LL-13-37 is an active fragment of the LL-37 peptide which has been shown to have anti-fungal properties against Candida albicans.

LL-37 is a member of the large cationic family of anti-microbial peptides called cathelicidins which have broad-spectrum anti-microbial activity and are expressed in many species. The only cathelicidin found in humans is LL-37; this is produced in epithelial cells, by proteolytic cleavage from the C-terminal of the hCAP-18 protein. LL-37 can be processed into different forms of anti-microbial peptides. As well as its anti-microbial properties LL-37 also has anti-cancer properties and regulates many aspects of the innate immune system; overexpression of LL-37 has been linked to autoimmune diseases such as asthma and psoriasis