This work aims to study the antioxidant interactions between S-allyl-L-cysteine (SAC) and six natural polyphenols (quercetin, caffeic acid, sinapic acid, catechin, ferulic acid, and 3,4-dihydroxybenzoic acid) through the measurement of free-radical-scavenging activity of 1,1-diphenyl- 2-picryl-hydrazyl (DPPH), the radical-cation-scavenging activity of 2,2-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS), and reducing power. Among the six natural polyphenols, caffeic acid showed the strongest synergistic effect with SAC according to DPPH and reducing power assays. Further investigations based on the results of interaction index and isobologram analysis showed that the antioxidant activity (DPPH, ABTS, and reducing power) of the combination of caffeic acid with SAC presented an increase with the raising of their individual concentrations in their mixture and along with a dose–response manner. The best synergistic effect between caffeic acid and SAC based on DPPH, ABTS, and reducing power assays were observed at the ratio of 1:20, 1:35, and 1:70, respectively. The excellent synergic antioxidant activity of the combination of caffeic acid with SAC in our study suggests SAC has a more broad and effective application prospects in food field.

In this paper, a simple and environmentally friendly method was developed for the preparation of highly stable C@Fe₃O₄ composites with controllable morphologies using sodium alginate as the carbon source and the easily obtained α-Fe₂O₃ as the precursors. The morphologies of the as-prepared C@Fe₃O₄ composites, inherited from their corresponding precursors of α-Fe₂O₃, survived from the annealing treatments, were characterized by the field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and inductively coupled plasma-atomic emission spectroscopy (ICP-AES). The C@Fe₃O₄ composites resisted to oxidation, acidification and aggregation, exhibiting porous structures and ferromagnetic properties at room temperature. Moreover, the adsorption performance of the C@Fe₃O₄ composites was evaluated by absorbing MB (methylene blue) in liquid environment. Experiments indicated that the C@Fe₃O₄ composites exhibited highly enhanced adsorption capacities and efficiencies as compared with their corresponding precursors of α-Fe₂O₃. This generalized method for the synthesis of C@Fe₃O₄ composites provides promising applications for the highly efficient removal of MB from industrial effluents.