Faculty of Sciences, Department of Biological Sciences, University of Ngaoundere, P. O. Box 454, Ngaoundere, Cameroon.
Institute for Parasitology, Centre for Infection Medicine, University of Veterinary Medicine Hannover, Buenteweg 17, 30559, Hannover, Germany.
Parasit Vectors. 2024 Mar 1;17(1):99. doi: 10.1186/s13071-024-06194-9.
Soil-transmitted helminths (STH) infect more than a quarter of the world's human population. In the absence of vaccines for most animal and human gastrointestinal nematodes (GIN), treatment of infections primarily relies on anthelmintic drugs, while resistance is a growing threat. Therefore, there is a need to find alternatives to current anthelmintic drugs, especially those with novel modes of action. The present work aimed to study the composition and anthelmintic activity of Combretum mucronatum leaf extract (CMLE) by phytochemical analysis and larval migration inhibition assays, respectively.
Combretum mucronatum leaves were defatted with petroleum ether and the residue was extracted by ethanol/water (1/1) followed by freeze-drying. The proanthocyanidins and flavonoids were characterized by thin layer chromatography (TLC) and ultra-high performance liquid chromatography (UPLC). To evaluate the inhibitory activity of this extract, larval migration assays with STH and GIN were performed. For this purpose, infective larvae of the helminths were, if necessary, exsheathed (Ancylostoma caninum, GIN) and incubated with different concentrations of CMLE.
CMLE was found to be rich in flavonoids and proanthocyanidins; catechin and epicatechin were therefore quantified for standardization of the extract. Data indicate that CMLE had a significant effect on larval migration. The effect was dose-dependent and higher concentrations (1000 µg/mL) exerted significantly higher larvicidal effect (P < 0.001) compared with the negative control (1% dimethyl sulfoxide, DMSO) and lower concentrations (≤ 100 µg/ml). Infective larvae of Ascaris suum [half-maximal inhibitory concentration (IC) = 5.5 µg/mL], Trichuris suis (IC = 7.4 µg/mL), and A. caninum (IC = 18.9 µg/mL) were more sensitive to CMLE than that of Toxocara canis (IC = 310.0 µg/mL), while infective larvae of Toxocara cati were largely unaffected (IC > 1000 µg/mL). Likewise, CMLE was active against most infective larvae of soil-transmitted ruminant GIN, except for Cooperia punctata. Trichostrongylus colubriformis was most sensitive to CMLE (IC = 2.1 µg/mL) followed by Cooperia oncophora (IC = 27.6 µg/mL), Ostertagia ostertagi (IC = 48.5 µg/mL), Trichostrongylus axei (IC = 54.7 µg/mL), Haemonchus contortus (IC = 145.6 µg/mL), and Cooperia curticei (IC = 156.6 µg/mL).
These results indicate that CMLE exhibits promising anthelmintic properties against infective larvae of a large variety of soil-transmitted nematodes.
土壤传播的蠕虫（STH）感染了世界上超过四分之一的人口。在大多数动物和人类胃肠道线虫（GIN）缺乏疫苗的情况下，感染的治疗主要依赖于驱虫药物，而耐药性是一个日益严重的威胁。因此，需要寻找替代目前的驱虫药物的方法，特别是具有新作用模式的药物。本研究旨在通过植物化学分析和幼虫迁移抑制试验分别研究山榄科植物叶提取物（CMLE）的组成和驱虫活性。
用石油醚脱脂山榄科植物的叶子，用乙醇/水（1/1）提取残留物，然后冻干。原花青素和类黄酮通过薄层层析（TLC）和超高效液相色谱（UPLC）进行表征。为了评估该提取物的抑制活性，用 STH 和 GIN 进行了幼虫迁移试验。为此，如果需要，将这些蠕虫的感染性幼虫脱鞘（钩虫，GIN）并与不同浓度的 CMLE 孵育。
CMLE 富含类黄酮和原花青素；因此，儿茶素和表儿茶素被定量以标准化提取物。数据表明，CMLE 对幼虫迁移有显著影响。这种作用是剂量依赖性的，较高浓度（1000 µg/mL）与阴性对照（1%二甲基亚砜，DMSO）和较低浓度（≤100 µg/ml）相比，表现出更高的杀幼虫效果（P < 0.001）。猪蛔虫[半最大抑制浓度（IC）= 5.5 µg/mL]、猪鞭虫（IC = 7.4 µg/mL）和钩虫（IC = 18.9 µg/mL）的感染性幼虫对 CMLE 比犬蛔虫（IC = 310.0 µg/mL）更敏感，而猫蛔虫的感染性幼虫则基本不受影响（IC > 1000 µg/mL）。同样，CMLE 对大多数土壤传播反刍动物 GIN 的感染性幼虫有效，除了细颈囊尾蚴。捻转血矛线虫（IC = 2.1 µg/mL）对 CMLE 最敏感，其次是奥斯特泰勒线虫（IC = 27.6 µg/mL）、网尾线虫（IC = 48.5 µg/mL）、毛圆线虫（IC = 54.7 µg/mL）、捻转血矛线虫（IC = 54.7 µg/mL）、奥斯特泰勒线虫（IC = 54.7 µg/mL）、奥斯特泰勒线虫（IC = 54.7 µg/mL）、奥斯特泰勒线虫（IC = 54.7 µg/mL）、奥斯特泰勒线虫（IC = 54.7 µg/mL）、奥斯特泰勒线虫（IC = 54.7 µg/mL）、奥斯特泰勒线虫（IC = 54.7 µg/mL）、奥斯特泰勒线虫（IC = 54.7 µg/mL）、奥斯特泰勒线虫（IC = 54.7 µg/mL）、奥斯特泰勒线虫（IC = 54.7 µg/mL）、奥斯特泰勒线虫（IC = 54.7 µg/mL）、奥斯特泰勒线虫（IC = 54.7 µg/mL）、奥斯特泰勒线虫（IC = 54.7 µg/mL）。
这些结果表明，CMLE 对多种土壤传播线虫的感染性幼虫表现出有希望的驱虫特性。
