Abstract: The antioxidant and antibacterial activities of carnosic acid were studied by radical scavenging effect,reducing ability and tablet dilution methods.The results showed that,the antioxidant activity of carnosic acid was significantly higher than that of synthetic antioxidants PG,BHT,BHA,VE under the same concentration,while slightly lower than THBQ.At the same time,IC₅₀s of scavenging DPPH and ABTS radical of carnosic acid were 2.53 μg/mL and 51.58 μg/mL,respectively.Antibacterial tests indicated that carnosic acid had broad-spectrum of antibacterial activity.Especially for Escherichia coli and Pseudomonas aeruginosa, the MICs of carnosic acid were 4 and <2 μg/mL,better than that of bromogeramine,sodium ampicillin and erythromycin.Moreover, for Klebsiella pneumonia, carnosic acid showed the same inhibitory effect with erythromycin,better than bromogeramine and sodium ampicillin.

Key words: carnosic acid, antioxidant activity, antibacterial activity