L4F

L4F, frequently written L-4F, is a synthetic peptide described in biomedical literature as an apolipoprotein A-I (apoA-I) mimetic peptide. It is one of several designed to imitate high-density lipoprotein (HDL) functions, especially its anti-inflammatory and antioxidant properties.

The peptide is designed to form amphipathic alpha helices that can bind oxidized lipids and promote cholesterol efflux, processes thought to underlie HDL’s protective effects against atherosclerosis. In experimental systems, L-4F has been used to model HDL activity and to investigate mechanisms of inflammation and oxidative stress.

In preclinical studies, L-4F has shown improvements in HDL functionality and reductions in atherosclerotic lesion development in animal models, along with decreases in inflammatory markers. Early-phase human studies have evaluated safety, tolerability, and biomarkers of HDL function, but results have not demonstrated clear clinical benefits, and L-4F is not approved as a medical therapy.

Research on L-4F has often occurred alongside the related D-4F peptide; together they form part of a broader effort to develop apoA-I mimetics for cardiovascular protection. Investigations have explored various routes of administration and dosing regimens, but clinical translation remains limited and no regulatory approval has been granted to date.