| With social development,the incidence of cancer is increasing highly due to environmental pollution,fast-paced life and unhealthy eating habits.The current treatments for cancer are surgical therapy,radiotherapy and chemotherapy.Therefore,it is of great significance to find a effective and no-toxic drug to make patients recover quickly for the clinical treatment of cancer and tumor.Sophorolipids are a kind of biological surfactants of extracellular polysaccharides produced by non-pathogenic yeasts through the secondary metabolism.According to the research results,sophorolipid not only has excellent physical and chemical properties as well as fine antineoplasmic activity,but also non-toxicity,which does not cause pollution to the environment.In recent years,many studies showed that sophorolipids have been further developed in the field of medicine,and more and more researchers began to constantly explore the anti-tumor activities about sophorolipids.This thesis first focused on the physical and chemical properties of sophorolipids produced through the fermentation with different types of carbon sources.Second,it was explored the relationship between p H solubility and antineoplasmic activity of sophorolipids,then compared anti-tumor effects of sophorolipids produced with various carbon sources.Finally,it was discussed the anti-tumor effects and mechanisms of the combination of sophorolipids and doxorubicin.All the data will provide the theoretical foundation for sophorolipids to become a new type of drug in the future.The main research aspects and results are as the following:Firstly,in this thesis it was studied sophorolipids production through the fermentation with different types of carbon sources including oleic acid,rapeseed oil and equal volumn of oleic acid and glycerol mixture.And compared the yield of total sophorolipids and lactonic sophorolipids and their proportions.After fermentation for 7 days at 30? and 170 r/min all parameters were tested.It was concluded that the final p H of fermentation broth with different carbon sources were all around 2.0.And the dry cell weights were respectively around 5.23 g/L(oleic acid),5.67 g/L(rapeseed oil)and 4.21 g/L(oleic acid and glycerol).The contents of residual sugar were respectively around 0.15 g/L,0.21 g/L and 1.58 g/L;The contents of total sophorolipids were respectively around 51.61 g/L,57.78 g/L and 30.32 g/L;The contents of lactonic sophorolipids were respectively around 26.29 g/L,23.46 g/L and 1.88 g/L;The proportions of lactonic sophorolipids were respectively around 50.94%,40.60% and 6.00%.The results indicated that all indicators were much lower in the condition of oleic acid and glycerol as the mixed substrate than the other two conditions.Therefore,we only discussed the antitumor effects of sophorolipids produced with oleic acid and rapeseed oil as substrates.Secondly,it was studied the relationship between p H solubility and antineoplasmic activity of sophorolipids.Sophorolipids were dissolved in the sterile three-steamed water and adjusted p H values including natural p H6.5,p H6.0,p H7.0 and p H8.0.Hela cells were treated with different the concentrations of sophrolipids including 80 ?g/m L,120 ?g/m L and 160 ?g/m L and 240 ?g/m L,respectively.Hep G2 cells were treated with different the concentrations of sophrolipids including 60?g/m L,120?g/m L and 240?g/m L,respectively.After treatment for 24 hours and 48 hours,the optimum p H value of lactonic sophorolipids with the highest cell mortality was obtained.All the lactonic sophorolipids at different concentrations had a good inhibitory effects on both Hela cells and Hep G2 cells.Furthermore,cell growth inhibition was increased with the sophorolipids concentration increasing and treatment time prolonging when the p H value was 6.0.Thirdly,it was compared the antitumor effects of sophorolipids produced with various carbon sources including oleic acid and rapeseed oil.Hela cells,Hep G2 cells and normal renal epithelial 293 cells were treated with different types of sophorolipids at the concentration of 240 ?g/m L under different p H values for 24 h or 48 h.The data showed that the anti-tumor effects were better at 48 h than 24 h.In addition,at p H6,the anti-tumor effects of sophorolipids with rapeseed oil as substrate were better than oleic acid as substrate.At the same time,the cell survival rates of renal epithelial 293 cells were over 50% under the different p H values.Fourthly,it was discussed the anti-tumor effects and mechanisms of the combination of sophorolipids and doxorubicin.Sophorolipids with oleic acid as substrate and sophorolipids with rapeseed oil as substrate were respectively combined with doxorubicin.First,we determined the minimum concentration(MIC)of antitumor when sophorolipids and doxorubicin alone,and then determined MIC when sophorolipids combined with doxorubicin,and finally calculated the anti-tumor concentration index FIC under the combination.For two kinds of tumor cells,both the FICs of the combination were more than 2,appearing the antagonism.What's more,we further conducted the research on the mechanism.The result showed that the morphology of tumor cells changed,the cells kept shrinking and became smaller,the membrane vesicles in the cells produced and some small structures appeared,some cells were even falling off from the wall of cell culture dish.Besides,the morphology of the nucleus was also changed.Chromatin and nucleolus have agglutinated and become dyed and even marginalized.In some cells,the nucleus has fragmented and flow out of the cell with the contents,and there were some structures enclosed by cell membrane without nucleolus.The results provided the possibility and theoretical foundation for sophorolipids serving as a new type of antitumor drug. |
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