21 compounds were identified by UPLC–PDA/QTOF–MS and used to multivariable analysis.
Four varieties of O. fragrans flowers were successfully classified by PCA and PLS–DA models.
Effective compounds were selected by UVE–SPA to predict the antioxidant activity values of DPPH, ABTS and FRAP assays.
The UVE–SPA–MLR model was the optimal method to predict the antioxidant activity values.