Effects of di-n-butyl phthalate (DBP) on activity of enzyms in different tissues of crimson snapper (Lutjanus erythropterus)

Abstract

Di-n-butyl phthalate(DBP),a member of the phthalate acid ester(PAE) family,is thought to have an endocrine disrupting effect on vertebrates and humans and has been identified as priority controlled hazardous substance in the United States and China.In order to evaluate the effect of DPB,we examined liver and gill levels of superoxide dismutase(SOD) and malondialdehyde(MDA),and brain levels of acetylcholinesterase(AChE) in the crimson snapper(Lutjanus erythropterus).Groups of fish were exposed to 0,0.125,0.5,or 2.0 mg/L DBP for 0,6,12,24,48,or 96 h.The 24,48 and 96h LC50 values were 7.13,7.02,and 6.75 mg/L,respectively.The safe con-centration(SC) of DBP was 2.04 mg.L.1.Gill superoxide dismutase(SOD) activity increased significantly as the concentration of DBP increased.In contrast,there was no clear pattern of induction or inhibition for liver SOD activity,though levels in the groups exposed to 0.5 and 2.0 mg/L were significantly different from the control(P0.05).Gill MDA content was significantly higher after 6 h,but decreased thereafter.Similarly,liver MDA content increased then decreased,and was not different from the control after 96 h(P0.05).Brain levels of ace-tylcholinesterase(AChE) were 32.07%,62.07%,and 61.60% higher in fish exposed to 0.125,0.5 or 2.0 mg/L,respectively,after 48 h.However,AChE activity was lower in the treatment groups than in the control group after 96 h exposure(28.87%,20.12%,and 21.14% lower,respectively).Our results suggest that the effects of DBP on enzyme activity is related to the time of exposure.It could be concluded that DBP causes oxidative stress and neurotoxicity in aquatic organisms.Thus,attention should be given to the potential ecological risk posed by this contaminant.