Antimicrobial　peptides　(AMPs)　play　pivotal　roles　in　the　innate　defense　of　vertebrates.　A　novel　AMP　(cathelicidin-PY)　has　been　identified　from　the　skin　secretions　of　the　frog　Paa　yunnanensis.　Cathelicidin-PY　has　an　amino　acid　sequence　of　RKCNFLCKLKEKLRTVITSHIDKVLRPQG.　Nuclear　magnetic　resonance　(NMR)　spectroscopy　analysis　revealed　that　cathelicidin-PY　adopts　a　tertiary　structure　with　a　mostly　positively　charged　surface　containing　a　helix　(Thr15-Ser19).　It　possesses　strong　antimicrobial　activity,　low　hemolytic　activity,　low　cytotoxicity　against　RAW　264.7　cells,　and　strong　anti-inflammatory　activity.　The　action　of　antimicrobial　activity　of　cathelicidin-PY　is　through　the　destruction　of　the　cell　membrane.　Moreover,　cathelicidin-PY　exerts　anti-inflammatory　activity　by　inhibiting　the　production　of　nitric　oxide　(NO)　and　inflammatory　cytokines　such　as　tumor　necrosis　factor　(TNF-α),　interleukin-6　(IL-6),　and　monocyte　chemoattractant　protein-1　(MCP-1).　Cathelicidin-PY　inhibits　the　activation　of　Toll-like　receptor　4　(TLR4)　inflammatory　response　pathways　induced　by　lipopolysaccharide　(LPS).　The　NMR　titration　experiments　indicated　that　cathelicidin-PY　can　bind　to　LPS.　In　conclusion,　we　have　identified　a　novel　potent　peptide　antibiotic　with　both　antimicrobial　and　anti-inflammatory　activities　and　laid　the　groundwork　for　future　research　and　development.　©　2013　American　Chemical　Society.