Poly-ε-Caprolactone Microsphere Polymers Containing Usnic Acid: Acute Toxicity and Anti-Inflammatory Activity

Abstract EN

Usnic acid (UA) has been studied by its pharmacological properties; however, it presents moderate toxicity, low solubility, and absorption by biological membranes.

The aim of this study was to develop poly-ε-caprolactone microsphere polymers containing UA (UA-micro) and evaluate their acute toxicity and anti-inflammatory activity.

The microspheres were prepared by multiple emulsion technique (water/oil/water) and characterized by the encapsulation efficiency, particle size, polydispersity index, and zeta potential.

The acute toxicity of UA and UA-micro (25–50 mg/kg; p.o.) was evaluated in mice.

The anti-inflammatory activity of UA and UA-micro was evaluated by subcutaneous air pouch and carrageenan-induced paw edema in rat, with measurement of inflammatory cytokines and MPO levels.

The UA presented encapsulation efficiency of 97.72%, particle size of 13.54 micrometers, polydispersity index of 2.36, and zeta potential of 44.5 ± 2.95 mV.

The UA-micro presented lower acute toxicity (LD50 value up to 2000 mg/kg; p.o.) when compared to UA.

UA-micro and UA (25 mg/kg) significantly reduced paw volume and decreased MPO levels, whereas only UA-micro (50 mg/kg) reduced significantly IL-1β, TNF-α, and NO levels in inflammatory exudate.

These results suggest that controlled release systems, as microspheres, can be a promising alternative to reduce the toxicity of UA, making it a viable compound for inflammation therapy.