胡椒生物碱提取、几何结构以及红外光谱的研究

Study on the Extraction,Geometry Structure and Spectral Characterization of Piperine Alkaloid

以海南胡椒果为原料,95%乙醇溶液为溶剂,采用回流法提取胡椒生物碱。通过调节pH值除去胡椒酸,乙醚除去脂溶物,用丙酮为溶剂重结晶纯化胡椒生物碱,并用高效液相色谱仪检测其纯度,以及对胡椒生物碱进行了红外光谱表征。同时运用密度泛函B3LYP/6—31G(d,p)方法,对胡椒生物碱的结构进行优化、频率和能量的计算,得到四种构型(构型Ⅰ胡椒碱、构型Ⅱ异胡椒碱、构型Ⅲ异胡椒脂碱和构型Ⅳ胡椒脂碱)的64种构象的稳定结构,并利用吉布斯自由能计算常温(298.15 K)下四种构型分子体系稳定构象的热力学平衡分布。并对实验红外光谱与理论红外光谱的特征峰进行了对比。结果表明,所提取的胡椒生物碱主要以构型Ⅰ中的构象1结构存在,即胡椒碱结构;经纯化后得到胡椒碱含量为7%,纯度达99%。经分析建立的胡椒生物碱提取、分离和纯化方法效果良好,建立的胡椒生物碱模型能与实验结果相吻合。该研究对指导胡椒生物碱的提取、结构模型的建立、表征和应用有重大意义。

Using pepper fruit of Hainan as raw material and 95% ethanol as solvent ,the alkaloid in pepper is extracted with reflux method in this paper .The piperonylic acid is removed by adjusting the pH ;the fat-soluble substance being removed by adding ethyl ether;the piperine alkaloid being purified with acetone by recrystallization anddetected with HPLC ,as well as char-acterized with IR .The characterizations of piperine are discussed .Meanwhile ,B3LYP/6-31G （d ,p） method of DFT is applied to optimize the structure ,calculate frequency and energy of pepper alkaloid ,then obtain four kinds of configurations （configurationⅠ as Piperine ,configuration Ⅱ as Iso Piperine ,configuration Ⅲ as Iso Chavicine ,configuration Ⅳ as Chavicine） with 64 kinds of stability conformational structure .The distribution of the thermodynamic equilibrium of stable conformations of four kinds of configurations of the molecular is calculated with Gibbs free energy at room temperature （298.15 K） .And IR spectra of the ex-perimental were compared with the IR spectra of the theoretical .The results show that the alkaloid extracted from pepper is mainly conformer 1 in configuration Ⅰ ,that is ,Piperine;after purifying ,the content of piperine is 7% with the purity of 99% . With analysis ,the methods of extraction ,separation and purification of piperine in this paper achieve good results .Established models are in good agreement with the experimental results .This research is of great significance in guiding extracting process , building structural model and the characterization and application of piperine .