Apoptotic-inducing epidioxysterols identified in hard clam (Meretrix lusoria)

Hard clams (HC), Meretrix lusoria are a popular seafood and traditionally used as a Chinese remedy for liver disease and chronic hepatitis. The goal of this study was to identify compounds from hard clam, which are responsible for inducing apoptosis using bioassay-directed isolation. The effects of ethyl acetate extract of HC (HC-EA) on cell viability in human cancer cells were investigated. The ethyl acetate fraction was then subjected to separation and purification using silica gel column chromatography. The compounds showing strong apoptosis inducing activity were identified by spectral methods as epidioxysterols (EDS). The molecular mechanisms of epidioxysterolds-induced apoptosis as determined by annexin V apoptosis assay, DNA condensation, and sub-G1 DNA were investigated. The results suggest that induction of apoptosis by epidioxysterols may provide a pivotal mechanism for its cancer chemoprevention.