Optimizing bioactive compounds extraction from different medicinal plants and prediction through nonlinear and linear models

•Extraction of five medicinal plants was investigated.•The Taguchi method was used to optimize the extraction conditions.•Total polyphenolic content and antioxidant activity can be predicted.•Nonlinear models can be used for prediction of bioactives in herbal extracts.•Piecewise linear regression models confirmed their dominance in quantification.