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