Gelatin membrane containing usnic acid-loaded liposome causes in vitro death of Leishmania braziliensis

Cutaneous leishmaniasis (CL) is a parasitic disease endemic in several countries, characterized by skin sores. Current treatments are limited by toxicity and high costs, necessitating the development of new, safer, and more effective antileishmanial compounds. Usnic acid, a secondary metabolite found in lichens, has shown promising wound healing and leishmanicidal properties. This study aimed to evaluate the in vitro efficacy of new gelatin membranes containing usnic acid-loaded liposomes (UAL) as a therapeutic agent against Leishmania braziliensis. Parasitic viability was assessed by directly counting parasites after exposure to the treatment. A significant and irreversible reduction in parasitic viability was observed in the group treated with usnic acid at a concentration of 0.8 µg/mL. UAL was not cytotoxic to macrophages and fibroblasts. Furthermore, treating human macrophages infected with L. braziliensis with UAL reduced the number of intracellular amastigotes and the viability of promastigotes. These findings suggest that UAL is a viable candidate for further investigation as a therapeutic treatment for L. braziliensis infection.