Study On The Application Of Raman Spectroscopy In Active Ingredients And Compound Preparations Of Traditional Chinese Medicine

As complementary and alternative medicine develops,the demand for traditional Chinese medicine（TCM）has been expanding year by year.With a wide variety of TCM,establishing fingerprint spectra is of great significance for characterizing the chemical components of TCM and controlling the quality of compound preparations.Raman spectroscopy is a fingerprint detection method based on molecular vibrations,which is characterized by being time-saving,non-destructive,informative,and not affected by water-soluble solutions.It can be used for qualitative and quantitative analysis of active ingredients in TCM,identification of adulteration in medicinal materials,and provides an effective means for the modernization of TCM research,with broad development prospects.This paper is based on Raman spectroscopy and focuses on two secoiridoid glycoside monomers and Kai Xin San（KXS）compound preparation.The paper consists of three parts:First,the Raman theoretical spectra of Gentiopicroside（GPS）and Swertiamarin（SWE）were calculated based on density functional theory and compared with actual spectra to attribute the vibration modes of the two molecules.Three types of metal nanoparticles were prepared as surface-enhanced substrates,and the colloid with the best enhancement effect was selected as Ag NPs reduced by hydroxylamine hydrochloride,through the study on surface-enhanced Raman spectra（SERS）of GPS and SWE,it’s preliminarily determined that the parent nucleus of this type of component is vertically adsorbed on the surface of the substrate.Second,Raman spectroscopy was used to quantitatively analyze GPS in the extract of Gentian.Based on the Raman spectra analysis of GPS,the Raman peak at 1685 cm^-1 was selected as the characteristic peak of GPS,and the peak at 1036 cm^-1 in methanol was chosen as the internal standard to establish a standard curve by plotting the ratio of the intensity of the two bands against the concentration of GPS.The results showed that there was a good linear relationship between the intensity ratio of GPS and the methanol characteristic peaks and the concentration of GPS.The linear equation was y=1.9968x+0.0178,R²=0.9989,the calculated average content value is 3.72±0.045%.Compared with the content value measured by HPLC method of 3.78±0.032%,the relative error is 1.59%,and there is no significant difference（p>0.05）.This indicates that the quantitative model established by this method can be used for the quantitative analysis of gentiopicroside.Third,a portable infrared-excited Raman spectroscopy instrument was used to analyze and study the classic prescription KXS.The Raman spectra of single herb powder,single herb decoction,herb pair decoction,and KXS decoction were obtained,and the Raman peaks were assigned,which can be used as their fingerprint for identification analysis.Finally,principal component analysis（PCA）was used to distinguish three different ratios of Kaixin San formula.The results showed that the sum of the variance contribution rates of the three most significant extracted principal components,PC1,PC2,and PC3,was 97.51%,indicating that these three principal components can provide sufficient information to distinguish different proportions of Kaixin San Tang D652,K984,and K652.In summary,the application of Raman spectroscopy to the analysis of secoiridoid glycoside components optimized their structures and attributed the molecular vibration modes,preliminary studied their adsorption modes with surface-enhanced substrates,established a Raman spectroscopy method for quantitatively studying GPS using an internal standard method,and laid the foundation for the research on the structure-effect relationship of this type of compound.Subsequently,this study confirmed the feasibility of using infrared excitation wavelength Raman spectroscopy technology for the detection of traditional Chinese medicine decoction.The obtained Raman spectra can be used as characteristic fingerprints of specific samples as a basis for discrimination and classification,opening up new feasible solutions for the quality control and detection of prescriptions.