Integrated extraction approach to increase the recovery of antioxidant compounds from Sida rhombifolia leaves

Integrated downstream processes, combining Supercritical Fluid Extraction (SFE) with Pressurized Liquid Extraction (PLE), were used to recover antioxidants from Sida rhombifolia leaves. The SFE depressurization step was evaluated to improve PLE efficiency in the recovery of phenolic compounds. Total phenolic content of the extracts was performed by Folin-Ciocalteu method, and in vitro antioxidant activity was obtained by DPPH and ABTS methods, while the cell wall disruption was observed by Scanning Electron Microscopy (SEM) analysis. The highest phenolic content (91 +/- 0 mg GAE g(-1)) and antioxidant capacity by ABTS (4.3 +/- 0.02 mmol TE g(-1) extract) was obtained by PLE from the SFE residue after fast depressurization rate. LC-ESI-MS/MS analysis identified 31 phenolic compounds from the extracts, of which 21 were firstly reported for Sida rhombifolia. Isoquercitin was the major phenolic in the extracts. The process integration recovered different fractions from S. rhombifolia leaves, improving extraction yield and antioxidant potential. (C) 2019 Elsevier B.V. All rights reserved.