Bioactivity of alginetin, a caramelization product of pectin: Cytometric analysis of rat thymic lymphocytes using fluorescent probes

Alginetin is the major product formed from pentoses and hexurionic acids. Alginetin is producted by cooking process of food including pection, a naturally-occurring polysacharride found in many plants. However, the biological interaction and toxicity of alginetin are not known at all. The aim of the present study was to investigate the cellular actions of alginetin on rat thymic lymphocytes. The effects of alginetin on the cell were examined using flow cytometry with fluorescent probes. Alginetin increased cellular content of non-protein thiols ([NPT](i)) and elevated intracellular Zn(2+) levels ([Zn(2+)](i)). Chelation of intracellular Zn(2+) reduced the effect of alginetin on [NPT](i), and chelation of external Zn(2+) almost completely diminished alginetin-induced elevation of [Zn(2+)](i), indicating that alginetin treatment increased Zn(2+) influx. Increased [NPT](i) and [Zn(2+)](i) levels in response to alginetin were positively correlated. Alginetin protected cells against oxidative stress induced by hydrogen peroxide and Ca(2+) overload by calcium ionophore. It is considered that the increases in [NPT](i) and [Zn(2+)](i) are responsible for the cytoprotective activity of alginetin because NPT attenuates oxidative stress and Zn(2+) competes with Ca(2+). Alginetin may be produced during manufacturing of jam, which may provide additional health benefits of jam.