Essential oil from Ocimum viride exerts caspase-3 interceded apoptosis in human leukemia HL-60 cells

The present study discusses the apoptotic potential of essential oil from whole plant of Ocimum viride (EOV) against human promyelocytic leukemia HL-60 cells. IC₅₀ value of EOV on HL-60 cells was 0.087, 0.0503, and 0.034 µl/ml respectively at 6, 12, and 24 h. Several parameters were used to access the role of EOV in inducing apoptosis in human HL-60 cancer cells, including nuclear binding fluoroprobes, electron micrographs, DNA laddering, and annexin V-FITC/PI affinity assay. Quantification of BrdU incorporation was done to determine the degree of DNA damage. It was further determined that EOV has an effect on the DNA cell cycle and mitochondria, which was observed in the form of a prominent subdivision of G₀ peaks in the analysis of the DNA cell cycle, as well as a reduction in the mitochondrial membrane potential. A higher level of cytosolic cytochrome-c was associated with these events. Bcl-2 depletion and increase in ROS were also analysed. Both initiator caspases namely caspase-9 and -8 activated caspase-3 which eventually leads to apoptosis. These effects revealed that EOV has apoptosis inducing potential towards HL-60 cells and can be a promising candidate for further anticancer studies.