Oral cancer is the eleventh most prevalent
cancer worldwide. The most prevalent
oral cancer is
oral squamous cell carcinoma (OSCC).
Damnacanthal (DAM) and
nordamnacanthal (NDAM), the
anthraquinone compounds, are isolated from the root of Morinda citrifolia L. (Noni), which has been used for the treatment of several
chronic diseases including
cancer. The objectives of this study were to evaluate the cytotoxicity, cell death mode, cell cycle, and the molecular mechanism of apoptosis induced by DAM and NDAM on OSCC. The cytotoxic effects of these compounds against OSCC cell lines were determined by MTT assay. The cell death mode was analysed by
DNA laddering and
FITC-
annexin V/PI flow cytometric assays. In addition, the mechanism of apoptosis induced by DAM and NDAM was detected using mitochondrial membrane potential,
Cytochrome c, and
caspases assays. Finally, the effect of DAM and NDAM on cell cycle phase distribution of OSCC cells was detected by flow cytometry. In the present study, DAM and NDAM showed cytotoxicity towards OSCC cell lines and the maximum growth inhibition for both compounds was observed in H400 cells with IC50 value of 1.9 and 6.8 μg/ml, respectively, after 72 h treatment. The results also demonstrated the inhibition of H400 OSCC cells proliferation, internucleosomal cleavage of
DNA, activation of intrinsic apoptosis pathway, and cell cycle arrest caused by DAM and NDAM. Therefore, these findings suggest that DAM and NDAM can be potentially used as
antitumor agents for
oral cancer therapy.