Radioprotective effects of centipedegrass extract on NIH-3T3 fibroblasts via anti-oxidative activity

Centipedegrass originates from China and South America, and has been reported to contain several C-glycosyl flavones and phenolic compounds, including maysin and luteolin. The present study aimed to investigate the radioprotective activity of centipedegrass extract (CGE) in radiation exposed-fibroblasts and to assess the affected molecular pathway. The radioprotective effects of CGE were determined in NIH-3T3 cells using Cell Counting Kit-8 and morphological changes were observed. Reactive oxygen species (ROS) levels and the apoptotic profile of NIH-3T3 cells were also measured. The expression levels of B-cell lymphoma-2 (Bcl-2) family proteins [Bcl-2, Bcl-2 like protein 4 (Bax), Bcl-2-associated death promoter (Bad), caspase-3, poly(ADP-ribose) polymerase (PARP)], AKT and MAPK family proteins (ERK, p38 and JNK) were measured in vitro. The results demonstrated that when 3T3 fibroblasts pretreated with CGE were subjected to H₂O₂-induced cell damage, their viability was significantly decreased. Additionally, CGE pretreatment decreased ROS levels and the protein expression levels of cleaved PARP upon H₂O₂ treatment, indicating that CGE induced cytoprotective effects against H₂O₂-induced oxidative stress. Moreover, significant protective effects of CGE against intracellular ROS, induced upon exposure to ionizing radiation (IR), were observed. The protective effects of CGE pretreatment were also determined by morphological observation of NIH-3T3 cells following exposure to IR. CGE pretreatment increased the expression levels of anti-apoptotic signals (Bcl-2, p-BAD) and decreased the levels of pro-apoptotic signals (Bax, Bad), and led to cleavage of PARP and caspase-3 proteins. Additionally, in cells pretreated with CGE, the phosphorylation of AKT and ERK was increased and that of p38 and JNK was decreased compared with in cells subjected only to IR. These results indicated that CGE may act as a radioprotector due to its anti-oxidative activity, restoring cell homeostasis and redox balance in radiation-exposed fibroblast cells. Therefore, it could be suggested that CGE may be an effective candidate in the treatment of oxidative stress-related diseases and in radioprotection.