Metal ions-enhanced classification of the origin and prediction of antioxidant activity of Chrysanthemum morifolium Ramat. cv. "Hangbaiju" by 3D fluorescence spectroscopy combined with chemometrics.

This study selected Hangbaiju (Chrysanthemum morifolium Ramat. cv. "Hangbaiju") from 5 different origins as the research objects and investigated its 3D (three-dimensional) fluorescence characteristics of organic acids and flavonoids et al. closely related to the origins. Based on the chelating quenching effect between organic acids with Fe3+ and the ESIPT (excited-state intramolecular proton transfer) effect between 3-hydroxyflavonoids with Al3+, a metal ion-enhanced method for antioxidant activity prediction and origin classification of Hangbaiju was established by using 3D fluorescence scanning technology combined with PARAFAC (parallel factor analysis) and RF (random forest) algorithm. The characteristic fluorescent components and their relative concentrations derived from PARAFAC serve as the data sources for RF origin classification and antioxidant activity prediction. The results show that, compared with the original 3D fluorescence spectra, the classification accuracy of Hangbaiju from 5 different origins based on Fe3+, Al3+-fluorescence spectra has increased from 91.0 % to 97.5 % and 100.0 % respectively. Meanwhile, after interacting with Fe3+ and Al3+, the correlation coefficient between the antioxidant activity of Hangbaiju and its characteristic fluorescent components increased to above 0.85. Furthermore, the correlation coefficients of the antioxidant activity prediction results based on characteristic fluorescent components increased from 0.69 to 0.89 to 0.86-0.93 and 0.85-0.95 respectively, with the RMSE (root mean square error) less than 0.1045. This method ingeniously combines the dimensional advantages of 3D fluorescence with the precise digital separation performance of the second-order correction algorithm, independently isolating the characteristic fluorescence component information in Hangbaiju, achieving its satisfactory origin classification and antioxidant activity prediction results.