The protective effects of Aspergillus candidus metabolites against hydrogen peroxide-induced oxidative damage to Int 407 cells

The protective effects of 3,3″-di-OH-terphenyllin (3,3″-DHT) and 3-OH-terphenyllin (3-HT), two secondary metabolites produced by Aspergillus candidus (CCRC31543), against hydrogen peroxide-induced oxidative damage to Int 407 cells, were evaluated. The results showed that H2O2 caused an increase in lactate dehydrogenase (LDH) leakage and DNA damage in Int 407 cells; however, the addition of 3,3″-DHT and 3-HT significantly reduced this effect (P<0.05). Intracellular reactive oxygen species (ROS) formation in Int 407 cells pre-incubated with 3,3″-DHT and 3-HT was decreased by 30 and 35%, respectively. The activity of glutathione peroxidase and catalase in Int 407 cells pre-incubated with 3,3″-DHT was increased 25 and 33%, respectively; however, the activity of catalase was increased 30% in Int 407 cells pre-incubated with 3-HT. The activity of glutathione reductase in Int 407 cells pre-incubated with 3,3″-DHT and 3-HT was decreased 36 and 21%, respectively. The intracellular glutathione level did not vary (P>0.05), but oxidized glutathione levels increased when Int 407 cells were pre-incubated with these two compounds. These findings suggest that 3,3″-DHT and 3-HT have the ability to protect against oxidative damage to Int 407 cells and that this protective effect may be associated with the ability to reduce ROS formation and increase catalase activity.