Extraction optimisation, purification and major antioxidant component of red pigments extracted from Camellia japonica

摘要

The optimised extraction conditions of red pigments (RP) from Camellia japonica obtained with an orthogonal design L_9(3~4) were solid/liquid ratio, temperature, pH and extraction time as 1/10,60 ℃, 1.5 and 4 h, respectively. The RP were then purified by the macroporous resin method, which showed the resin LX-68 was appropriate for purifying the pigments from C. japonica. The antioxidant activities of these pigments were also investigated using l,l-diphenyl-2-picrylhydrazyl (DPPH) and hydroxyl radical in vitro model systems. The DPPH scavenging activity of pigment extract was comparable to that of standard butylated hydroxyanisole (BHA). The IC_(50) values of the RP and BHA were 4.55 and 4.17 μg ml_(-1), respectively. The pigments showed higher hydroxyl radical-scavenging activities than that of mannitol at the same concentration. Following activity-oriented separation, (-)-epicatechin was isolated as an active principle, which exhibited excellent DPPH free radical scavenging activities with IC_(50) 5.08μg ml"1.