白芥子炒制过程的红外及二维相关光谱研究

采用傅里叶变换红外光谱技术动态跟踪药用植物白芥子的炒制过程，获得了不同炒制时间样本的红外谱，二阶导数谱和热扰动下的二维相关红外谱。白芥子的红外谱表明，白芥子在炒制过程中1 747 cm-1油脂特征蜂的相对强度变化不明显，说明白芥子羧酸酯相对较稳定;而1 657 cm-1附近酰胺Ⅰ带峰和1 546 cm-1附近的酰胺Ⅱ带的吸收峰相对强度显著减小，是因为白芥子在高温炒制过程中，蛋白质(酶)发生了热变性;1 055 cm-1附近的纤维多糖的特征吸收峰在炒制10 min后明显减弱，这与药材表皮纤维多糖加热分解相关联。二阶导数谱和二维相关红外谱的变化规律与红外谱的结果相一致，进一步验证了白芥子药材在炒制过程中发生的主要变化是蛋白质变性及多糖的分解。该方法揭示了药材在炮制过程中所发生的物理化学变化过程，从分子光谱水平上奠定了白芥子药材炮制的目的“杀酶保甙”的理论基础。

Research on Parching Procedure of White Mustard Seed with Fourier Transform Infrared Spectroscopy and Two-Dimensional IR Correlation Spectroscopy

Using multi-steps macro-fingerprint infrared(IR) spectroscopy,which combines three steps: conventional Fourier transform infrared spectroscopy(FTIR),second derivative spectroscopy,and two-dimensional infrared(2D-IR) correlation spectroscopy,the authors tracked dynamically the parching procedure of mustard seed to analyze the main transformation during the process.Compared with conventional IR spectra of samples parched for different time,the authors found that the characteristic peaks of protein decreased gradually,indicating the reduction of protein with the parching process,maybe because under a longtime parching procedure the heat denaturation occurred in protein compound.In addition,the essence of enzyme was protein,therefore,its transformation trend was closely related to that of protein,which also underwent heat denaturation.The absorption peak around 1 055 cm~(-1),which was due to the vibrations of fibred saccharides,began to minish rapidly at early time,then vanished after ten minutes because of the decomposition of fibred saccharides at the beginning of the process.Moreover the results of second derivative spectroscopy and 2D IR correlation spectroscopy validated that of conventional IR spectroscopy,which also indicated the heat denaturation of enzyme and decomposition of saccharides.This multi-steps macro-fingerprint IR spectroscopy method can track dynamically the processing procedure of medicinal herbs and reveal the main transformations;it must play an important role in studying medicinal herbs in the future.