Usnic acid-loaded nanocapsules: an evaluation of cytotoxicity

The aim of the present study is the design of nanocapsules containing usnic acid (UA-NC) and the evaluation of their physicochemical properties, in vitro kinetic profile and cytotoxic effect on human lung carcinoma cells. The usnic acid was encapsulated into nanocapsules prepared with a copolymer of lactic and glycolic acid using an interfacial deposition of a preformed polymer on oil-in-water emulsion. The cytotoxicity of nanocapsules was evaluated by the MTT method. UA-NC were obtained with a mean diameter of 324 ± 88 nm. An encapsulation ratio of 99.4 ± 0.16% was attained at an usnic acid concentration of 1 mg/ml. An usnic acid release of 78.3% from nanocapsules within 48 h was achieved. Concentrations required to inhibit 50% of cell growth were 10.0 and 11.5 μg/ml for free and encapsulated usnic acid, respectively. In conclusion, usnic acid was, for the first time, efficiently encapsulated into PLGA nanocapsules, providing a suitable dosage form for introducing usnic acid in in vivo studies, the use of which has been limited by its poor solubility and toxic properties.