Nagagi Yakob P, Silayo Richard S, Luziga Claudius, Kweka Eliningaya J
Department of Microbiology, Parasitology and Immunology, College of Veterinary and Medical Sciences, Sokoine University of Agriculture, P. O. Box 3019, Chuo Kikuu, Morogoro, Tanzania.
Tropical Pesticides Research Institute, Division of Livestock and Human Diseases Vector Control, P.O. Box 3024, Arusha, Tanzania.
BMC Complement Altern Med. 2017 May 23;17(1):275. doi: 10.1186/s12906-017-1785-1.
The search for alternative trypanocidal compounds which can be available at affordable price is of paramount importance for control of trypanosomosis in human and animals. The current study evaluates the in vivo activity of ethanolic stem bark extracts on Trypanosoma congolense and selected immunological components in an inbred Swiss albino mouse model.
Groups of mice infected with T. congolense were treated with the stem bark extracts at a rate of 1000 mg/kg, 1500 mg/kg, and 2000 mg/kg, twice a day in one set and thrice a day in another setting for three days consecutively. Negative (infected and untreated) and positive (infected treated with diminazene diaceturate at 3.5 mg/kg) control groups were used. Levels of parasitaemia were monitored daily for the first 10 days and thereafter 2-3 times per week to the end of experiment. In the other setting, uninfected mice, randomized in groups were treated with the extract but categorized as: thorough mixed extract (TME) and supernatant extract (SE) each at 500 mg/kg and 1500 mg/kg, in 8 hourly intervals respectively for three days consecutively. Control group was administered with phosphate buffered saline with glucose at 0.1 ml/10 g in a similar manner as for the extract. Whole blood and spleen were taken 24 h after the last treatment for hematological and histopathological analysis.
The groups that received the extracts at 8 hourly intervals drastically reduced the parasitaemia. The higher dose of SE significantly reduced the percentage of lymphocytes (P < 0.05). Both high and low dose of TME significantly reduced lymphocytes percent (P < 0.05) while percent of neutrophils and monocytes increased significantly (P < 0.05). Histopathological changes of the spleen in the mice treated with higher concentrations of the extract of C. swynnertonii were suggestive of lymphocytes toxicity.
The current study has provided evidence that, in vivo trypanocidal activity of ethanolic bark extracts of C. swynnertonii is probably affected by its negative effect on humoral mediated immune response. Further studies are recommended to determine its potential as an alternative source of lead compounds for trypanocidal drug discovery.
寻找价格亲民的新型杀锥虫化合物对于控制人和动物的锥虫病至关重要。本研究评估了在近交系瑞士白化小鼠模型中，乙醇提取的茎皮提取物对刚果锥虫的体内活性以及选定的免疫成分。
感染刚果锥虫的小鼠组，一组以1000mg/kg、1500mg/kg和2000mg/kg的剂量，每天两次连续三天进行茎皮提取物治疗；另一组以相同剂量每天三次连续三天进行治疗。设置阴性（感染未治疗）和阳性（感染后用3.5mg/kg双乙酰甲氧苄氨嘧啶治疗）对照组。在实验的前10天每天监测寄生虫血症水平，此后每周监测2 - 3次直至实验结束。在另一种情况下，将未感染的小鼠随机分组，分别用提取物治疗，但分为：全混合提取物（TME）和上清液提取物（SE），分别以500mg/kg和1500mg/kg的剂量，每8小时给药一次，连续三天。对照组以与提取物相同的方式给予含葡萄糖的磷酸盐缓冲盐水，剂量为0.1ml/10g。在最后一次治疗24小时后采集全血和脾脏进行血液学和组织病理学分析。
每8小时接受提取物治疗的组寄生虫血症显著降低。较高剂量SE显著降低淋巴细胞百分比（P < 0.05）。高剂量和低剂量TME均显著降低淋巴细胞百分比（P < 0.05），而中性粒细胞和单核细胞百分比显著增加（P < 0.05）。用较高浓度的斯氏柯罗木提取物治疗的小鼠脾脏组织病理学变化提示淋巴细胞毒性。
本研究提供了证据表明，斯氏柯罗木乙醇树皮提取物的体内杀锥虫活性可能受其对体液介导免疫反应的负面影响。建议进一步研究以确定其作为杀锥虫药物发现中先导化合物替代来源 的潜力。
