Usnic acid

Usnic acid is a secondary metabolite of lichens with a unique dibenzofuran skeleton. Usnic acid inhibits DNA/RNA synthesis and has antibacterial activity. Usnic acid induces cell cycle arrest and apoptosis and has anticancer activity. Usnic acid inhibits RANKL-mediated osteoclast formation and function by reducing the transcriptional and translational expression of NFATc1. Usnic acid has antioxidant and anti-inflammatory activities by inhibiting lipid peroxidation and myeloperoxidase^[1][2][3][4]. In Vitro:Usnic acid (0-40 μg/mL, 0-150 min) inhibits the growth of B. subtilis, S. aureus and V. harveyi^[1].
Usnic acid (0.5/1 μg/mL, 15-150 min) inhibits the incorporation rate of DNA, RNA and protein synthesis macromolecular precursors thymidine, uridine and leucine in B. subtilis and S. aureus^[1].
Usnic acid (25-100 μM, 24-48 h) inhibits the viability and clonogenicity of A549 cells. It also induces G0/G1 cell cycle arrest, mitochondrial membrane depolarization and apoptosis of A549 cells^[2].
Usnic acid (0.3-3 μM, 4 d) inhibits the differentiation of bone marrow-derived macrophages (BMM) into mature osteoclasts in a dose-dependent manner^[4].
Usnic acid (3 μM, 0-3 d) inhibits the transcriptional and translational expression of RANKL on NFATc1 in BMMs^[4].
Usnic acid (3 μM, 5-30 min) inhibits RANKL-induced activities of MAP kinases p38, ERK and JNK in BMMs^[4].
In Vivo:Usnic acid (25-200 mg/kg, p.o., once) can inhibit Indomethacin (HY-14397)-induced gastric injury in rats (80.2-96.4%)^[3].
Usnic acid (1 μg/g, i.p., every day for up to 8 days) inhibited osteoclastic bone resorption in the lipopolysaccharide (LPS) bone erosion model ^[4].