL and W2: IC = 65.8 ± 14.9 μg/mL). Thus, the focus of the phytochemical investigation was laid on the chloroform fraction, which led to the identification of four ursane-type (19α-hydroxyasiatic acid (1), 6β,23-dihydroxytormentic acid (4), madecassic acid (8), nigaichigoside F1 (10)) and four oleanane-type (arjungenin (2), combregenin (5), terminolic acid (7), arjunglucoside I (11)) triterpenes, as well as abscisic acid (9). Compounds 1 and 2, 4 and 5, 7 and 8 as well as 10 and 11 were isolated as isomeric mixtures in fractions CR-A, CR-C, CR-E and CR-H, respectively. All isolated compounds and mixtures exhibited moderate to low activity, with madecassic acid being most active (D10: IC = 28 ± 12 μg/mL and W2: IC = 17.2 ± 4.3 μg/mL).
This paper reports for the first time antiplasmodial principles from C. racemosum and thereby gives reason to the traditional use of the plant.
在先前对用于治疗西非部分地区疟疾的某些 Combretum 物种的民族药理学研究中，Combretum racemosum 表现出活性。
本研究旨在通过活性导向分离其活性成分来证实该植物的抗疟潜力。
对 Combretum racemosum 的甲醇粗提叶提取物及其用氯仿和正丁醇进行分配得到的馏分进行了抗疟活性研究，以检测其对氯喹敏感（D10）和氯喹耐药（W2）株疟原虫的活性。对氯仿部分进行了多次色谱分离，以分离出具有抗疟活性的化合物，以便进一步进行抗疟活性测试。通过应用 NMR 和 MS 技术（ESI-MS、HR-ESIMS、1D 和 2D NMR）对分离出的物质进行了表征。
氯仿部分（D10：IC = 33.8 ± 1.5 µg/mL 和 W2：IC = 27.8 ± 2.9 µg/mL）的抗疟活性优于正丁醇部分（D10：IC = 78.1 ± 7.3 µg/mL 和 W2：IC = 78 ± 15 µg/mL）以及甲醇粗提取物（D10：IC = 64.2 ± 2.7 µg/mL 和 W2：IC = 65.8 ± 14.9 µg/mL）。因此，植物化学研究的重点放在了氯仿部分，这导致了四种熊果酸型（19α-羟基齐墩果酸（1）、6β，23-二羟基吐木酸（4）、马德卡酸（8）、尼加昔福苷 F1（10））和四种齐墩果烷型（阿魏根宁（2）、考布脂素（5）、特女贞酸（7）、阿魏糖苷 I（11））三萜类化合物以及脱落酸（9）的鉴定。化合物 1 和 2、4 和 5、7 和 8 以及 10 和 11 分别以异构体混合物的形式在 CR-A、CR-C、CR-E 和 CR-H 馏分中分离出来。所有分离出的化合物和混合物均表现出中等至低活性，其中马德卡酸的活性最高（D10：IC = 28 ± 12 µg/mL 和 W2：IC = 17.2 ± 4.3 µg/mL）。
本文首次报道了来自 C. racemosum 的抗疟成分，从而为该植物的传统用途提供了依据。
