Prisconnatanones A, a cytotoxic naphthoquinone from Prismatomeris connata, suppresses the proliferation of human laryngocarcinoma HEp-2 cells in vitro.

Prisconnatanones A (Priscon-A) is a rare tetrahydroanthraquinone isolated from herbal Prismatomeris connate. In this study, we examine its anti-tumour activity on human laryngocarcinoma HEp-2 cells in vitro. The CCK-8 assay was performed to evaluate its cytotoxicity. Cell cycle and apoptosis were analysed using flow cytometric analysis. Here, we showed Priscon-A inhibited the proliferation of HEp-2 cells in a dose-dependent manner, and at 5 μM it almost completely inhibited cell growth. Its cytotoxicity was associated with the cell cycle arrest at G2/M phase. The Annexin V-FITC/PI binding assay showed that the cell death induced by Priscon-A was associated with apoptosis. And, western blot analysis revealed that the levels of the apoptosis protein, cleaved caspase-3, PARP, p21 and Bax protein increased, while the level of anti-apoptosis protein Bcl-2 decreased.. These data demonstrated that Priscon-A significantly inhibited HEp-2 cell growth, induced the cell cycle arrest at the G2/M phase and efficiently induced cell apoptosis.