Acanthus ebracteatus Vahl. is commonly consumed with the aim of curing cancer, inflammatory conditions and skin diseases in traditional Thai medicine. It is known to contain various phytochemicals; however, very little is known about the effects of A. ebracteatus protein hydrolysate on cancer cells, including its molecular mechanisms. The present study therefore investigated the anti-cancer activity of A. ebracteatus protein hydrolysates against epidermoid cancer of the skin cell line A431. Their effects on the apoptosis pathway and expression of proteins involved in the regulation of apoptosis, cell proliferation or cell cycle were also investigated. Crude extract of protein hydrolysate, partially purified peptides and purified peptides extracted from the aerial part of A. ebracteatus were administered to the A431 cells. The cytotoxicity effects were then determined using an MTT assay. As a result, A. ebracteatus protein hydrolysate significantly inhibited A431 cells with half inhibitory concentration equals to 425.9 ng protein/ml. By performing Annexin V assay, the partially purified peptides of A. ebracteatus were demonstrated to enhance the apoptosis pathway. Furthermore, western blot analysis revealed that the partially purified peptides of A. ebracteatus increased protein expression levels of RelA (p65) and Cyclin D1 proteins. However, A. ebracteatus did not increase the expression levels of p53-serine 15 phosphorylation (Ser15P).
Keywords: Acanthus ebracteatus Vahl; anti-cancer activity; apoptosis; nonmelanoma skin cancer; peptide; protein hydrolysate.