山奈酚和槲皮素对大鼠体内Neu5Gc合成的影响及分子机制探究

非人源性唾液酸N-羟乙酰神经氨酸(N-glycolylneuraminic acid, Neu5Gc)是红肉中潜在的致癌性因子。唾液酸转移酶是涉及转运其前体物质的关键酶之一。大鼠用不同浓度的山奈酚(kaempferol,KA)和槲皮素(quercetin,Qu)灌胃,并模拟宰前对Neu5Gc合成影响的结果表明,不同浓度的KA、Qu对大鼠体内肌肉组织、肝和肾中Neu5Gc的含量均有一定的影响,最大抑制率分别为36.44%±0.11%和33.37%±0.08%。为探究其抑制机制,采用唾液酸转移酶(sialyltransferase,ST)与KA、Qu进行分子对接和分子动力学模拟分析。分子对接复合物二维相互作用图表明:KA和Qu能有效占据ST特异性抑制剂5′-胞苷单磷酸的活性位点氨基酸残基;对最佳复合物进行200 ns的动力学模拟结果显示,ST和KA产生稳定氢键作用的氨基酸残基主要是His301和Gly298,与Qu产生氢键作用的氨基酸残基主要是Gly293、Glu324、Thr272和Ser276。结合自由能分析表明,范德华力、静电吸引作用对抑制过程具有重要作用。本研究为合成和筛选高效ST抑制剂提供了一定实验依据。

Effects of Kaempferol and Quercetin on the Synthesis of Neu5Gc in Rats and its Molecular Mechanism

Non-human sialic acid N-glycolylneuraminic acidis a potential carcinogenic factor in red meat, and sialyltransferase is one of the key enzymes involved in the transport of its precursors. The effects of different concentrations of kaempferol and quercetin on the synthesis of glycolylneuraminic acid (Ne5Gc) in rats were observed. Different concentrations of KA and Qu were observed in rats. The content of Neu5Gc in muscle tissues, livers and kidneys has a certain effect, and the maximum inhibition rate is 36.44%±0.11%, 33.37%±0.08%, respectively. In order to explore its inhibitory mechanism, sialyltransferase (ST) was used for molecular docking and molecular dynamics simulation analysis with KA and Qu. The two-dimensional interaction diagram of the molecular docking complex indicates that KA and Qu can effectively occupy the active residues of the 5′-cytidine monophosphate of the ST specific inhibitor. The simulation results from the kinetics of the optimal complex for 200 ns show that the residues of producing stable hydrogen bonding between ST and kaempferol are mainly His301 and Gly298, and the residues that generate hydrogen bonding with quercetin are mainly Gly293, Glu324, Thr272 and Ser276. Van der Waals force and electrostatic attraction play an important role in the inhibition process. This study provides a theoretical basis for the synthesis and screening of highly efficient sialyltransferase inhibitors.