In vitro cytotoxic activity of five commercial samples of Tribulus terrestris Linn in Espírito Santo (Brazil)

ABSTRACT The objective was to investigate the total saponin and protodioscin concentrations and the cytotoxicity in vitro, of five samples of the plant Tribulus terrestris, commercially available in the metropolitan region of Vitória - Espirito Santo, Brazil, and to compare them with the aqueous extract of the plant. The chromatographic profile and quantification of protodioscin in commercial samples and plant extract were evaluated by LC-MS/MS. The percentage of total saponins were determined by the colorimetric method. Extracts and protodioscin cytotoxicity were analyzed by the MTT assay in three cell lineages: fibroblasts (L929), ovarian cancer (Ovcar3) and murine hepatoma (Hepa1c1c7). All extracts displayed high levels of total saponins (207.2 to 780.3 mg g-1 of dry extract). The chromatographic profile revealed a wide diversity of compounds, and the saponin protodioscin was detected in only two extracts. One extract displayed high cytotoxicity, with IC50 values of 157.0, 38.2 and 7.4 µg mL-1 for the Ovcar3, Hepa1c1c7 and L929 cell lines, respectively. The other extracts displayed cytotoxic effects only at concentrations equal to or greater than 125.0 µg mL-1. Surprisingly, the most cytotoxic extract displayed the highest protodioscin concentration. Therefore, it is suggested that these products be marketed with caution, and followed-up by a certified healthcare professional.

摘要
本研究旨在探究巴西圣埃斯皮里图州维多利亚大都会地区市售的5份蒺藜（Tribulus terrestris）样品的总皂苷、原薯蓣皂苷（protodioscin）含量及其体外细胞毒性，并与该植物的水提物进行对比。采用液相色谱-串联质谱（LC-MS/MS）对市售样品与植物水提物的色谱特征及原薯蓣皂苷含量进行分析与定量；总皂苷的质量百分比通过比色法测定。采用MTT法对提取物及原薯蓣皂苷的细胞毒性进行检测，所用细胞系包括成纤维细胞（L929）、卵巢癌细胞（Ovcar3）与小鼠肝癌细胞（Hepa1c1c7）。
所有提取物的总皂苷含量均较高，范围为207.2~780.3 mg·g⁻¹干提取物。色谱特征分析表明样品中化合物种类丰富，但仅在2份提取物中检测到原薯蓣皂苷成分。其中1份提取物表现出较强细胞毒性，其对Ovcar3、Hepa1c1c7及L929细胞系的半数抑制浓度（IC50）分别为157.0、38.2和7.4 μg·mL⁻¹；其余提取物仅在浓度≥125.0 μg·mL⁻¹时才表现出细胞毒性效应。令人意外的是，细胞毒性最强的提取物其原薯蓣皂苷含量也最高。因此，建议对该类产品的市场流通采取审慎态度，并由持证医疗专业人员开展跟踪监测。