Table 2.

Select antimicrobial peptides in use or under development¹

Class	Peptide	Source	Activity spectrum	Mechanism of action	Approval/Use	Ref
I	Gramicidin	Bacillus brevis	Gram +/− pathogens	Forms an ion channel in membranes.	Ophthalmic use as solutions/drops (1940s)	[85]
II	Nisin	Lactococcus lactis	Gram +pathogens	Binds lipid II and inhibits cell wall synthesis.	Food preservative (1969, WHO; 1988, FDA)	[86]
III	Bacitracin	Bacillus subtilis	Gram +/− pathogens	Inhibits cell wall and peptidoglycan synthesis.	Powder form (before 1982)	[87]
III	Polymyxin B	Bacillus polymyxa	Gram− pathogens (e.g., P. aeruginosa)	Damages membranes	Aerosporin injection (before 1982); endotoxin removing (2003)	[88]
III	Colistin, or polymyxin E	Paenibacillu s polymyxa	Pseudomon as and Acinetobacter sp.	Damages membranes	Suspension/drops (1982)	[89]
III	Daptomycin	Streptomyces roseosporus.	Gram+ MRSA	Damages membranes	Treat complicated skin infection (2003, FDA).	[90]
III	Echinocandin2	Glarea lozoyensis; Coleophoma empedra; A. nidulans	Fungi (C. albicans)	Inhibits the synthesis of glucan and cell wall.	FDA approved	[91]
IV	Gramicidin S	Bacillus brevis	Gram+/− pathogens	Disrupts the outer membrane.	Wound infections (1942, Soviet Union)	[92]
I	Pexiganan (Magainin)	Xenopus laevis	Diabetic foot ulcers	Membranes	Phase III	[93]
I	Omiganan (indolicidin)	Bos taurus	Rosacea	Membrane/DNA	Phase II	[94]
I	OP-145 (LL-37)	Homo sapiens	Chronic middle ear infection	Membranes	Phase I/II	[94]
I	PXL01 (lactoferricin)	Homo sapiens	Prevention of postsurgical adhesion formation	Repressing proinflammatory cytokine secretion and promoting fibrinolysis.	Phase II	[94]
I	PAC-113 (histatin 3)	Homo sapiens	Oral candidiasis	Membranes/Inhibiting cytokine production.	Phase II	[94]
II	Iseganan/IB-367 (protegrin-1)	Sus scrofa	Oral mucositis	Membranes	Phase III	[94]
II	Novexatin/NP-213 (defensin)	Homo sapiens	Fungal nail infection	Membrane lysis	Phase II	[94]
III	Iturin A (lipopeptide)	Bacillus subtilis	Fungi; G +/− bacteria	Forms ion conducting pores in membranes.	Preclinical	[95]
III	Ramoplanin	Actinoplanes sp. ATCC 33076.	Gram+ bacteria	Inhibits cell wall synthesis.	VRE (Phase III); C. difficile (Phase II).	[96]
III	WAP-8294A2 (Lotilibcin)	Lysobacter sp.	Gram+ bacteria (VRE and MRSA)	Interacts with membranes.	Systemic infection (Phase I/II)	[97]
IV	Valinomycin	Streptomyces tsusimaensis; S. fulvissimus	Gram+ bacteria; Fungi (C. albicans)	Forms a K+ ion channel in membranes.	Not available	[98]

¹Data from http://www.accessdata.fda.gov/scripts/cder/ob/search_product.cfm; https://clinicaltrials.gov/; https://pubchem.ncbi.nlm.nih.gov/; http://aps.unmc.edu/AP.

²The FDA-approved echinocandins are seminsynthetic lipopeptides derived from caspofungin, micafungin, and anidulafungin.