Rapidly and Simultaneously Determining the Total Polysaccharides Content, Total Flavonoids Content, and Antioxidant Activity in Polygonatum cyrtonema Hua by NIR Spectroscopy and Chemometrics

BACKGROUND: Polygonatum cyrtonema Hua (PCH) is widely used in traditional Chinese medicine. The components and activity are important for simultaneous quality evaluation in PCH. OBJECTIVE: This study aimed to establish an accurate, rapid, and comprehensive quality evaluation method by near-infrared spectroscopy (NIR) for forecasting the total polysaccharides content (TPsC), total flavonoids content (TFC), and antioxidant activity (AA) in PCH. METHODS: PCH samples were used to establish a model of TPsC, TFC, and AA in PCH by NIR combined with partial least-squares regression (PLS). To enhance the accuracy of the models and remove non-essential variables, we used multiple spectral preprocessing methods and multiple chemometrics to analyze the processed full spectrum, such as competitive adaptive reweighted sampling partial least-squares regression (CARS-PLS), moving-window partial least-squares regression (MW-PLS), and interval random frog partial least squares regression (iRF-PLS). The remaining samples were used to complete external validation. RESULTS: Satisfactory prediction results of PLS models combined with chemometrics were obtained. The optimal chemometric of TPsC, TFC, and AA selected 157, 105, and 134 variables, respectively. For the TPsC, TFC, and AA models, which incorporated optimal spectral preprocessing and chemometrics, the root-mean-square error of calibration (RMSEC, %) values were 0.743, 0.069, and 0.136, while the R2 values were above 0.95. The root-mean-square error of prediction (RMSEP, %) for these models were 1.00, 0.074, and 0.153, while R2 values were above 0.90. The remaining 20 samples were used to complete external validation, which confirmed the preeminent comparability and ability of the proposed method. CONCLUSION: NIR combined with chemometrics provides an effective, fast, and nondestructive approach for evaluating quality via multiple indicators of PCH and provides a meaningful reference for evaluation of herbal medicine quality. HIGHLIGHTS: NIR combined with chemometrics offers an effective, quick, nondestructive way to evaluate herbal medicine quality with multiple indicators.