Evaluation of cytotoxic, apoptotic effects and phenolic compounds of sea cucumber Holothuria tubulosa (Gmelin, 1791) extracts

Abstract

This study aimed to investigate the potential cytotoxic effects and phenolic contents of aqueous (HTS) and methanolic (HTM) extracts of Holothuria tubulosa gathered from Mugla (Turkey) against different cancer cells for the first time. An MTT assay was carried out to determine cellular viability. Apoptotic cell death was determined using flow cytometry. DNA fragmentation assay and caspase-3 activity analysis were carried out. Both extracts were analyzed by high performance liquid chromatography (HPLC) for quantification of phenolic compounds. Both HTS and HTM extracts generally caused a decrease in the cell viability in a concentration- and time-dependent manner. The lowest IC50 value was found in the HeLa cell line with 21.01 mu g/mL for the HTS extract at 72 h. Both extracts are capable of significantly enhancing the apoptotic process in HeLa and A549 cells, causing DNA fragmentation, and also increasing activity of caspase-3 in both these cell lines, especially after treatment with at 500 mu g/mL. Based on HPLC analysis, the most abundant component was epicatechin (790.091 mu g/g extract) and 2.5 dihydroxybenzoic acid (153.890 mu g/g extract) in the HTS and HTM extracts, respectively. This is the first study showing potential cytotoxic activity of H. tubulosa extracts from Mugla, Turkey against human cancer cells. Our results suggest that H. tubulosa may be a good source for development of anticancer agents.