Cytotoxic Activity of Boesenbergia rotunda Extracts against Nasopharyngeal Carcinoma Cells (HK1). Cardamonin, a Boesenbergia rotunda Constituent, Inhibits Growth and Migration of HK1 Cells by Inducing Caspase-Dependent Apoptosis and G2/M–Phase Arrest

Abstract

Boesenbergia rotunda (L.) Mansf. is an edible herb that is commonly used in the cuisine of several Asian countries. Studies have shown that it possesses high bioactivity against a variety of cancer cells. In this study, we investigated the cytotoxic activity of Boesenbergia rotunda rhizomes and some of its constituents on nasopharyngeal carcinoma cells (HK1). MTT assay results showed that the methanolic and hexane extracts of Boesenbergia rotunda decreased HK1 cell viability with IC₅₀ values of 136 µg/ml and 66 µg/ml, respectively. Cardamonin, a constituent of Boesenbergia rotunda, exhibited the highest cytotoxic activity with an IC₅₀ value of 27 μg/ml. Further studies on cardamonin revealed that it inhibited the migration of HK1 cells, caused G2/M-phase arrest and induced apoptosis. Apoptosis was induced via activating caspase-8 and caspase-3, but independent of caspase-9. This indicated that cardamonin induced extrinsic apoptosis. Western blot analysis further showed that cardamonin caused extrinsic apoptosis, as the expression levels of intrinsic apoptosis-related proteins (Bcl-X_L, Bcl-2 and Bax), were not affected. Finally, JC-1 staining of HK1 cells revealed an increase in the mitochondrial membrane potential after treatment, further proving that cardamonin did not induce apoptosis via the intrinsic pathway. These results reflect cardamonin’s potential as an anticancer agent.

Disclosure of Interest

The authors report no conflict of interest.

Authors’ Contributions

M.K.B. and M.C. performed the experiments, analyzed the results and wrote the manuscript. C.W., C.F.C. and T.J.K. supervised the research study and provided the necessary laboratory equipment and some funding for the project. A.S.B.K provided the research team with the HK1 cells that were used in the study. Authors have approved the submission of the manuscript.

Additional information

Funding

This work was supported by Public Service Department of Malaysia (JPA).