title: Cationic antimicrobial peptides and biogenic silver nanoparticles kill mycobacteria without eliciting DNA damage and cytotoxicity in mouse macrophages.
abstract: With the emergence of multidrug-resistant mycobacterial strains, better therapeutic strategies are required for the successful treatment of the infection. Although antimicrobial peptides (AMPs) and silver nanoparticles (AgNPs) are becoming one of the popular antibacterial agents, their antimycobacterial potential is not fully evaluated. In this study, we synthesized biogenic-silver nanoparticles using bacterial, fungal, and plant biomasses and analyzed their antibacterial activities in combination with AMPs against mycobacteria. Mycobacterium smegmatis was found to be more susceptible to AgNPs compared to M. marinum. We found that NK-2 showed enhanced killing effect with NP-1 and NP-2 biogenic nanoparticles at a 0.5-ppm concentration, whereas LLKKK-18 showed antibacterial activity only with NP-2 at 0.5-ppm dose against M. smegmatis. In case of M. marinum NK-2 did not show any additive activity with NP-1 and NP-2 and LLKKK-18 alone completely inhibited the bacterial growth. Both NP-1 and NP-2 also showed increased killing of M. smegmatis in combination with the antituberculosis drug rifampin. The sizes and shapes of the AgNPs were determined by transmission electron microscopy and dynamic light scattering. AgNPs showed no cytotoxic or DNA damage effects on macrophages at the mycobactericidal dose, whereas treatment with higher doses of AgNPs caused toxicity and micronuclei formation in cytokinesis blocked cells. Macrophages actively endocytosed fluorescein isothiocyanate-labeled AgNPs resulting in nitric oxide independent intracellular killing of M. smegmatis. Apoptosis and cell cycle studies showed that treatment with higher dose of AgNPs arrested macrophages at the G1-phase. In summary, our data suggest the combined effect of biogenic-AgNPs and antimicrobial peptides as a promising antimycobacterial template.
authors.affiliation: School of Biotechnology, KIIT University, Bhubaneswar, Orissa, India.
authors.forename: Soumitra
authors.initials: S
authors.lastname: Mohanty
authors.forename: Prajna
authors.initials: P
authors.lastname: Jena
authors.forename: Ranjit
authors.initials: R
authors.lastname: Mehta
authors.forename: Rashmirekha
authors.initials: R
authors.lastname: Pati
authors.forename: Birendranath
authors.initials: B
authors.lastname: Banerjee
authors.forename: Satish
authors.initials: S
authors.lastname: Patil
authors.forename: Avinash
authors.initials: A
authors.lastname: Sonawane
mesh_terms: D031051:Alstonia / Q000737:chemistry; D000595:Amino Acid Sequence; D000818:Animals; D023181:Antimicrobial Cationic Peptides / Q000008:administration & dosage / Q000494:pharmacology*; D000995:Antitubercular Agents / Q000008:administration & dosage / Q000494:pharmacology; D017209:Apoptosis; D045744:Cell Line, Tumor; D004249:DNA Damage / Q000187:drug effects*; D004338:Drug Combinations; D004353:Drug Evaluation, Preclinical; D059585:G1 Phase Cell Cycle Checkpoints; D008264:Macrophages / Q000187:drug effects*; D053768:Metal Nanoparticles / Q000008:administration & dosage* / Q000648:ultrastructure; D051379:Mice; D015162:Micronucleus Tests; D046529:Microscopy, Electron, Transmission; D008969:Molecular Sequence Data; D020102:Mycobacterium smegmatis / Q000187:drug effects*; D010316:Particle Size; D012293:Rifampin / Q000494:pharmacology; D012834:Silver / Q000494:pharmacology*; D013172:Spores, Fungal / Q000737:chemistry; D014242:Trichoderma / Q000737:chemistry
chemical_list: D023181:Antimicrobial Cationic Peptides; D000995:Antitubercular Agents; D004338:Drug Combinations; D012834:Silver; D012293:Rifampin