Water-soluble compounds of lettuce inhibit DNA damage and lipid peroxidation induced by glucose/serum deprivation in N2a cells.

Oxidative stress, increase of lipid peroxidation and resultant DNA damage are associated with pathophysiology of many human diseases such as acute and chronic CNS injuries and diseases, cancer, and also aging. This work was done to investigate whether water fraction from the hydroalcoholic extract of green leaf lettuce (Lactuca sativa L.) can protect N2a cells against glucose/serum deprivation (GSD)-induced lipid peroxidation and DNA fragmentation. The cells were cultivated for 12 h in GSD condition in the absence or presence of the lettuce fraction. The total antioxidant ability of the lettuce water fraction was determined using ferric reducing antioxidant power (FRAP) assay. The intracellular lipid peroxidation was evaluated by malondialdehyde (MDA) level. DNA damage was determined using single cell gel electrophoresis. Using FRAP assay, the antioxidant activity of lettuce water fraction was found to be 574 micromol/g, which is equivalent to 64.1 mg of pure ascorbic acid. Exposure of the cells to GSD condition led to a significant increase of MDA level and DNA fragmentation. Lettuce extract at 400 microg/mL could decrease the elevated intracellular lipid peroxidation and DNA damage. The present study demonstrates that lettuce exerts genoprotective effect through inhibition of oxidative stress.