Evaluation of Emulsification Techniques to Optimize the Properties of Chalcone Nanoemulsions for Antifungal Applications

Abstract

Background/Objectives: Nanoemulsions (NEs) possess properties that enhance the solubility, bioavailability and therapeutic efficacy of drugs. Chalcones are compounds known for their antifungal properties. In this study, we evaluated different emulsification techniques to create alginate nanoemulsions containing chalcone (1E,4E)-1,5-bis (4-methoxyphenyl) penta-1,4-dien-3-one (DB4OCH₃). Our goal was to develop an antifungal formulation targeting Candida albicans strains. Methods: Ultrasound and ultrasound combined with high-speed homogenization techniques were used to prepare alginate-stabilized nanoemulsions. Particle size, zeta potential and encapsulation efficiency were evaluated. Additionally, in vitro release studies were conducted. Results: The combined emulsification technique produced stable nanoparticles with high encapsulation efficiency and antifungal activity, with a minimum inhibitory concentration of 8.75 μg/mL for the nanoemulsions compared to 312 µg/mL for free DB4OCH₃. NEs' effectiveness can be attributed to their ability to form nanodroplets efficiently, facilitating the solubilization of the chalcone in the oily phase. The particle size varied between 195.70 ± 2.69 and 243.40 ± 4.49 nm, with an increase in chalcone concentration leading to larger particle sizes. The zeta potential showed values from -91.77 ± 5.58 to -76.90 ± 4.44 mV. The UHS-7 sample exhibited an encapsulation efficiency of 92.10% ± 0.77, with a controlled in vitro release of 83% after 34 h. Molecular docking simulations showed that the aromatic nature of DB4OCH₃ resulted in the formation of apolar interactions with aromatic residues located in the active site of the TMK, as observed in their respective co-crystallized inhibitors, within an affinity energy range that enables optimum specificity of the ligand for these two pathways. Pharmacokinetic analyses indicated high passive cell permeability and low hepatic clearance, and phase I metabolism reduces its oral bioavailability and metabolic stability, suggesting a promising active ingredient as an oral drug with control of the daily oral dose administered. Conclusions: The combined nanoemulsification technique led to the formation of finely dispersed nanodroplets that favored the solubilization of the chalcone in the oil phase, which led to a better performance in the antifungal properties. DB4OCH₃ shows promise as an oral drug with controlled dosing.

Keywords: Candida albicans; drug delivery; homogenization; molecular docking; nanodroplets; nanotechnology.

Figure 1

Representation of the components used in NEs; (a) the sodium alginate used as a stabilizer; (b) Tween 80 (T80) used as surfactant; (c) soybean oil used as co-surfactant and (d) the chalcone DB4OCH₃, the synthetic compound with biological properties.

Figure 2

Creaming index (%) as a function of time (days) for samples produced by ultrasound and ultrastirrer (UHS-7 and UHS-12) and by ultrasound technique (U-7, U-12).

Figure 3

Micrographs of samples UHS-7, UHS-12, U-7 and U-12.

Figure 4

Scanning electron microscopy of samples UHS-7, UHS-12, U-7 and U-12.

Figure 5

In vitro controlled release profile of UHS-7 and free chalcone DB4OCH₃.

Figure 6

(A) Three-dimensional representation of the docking of the ligands DB4OCH₃ (purple), OXA (blue) and the co-crystallized inhibitor 32C at the inhibition site of the TMK enzyme, (B) three-dimensional representation of the ligand–receptor interactions and (C) 2D map of the structural contribution of DB4OCH₃ in the interactions with the residues of the TMK binding site.

Figure 7

(A) Three-dimensional representation of the docking of the ligands DB4OCH₃ (purple), OXA (blue) and the co-crystallized inhibitor CWW at the inhibition site of the DNA Gyrase B, (B) three-dimensional representation of the ligand–receptor interactions and (C) 2D map of the structural contribution of DB4OCH₃ in the interactions with the residues of the DNA Gyrase B binding site.

Figure 8

Molecular lipophilicity potential (MLP) map plotted to analyze the relationship between apparent lipophilicity (logP) and topological polar surface area (TPSA), where the color spectrum ranges from red (hydrophilic fragments) to blue (hydrophobic fragments).

Figure 9

(A) multiparameter optimization (MPO) radar for estimating the pharmacokinetic and pharmacodynamic viability of DB4OCH₃, (B) alignment between lipophilicity at physiological pH (logD7.4) and molecular weight (MW) for estimating the Papp, A → B and CLMicro profile and predicting (C) the percentage of human intestinal absorption (HIA) and (D) the coefficient of permeability at the blood–brain barrier (logBB).

Figure 10

(A) similarity test with compounds with optimized cell permeability and hepatic clearance properties deposited in the DrugBank^® database, (B) prediction of toxicity endpoints and analysis of the structural contributions of DB4OCH₃ to the model of (C) metabolism site and (D) hERG channel inhibition.