| Due to the different ecological environment,cultivation management,and processing methods,the qualities of plant herb and its decoction pieces are varied on market.To ensure the quality of medicinal materials and its decoction pieces,it is an inevitable requirement to study their grade evaluation standard.Therefore,in this study,the quality grade of Andrographis Herba and its decoction pieces were evaluated through analyzing their macroscopical characteristic and chemical indices.Forty two batches of Andrographis Herba and thirty batches of its decoction pieces were collected for this study.The macroscopical characteristic indices of these samples were determined and encoded using the method of numerical taxonomy;the qualitative analysis were conducted by microscopic identification and thin-layer chromatography(TLC);the chemical indices(the content of four active diterpenoids and the content of ethanol-soluble extract)were determined and HPLC fingerprint was established;the encoded macroscopical characteristic indices and chemical indices were made a statistical description and correlation analysis to screen out the suitable indices for classification,and the quality grade was figured out by principal component clustering analysis according these evaluation indices,then the gradation was analyzed through partial least squares discriminant analysis(PLS-DA).Furthermore,a partial least squares(PLS)regression was constructed for the quality grade prediction of Andrographis Herba and its decoction pieces.The main results of this study were as follows:1.It was showed that these macroscopical characteristic indices(the number of branch,the diameter of base,middle and upper part of stem,plant height,the leaf content,the color of stem and leaf)might be the suitable evaluation indices of the quality grade for Andrographis Herba.Also,it was showed that the macroscopical characteristic indices such as the leaf content,the impurity content,the color of stem and leaf,might be the reference indices for evaluating the quality grade of Andrographis decoction pieces.The microscopic characteristics of cystolith number,gland phosphonic number and powder color,were no significant difference among the different batches of Andrographis Herba and its decoction pieces,therefore the microscopic identification should not be considered as a key factor to evaluate the quality grade;and little difference was observed about the size,number and color of spot in TLC identification,which could not be quantitative,thus,we considered that the characteristics of TLC identification was not suitable for evaluating the quality grade.2.The contents of ethanol-soluble extract in different batches of Andrographis Herba and its decoction pieces were between 7.33%-12.89% and 7.16%-12.64%,respectively.The content ranges of andrographolide,neoandrographolide,deoxyandrographolide,dehydroandrographolide in different batches of Andrographis Herba were: 0.21%-1.51%,0.12%-0.74%,0.18%-0.97%,0.27%-0.98%,respectively.In total,the content ranges of the above four diterpenoids in the herb were 1.11%-2.73%.While in Andrographis decoction pieces,the contents of the above four diterpenoids were little lower than the herb,the content ranges were: 0.16%-0.51%,0.13%-0.34%,0.12%-0.49%,0.11%-0.55%,respectively.The content ranges of the above four diterpenoids in the decoction pieces were between 0.75%-1.52%.Hence,the ethanol-soluble extract,the respective content and total content of the above diterpene lactones were suitable for evaluating the quality grade due to the significant difference among different batches of Andrographis Herba and its decoction pieces.Furthermore,the similarity evaluation results of HPLC fingerprint was also showed the grade difference among each batches of Andrographis Herba and its decoction pieces.3.It was showed that the samples of Andrographis Herba could be divided into three grades according to the principal component clustering analysis,and was reasonably evaluating by PLS-DA.The PLS regression model for quality grade of Andrographis Herba was constructed as follows: grade(Y)=3.715-0.024*the leaf content-0.484*the content of andrographolide-1.316*the content of neoandrographolide-0.084*the content of deoxyandrographolide-0.353*the content of four active diterpenoids-0.116* the content of ethanol-soluble extract-0.019*the color of stem-0.035*the color of leaf+0.030*the number of branch+0.009*the diameter of base part of stem+0.146*the diameter of the upper stem+0.009*plant height+0.068*the content of dehydroandrographolide,if Y=0.5-1.4,the predicted quality is grade A,if Y=1.5-2.4,then B grade,and if Y=2.5-3.4,C grade or qualified product.Similarly,results showed that Andrographis decoction pieces could be divided into two grades according to the principal component clustering analysis,and was reasonably evaluating by PLS-DA.The PLS regression model for quality grade of Andrographis decoction pieces was constructed as follows: grade(Y)=3.726-0.015* the leaf content-0.900*the content of andrographolide-1.546*the content of neoandrographolide-0.639*the content of dehydroandrographolide-0.428*the content of four active diterpenoids-0.054*the content of ethanol-soluble extract+0.096*the impurity content+ 0.040*the color of stem+0.023*the color of leaf,if Y=0.5-1.4,the predicted quality is grade A,if Y= 1.5-2.4,B grade or qualified product.In conclusion,the grade evaluation model,based on their macroscopical characteristic indices and chemical indices together,were constructed using principal component clustering analysis combing with PLS regression analysis.The model performed well in evaluating the quality grade of Andrographis Herba and its decoction pieces,which might provide a new strategy for studies on grade standard of traditional Chinese medicines. |
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