| Objective:Dalbergia odoriferae lignum,commonly known as"Jiangxiang"in Chinese,is the dried heartwood of the leguminous plant Dalbergia odorifera T.Chen.Besides its medicinal value,it is also a valuable redwood resource in China.Due to its high demand and limited supply,the market for"Jiangxiang"has been flooded with counterfeit products,which not only disrupt the market but also pose a serious threat to the safety of traditional Chinese medicine.The limited morphological characteristics of"Jiangxiang"make it difficult to accurately identify its authenticity using traditional methods.Therefore,this study aims to identify the authenticity of"Jiangxiang"and its counterfeit products and commercial samples using traditional,chromatographic,and spectroscopic methods.By clarifying the key identification points and assigning the origin of the counterfeit products,we aim to provide a scientific basis for the identification of"Jiangxiang"and develop efficient and accurate identification methods.Methods:1.Microscopic tissue identification,a traditional method for identifying authenticity,was used to identify the origin of counterfeit Dalbergia odorifera lignum and summarize its microscopic features,in order to find the distinguishing characteristics of authentic Dalbergia odorifera lignum.The traditional morphological identification was employed to compare the characteristics of commercially available Dalbergia odorifera lignum,combined with the morphological features of counterfeit products,to determine the origin of counterfeit products in the commercial market.2.Thin layer chromatography was used to distinguish between authentic and counterfeit Dalbergia odorifera lignum,as well as commercially available samples,and to determine the key features of thin layer chromatography for Dalbergia odorifera lignum identification.High-performance liquid chromatography was employed to analyze the similarity of the three types of samples and to discriminate between them.3.Infrared spectroscopy was used to obtain data for authentic and counterfeit Dalbergia odorifera lignum as well as commercially available samples.The obtained data were optimized and then subjected to first and second derivative processing.The chemical component types present in Dalbergia odorifera lignum and its counterfeit products were inferred through peak attribution in the infrared spectra.The combined data of infrared spectra,first and second derivative infrared spectra,similarity analysis,cluster analysis,principal component analysis(PCA),partial least squares discriminant analysis(PLS-DA),and orthogonal partial least squares discriminant analysis(OPLS-DA)were used for classification to identify authentic and counterfeit Dalbergia odorifera lignum and commercially available samples.4.Hydrogen nuclear magnetic resonance(1H-NMR)spectroscopy was used to obtain data for authentic and counterfeit Dalbergia odorifera lignum and commercially available samples.The obtained data were optimized and then subjected to similarity analysis,cluster analysis,and orthogonal partial least squares discriminant analysis(OPLS-DA)for classification to identify authentic and counterfeit Dalbergia odorifera lignum and commercially available samples.Results:1.Microscopic identification of counterfeit Dalbergia odorifera lignum showed that it included Pterocarpus erinaceus,Pterocarpus macrocarpus,Dalbergia cochinchinensis,Dalbergia benthamii,and Dalbergia pinnata.Macroscopically,it was difficult to distinguish Pterocarpus erinaceus,Pterocarpus macrocarpus,and Dalbergia cochinchinensi from Dalbergia odorifera,while Dalbergia benthamii,and Dalbergia pinnata were easily distinguished due to their macroscopic features as woody vines.Microscopically,Dalbergia odorifera could be distinguished from its counterfeits by the main axial thin-walled tissue being polycyclic in shape.In terms of physical characteristics,only 2 batches of Dalbergia odoriferae lignum samples were identified as counterfeit,and the 5 counterfeits were similar in color to Dalbergia odoriferae lignum,making it difficult to attribute them to counterfeit samples in the market.2.Thin-layer chromatography and high-performance liquid chromatography were used to identify the authenticity of Dalbergia odoriferae lignum in the market,and the counterfeits were correctly attributed to Dalbergia cochinchinensis and Dalbergia pinnata.3.Based on the average infrared spectra of Dalbergia odoriferae lignum and its counterfeits,it was inferred that they all contained rich benzene ring compounds,as well as carboxylic acids,alcohols,and phenolic components.The similarity analysis between Dalbergia odoriferae lignum and its counterfeits showed that it was difficult to completely distinguish between them.The comparison of infrared spectra similarity between market samples and Dalbergia odoriferae lignum and its counterfeits showed that the differentiation of Dalbergia cochinchinensis counterfeits in market agarwood was obvious.However,the similarity analysis of derivative processed infrared spectra could not significantly differentiate between the authenticity of market Dalbergia odoriferae lignum.Clustering analysis showed that only first-order infrared spectra clustering analysis could distinguish between authentic and counterfeit Dalbergia odoriferae lignum,but could not correctly attribute the origin of counterfeit samples in the market.OPLS-DA analysis of first-order derivative infrared spectra of Dalbergia odoriferae lignum and its counterfeits and market samples could completely distinguish between authentic and counterfeit Dalbergia odoriferae lignum in the market,but could not correctly attribute counterfeit samples to their origins.4.Similarity analysis and clustering analysis of ~1H-NMR spectra data showed a clear distinction between Dalbergia odoriferae lignum and its counterfeits.OPLS-DA analysis of Dalbergia odoriferae lignum and its counterfeits identified the proton signal peaks atδ1.05andδ1.60 as trans-nerolidol,which were attributed to the differentiation between them.The class variable value was calculated in the OPLS-DA model,with a value of 1±0.3 indicating samples as authentic,and a value of 0±0.3 indicating samples as counterfeit.This approach was effective in identifying the authenticity of Dalbergia odoriferae lignum samples in the market,and the OPLS-DA score plot was used to determine the origin of counterfeit samples as Dalbergia cochinchinensis and Dalbergia pinnata.Discussion:As one of China’s precious traditional Chinese medicines,the scarcity of resources and the prevalence of counterfeit products on the market pose a serious threat to the safety of Dalbergia odoriferae lignum.This study collected counterfeit and commercially available samples of Dalbergia odoriferae lignum,and used different methods to identify its distinguishing features.The study also revealed the phenomenon of using Dalbergia cochinchinensis and Dalbergia pinnata as substitutes for Dalbergia odoriferae lignum in the market.The study employed nuclear magnetic resonance hydrogen spectroscopy as a method of identification,which has the advantages of quantifiable identification indicators,being fast,efficient,and accurate,and can provide guarantees for the safe use of Dalbergia odoriferae lignum.Therefore,this study is of great significance for protecting Dalbergia odoriferae lignum resources and maintaining medication safety. |
PDF Full Text Request