Antioxidant and antilisterial effect of seed essential oil and organic extracts from Zizyphus jujuba.

Hydrodistilled volatile oil from the seeds of Zizyphus jujuba was analyzed by GC-MS. Twenty three compounds representing 91.59% of the total oil was identified. The oil and organic extracts revealed a great potential of antilisterial effect against all five strains of Listeria monocytogenes ATCC 19111, 19116, 19118, 19166 and 15313. Also the oil had strong detrimental effect on the viable count of the tested bacteria. The samples were also subjected to screening for the antioxidant activity by using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and superoxide radicals scavenging activities assay. In the first case, the IC(50) value of the Z. jujuba essential oil was determined to be 5.21+/-0.01 microg/ml. Among the extracts, the strongest activity was exhibited by the methanol extract with an IC(50) value of 20.44+/-0.18 microg/ml. In the superoxide radicals scavenging activities assay, methanol extract was superior to all other extracts (IC(50)=18.60+/-0.3 microg/ml). Furthermore, the amount of total phenolic compounds was determined. The results indicate that the essential oil and extracts of Z. jujuba could serve as natural antimicrobial and antioxidant agents for the food industry.