RIPE CLEISTOCALYX NERVOSUM VAR. PANIALA BERRY FRUIT EXTRACT PREVENTS HYDROGEN PEROXIDE-INDUCED DNA DAMAGE IN HUMAN MONOCYTE U937 CELLS

Intracellular reactive oxygen species (ROS) production and accumulation cause oxidative stress, leading to an increase in DNA damage, which is one of the major causes of mutation and diseases, especially cancer. Antioxidants in various fruits that play an important role in reducing ROS and oxidative stress. Cleistocalyx nervosum var. paniala (Ma-kiang: MK) is a native berry found in Northern Thailand which has strong antioxidants properties. The present study aimed to examine the preventive effect of ripe MK fruit extract on hydrogen peroxide-induced DNA damage in human monocyte U937 cells. Firstly, MK was extracted with 95% ethanol, then antioxidant capacities were evaluated. The results exhibited that MK extract was strongly able to scavenge radicals, especially the hydroxyl radicals, and had potent total flavonoid and phenolic contents. For the cell-based experiments, we found that pretreatment U937 cells with MK extract obviously increased cell viability and suppressed intracellular ROS in the cells induced by hydrogen peroxide. Furthermore, MK extract could significantly inhibit hydrogen peroxide-induced oxidative DNA damage in human monocyte U937 cell model. Thus, these results indicate that ripe MK berry extract might be utilized as an alternative antioxidant and geno-protective agent for reducing risk of oxidative stress and mutation-related diseases.