理论分析5-氟尿嘧啶分子的反应活性位点

Theoretical Analysis of the Reactive Sites in the 5-Fluorouracil Molecule

摘要: 为解决传统化疗药物靶向性差、毒副作用大的临床挑战，本研究以经典化疗药物5-氟尿嘧啶(5-FU)为研究对象，结合量子化学计算与理论分析，系统探究了药物分子的反应活性位点特征及其与药物代谢稳定性的关联。首先，确定了5-FU由C、H、O、N、F原子构成的稳定几何构型，其HOMO-LUMO轨道的电子云主要富集于嘧啶环上的碳、氮和氧原子，HOMO-LUMO能隙为7.9567 eV。分析明确了8位(C)、3位(O)和5位(N)为优先的亲电反应位点，而9位(C)、2位(O)和6位(C)为主要的亲核反应位点。通过福井函数、双描述符和局部亲电性指数等多维度定量分析，证实8位(C) (f⁻ = 0.1610)和9位(C) (f⁺ = 0.1784)分别为最强的亲电和亲核活性位点。结合5-FU已知代谢途径分析，8位(C)的高亲电活性是其体内磷酸化活化的关键，保障药物转化为活性代谢产物；3位(O)、5位(N)及2位(O)、6位(C)的适度活性则维持药物代谢平衡，避免过快失活或蓄积中毒。该研究结果为优化5-FU靶向递送系统设计、提高抗癌药物的生物利用度和靶向治疗效果提供了理论依据，有助于降低其副作用，为纳米医药技术在肿瘤治疗领域的应用奠定了基础。自临床应用以来，5-氟尿嘧啶作为一种经典的抗代谢化疗药物，始终在恶性肿瘤治疗中占据核心地位，其核心优势体现在四个关键维度：精确的作用机制、广泛的癌种适用性、强大的联合治疗兼容性以及突出的性价比，为癌症治疗提供了一种高效且可及的选择方案。

Abstract: To address the clinical challenges of poor targeting and significant side effects associated with traditional chemotherapeutic agents, this study focuses on the classic chemotherapeutic drug 5-fluorouracil (5-FU) as the research subject. By combining quantum chemical calculations with theoretical analysis, we systematically investigate the characteristics of the drug molecule’s reactive sites and their correlation with drug metabolic stability. Firstly, the stable geometric configuration of 5-FU, composed of C, H, O, N, and F atoms, was determined. The electron clouds of its HOMO-LUMO orbitals are primarily concentrated on the carbon, nitrogen, and oxygen atoms of the pyrimidine ring, with a HOMO-LUMO energy gap of 7.9567 eV. Analysis identified sites 8 (C), 3 (O), and 5 (N) as preferential electrophilic reaction sites, while sites 9 (C), 2 (O), and 6 (C) are core nucleophilic reaction sites. Multidimensional quantitative analyses, including Fukui functions, dual descriptors, and local electrophilicity indices, confirmed that site 8 (C) (f⁻ = 0.1610) and site 9 (C) (f⁺ = 0.1784) are the most potent electrophilic and nucleophilic sites, respectively. Combined with the analysis of 5-FU’s known metabolic pathways, the high electrophilic activity of site 8 (C) is crucial for its phosphorylation activation in vivo, ensuring the drug is converted into active metabolites. The moderate activity of sites 3 (O), 5 (N), 2 (O), and 6 (C) maintains the balance of drug metabolism, avoiding rapid inactivation or accumulation-induced toxicity. The findings provide a theoretical basis for optimizing the design of 5-FU targeted drug delivery systems, enhancing the bioavailability and targeted therapeutic efficacy of anticancer drugs while reducing their side effects, thereby laying a foundation for the application of nanomedical technology in tumor treatment. Since its clinical introduction, 5-fluorouracil has maintained a central role in the treatment of malignant tumors as a classic antimetabolite chemotherapeutic agent. Its core advantages encompass four key dimensions: a precise mechanism of action, broad applicability across cancer types, strong compatibility with combination therapies, and outstanding cost-effectiveness, providing an efficient and accessible therapeutic option for cancer treatment.