Extraction optimization of polyphenols, oxindole alkaloids and quinovic acid glycosides from cat's claw bark by Box–Behnken design

• The concurrent extraction of cat's claw bioactive compounds was optimized by a BBD.
• A 2-h extraction with EtOH 50% and 0.5:10 plant:solvent ratio allows the best PPH yield.
• A 2-h extraction with EtOH 63% and 0.5:10 plant:solvent ratio maximizes POA and TOA yields.
• A 2-h extraction with EtOH 69% and 0.5:10 plant:solvent ratio allows the best QAG yield.
• The validated mathematical models showed a predictive capacity of 82–107%.

This work focused on extraction optimization by dynamic maceration of the foremost bioactive compounds of cat's claw bark, namely, polyphenols (PPH), pentacyclic (POA) and tetracyclic oxindole alkaloids (TOA), and quinovic acid glycosides (QAG). A three-level Box–Behnken design was applied for this purpose, using ethanol concentration (X1), extraction time (X2) and plant:solvent ratio (X3) as factors. The data fitting revealed R2 > 0.929, and no lack-of-fit could be verified (P > 0.05). X1 showed a negative quadratic effect on all responses evaluated (P < 0.05). X3 had negative linear effects only on PPH and POA indicating solvent saturation. No significant effect associated with X2 was observed, owing to a favorable mass transfer facilitated by the extraction process. Maximum extraction yields regarding PPH, POA, TOA, QAG, and all compounds together were achieved with 50, 63, 62, 69, and 61% (v/v) of hydroethanolic solutions, respectively, linked to a plant:solvent ratio of 0.5:10 (w/v) and an extraction time of 2 h. In addition, the mathematical models developed showed a good predictive capacity (82–107%) in the optimized extraction conditions for all responses evaluated.

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