Effects Of Methyl And Ethyl P-hydroxybenzoate On The Feeding Of Drosophila And Its Metabolism In Vivo

Parabens are esters by p-hydroxybenzoic acid with different alcohols dehydration condensation,mainly including methylparaben(MP),ethylparaben(EP),propylparaben(PP),butylparaben(BP)and so on.These compounds are widely used in food,medicine and cosmetics because of their colorless,tasteless,high efficiency and low toxicity.But in recent years,people have concerns about their safety,their estrogenic effects can not be ignored,and parabens have been detected in the environment,it is necessary to study its effects on organisms and their metabolism in vivo.In this study,the wild type Drosophila melanogaster Canton-S strain was used as the experimental animal,one control group,three MP concentration groups(300 mg· L-1,700 mg·L-1 and 1000 mg·L-1)and three EP concentration groups(300mg·L-1,700 mg·L-1 and 1000 mg·L-1)were established,culture of fruit flies by capillary feeding(CAFE),detection the effects of MP or EP on fruit flies food intake,and statistics flies daily survival,calculate average life and maximum life.Detect fruit flies different exposure stages(0 d,1 d,2 d,3 d,6 d,9 d,12 d,15 d and 18 d)the activity of carboxylesterase(CarE),which is related to the metabolism of parabens.The contents of free and total metabolites(3,4-DHB,4-HB and transesterification products PP and MP or EP)and non-metabolites(MP or EP)were measured in different exposure stages of fruit flies(1 d,2 d,3 d,6 d,9 d,12 d,15 d and 18 d),investigate the effects of MP and EP exposure on feeding,longevity and related metabolism in fruit flies.The results show:(1)The food intake of flies increased to maximum at about 18th day and remained stable,female flies eat more than male.MP and EP could inhibit the feeding of flies,EP inhibition is greater than MP.The average life span of flies increased with the increase of MP and EP,the maximum life span of MP group also has increased trend with the increase of concentration,EP group increased and then decreased,showing a toxic effect,male flies live longer than females.(2)In control group,the activity of carboxylesterase in fruit flies fluctuate with days,the activity of carboxylesterase in flies was significantly increased at second day by the exposure of MP and EP,sixth day down to the equilibrium value and remained stable,but still higher than the control group,meanwhile,there was a significant dose effect among the concentration group,female flies fluctuate more sharply than male.(3)Most groups the metabolite 3,4-DHB was detected very few,no transester product PP was detected in all groups,but can detect 4-HB,MP and EP,the detection of metabolites and non-metabolites in flies fluctuate with days,the higher the exposure concentration,the higher the detection.(4)After MP exposure,about 50%hydrolysis to 4-HB,among them,43%-67%is conjugated form,the others is free form.Less than 5%of the MP was transesterificated to EP,and present in free form.The rest of the MP mainly exists in free form,conjugated MP very few,and the higher the exposure concentration,the greater the proportion of non-metabolized MPR(5)After EP exposure,also has about 50%hydrolysis to 4-HB,but 63%-80%is conjugated form,free 4-HB is relatively small.More than 15%of the EP was transesterificated to MP,and the higher the exposure concentration,the higher the proportion of conjugated MP.In 300 mg·L-1 and 700 mg·L-1 groups,the remaining EP was free form,and in 1000 mg L-1 group there was a small amount of conjugated form.In sum,MP and EP can inhibit fruit flies feeding,extend the life span of flies at a certain concentration,and improve the activity of detoxification related carboxylesterase in flies,in order to make more MP and EP metabolism to 4-HB,more than half of 4-HB form conjugated state,the transesterification of MP is less than EP,the rest of the MP and EP exist in free state,the results of this study provide data support for the study of the metabolism of parabens in Drosophila melanogaster.