Hemolytic and mice acute oral toxicity evaluation of a new antimicrobial peptide APNT-6

In this paper, the hemolytic and mice acute oral toxicity of a new antibacterial peptide APNT-6 with antibacterial lipopeptide surfactin, iturin and fengycin as the main components was evaluated. At first, hemolytic activity of the antibacterial peptide was studied in vitro; a 100-fold dilution of the antibacterial peptide was added to an Oxford cup placed on rabbit blood agar plate, after 37 ℃ overnight, the hemo-lytic activity was determined. The results showed that, 100-fold dilution of the antibacterial peptide in the Oxford cup formed 32 mm hemolytic circle on the plate medium, indicating that it has a strong hemolytic toxicity in vitro that is possible barriers to actual use. Meanwhile, a study for acute oral toxicity of the an-tibacterial peptide in mice was conducted, 60 male and female Kunming mice were randomly divided into six groups, with normal saline as a control, each group of mice was respectively fed 8, 40, 200, 1 000 and 5 000 mg/kg of the antibacterial peptide dose at one-time, within 7 d, observing toxicity body signs and death situation of mice and determining feed intake, water intake, weight gain and organ index, and exam-ining pathological changes for the abnormal organs. The results showed that in each dose group of mice death and any signs of poisoning were not seen. The oral median lethal dose (LD50) is greater than 5 000 mg/kg body weight; feed intake and water intake of each group mice have no significant change; except that the highest dose group had slightly lower weight gain, there were no significant differences in weight gain between the other groups and the control group; the spleen, kidney, lung and cardiac index of each group had no statistically significant differences and liver index of more than 1 000 mg/kg dose group was higher compared with the control group; mice organs and tissues of each dose group have no obvious pa-thological changes. These results suggest that high doses of the antibacterial peptide by oral administration can not achieve an effective hemolytic concentration in mice; in accordance with the acute toxic standard of disinfectant, it really has no toxicity, and that oral administration of the antibacterial peptide in mice does not constitute significant acute toxic effects. Based on the above results, it can be concluded that the new antibacterial peptide APNT-6 has strong hemolytic toxicity in vitro, but no acute oral toxicity in mice.