Introduction

Trypanosomiasis is a neglected disease of humans and livestock caused by single-celled flagellated haemo-protozoan parasites belonging to the genus Trypanosoma.

Purpose

Widespread resistance to trypanocidal drugs creates urgent need for new, more effective drugs with potential to inhibit important trypanosome molecular targets.

Methods

Nine column chromatographic, partially purified leaf fractions of Azadirachta indica (AIF) were subjected to trypanosome alternative oxidase (TAO) inhibition assay using ubiquinol oxidase assay. The potent TAO inhibitors were evaluated for trypanocidal activities against T. congolense in rat model using in vitro, ex vivo, and in vivo assays. Complete cessation or reduction in parasite motility was scored from 0 (no parasite) to 6 (greater than or equal to 6 × 10⁷ trypanosomes/milliliter of blood), and was used to evaluate the efficacy of in vitro treatments.

Results

Only AIF1, AIF2, and AIF5 significantly inhibited TAO. AIF1 and AIF5 produced significant, dose-dependent suppression of parasite motility reaching score zero within 1 h with EC₅₀ of 0.005 and 0.004 µg/µL, respectively, while trypanosome-laden blood was still at score six with an EC₅₀ of 44,086 µg/µL. Mice inoculated with the concentrations at scores 0 and 1 (1–2 moribund parasites) at the end of the experiment did not develop parasitaemia. The two fractions significantly (p < 0.05) lowered parasite burden, with the AIF5 exhibiting highest in vivo trypanocidal effects. Packed cell volume was significantly higher in AIF1 (p < 0.05) and AIF5 (p < 0.001) groups compared to DMSO-treated group. Only AIF5 significantly (p < 0.05) lowered malondialdehyde.

Conclusion

AIF1 and AIF5 offer prospects for the discovery of TAO inhibitor(s).

中文翻译：

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部分纯化的印楝叶组分抑制锥虫替代氧化酶并对刚果锥虫发挥抗锥虫作用

介绍

锥虫病是一种被忽视的人类和牲畜疾病，由属于锥虫属的单细胞鞭毛血原虫寄生虫引起。

目的

对杀锥虫药物的广泛耐药性迫切需要新的、更有效的药物，这些药物有可能抑制重要的锥虫分子靶点。

方法

使用泛醇氧化酶测定法对九个柱层析、部分纯化的印楝叶组分(AIF) 进行锥虫替代氧化酶 (TAO) 抑制测定。使用体外、离体和体内测定法在大鼠模型中评估了有效的 TAO 抑制剂对刚果锥虫的杀锥虫活性。寄生虫运动的完全停止或减少从 0（无寄生虫）到 6（大于或等于 6 × 10 ⁷ 锥虫/毫升血液）评分，并用于评估体外治疗的功效。

结果

只有 AIF1、AIF2 和 AIF5 显着抑制 TAO。AIF1 和 AIF5 对寄生虫运动产生显着的剂量依赖性抑制，在 1 小时内达到零分，EC ₅₀分别为 0.005 和 0.004 µg/µL，而富含锥虫的血液仍为六分，EC ₅₀为 44,086 µg/微升。在实验结束时接种浓度为 0 和 1（1-2 垂死的寄生虫）的小鼠没有发生寄生虫血症。这两个部分显着降低了寄生虫负担 ( p  < 0.05)，其中 AIF5 表现出最高的体内杀锥虫作用。AIF1 ( p  < 0.05) 和 AIF5 ( p < 0.001) 组与 DMSO 治疗组相比。只有 AIF5 显着 ( p  < 0.05) 降低了丙二醛。

结论

AIF1 和 AIF5 为发现 TAO 抑制剂提供了前景。