Antileishmanial Activities of Carvacrol Nanoencapsulate in Biopolymeric Nanoparticles

Visceral leishmaniasis (VL) is a neglected parasitic disease, and the first-line treatments for VL include drugs that exhibit serious toxicological issues. In this sense, new molecules are sought for VL treatment, such as Carvacrol (Car), a phenolic monoterpene that has shown strong activity against Leishmania spp. However, its low solubility prevents its free administration, requiring a new therapeutic strategy such as encapsulation in chitosan biopolymeric nanoparticles. This study aimed to develop chitosan biopolymeric nanoparticles (NPChi) encapsulating Car (NPCar) and evaluate their in vitro anti-leishmanial activity. The NPChi had particle sizes of 89.43 ± 0.774 nm, a polydispersity index (PDI) of 0.168 ± 0.01 and zeta potential of 12.8 ± 2.17 mV. The NPCar showed particle size of 144.9 ± 1.7 nm, PDI of 0.224 and zeta potential of 15.7 ± 1.01 mV. NPCar reduced the cytotoxicity of Car on human erythrocytes. Moreover, NPCar showed inhibition of Leishmania infantum with an inhibitory concentration (IC₅₀) of 2.659 ± 0.26 µg/mL. Thus, NPCar exhibited enhanced anti-leishmanial activity compared to free Car while reducing cytotoxicity on human erythrocytes, making them promising candidates for further studies on VL treatment.