Baicalein-Loaded Aspasomal Formulations: Development, Characterization and Evaluation of Antioxidant and Anti-Inflammatory Effects

Abstract

Background

Aspasomes are bilayer vesicular systems developed with ascorbyl palmitate (AP), the ester form of ascorbic acid. Baicalein is a flavonoid structure, a powerful antioxidant, can neutralize free radicals, helps protect cells from oxidative damage, has an anti-inflammatory effect by suppressing the release of inflammatory mediators and relieves related symptoms, but its poor solubility and stability play a critical role in limiting its activity.

Purpose

To relieve the above-mentioned problems and to increase the effectiveness of baicalein, we prepared aspasomal formulations.

Methods

We produced five different baicalein-loaded aspasomal formulations prepared with different components and characterized in terms of particle size (PS), polydispersity index (PDI), zeta potential (ZP), scanning electron microscopy (SEM), drug encapsulation efficiency (EE%) and drug release. The best formulation was selected and used to prepare the aspasomal gel by using Carbopol 980 as a gelling agent at a ratio of 1:1 (v/v). The cytotoxicity of the aspasomes and different baicalein solutions on the RAW 264.7 cell line by using 3-(4,5-dimethyldiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) test. In the stability studies, changes in characterization parameters and baicalein content in two different conditions over 3 months were monitored. The cell permeation study was performed using RAW 264.7 murine macrophages cell with aspasomes in suspension and gel form and the amounts of penetrated baicalein were measured. At the end of the permeation study, the antioxidant and anti-inflammatory effect were determined. Within the scope of antioxidant activity studies, 1,1-diphenyl-2-picrylhydrazyl (DPPH●) and 2,2’-azino-bis (3-ethylbenzathiazoline-6-sulfonic acid) (ABTS+●) radical scavenging effects were determined. Nitric oxide (NO), tumor necrosis factor-alpha (TNF-α) and prostaglandin 2 (PGE2) levels released into the intracellular and nutrient medium were determined in the anti-inflammatory effect determination.

Results

Based on results, the selected optimum aspasomal formulation (F2 coded) showed PS of 425 ± 1.00 nm, ZP of -38.1 ± 1.31, PDI of 0.207 ± 0.015, EE of 40 ± 1.02% and drug release of 85 ± 0.95%. The baicalein content of aspasomes were physically stable, and it was not observed decrease significantly during 3 months of storage at 4ºC. The gel formulation stored at 4 °C showed better physicochemical properties compared to 25 °C ± 65% relative humidity and did not show a significant change at the end of 3 months. Although the pH of aspasomal gel decreased slightly over time and with increasing temperature, it was still in the appropriate range for skin pH. The cell permeation assay results showed effective baicalein permeation rate. The antioxidant and anti-inflammatory effects obtained were significant, although low, compared to the positive control indomethacin.

Conclusion

Baicalein encapsulated in aspasomal formulations may be a promising strategy with increased stability, solubility and potentially demonstrating long-term antioxidant and anti-inflammatory effects.