In vitro and in vivo efficacy and toxicity assessments of Melittin antimicrobial peptide produced in the yeast system

Background and Aim : Some studies introduced the Melittin peptide, the main component of honeybee venom, as an antimicrobial peptide. The aim of the present study was to produce Melittin peptide using yeast system and evaluate its efficiency as well as toxicity in both in vivo and in vitro systems.Methods : The chemically synthesized Melittin was obtained by cloning its sequence in the pPIC۹ vector and then transformed it into the Pichia pastoris GS۱۱۵. Minimum inhibitory concentration (MIC) of Melittin (range ۰.۵-۳۲ μg/ml) was determined by the microwell dilution method against an extensively drug-resistant (XDR) Acinetobacter baumannii. Human primary fibroblast cells were used to assay in vitro toxicity of Melittin by ۳-(۴,۵-dimethylthiazol-۲-yl)-۲,۵-diphenyltetrazolium bromide (MTT) test. Acute and sub-acute in vivo toxicity doses were determined using BALB/c mouse model.Results : The MIC of Melittin against an XDR A. baumannii was ۱۶ug/mL, Its half maximal inhibitory concentration (IC۵۰) value on primary fibroblast cells was ۷.۵ug/mL, the single intraperitoneal median lethal dose (i.p. LD۵۰) was ۵.۴ mg/kg and repeated i.p.LD۵۰ (۸h interval) was ۴.۲ mg/kg.Conclusion : The results of present study, for the first time clearly demonstrate that despite valuable antimicrobial activity of melittin, we could not prescribe it as a systemic agent because in therapeutic doses it has different levels of in vivo and in vitro toxicities.

کلیدواژه ها:

Mellitin ، toxicity ، Acinetobacter baumannii