| Chinese herbal medicines play an important role in maintaining people’s health,and the authenticity of Chinese herbal medicines has always been the focus of the people’s attention.As a traditional and precious Chinese medicine,Eucommia ulmoides has a long history of medicinal use.It contains various active ingredients such as lignans,flavonoids,polysaccharides and iridoids,which have various effects such as hypoglycemic activity,hypotensive effect,hypolipidemic effect,anti-inflammatory and anti-osteoporosis.Over the years,it has been widely used as a health product in Asian countries such as China,Japan and South Korea.In daily life,Eucommia ulmoides usually makes a soup into a dinner in a small fire,or in boiling water to make tea to eat.China is the largest producer of Eucommia ulmoides,which is widely planted all over the country,and the main cultivation areas are Shaanxi,Gansu,Sichuan,Hubei,Guizhou and other provinces.Eucommia ulmoides with national geographical indication product labels,such as Lueyang Eucommia ulmoides and Wangcang Eucommia ulmoides,are the best products of Eucommia ulmoides.Different growing environments,climatic conditions,farming methods and soil types make Eucommia ulmoides in different origins with great differences in quality,efficacy and price.The price difference of Eucommia ulmoides from different origins in the market can reach 8 times,and the price of Eucommia ulmoides with protected geographic indication(PGI)product label is generally higher than that of ordinary Eucommia ulmoides.Driven by interests,fake and shoddy Eucommia ulmoides products often appear in the market.Illegal businesses deliberately disguise Eucommia ulmoides from low-quality and low-price origin as Eucommia ulmoides from high-quality and high-price origin,and even adulterate it directly with ordinary bark with similar shape.These fraudulent acts not only greatly reduce the efficacy of Eucommia ulmoides,damage the interests of consumers,but also affect the sustainable development of Eucommia ulmoides medicinal resources.Therefore,establishing a fast,simple and accurate method for origin tracing and authenticity identification of Eucommia ulmoides has important research value and practical significance.By investigating the current research status of Eucommia ulmoides authenticity detection methods,this paper developed a series of multivariate spectroscopy combined with chemometrics methods,which were successfully applied to the authenticity detection of Eucommia ulmoides.The main research contents are as follows:Chapter one: Introduction This paper firstly summarizes the pharmacological effects of Eucommia ulmoides,the main active components and its distribution in China.Then,it reviews the origin identification of traditional Chinese medicinal materials and the modern instrumental analysis methods for adulteration identification.Subsequently,it summarizes the authenticity detection of Eucommia ulmoides research status at home and abroad.Finally,the research content and characteristics of this paper are presented.Chapter two: Identification of the geographical origin of Eucommia ulmoides by three-dimensional fluorescence spectroscopy combined with chemometrics In view of the difficulty of identifying Eucommia ulmoides samples from different places on the market with the naked eye,and the problems of complex sample pretreatment,time-consuming and laborious,expensive instruments and strong professionalism based on chromatography,mass spectrometry and other large-scale instrument analysis methods.Considering that Eucommia ulmoides soup possesses the characteristics of endogenous fluorescence,the chapter takes Eucommia ulmoides from 8 different provinces as the research object,and puts forward a strategy of three-dimensional fluorescence spectroscopy combined with chemometrics to identify the origin of Eucommia ulmoides simply and quickly.After a simple sample extraction step,the three-dimensional fluorescence spectroscopy of Eucommia ulmoides samples was quickly obtained.Then,chemometric methods(PCA-LDA and PLS-DA)are used to model the obtained three-dimensional fluorescence data.Finally,the classification results obtained by these classification methods are compared and discussed.Compared with PCA-LDA,PLS-DA obtained better classification results.The recognition rate of the cross validation,training sets and prediction set provided by PLS-DA are 86%,100% and 81%,respectively.In addition,PLS-DA has high sensitivity and specificity.So,the proposed method that three-dimensional fluorescence spectroscopy combined with chemometrics can be used to identify Eucommia ulmoides samples from different geographical origin.Chapter three: Identification of the geographical origin of Eucommia ulmoides by nano effect fluorescence spectroscopy combined with chemometrics In this chapter,in view of the problems of fluorescence spectral detection methods,such as serious peak overlap and difficult to extract and screen the subtle difference information between different samples,the author developed a simple and efficient analysis method,that is,the combination of nano effect fluorescence spectroscopy and chemometrics,so as to realize the rapid and accurate identification of the geographical origin Eucommia ulmoides.Firstly,cadmium telluride(Cd Te)quantum dots were synthesized by hydrothermal method as spectral signal amplifier to amplify the difference of fluorescence spectral signals between Eucommia ulmoides samples from different origin.Then,based on the collected nano effect fluorescence spectrum,PLS-DA model was used to distinguish the origin of Eucommia ulmoides.The results show that compared with the original fluorescence spectrum,the nano effect fluorescence spectrum can obtain better recognition effect,and the recognition accuracy of the test set is improved from 80% of the original fluorescence spectrum to 95%.Therefore,compared with the single original fluorescence spectrum detection method,the proposed method improves the specificity of spectrum detection and the amount of information extraction of traditional Chinese medicine samples,can obtain better recognition effect.It provides a new idea for the rapid recognition and analysis of traditional Chinese medicine from different producing areas.Chapter four: Identification of the geographical origin of Eucommia ulmoides by near infrared and mid infrared spectroscopy combined with chemometrics Although the fluorescence spectroscopy method is simple and fast,the recognition rate of this method does not reach 100% due to the limited substances with endogenous fluorescence response.In order to comprehensively reflect the difference information between samples from different producing areas,this chapter developed a method that near-infrared spectroscopy,mid infrared spectroscopy combined with chemometrics for the rapid identification of the origin of Eucommia ulmoides.The results show that with the pretreated near infrared spectrum,among the three chemometrics methods which are respectively k-nearest neighbor analysis(k NN),principal component analysis-linear discriminant analysis(PCA-LDA)and partial least squares discriminant analysis(PLS-DA),the k NN method obtained more accurate and reliable classification results,and the recognition rate of Eucommia ulmoides from different origins reached 100%;And after the mid infrared spectrum is pretreated by multivariate scattering,the PLS-DA method achieves the best classification performance.The recognition rates of the cross-validation,training set and prediction set provided by it are 99%,99% and 98%,respectively.This conclusion proves that the proposed strategy of infrared spectroscopy combined with chemometric methods can be used to distinguish Eucommia ulmoides samples from different geographical origins.The strategy is expected to be more widely used in origin recognition of other traditional Chinese medicines.Chapter five: Identification of Eucommia ulmoides adulteration by near infrared spectroscopy combined with chemometrics In this chapter,aiming at the problem of Eucommia ulmoides adulteration in the market,the author combines near-infrared spectroscopy with two chemometric methods to quickly identify the types and amount of adulterants(Parabarium micranthum,Smallflower Parabarium and pine bark)in Eucommia ulmoides.Firstly,Eucommia ulmoides and adulterated Eucommia ulmoides were classified by random forest(RF)and partial least squares discriminant analysis(PLS-DA).The results show that the two methods have obtained accurate and reliable classification results,and can be an effective means to distinguish pure Eucommia ulmoides and adulterated Eucommia ulmoides samples.Then,the adulteration levels of different types of adulterants in Eucommia ulmoides were quantified by partial least squares regression(PLSR)model,and satisfactory accuracy was obtained.All the results show that the proposed method can be used for the authenticity identification of Eucommia ulmoides and the adulteration level prediction of adulterated samples,and is expected to be applied to the authenticity identification of other precious medicinal materials. |
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