In vitro and in vivo antimicrobial activity of self-assembled melittin nanoparticles: A comparative study with melittin peptide

Abstract

The aim of the present study was to analyse the efficacy of self-assembled melittin nanoparticles (MelNP) and compare with native melittin peptide (Mel). Self-assembly formation of the melittin was promoted by heating at 90 °C for 50 min followed by cooling at room temperature. SEM micrographs revealed the formation of nanovesicles. MIC of MelNP against E. coli, S. aureus and P. aeruginosa was found to be 4, 2, and 2 μM, respectively while it was 8, 8 and 4 μM for Mel peptide. Markedly, MelNP showed 12.6 % hemolysis at 8 μM whereas with Mel it was about 71.63 %. The lytic activity of MelNP was also higher in the presence of trypsin/serum than Mel. Both MelNP and Mel exhibited membranolytic activity with cellular disintegration. Further, toxicity analysis studied up to 72 h showed that MelNP was non-toxic to zebrafish embryos up to 6 μM; however, with Mel exposed embryos showed up 30 dead embryos. Bacterial load was markedly reduced in MelNP and Mel exposed infected embryos than compared to the infected one. Moreover, the peptides were also responsible for reducing the infection and prolonging the survivability in infected embryos. Thus, MelNP could be considered an efficient and safer therapeutic molecule that Mel and wherein further experiments are warranted to affirm the broad spectrum efficiency.