Macrophage-targeted Hyaluronic-acid Coated Liposomes Bearing Ursolic Acid for Visceral Leishmaniasis: In Vitro Characterisation and Pharmacokinetic Analysis.

Ursolic acid (UA), a natural triterpene, demonstrated promising activity against visceral leishmaniasis (VL); however, its clinical use is limited by poor aqueous solubility (< 5.64 µg/mL), low permeability, hindered oral bioavailability (< 3%), and extensive first-pass metabolism. Hence, hyaluronic acid-coated ursolic acid-bearing liposomes (HA-UA-Lips) were formulated using the thin-film hydration method integrated with Box-Behnken Design (BBD). HA-UA-Lips displayed a vesicle size of 200.2 ± 5.2 nm, PDI of 0.164 ± 0.041, and zeta potential of -21.39 ± 0.27 mV. The surface topography analysis confirmed spherical shape and uniform dispersion of vesicles. Additionally, HA-UA-Lips indicated a significant (P < 0.0001) sustained release of drug after 72 h (70.4 ± 1.68%) as compared to ursolic acid-loaded liposomes (UA-Lips; 87.4 ± 2.61%). The IC50 of HA-UA-Lips was calculated to be 0.6316 ± 0.0004 µg/mL, which was notably declined (P < 0.0001) as compared to UA (22.0 ± 0.35 µg/mL) and blank liposomes (Blk-Lips; 36.205 ± 0.745-µg/mL), respectively, in L. donovani-infected murine macrophage cell line J774A.1. The C6-HA-UA-Lips (Coumarin-6-dye-loaded hyaluronic acid-coated ursolic acid bearing liposomes) further demonstrated augmented uptake in RAW264.7 cells compared to C6-UA-Lips (Coumarin-6-dye-loaded ursolic acid bearing liposomes), which probably followed the receptor-mediated endocytosis pathway through extracellular CD44 receptors, enhancing site-specific accumulation. HA-UA-Lips showed significantly improved pharmacokinetics over UA, with 2.6, 4.27, 4.75, and 2.85 fold increases in t1/2 (P < 0.01), AUC0-∞ (P < 0.0001), AUC0-t (P < 0.0001), and MRT (P < 0.05), respectively, compared to UA. In conclusion, HA-UA-Lips are a novel vesicular drug delivery cargo that should be further tested in a validated preclinical model of VL under stringent in vitro and in vivo parameters for translational research.