Analysis And Characterization Of Chemical Constituents Of Dendrobium Species Based On Infrared Spectroscopy

Herba Dendrobii(Shi-hu)is a kind of common rare traditional Chinese medicinal material,it is used as "Medicine food homology".Their allied species for nourishing"Yin" and clearing heat and nourishing the stomach.In recent years,with the enhancement of people’s awareness of health care makes Dendrobii Caulis(DC)market demand increasing.But most of DC have higher requirement on environmental,and they have been over-harvested,which resulting in DC resources in short supply.At present,Dendrobium officinale and Dendrobium nobile have planted a certain scale of planting area,but the Dendrobium plants have few sources and higher prices.In addition,with the growing acreage,more species and varieties,these factors have not been given sufficient attention,which has great influence on the the quality and the evaluation system.These are the problems we need to solve now.The research collected different growing provinces,different years and different varieties domestic samples,using macro-fingerprint infrared spectroscopyic identification method to study different varieties,different years and different origin extracting of DC,while establishing a infrared expert idendification model.The main findings are as follows:1.Analyze different varieties,origin,growth of DC via the multi-steps IR macro-finger print method.We have analyzed and identified the quality of DC via the multi-steps IR macro-fingerprintmethod.Different growth and regions of DC had no obvious difference in Fourier transform infrared(FT-IR),there were some absorption peaks location in their infared(IR)spectra which differed 0-3 wavenumber.Different species of DC had some differences in their IR spectra.According to the relative intensity of the 1737cm-1 and peak group of 1426 cm-1,1377 cm-1,1329 cm-1,1248 cm-1,combined with the original plant stems.The 13 species of DC samples were divided into 3 groups.Group 1 was Dendrobium huoshanense,Henan Dendrobium,Dendrobium flexicaule.Group 2 was Dendrobium officinale,Dendrobium nobile,Dendrobium chrysotoxum,Dendrobium tongpi,Dendrobium wilsonii,Dendrobium herco glossum and Dendrobium hancockii.Group 3 was Dendrobium moniliforme,Dendrobium aduncum and Dendrobium lohohense.The samples in every group were similar,but there were obvious fingerprint characteristics in their second derivative infrared(SD-IR)spectra and two-dimensional infrared(2D-IR)correlation spectroscopy.Therefore,the DC samples could be rapidly identified by three-step identification.2.The Integral analysis of IR in different varieties of DCComparing standard IR spectrum of starch and oil which used as a reference to Dendrobium officinale,Dendrobium nobile and Dendrobium chrysotoxum.Using 1155 cm-1、1081 cm-1 and 1019 cm-1 which are the stronger peaks in starch IR spectrum and 2926 cm-1,2854 cm-1,1745 cm-1 which are the stronger peaks in oil IR spectrum as references.The three of DC all contained starch and lipid components.In addition,Dendrobium nobile had more lipid,and Dendrobium officinale had more polysaccharide than other kinds of DC.Comparing calcium oxalate IR spectrum which used as a reference to the three DCs,there were the characteristic absorption peaks of calcium oxalate in the three DCs.There were no obvious absorption peaks of calcium oxalate in IR spectrum,but there were characteristic peaks of calcium oxalate in SD-IR spectra,those illustrated they all contained calcium oxalate.The IR spectrum of Dendrobium officinale,Dendrobium nobile and Dendrobium chrysotoxum had the fingerprint characteristic peaks of aromatic compounds,which stretching vibration of non-conjugated C=O and stretching vibration absorption peak of benzene ring skeleton,while Dendrobium chrysotoxum also had a strong peak at 1658cm-1 referring to the conjugated carbonyl C=O.The differences of fingerprint characteristic peaks position of aromatic compounds were more apparent in SD-IR spectra.Comparing standard IR spectrum of starch which used as a reference to the ethanol precipitate from the aqueous extractive of Dendrobium officinale,Dendrobium nobile and Dendrobium chrysotoxum.The result showed that polysaccharide compositions of Dendrobium nobile and Dendrobium chrysotoxum were starch.Comparing standard IR spectrum of mucopolysaccharide which used as a reference to the ethanol precipitate from the aqueous extractive of Dendrobium officinale,the polysaccharide of Dendrobium officinale were mucopolysaccharide.Comparing oil IR spectrum which used as a reference to the anhydrous ethanol extractive of DCs,they all contained lipid.Moreover,the anhydrous ethanol extractive of three DCs had the fingerprint characteristic peaks of aromatic compounds.In addition,the anhydrous ethanol extractive of Dendrobium chrysotoxum contained more aromatic compounds than other extractives.The type and content of the extracts were different from the original medicinal materials,this may be because the chemical composition were complicated in the original medicinal materials,The characteristic peaks represented the characteristic peaks of the mixture,which is different from the pure chemical composition.3.Using experts identification to identify Dendrobium officinale and Dendrobium nobile quicklyUsing PCA of infrared spectrum method to analysis different regions,different growth of Dendrobium officinale and Dendrobium nobile.The result of clustering analysis of PCA revealed that Dendrobium officinale and Dendrobium nobile were divided into two parts accuratly and dentified effectively.But two kinds of samples were not completely gathered together,while they irregularly dispersed.This may be a relationship with different habitats and different growth period.Because of the influence of geography and artificial factors,different species of samples had different accumulation of chemical composition.Therefore,the distributed aggregation state was presented in the PCA diagram.Two species of samples could be well classified,the PCA result was meaningful to judge the change of chemical constituents of Dendrobium samples.Results of this research proved that macro-fingerprint infrared spectroscopic identification method had important influence on the analysis of chemical constituents.It not only identified different species of DC in different periods and different areas,but also evaluated the chemical composition and content of Dendrobium species.It is a simple and effective method to identify DC Chinese medicines.To provide a scientific basis for the control of variety and quality.So as to provide a new idea for the quality control of traditional Chinese medicine.