Oxidation is a chemical reaction that transfers electrons from a substance to an oxidizing agent, which produces harmful free radicals. However, natural antioxidants possess antioxidative properties and exogenous antioxidants are normally capable of inhibiting the oxidation in an organism. The synergy of different antioxidants would reverse the oxidation to a greater extent compared with a single antioxidant. We analyzed ursolic acid (UA) together with foodborne phosphate-containing viili exopolysaccharides (EPS) for antioxidant activities, and anti-proliferation properties of cancer cells. The strong antioxidant capacity of UA was observed at concentrations of 100 mu g/ml in ferric reducing antioxidant power test, where mild synergy with viili EPS was visible. Interestingly viili EPS had as strong antioxidative power as UA for the free radical scavenging activity in Fenton assay. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) assay with hepatoma HepG2 cells, the mild, but significant anti-proliferation by UA and EPS was seen at concentration of 200 mu g/ml, a synergic inhibition were particularly seen at 12.5 mu g/ml with a ratio of 3:2 EPS and UA. The senescence of HepG2 cancer cells after the combined treatment of UA and viili EPS at 12.5 mu g/ml were observed. These data indicated that UA is compatible with North European diets together with potential antioxidative and anti-proliferation complement modulating activities.