Jaramillo Jaramillo Carmita, Jaramillo Espinoza Anyi, D'Armas Haydelba, Troccoli Luis, Rojas de Astudillo Luisa
Rev Biol Trop. 2016 Sep;64(3):1171-84.
Alkaloids, polyphenols, cyanogenic glycosides and saponins are among the main chemical compounds synthesized by plants but not considered essential for their basic metabolism. These compounds have different functions in plants, and have been recognized with medicinal and pharmacological properties. In this research, concentrations of the mentioned secondary metabolites were determined in the medicinal plants Artemisia absinthium, Cnidoscolus aconitifolius, Parthenium hysterophorus, Piper carpunya and Taraxacum officinale, from Ecuador, and related with cytotoxic effects against Artemia salina. Alcoholic and aqueous extracts from leaves of these selected plants were prepared at different concentrations. To assess cytotoxicity of these extracts, different bioassays with A. salina were undertaken, and the mortality rates and LC50 were obtained. Besides, concentrations of alkaloids, cyanogenic glycosides, phenols, tannins and saponins were determined by spectrophotometric methods; this constituted the first report of quantification of secondary metabolites in the selected plants from Ecuador. T. officinale had the highest concentration of total phenols (22.30 ± 0.23 mg/g) and tannins (11.70 ± 0.10 mg/g), C. aconitifolius of cyanogenic glycosides (5.02 ± 0.37 µg/g) and P. hysterophorus of saponins (6.12 ± 0.02 mg/g). Tannins values obtained were not adverse to their consumption. Alcoholic and aqueous extracts of selected plants had hemolytic activity depending on the concentration of saponins. Although the values of cyanogenic glycosides were permissible, it was necessary to monitor the presence of this metabolite in plants to minimize health problems. LC50 values ranged from extremely toxic (3.37 µg/mL) to highly toxic (274.34 μg/mL), in P. carpunya and T. officinale, respectively. From correlation analysis, it was observed that increase values of alkaloids concentrations had highly significant (p<0.001) acute toxicity against A. salina, while at a higher polyphenol concentration the level of plants cytotoxicity decreased significantly (p<0.001). The results of principal component analysis showed that saponins apparently were in synergy with polyphenols to decrease cytotoxicity, but antagonize with alkaloids and cyanogenic glycosides, indicating that these secondary metabolites present variability in the mechanisms of action against A. salina, as cytotoxic compounds. These results also demonstrate that polyphenols and saponins can be lethal at low concentrations, demonstrating the potential of brine shrimp bioassay as a model to evaluate plant extracts containing low concentrations of chemical compounds with high polarities. The significant positive correlation between cytotoxicity and concentration of alkaloids confirmed by the bioassay of brine shrimp can be useful to identify promising sources of antitumor compounds, and to evaluate tolerable limits not affecting other benign cells. Contents of secondary metabolites found in the selected plants confer them great pharmacologic values.
生物碱、多酚、氰苷和皂苷是植物合成的主要化合物，但并非其基本代谢所必需。这些化合物在植物中具有不同的功能，并已被确认具有药用和药理特性。在本研究中，测定了来自厄瓜多尔的药用植物苦艾、刺萼龙葵、银胶菊、卡普尼亚胡椒和药用蒲公英中上述次生代谢物的浓度，并将其与对卤虫的细胞毒性作用相关联。以不同浓度制备了这些选定植物叶片的乙醇提取物和水提取物。为了评估这些提取物的细胞毒性，采用卤虫进行了不同的生物测定，并获得了死亡率和半数致死浓度（LC50）。此外，通过分光光度法测定了生物碱、氰苷、酚类、单宁和皂苷的浓度；这是对来自厄瓜多尔的选定植物中次生代谢物进行定量的首次报告。药用蒲公英的总酚（22.30±0.23毫克/克）和单宁（11.70±0.10毫克/克）浓度最高，刺萼龙葵的氰苷（5.02±0.37微克/克）浓度最高，银胶菊的皂苷（6.12±0.02毫克/克）浓度最高。所获得的单宁值对其食用并无不利影响。选定植物的乙醇提取物和水提取物具有溶血活性，这取决于皂苷的浓度。尽管氰苷的值是允许的，但有必要监测植物中这种代谢物的存在，以尽量减少健康问题。半数致死浓度值范围从极毒（3.37微克/毫升）到高毒（274.34微克/毫升），分别出现在卡普尼亚胡椒和药用蒲公英中。通过相关性分析观察到，生物碱浓度的增加对卤虫具有高度显著（p<0.001）的急性毒性，而在较高的多酚浓度下，植物细胞毒性水平显著降低（p<0.001）。主成分分析结果表明，皂苷显然与多酚协同作用以降低细胞毒性，但与生物碱和氰苷拮抗，表明这些次生代谢物作为细胞毒性化合物，在对卤虫的作用机制上存在变异性。这些结果还表明，多酚和皂苷在低浓度下可能具有致死性，证明了卤虫生物测定作为评估含有低浓度高极性化合物的植物提取物的模型的潜力。卤虫生物测定所证实的细胞毒性与生物碱浓度之间的显著正相关，可有助于识别有前景的抗肿瘤化合物来源，并评估不影响其他良性细胞的耐受限度。在选定植物中发现的次生代谢物含量赋予它们巨大的药理价值。
