One-Step Preparation of Luteolin Nanoemulsion and Evaluation of its Anti-inflammatory Effect in Animal Models

Background: Nanoemulsions are promising drug delivery systems for topical application owing to the high transdermal penetration. Objective: Due to the side effects of existing anti-inflammatory drugs, much attention has been paid to natural products such as flavonoids. The aim of this work was to formulate luteolin nanoemulsion (LNE) and to evaluate its anti-inflammatory effect. Methods: LNE was prepared using the low-energy spontaneous emulsion method and characterized by transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy and dynamic light scattering (DLS). The anti-inflammatory effect of LNE was assessed in formalin and acetic acid-induced inflammation methods (Whittle test). Treatment with LNE (i.p, 4 consecutive days, 40 mg/kg) was compared with diclofenac 25 mg/kg and normal saline. In the formalin test, data were recorded at 1, 2 and 4 hours after formalin injection and in the Wittle test, the extent of Evans blue leakage in the peritoneal cavity was considered as vascular permeability. Results: Formalin-induced edema decreased in the LNE group, but this reduction was not significant (p > 0.05), however, in Whittle test, both LNE and diclofenac significantly reduced Evans blue leakage compared with the group treated with acetic acid alone (p < 0.05). Conclusion: Our results confirm the anti-inflammatory effect of LNE and give up a new platform for the design and development of bio-based carriers for more successful drug delivery.