Studies On Biological Characteristics Of Animal Innate Peptide CGA-N46

In recent years, the infection of pathogenic fungal is becoming more and more serious,and the super resistant strains also appear constantly. It is urgent to increase the efforts todevelop a new antimicrobial drug. CGA-N46is a novel antifungal polypeptide. Studies on itsstability, the effects on different eukaryotic cells, and the effects on DNA and protein ofCandida krusei could lay the theoretical foundation for the development of new antifungalagents.Stability study showed that the antibacterial activity of CGA-N46remained unchangedwhen it was heated15min at100℃or repeated freezing and thawing six times. Theantibacterial activity of CGA-N46was affected after stored at room temperature for72h, butthere was no significant change(P>0.05). When pH is in the range of4.0-7.0, antibacterialactivity of CGA-N46was completely unchanged.The hemolysis of CGA-N46was tested by test tube method and spectrophotometry. Theresults showed that CGA-N46had no hemolysis even at eight times the concentration of MIC.The effects on proliferation of lung cancer cells A549and normal chicken embryo fibroblast(CEF) were detected by MTT method, and the results showed that CGA-N46had inhibitoryeffect on lung cancer cells A549, and the inhibition rate reached60.53%after incubation for72h, while it had no inhibition on chick embryo fibroblast cells. The combination studyshowed additive effect between CGA-N46and fluconazole, as well as CGA-N46andterbinafine, this could not only improved the antibacterial activity but also reduced the dosageof antibiotics.CGA-N46didn’t cause the leakage of UV absorption materials of Candida krusei in vivoby UV spectrophotometry. DNA-CGA-N46gel retardation experiment proved that CGA-N46could not make Candida krusei DNA degraded in vitro. The flow cytometry examinationshowed that CGA-N46caused the percentage of cells in S phase increased, the percentage ofcells in G2/M phase decreased. Effect of CGA-N46on PCR reaction showed that in theprocess of DNA synthesis, CGA-N46could inhibit DNA synthesis according to affecting the function of TaqDNA polymerase. SDS-PAGE electrophoresis showed that CGA-N46couldinhibit the normal expression of proteins of Candida krusei in vivo.Therefore, CGA-N46had thermal stability, structural stability in vitro, long storage timeat room temperature, good acid-base stability, low hemolysis, and had inhibitory effect oncancer cells, no effect on normal fibroblast growth. The combination use between CGA-N46and antibiotics showed additive effect. CGA-N46could block cell division, so the cells werearrested in S phase. PCR results also confirmed that CGA-N46block DNA synthesis.Meanwhile CGA-N46also had an effect on protein synthesis.