The Study Of Ectropis Obliqua (Lepideptera: Geometridae) Metabolite Catechins And Caffeine In Camellia Sinensis

Plants produce a diverse array of secondary metabolites,such as alkaloids,terpenoids,and phenolics,which can facilitated to defending against herbivores.When herbivores feed on these secondary metabolites.to ensure proper growth,development and reproduction,insect have developed different ways to overcome these chemical barriers,e.g.degrading and metabolizing.Catechins and caffeine is the main secondary metabolites of tea plant,but tea geometrid,a main destructive insect of tea garden,after which feeding on tea plant fresh leaves,it will be necessary for tea geometrid to face these materials,however,the studies correlation with tea geometrid metabolite catechins and caffeine of tea plant are very little.It is necessary to carry out the study of tea geometrid metabolite catechins and caffeine in tea plant.In our study,after tea geometrid feeding tea plant fresh leaves,we firstly have studied the changes of tea plant secondary metabolites catechins and caffeine(CF)content in digestive tract of tea geometrid.We have found that,compare to tea fresh leaves,in foregut and midgut contents,except for EC,the content of other catechins,such as,(+)-gallocatechin(GC),(+)-catechin(C),epigallocatechin(EGC),(-)-gallocatechin-3-gallate(GCG),(-)-epicatechin-3-gallate(ECG),(-)-epigallocatechin-3-gallate(EGCG)are significantly decreased,especially,without EGCG content detected in foregut and midgut contents,suggesting that the most part of catechins in tea plant were digested in tea geometrid foregut and midgut.On the other hand,compare to tea fresh leaves,foregut,midgut,hindgut content and faeces,ester type catechins content are significantly decreased,suggesting that ester type catechins were digested during transmiting tea geometrid digestive tract,and the non-ester type catechins content were gradually increased from foregut,midgut,hindgut content to faeces,this maybe correlated with the digested ester type catechins.Meanwhile,from foregut,midgut to hindgut content,caffeine content was gradually significantly decreased,demonstrating that the digestion catechins and caffeine ability of tea geometrid foregut,midgut,hindgut was more and more shronger.And during caffeine digested through tea geometrid digestive tract,only a little content was detected,suggesting that most of caffeine of tea plant fresh leaves were digested.For understanding whether enzymes in tea geometrid vivo are associated with the of tea plant catechins and caffeine digestion and metabolite,we have carried out tea geometrid vivo different parts crude enzymes in vitro reaction with EGCG and caffeine,the result indicating that,after reaction with enzymes,no matter reaction with oral crude enzyme,foregut crude enzyme,midgut crude enzyme and hindgut crude enzyme,EGCG content was significantly decreased,demonstrating that tea geometrid different parts crude enzymes have reacted with EGCG.Contraily,after reaction with different parts oral crude enzyme,foregut crude enzyme,midgut crude enzyme and hindgut crude enzyme,caffeine content was not significantly changes,demonstrating that tea geometrid different parts crude enzymes have not reacted with caffeine.For understanding the metabolites of tea plant catechins and caffeine in tea geometrid vivo.We have primary analyzed the metabolites of EGCG and caffeine in tea geometrid vivo through LC-MS/MS GNPS molecular networking method,the result shows that the tea plant catechins EGCG were matabolited through decomposition,polymerization,removal of gallic acid,dehydroxylation,methylation of pathway,caffeine were matabolited through removal methyl group pathway.Overall,our studies have found that during tea geometrid mutual effection,it have envolved some ability to mebobilite secondary metabolites catechins and caffeine in tea plant,this ability maybe facilitate tea geometrid to adapt tea plant secondary metabolites environment.