New Curcuminoids Isolated from Zingiber cassumunar Protect Cells Suffering from Oxidative Stress: A Flow-Cytometric Study Using Rat Thymocytes and H₂0₂

Abstract

Effects of new complex curcuminoids (cassumunin A and cassumunin B) isolated from tropical ginger, Zingiber cassumunar, were examined in dissociated rat thymocytes suffering from oxidative stress induced by 3 mM hydrogen peroxide by using a flow cytometer and ethidium bromide. The effects were compared with those of curcumin, a natural antioxidant, whose chemical structure is included in those of cassumunins A and B. Pretreatment of rat thymocytes with the respective cassumunins at concentrations ranging from 100 nM to 3 μM dose-dependently prevented the hydrogen peroxide (H₂0₂)-induced decrease in cell viability. It had the same action, although less effective, against the treatment with cassumunin A or B (3 μM) immediately after or 60 min after start of the oxidative stress. Respective potencies of cassumunins A and B in protecting the cells suffering from H₂0₂-induced oxidative stress were greater than that of curcumin. It is suggested that cassumunins A and B may possess a potent protective action on living cells suffering from oxidative stress.