[Rapid Prediction Study of Total Flavonids Content in Panax notoginseng Using Infrared Spectroscopy Combined with...

The variation on origin and growth environment could make a holistic impact on the secondary metabolites and quality of traditional Chinese medicine. In recent years, the origin of Panax notoginseng is spread from the genuine producing area of Wenshan to surrounding cities. The content of three saponins, as an indicator, is to ensure the quality of Panax notoginseng in Chinese pharmacopoeia. However, a single indicator is limited to comprehensive quality evaluation of Panax notoginseng. In this study, the total flavonoids content of Panax notoginseng was determinated by ultraviolet-visible (UV-Vis) spectrophotometry, Fourier transform infrared (FTIR) spectroscopy combined with chemometrics, as a rapid prediction model of total flavonoids content, was establish to provide some basic information for rapid and holistic quality assessment of Panax notoginseng. A total of 96 UV-Vis and FTIR spectra of Panax notoginseng originated from 12 regions were collected. The UV-Vis spectra of samples were recorded at 268 nm, and the content of total flavonoids was calculated based on standard linear equation of rutin. Pre-processing data were calculated with first (1D) and second derivative (2D), Savitsky-Golay smoothing with seven, nine, and eleven points. 2/3 of the 96 individuals were selected to form the training set by using Kennard-stone algorithm, and the rest were used as prediction set. Training set data were used to establish the orthogonal signal correction-partial least squares regression (OSC-PLSR) model and the 1/7 cross-validation method was used for screening optimal numbers of principal component, the prediction set was utilized to verify the accuracy and reliability of the OSC-PLSR model. Results showed that: (1) The correlation coefficient r of standard rutin was 0.9997, and the linear concentration range was from 5.6 to 72.0 μg·mL(-1), namely, there were good correlation between the absorbance and concentration. (2) The Panax notoginseng contained higher content of total flavonoids (more than 7 mg·g(-1)) in three genuie producing areas of Wenshan, Luoping county and Shilin county. (3) After the same points of Savitsky-Golay smoothing, the model predictive ability of 2D is better than that of 1D, and the predictive ability of different processing model has an obvious difference. (4) In all prediction models, the 2D+SG 7+OSC-PLSR (R(2)(pre)=0.976 1, RMSEP=0.325 2) and 2D+SG 11+OSC-PLSR (R(2)(pre)=0.946 9, RMSEP=0.382 0) model showed an excellent predictive effect, the value of RMSEP was below 0.4, and the predicted values were close to the detection values. The result indicated that FTIR combined with OSC-PLSR could accurately predict the content of total flavonoids. It could provide a rapid, simple, and effective method for the holistic quality control of Panax notoginseng.