背景:乳酸脱氢酶(LDH)是糖酵解和糖异生的重要酶系统之一。能催化丙酸与L-乳酸的还原和氧化反应,通常在癌细胞中过度表达。因此,抑制LDH的活性是治疗癌症的一种有前景的方法。在这项研究中,建立了一种基于配体钓鱼和超高效液相色谱-质谱(UPLC-MS)的有效方法,以筛选和鉴定具有潜在抑制LDH活性的卷柏的活性成分。
方法:首先,将LDH固定在磁性纳米颗粒(MNPs)上,三个固定化参数,包括LDH浓度,通过单因素和响应面法优化固定化时间和pH,以获得最大(max)固定化产量。然后,使用加洛黄素和绿原酸(LDH的抑制剂和非抑制剂)的混合模型来验证固定化LDH配体捕捞的特异性,并进一步优化了配体捕捞条件。最后,结合UPLC-MS,固定化LDH用于同时筛选和鉴定卷柏的乙酸乙酯提取物中潜在的LDH抑制剂。
结果:通过扫描电子显微镜(SEM)对制备的钓鱼材料进行了全面表征,透射电子显微镜(TEM),X射线衍射(XRD)和傅里叶变换红外光谱仪(FT-IR)。最佳固定化条件为LDH浓度为0.7mg/mL,pH值为4.5,固定化时间为3.5h。在这些条件下,最大固定化产量为(3.79±0.08)×103U/g。特异性分析表明,固定化LDH能够识别和捕获配体,最佳配体捕捞条件包括孵化时间为30分钟,洗脱时间为20分钟,洗脱液甲醇浓度为80%。最后,两种LDH抑制剂,黄酮和罗布塔夫拉酮,通过固定化LDH从卷柏的乙酸乙酯提取物中筛选。
结论:该研究为发现卷柏乙酸乙酯提取物中与癌症治疗相关的生物活性成分提供了有意义的证据。这种配体打捞方法对于从相似的复杂混合物中筛选酶抑制剂是可行的。
BACKGROUND: Lactate dehydrogenase (LDH) is one of the important enzyme systems for glycolysis and gluconeogenesis. It can catalyze the reduction and oxidation reaction between propionic acid and L-lactic acid, which is usually overexpressed in cancer cells. Therefore, inhibiting the activity of LDH is a promising way for the treatment of cancer. In this study, an effective method based on ligand fishing and ultra performance liquid chromatography-mass spectrum (UPLC-MS) was established to screen and identify active ingredients from Selaginella doederleinii with potential inhibitory activity for LDH.
METHODS: Firstly, LDH was immobilized on the magnetic nanoparticles (MNPs), three immobilization parameters including LDH concentration, immobilization time and pH were optimized by single factor and response surface methodology for maximum (max) immobilization yield. Then, a mixed model of galloflavin and chlorogenic acid (inhibitors and non-inhibitors of LDH) was used to verify the specificity of immobilized LDH ligand fishing, and the conditions of ligand fishing were further optimized. Finally, combined with UPLC-MS, immobilized LDH was used to simultaneously screen and identify potential LDH inhibitors from the ethyl acetate extract of Selaginella doederleinii.
RESULTS: The prepared fishing material was comprehensively characterized by scanning electron microscopy (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD) and fourier transform infrared spectrometer (FT-IR). The optimal immobilization conditions were obtained as LDH concentration of 0.7 mg/mL, pH value of 4.5, and immobilization time of 3.5 h. Under these conditions, the max immobilization yield was (3.79 ± 0.08) × 103 U/g. The specificity analysis showed that immobilized LDH could recognize and capture ligands, and the optimal ligand fishing conditions included that the incubation time was 30 min, the elution time was 20 min, and the concentration of methanol as eluent was 80%. Finally, two LDH inhibitors, amentoflavone and robustaflavone, were screened by immobilized LDH from the ethyl acetate extract of Selaginella doederleinii.
CONCLUSIONS: The study provided a meaningful evidence for discovering the bioactive constituents in ethyl acetate extract of Selaginella doederleinii related to cancer treatment, and this ligand fishing method was feasible for screening enzyme inhibitors from similar complex mixtures.