Antitumor Effect And Mechanism Of Preserved Egg

Preserved egg is one type of traditional duck egg products in China.Preserved egg was recorded to sober up and treat diarrhoea in ancient books.Studies have shown that preserved egg white hydrolysates display anti-inflammatory activity in vitro and in vivo experiments and can significantly decrease the expression levels of IL-8 and TNF-?.However,there are few studies on the antitumor activity and mechanisms of preserved eggs.This paper studied the safety and physiological functions of preserved eggs in vivo and studied the antitumor function and mechanisms of preserved eggs in virto.The main results are as follows:(1)The healthy SD rats were fed with preserved eggs for 80 days.The effects of preserved eggs on rats were investigated in this study.The study found that high dose of preserved egg(4.2 mg/mL)can provide nutrition for SD rats and increase body weight of SD rats.Furthermore,preserved eggs could reduce the level of TG,TCHO and LDL-C/HDL-C in the rats' livers,especially when the dosement reached to 4.2 mg/mL.No tissue damage was caused by the preserved eggs.Under the light microscope,liver sections with HE staining shows that the structure of hepatic lobules was obviously complete,the liver cells arranged rule,and there were no cell denaturation and inflammatory cell infiltration after treatment with preserved eggs.Preserved eggs could also reduce the expression of IL-6 and TNF-? in rats' liver.These results showed that preserved egg could reduce the level of lipid and proinflammatory cytokines in rats.(2)The antioxidant capacity and antitumor effects of preservd eggs were investigated based on gastrointestinal digestion.The results showed that preserved eggs had high antioxidant capacity during the digestive process of the gastrointestinal tract.The capacity to reduce the reduction ability of preserved eggs before digestion was better than that after digestion.The highest ability to scavenge OH radical was 99.80%,the ability to scavenge DPPH free radical was 68.40%,and the highest ability to clear ABTS free radical was 54.90%.What's more,in vitro antitumor studies were performed on Caco-2 cells,a human epithelial colorectal adenocarcinoma cell line.It demonstrated that the gastrointestinal(GI)digests of preserved eggs significantly accelerated the apoptosis by upregulating caspase-3 in the Caco-2 cells.Besides,after treated with preserved eggs,the half maximal inhibitory concentration(IC50)of preserved eggs digests to Caco-2 cells was 5.75 mg/mL,indicating the significant inhibition of cell proliferation provided by preserved eggs.The results shown in this study demonstrated that preserved eggs may be a novel functional food involved with antilipemic,anti-inflammatory activity as well as the effect on accelarating the apoptosis of Caco-2 cells.(3)In order to further study the antitumor effect and antitumor mechanism of preserved egg,we investigated the effects of preserved eggs on the apoptosis of HT-29 and HepG2 cells by evaluating associated protein expression.The cell morphology was observed by fluorescence inverted microscope and the apoptosis of cells was measured by flow cytometry.Bcl-2,Bax and COX-2 were detected by RT-qPCR.Caspase-3 and caspase-9 were detected by Elisa.Our results showed that preserved eggs significantly upregulated the expression of genes Bax,caspase-3 and caspase-9,which are involved in cell apoptosis,and upregulated the expression of the pro-apoptotic factors Bcl-2 and COX-2 both in HT-29 and HepG2 cells,leading to a reduction in the ratio of Bcl? 2/Bax proteins.Furthermore,the results showed that the apoptosis of HT-29 and HepG2 cells was promoted by preserved eggs in a dose-dependent manner.Thus,preserved eggs could promote cell apoptosis by up-regulating apoptosis factors and down-regulating anti apoptotic factors,which may be related to Bcl-2/Bax and caspase pathway.(4)In order to further understand the anti-tumor active ingredients in preserved eggs,the digested products were deeply separated and purified.Firstly,a single component of two kinds of digestive mixture of preserved eggs was obtained by multistage separation and purification.The molecular weight was above 10 kDa.The anti tumor drug 5-FU was used as a positive control and HT-29 cells were served as the research object.The experimental results showed that all the egg components could increase the content of cell apoptosis factor CytC,caspase-3 and casase-9 and promote the apoptosis of HT-29 cells.The pro apoptotic factor is closely related to the mitochondrial pathway.It is worth noting that the effect of mixture of preserved eggs is better than that of a single component.Therefore,preserved eggs may be achieved through the interaction of mixtures to achieve the purpose of anti-tumor,which is generated through mitochondrial pathway.