RESUMEN
Objective: To investigat the mechanism of antitumor efficacy of Origanum dayi (O. dayi) and Ochradenus baccatus (O. baccatus) extracts by exploring apoptosis-inducing potential. Methods: The aqueous extracts of aerial parts of aforementioned plants were prepared and used for this study. HepG2 cells were treated with varying concentrations (0, 2 and 5 mg/mL) of each plant extract for 24 or 48 h. Cell apoptosis was measured by annexin V-fluorescein isothiocyanate binding assay and flow cytometry. The expression levels of various apoptosisrelated genes were determined by semi-quantitative reverse transcription-polymerase chain reaction. Results: O. dayi and O. baccatus extracts exerted apoptotic effects on HepG2 cells for 48 h following treatment. O. dayi extract was found to be a better apoptosis-inducing agent than O. baccatus extract as the former delivered greater efficacy at a lower concentration. Both extracts manifested upregulation of Bax, Bad, cytochrome c, caspase-3, caspase-7, caspase-9 and poly (adenosine diphosphate-ribose) polymerase. Conclusions: The aqueous extracts of O. dayi and O. baccatus are capable of inducing apoptosis in HepG2 cells through modulation of mitochondrial pathway which explains their antitumor activities. These desert plants may serve as useful resources to develop effective remedies for hepatocellular carcinoma and other human malignancies.