Curcumin-loaded low-energy nanoemulsions as a prototype of multifunctional vehicles for different administration routes: Physicochemical and in vitro peculiarities important for dermal application

Abstract

The objective of this work was to investigate and profoundly characterize low-energy nanoemulsions as multifunctional carriers, with slight reference to dermal administration. An evidence-based approach was offered for deepening the knowledge on their formation via spontaneous emulsification. Curcumin, a compound of natural origin, potentially powerful therapeutic, was chosen as a model API. Due to curcumin's demanding properties (instability, poor solubility, low permeability), its potentials remain unreached. Low-energy nanoemulsions were considered carriers capable of overcoming imposed obstacles. Formulation consisting of Polysorbate 80 and soybean lecithin as stabilizers (9:1, 10%), medium-chain triglycerides as the oil phase (10%) and ultrapure water was selected for curcumin incorporation in 3 different concentrations (1, 2 and 3 mg/mL). Physicochemical stability was demonstrated during 3 months of monitoring (mean droplet size: 111.3-146.8 nm; PDI < 0.2; pH: 4.73-5.73). Curcumin's release from developed vehicles followed Higuchi's kinetics. DPPH (IC50 = 0.1187 mg/mL) and FRAP (1.19 ± 0.02 mmol/g) assays confirmed that curcumin acts as a potent antioxidant through different mechanisms, with no alterations after incorporation in the formulation. High biocompatibility in line with antigenotoxic activity of curcumin-loaded formulations (protective and reparative) was estimated through Comet assay. A multidisciplinary approach is needed to fully characterize developed systems, directing them to more concrete application possibilities.

Low-energy nanoemulsions as carriers for red raspberry seed oil: Formulation approach based on Raman spectroscopy and textural analysis, physicochemical properties, stability and in vitro antioxidant/ biological activity

“…F2, and F3) indicating that the water became the outer phase, which can be ascribed to the formation of liquid O/W LE-NE. With further increase of the water phase content (from 65 to 80 wt%), the electrical conductivity values decreased, which is a known phenomenon that can be explained by the dilution of the system [41].…”

“…Microscopical investigations-Optical (polarized) light microscopy, atomic force microscopy. Microscopical investigations, as direct techniques complementary to indirect DLS/LD measurements [17,41] were employed during the PTPD study revealing that…”

“…The micrographs presented in Fig 4 showed no visible signs of large aggregates in the LE-NEs after 7 and 45 days of storage at room temperature, which was in accordance with the narrow particle size distribution bellow 150 nm obtained via DLS and LD measurements (Table 4). AFM is known as a useful technique in the evaluation of the nanoemulsion internal structure [41] in the submicron range. As it can be seen from Fig 5, the RO2-loaded LE-NE (F1) consisted of "oval-shaped" nano-droplets, and the size range of these droplets was generally in line with DLS/LD findings.…”

“…discoloration of the blue-green ABTS + radical solution [7]. In the DPPH assay, methanol was used to dissolve tested nanoemulsions, assuming that the oil phase was extracted from the nano-droplets [25,41], and the discoloration of the purple DPPH radical solution is proportional to the antioxidant activity of the samples [25,41,48]. Table 6 presents the results of the screening study of the antioxidant activity of the raw materials and nanoemulsions F1 -F4 (composition list presented in Table 2) depending on the sample concentration.…”

Nano- and Microcarriers as Drug Delivery Systems for Usnic Acid: Review of Literature

“…Thereby, oil-in-water nanoemulsions are more commonly used as drug carriers, aiming to encapsulate lipophilic drugs in aqueous environment. In recent years, a growing interest in nanoemulsions research could be observed, owing to their potential for their high solubilization capacity for hydrophobic activities, protection of unstable compounds and enhanced delivery and tissue-penetrating properties associated with good stability and relative easiness of preparation [9,10].…”