Lipid nanodiscs of poly(styrene-alt-maleic acid) to enhance plant antioxidant extraction

Abstract

Plant antioxidants can be applied in the management of various human diseases. Despite these, extraction of these compounds still suffers from residual solvent impurities, low recovery yields, and the risks of undesirable chemical changes. Inspired by the protein-lipid interactions in the cell membranes, we proposed using poly(styrene-alt-maleic acid) (PSMA) to destabilize and associate with the bilayer lipids into the membrane-like nanodiscs. Such nanostructures could serve as protective reservoirs for the active compounds to reside with preserved bioactivities. This concept was demonstrated in the antioxidant extraction from robusta coffee leaves. Results indicated that aqueous PSMA extraction (no buffer agent) yielded products with the highest contents of phenolic acids (11.6 mg GAE·g-1) and flavonoids (9.6 mg CE·g-1). They also showed the highest antioxidant activity (IC50 = 3.7 μg·mL-1) compared to those obtained by typical sodium dodecyl sulfate and water extraction. This biomimetic approach could be considered for developing environmentally friendly extraction protocols in the future.