Kahaliw Wubayehu, Hellman Bjorn, Engidawork Ephrem
Department of Pharmacology, School of Pharmacy, College of Medicine and Health Sciences, University of Gondar, P. O. Box: 196, Gondar, Ethiopia.
Department of Pharmaceutical Biosciences, Division of Toxicology, Uppsala University, Box 594, 751 24, Uppsala, Sweden.
BMC Complement Altern Med. 2018 Feb 1;18(1):45. doi: 10.1186/s12906-017-2056-x.
Most of herbal medicines are used without any standard safety and toxicological trials although common assumption is that these products are nontoxic. However, this assumption is incorrect and dangerous, so toxicological studies should be done for herbal drugs. Although Pterolobium stellatum, Otostegia integrifolia and Vernonia amygdalina root extracts are frequently used in Ethiopian traditional medicine, there are no evidences of their active toxic compounds. Therefore, we made an effort to assess probable genotoxic effect of these plant extracts on DNA of human hematoma (HepG) cells using alkaline comet assay.
Genotoxic effects of extracts were evaluated using single cell gel electrophoresis (SCGE) method on HepG cell. Regarding comet data, the average mean tail intensities (TI) from each individual experiment and treatment (usually at least 3 cultures/treatment) were pooled and the average mean TI was used as an indicator of DNA damage and the standard error of mean (SEM) as the measure of variance.
DNA damage in the form of comet tail has been observed for 1 and 0.5 mg/ml P. stellatum chloroform and 80% methanol extracts on HepG cells, respectively. The chloroform extract of P. stellatum showed increased tail DNA percentage in a concentration dependent manner. Comet tail length in the chloroform P. stellatum extract treated cells (1 mg/ml) was significantly higher by 89% (p < 0.05) compared to vehicle treated controls. The rest of test extracts seemed to be without genotoxic effect up to a concentration of 0.5 mg/ml.
Our findings show that two extracts from one plant evaluated have a genotoxic potential in vitro which calls for a more thorough safety evaluation. Such evaluation should include other end-points of genotoxicity apart from DNA damage, and possibly also pure compounds.
尽管人们普遍认为草药产品无毒，但大多数草药在使用时并未经过任何标准的安全性和毒理学试验。然而，这种假设是不正确且危险的，因此应对草药进行毒理学研究。虽然翼叶豆、全缘耳草和扁桃斑鸠菊根提取物在埃塞俄比亚传统医学中经常使用，但尚无关于其活性有毒化合物的证据。因此，我们努力使用碱性彗星试验评估这些植物提取物对人肝癌（HepG）细胞DNA的潜在遗传毒性作用。
使用单细胞凝胶电泳（SCGE）方法在HepG细胞上评估提取物的遗传毒性作用。对于彗星试验数据，汇总每个单独实验和处理（通常每个处理至少3个培养物）的平均尾强度（TI），并将平均TI用作DNA损伤的指标，将平均标准误差（SEM）用作方差的度量。
分别在HepG细胞上观察到1mg/ml和0.5mg/ml翼叶豆氯仿提取物和80%甲醇提取物以彗星尾形式出现的DNA损伤。翼叶豆氯仿提取物显示尾DNA百分比呈浓度依赖性增加。与溶剂处理的对照相比，氯仿翼叶豆提取物处理的细胞（1mg/ml）中的彗星尾长度显著高出89%（p<0.05）。其余测试提取物在浓度高达0.5mg/ml时似乎没有遗传毒性作用。
我们的研究结果表明，所评估的一种植物的两种提取物在体外具有遗传毒性潜力，这需要进行更全面的安全性评估。这种评估除了DNA损伤外，还应包括遗传毒性的其他终点，可能还包括纯化合物。
