Key Findings:
SDG pre-treatment protected lung cells from radiation-induced DNA damage and increased their clonogenic survival. SDG also significantly enhanced the endogenous antioxidant capacity of the lung cells, increasing the gene expression and protein levels of antioxidant enzymes such as HO-1, GSTM1 and NQ01. SDG appears to be a radioprotective agent for normal lung cells due to its ability for free-radical scavenging and increasing antioxidant defenses.
ABSTRACT:
Plant phenolic compounds are common dietary antioxidants that possess antioxidant and anti-inflammatory properties. Flaxseed has been reported to be radio protective in murine models or oxidative lung damage. Flaxseed’s protective properties are attributed to its main biphenolic lignan, secoisolariciresinol diglucoside (SDG). SDG is a free radical scavenger, shown in cell free systems to protect DNA from radiation-induced damage. The objective of this study was to investigate the in vitro radio protective efficacy of SDG in murine lung cells. Protection against irradiation-induced DNA double and single strand breaks was assessed by gamma-H2AX labelling and alkaline comet assay, respectively. The role of SDG in modulating the levels of cyto protective enzymes was evaluated by qPCR and confirmed by Western blotting. Additionally, effects of SDG on clonogenic survival of irradiated cells were evaluated. SDG protected cells from IR-induced death and ameliorated DNA damage by reducing mean comet tail length and percentage of gamma-H2AX positive cells. Importantly, SDG significantly increased gene and protein levels of antioxidant HO-1, GSTM1 and NQ01. Our results identify the potent radio protective properties of the synthetic biphenolic SDG, preventing DNA damage and enhancing the antioxidant capacity of normal lung cells, thus rendering SDG a potential radio protector against radiation exposure. (Authors abstract)