Abstract: Black pepper oleoresin (BPO) was extracted using supercritical CO2 fluid extraction, and analyzed by gaschromatography-mass spectrometry (GC-MS). The antioxidant activity of BPO was determined by 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging assay and reducing capacity assay. In addition, Saccharomyces cerevisiae wasused to determine its antioxidant activity in vivo. The results indicated that the main constituent of BPO was piperine (40.2%)and its DPPH radical scavenging capacity and reducing power were a bit lower than those of butylated hydroxytoluene(BHT) and VC. BPO increased the survival rates of Saccharomyces cerevisiae under the stress of CCl4, H2O2 and CdSO4 todifferent extents, and significantly decreased the levels of cellular oxidation and lipid peroxidation under oxidative stress.Additionally, our results showed the catalase encoded by the ctt1 gene may be involved in the mechanism of action of BPOagainst lipid peroxidation.

Key words: black pepper oleoresin, antioxidant, Saccharomyces cerevisiae, lipid peroxidation, cellular oxidation