Abstract
Plant extracts from Origanum majorana and Olea europe were evaluated for their antiproliferative and antioxidait effects using human T-lymphoblastic leukemia cell lines (CEM and Jurkat). Cytotoxicity of various concentrations of plant extracts were examined using non-radioactive cytotoxicity assay and the IC sub(50) was calculated. Olive leaves were found to be more cytotoxic than majoram since they have lower IC sub(50). At noncytotoxic concentrations, the viability of cells decreased with the increase in concentration of plan extract as determined by the WST-1 proliferation kit. The antiproliferative effect was further analyzed using the [ super(3)H]-thymidine incorporation method and was dose dependent. To investigate whether cell death was due to apoptosis, cells were stained with annexin V-FITC and PI. Flow cytometry showed that majoram and olive leaves extracts induced apoptosis. The antioxidant activity of plant extracts was studied using the DPPH scavenging method. Majoram (IC sub(50)=0.03 mg dry weight) exhibited a stronger scavenging activity than olive leaves (IC sub(50)=0.1 mg dry weight). The conclusions from this study suggest that majoram and olive leave extracts exhibit antiproliferative effect on malignant T-cells and have a high antioxidant activity. For that they merit further investigation as a potential therapeutic agent.