| Phthalate(Phthalatic Acid Esters,PAEs)is an important plasticizer.According to the different alkyl chains,there are more than 20 kinds of PAEs,which are widely used in industrial production because of their excellent performance and low cost.In China,Phthalate esters account for about 90%of plasticizers.PAEs binds to the plastic matrix through hydrogen bonds and Vander Waals force,so it is easy to free from plastic products and release and transfer to surrounding air,water,soil and even food,and become a common pollutant in the environment.Diisobutyl Phthalate(DIBP)is one kind of PAEs.In recent years,due to the increasing international control of DEHP and other substances,DIBP is used more and more frequently as its excellent substitute,and its environmental pollution has attracted more and more attention.For exploring the ecotoxicological effects of DIBP on soil organisms,finding appropriate biomarkers to DIBP soil pollution,in this study we make Eisenia fetidas as trial target,DIBP as source of pollution.Eisenia fetidas were treated with 300,600,1200 mg·L-1DIBP solution for a 28-day period.At the same time,blank control and acetone control were set up.Tissue fluids were collected on the 7th,14th,21st,28th day from the organisms to determine the activities of superoxide dismutase(SOD),catalase(CAT),peroxidase(POD),glutathione transferase(GST).At the same time,the degree of oxidative damage(ROS content),lipid peroxidation(malondialdehyde MDA content),and DNA damage(8-OHd G)were also determined.In addition,the toxicity of DIBP to Eisenia fetidas were evaluated quantitatively with an integrated biomarker response(IBR)index.Finally,the molecular docking method was employed to predict the action of simulated DIBP on the trial organisms.The main conclusions of this study are as follows:(1)The effects of DIBP on the antioxidant enzyme system of earthworms were determined(0 mg·kg-1?300 mg·kg-1?600 mg·kg-1?1200 mg·kg-1).The results showed that DIBP inhibited the SOD enzyme and the CAT enzyme in the early time and then the two enzymes were stabilized.On the whole,the IBR values of the two enzymes were higher than those of the other enzymes,indicating that DIBP had a strong toxic effect on the two enzymes.(2)The effects of different concentrations of DIBP on earthworm POD and GST enzymes were determined.The results showed that the two enzymes were activated by DIBP in the early time and then stabilized,indicating that the sensitivity of the two enzymes to the DIBP was not high and the toxicity was small.(3)The effects of different concentrations of DIBP on earthworm ROS,MDA were determined.The results showed that the ROS could reach the quantitative maximum quickly in the first two weeks when the toxicity was strong.The toxicity decreased due to the excessive decline of ROS in the second two weeks,and the earthworm MDA reached the quantitative maximum in the second week which subjected to the oxidation stress of DIBP,and then gradually decreased.IBR value analysis shows that DIBP has a potential ecological risk to soil organisms(4)The damage effect of DIBP on earthworm DNA was determined.The results showed that the damage caused by higher concentration of DIBP could cause damage to earthworm,and the damage effect increased with the increase of the DIBP concentration.(5)To conduct the molecular docking experiments with the SOD,CAT enzymes which were sensitive to DIBP.The results showed that the combining comformation was subjected to hydrogen bond,electrostatic interaction and hydrophobic force at the same time. |
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