Topical Unsaturated Fatty Acid Vesicles Improve Antioxidant Activity of Ammonium Glycyrrhizinate

Design of thermo-responsive self-assembly of PEGylated fatty acids: Switching reversibly from tubes or vesicles to micelles at physiological temperature

HYPOTHESIS

The mixing of end-capped poly(ethylene glycol) (PEG) chains with 12-hydroxy stearic acid (12-HSA) molecules is a simple one-pot strategy to design thermo-responsive PEGylated self-assemblies of fatty acids with various morphology types at room temperature (multi-lamellar tubes or vesicles) that transit reversibly upon heating into small micelles around physiological temperature.

EXPERIMENTAL

4 types of 4k end-capped poly(ethylene glycol) (PEG) chains, capped respectively at one end or at both ends with either 12-HSA or stearic acid (SA), were mixed with 12-hydroxy stearic acid molecules, at a low constant ratio of end capped fatty acid moieties brought by the chains to that of free 12-HSA molecules. The detailed structure of the self-assemblies of mixtures was obtained using Small Angle Neutron Scattering with contrast variation at both 20 °C and 45 °C, and their temperature-dependent rheological behavior was characterized.

FINDINGS

For both types of mono-functionalized PEG, the chains insert homogenously in the multi-lamellar tubes formed by 12-HSA molecules. The mixtures of di-functionalized chains by 12-HSA with 12-HSA molecules produce PEGylated vesicles, since the change of packing parameter induced by insertion of the telechelic chains no longer allows the formation of tubes. Conversely, mixtures of di-functionalized chains by SA with 12-HSA molecules enable to keep multi-lamellar tubes, a specific behavior that likely comes from the fact that they only insert by one end within the 12-HSA bilayers. All systems transit reversibly into small PEGylated ellipsoidal micelles. The morphological transitions enable to tune the rheological properties of suspensions, that are gelled at low temperature and turn Newtonian liquid at around 37 °C.

Naringenin-Loaded Solid Lipid Nanoparticles: Physical-Chemical Characterization and In Vitro Antibacterial Activity

Currently, problems related to antibiotic resistance are shifting the focus of pharmaceutical research towards natural molecules with antibacterial properties. Among them, flavonoids represent promising molecules with strong antibacterial features; however, they have poor biopharmaceutical properties. In this study, we developed solid lipid nanoparticles (SLNs) loaded with the flavanone naringenin (NRG) to offer an option for treating bacterial infections. NRG-SLNs systems were prepared by a solvent emulsification/diffusion and ultrasonication method, using Compritol® 888 ATO (COM) as the lipid. The optimal formulation was obtained using a 10% (w/w) theoretical amount of NRG (NRG10-SLNs), exhibiting homogeneous sizes (approximately 50 nm and 0.15 polydispersity index), negative zeta potential (-30 mV), and excellent encapsulation parameters (an encapsulation efficiency percentage of 97.9% and a drug content of 4%). NRG10-SLNs presented good physical stability over 4 weeks. A cumulative drug release of 55% in 24 h and the prolonged release of the remaining amount over 10 days was observed. In addition, µ-Raman spectroscopy, differential scanning calorimetry, thermogravimetric analysis, and X-ray diffraction measurements were carried out to characterize the drug-lipid interactions. Finally, the in vitro antibacterial and antibiofilm activities of NRG10-SLNs were assayed and compared to free NRG. NRG10-SLNs were bacteriostatic against Staphylococcus aureus, including the methicillin-resistant S. aureus (MRSA) and Escherichia coli strains. An improvement in the antibacterial activity of NRG-loaded SLNs compared to the free molecule was observed against S. aureus strains, probably due to the interaction of the surfactant-coated SLNs with the bacterial surface. A similar trend was observed for the biofilm inhibition.

Lipid Nanovesicles for Antioxidant Delivery in Skin: Liposomes, Ufasomes, Ethosomes, and Niosomes

The skin, being the largest organ of the human body, serves as the primary barrier against external insults, including UV radiation, pollutants, and microbial pathogens. However, prolonged exposure to these environmental stressors can lead to the generation of reactive oxygen species (ROS), causing oxidative stress, inflammation, and ultimately, skin aging and diseases. Antioxidants play a crucial role in neutralizing ROS and preserving skin health by preventing oxidative damage. In recent years, nanotechnology has emerged as a powerful tool for enhancing the delivery of antioxidants onto the skin. In particular, liposomal formulations have offered unique advantages such as improved stability, controlled release, and enhanced penetration through the skin barrier. This has led to a surge in research focused on developing liposomal-based antioxidant delivery systems tailored for skin health applications. Through a comprehensive analysis of the literature from the 2019-2024 period, this review provides an overview of emerging trends in the use of liposomal delivery systems developed for antioxidants aimed at improving skin health. It explores the latest advancements in liposomal formulation strategies, vesicle characterization, and their applications in delivering antioxidants to combat oxidative stress-induced skin damage and other associated skin pathologies. A comparison of various delivery systems is conducted for the most common antioxidants. Finally, a brief analysis of lipid nanovesicles used in the cosmeceutical industry is provided.

Design of oleic acid/alkyl glycoside composite vesicles as cosmetics carrier: stability, skin permeability and antioxidant activity

Biocompatible fatty acids are natural biological materials which exhibit widespread biomedical applications. Nevertheless, their application in vesicle forms is hampered by strong pH sensitivity and poor stability to changes in ionic strength, temperature, and storage. In the investigation, the incorporation of alkyl glycoside (APG), a surfactant with non-ionic properties, into the oleic acid (OA) vesicles was undertaken as a means to address this issue. The newly formed OA/APG composite vesicles form in a pH range of between 5.4 and 7.4, which is close to the pH range of the physiological environment. The stability studies results showed that the OA/APG composite vesicles have excellent stability in terms of ionic strengths, temperature and storage. The formation of NAR-loaded OA/APG composite vesicles was demonstrated through FT-IR, DSC and XRD. In vitro topical delivery and skin retention studies confirmed that the composite vesicles improve skin permeation rate and have better skin permeation behavior. Antioxidant activity experiments confirmed that the antioxidant effect composite vesicles were significantly increased as compared to the naringenin (NAR). This finding has theoretical implications for the use of drug-loaded fatty acid vesicles in cosmetics industries and topical delivery systems.

Hypothesizing the Oleic Acid-Mediated Enhanced and Sustained Transdermal Codelivery of Pregabalin and Diclofenac Adhesive Nanogel: A Proof of Concept

Pregabalin (PG) and diclofenac diethylamine (DEE) are anti-inflammatory molecules that are effective in relieving inflammation and pain associated with musculoskeletal disorders, arthritis, and post-traumatic pain, among others. Intravenous and oral delivery of these two molecules has their limitations. However, the transdermal route is believed to be an alternate viable option for the delivery of therapeutic molecules with desired physicochemical properties. To this end, it is vital to understand the physicochemical properties of these drugs, dosage, and strategies to enhance permeation, thereby surmounting the associated constraints and concurrently attaining a sustained release of these therapeutic molecules when administered in combination. The present work hypothesizes the enhanced permeation and sustained release of pregabalin and diclofenac diethylamine across the skin, entrapped in the adhesive nano-organogel formulation, including permeation enhancers. The solubility studies of pregabalin and diclofenac diethylamine in combination were performed in different permeation enhancers. Oleic acid was optimized as the best permeation enhancer based on in vitro studies. Pluronic organogel containing pregabalin and diclofenac diethylamine with oleic acid was fabricated. Duro-Tak® (87-2196) was added to the organogel formulation as a pressure-sensitive adhesive to sustain the release profile of these two therapeutic molecules. The adhesive organogel was characterized for particle size, scanning electron microscopy, and contact angle measurement. The HPLC method developed for the quantification of the dual drug showed a retention time of 3.84 minutes and 9.69 minutes for pregabalin and diclofenac, respectively. The fabricated nanogel adhesive formulation showed the desired results with particle size and contact angle of 282 ± 57 nm and ≥120⁰, respectively. In vitro studies showed the percentage cumulative release of 24.90 ± 4.65% and 33.29 ± 4.81% for pregabalin and diclofenac, respectively. In order to accomplish transdermal permeation, the suggested hypothesis of fabricating PG and DEE nano-organogel in combination with permeation enhancers will be a viable drug delivery method. In comparison to a traditional gel formulation, oleic acid as a permeation enhancer increased the penetration of both PG and DEE from the organogel formulation. Notably, the studies showed that the use of pressure-sensitive adhesives enabled the sustained release of both PG and DEE.Therefore, the results anticipated the hypothesis that the transdermal delivery of adhesive PG and DEEbased nanogel across the human skin can be achieved to inhibit inflammation and pain.

Self-Assembly of Palmitic Acid in the Presence of Choline Hydroxide

To disperse fatty acids in aqueous solution, choline, a quaternary ammonium ion, has been used recently. So far, only the self-assembly of myristic acid (MA) in the presence of choline hydroxide as a function of the molar ratio has been investigated, and, thus, the current understanding of these fatty acid systems is still limited. We investigated the self-assembly of palmitic acid (PA) in the presence of choline hydroxide (ChOH) as a function of the molar ratio (R) between ChOH and PA. The self-assemblies were characterized by phase contrast microscopy, cryo-TEM, small-angle X-ray scattering, and 2H NMR. The ionization state of PA was determined by pH, conductivity, and FT-IR measurements. With increase in R, various self-assembled structures, including vesicles, lamellar phase, rigid membranes (large sheets, tubules, cones, and polyhedrals), and micelles, form in the PA/ChOH system, different from those of the MA/ChOH system. The change in R induces pH variation and, consequently, a change in the PA ionization state, which, in turn, regulates the molecular interactions, including hydrogen bonding and electrostatic interaction, leading to various self-assemblies. Temperature is an important factor used to tune the self-assembly transitions. The fatty acid choline systems studied here potentially may be applicable in medicine, chemical engineering, and biotechnology.

Characterization and In Vivo Antiangiogenic Activity Evaluation of Morin-Based Cyclodextrin Inclusion Complexes

Morin (MRN) is a natural compound with antiangiogenic, antioxidant, anti-inflammatory, and anticancer activity. However, it shows a very low water solubility (28 μg/mL) that reduces its oral absorption, making bioavailability low and unpredictable. To improve MRN solubility and positively affect its biological activity, particularly its antiangiogenic activity, in this work, we prepared the inclusion complexes of MNR with sulfobutylether-β-cyclodextrin (SBE-β-CD) and hydroxypropyl-β-cyclodextrin (HP-β-CD). The inclusion complexes obtained by the freeze-drying method were extensively characterized in solution (phase-solubility studies, UV-Vis titration, and NMR spectroscopy) and in the solid state (TGA, DSC, and WAXD analysis). The complexation significantly increased the water solubility by about 100 times for MRN/HP-β-CD and 115 times for MRN/SBE-β-CD. Furthermore, quantitative dissolution of the complexes was observed within 60 min, whilst 1% of the free drug dissolved in the same experimental time. 1H NMR and UV-Vis titration studies demonstrated both CDs well include the benzoyl moiety of the drug. Additionally, SBE-β-CD could interact with the cinnamoyl moiety of MRN too. The complexes are stable in solution, showing a high value of association constant, that is, 3380 M-1 for MRN/HP-β-CD and 2870 M-1 for MRN/SBE-β-CD. In vivo biological studies on chick embryo chorioallantoic membrane (CAM) and zebrafish embryo models demonstrated the high biocompatibility of the inclusion complexes and the effective increase in antiangiogenic activity of complexed MRN with respect to the free drug.

Solid Lipid Nanoparticles Containing Morin: Preparation, Characterization, and Ex Vivo Permeation Studies

In recent years, bioactive compounds have been the focus of much interest in scientific research, due to their low toxicity and extraordinary properties. However, they possess poor solubility, low chemical stability, and unsustainable bioavailability. New drug delivery systems, and among them solid lipid nanoparticles (SLNs), could minimize these drawbacks. In this work, morin (MRN)-loaded SLNs (MRN-SLNs) were prepared using a solvent emulsification/diffusion method, using two different lipids, Compritol^® 888 ATO (COM) or Phospholipon^® 80H (PHO). SLNs were investigated for their physical-chemical, morphological, and technological (encapsulation parameters and in vitro release) properties. We obtained spherical and non-aggregated nanoparticles with hydrodynamic radii ranging from 60 to 70 nm and negative zeta potentials (about -30 mV and -22 mV for MRN-SLNs-COM and MRN-SLNs-PHO, respectively). The interaction of MRN with the lipids was demonstrated via μ-Raman spectroscopy, X-ray diffraction, and DSC analysis. High encapsulation efficiency was obtained for all formulations (about 99%, w/w), particularly for the SLNs prepared starting from a 10% (w/w) theoretical MRN amount. In vitro release studies showed that about 60% of MRN was released within 24 h and there was a subsequent sustained release within 10 days. Finally, ex vivo permeation studies with excised bovine nasal mucosa demonstrated the ability of SLNs to act as a penetration enhancer for MRN due to the intimate contact and interaction of the carrier with the mucosa.

Unraveling the pharmaceutical and clinical relevance of the influence of syringic acid loaded linoleic acid transferosomes on acne

Natural medicines are promising platforms for competent topical treatment modalities benefiting the cosmetic implementation and proffering solutions to the current remedies. Therefore, the objective of this study was to formulate syringic acid (SA), well-known for its multilateral anti-inflammatory, antimicrobial and antioxidant potentials, in newly developed linoleic acid (LA) transferosomes as an anti-acne nano-form remedy. Herein, LA was incorporated in transferosomes owing to its antimicrobial effect and dermal penetrability. Comprehensive appraisal through physicochemical, antioxidant and dermal deposition investigations was conducted. Clinical assessment was also performed in acne patients and compared with the marketed product (Adapalene® gel). The relevant investigations of the optimum formula indicated stable vesicles with a small-sized diameter (147.46 nm), surface charge (-26.86 mV), spherical architecture, reasonable entrapment (76.63%), considerable antioxidant activity (IC50 = 11.1 µg/mL) and remarkable skin deposition (78.72%).More importantly, LA based transferosomes enclosing SA exhibited inflammation lessening in acne sufferers as manifested by greater reduction in the total count of the acne lesions reaching 79.5% in contrast to Adapalene® gel with only 18.7% reduction in acne lesions. Interestingly, no irritation and erythema were reported for the proposed transferosomes. Inclusively, the cosmetic formulation practice could reap benefits of the development of such vesicles.

Efficient Co-production of Docosahexaenoic Acid Oil and Carotenoids in Aurantiochytrium sp. Using a Light Intensity Gradient Strategy

Aurantiochytrium is a promising source of docosahexaenoic acid (DHA) and carotenoids, but their synthesis is influenced by environmental stress factors. In this study, the effect of different light intensities on the fermentation of DHA oil and carotenoids using Aurantiochytrium sp. TZ209 was investigated. The results showed that dark culture and low light intensity conditions did not affect the normal growth of cells, but were not conducive to the accumulation of carotenoids. High light intensity promoted the synthesis of DHA and carotenoids, but caused cell damage, resulting in a decrease of oil yield. To solve this issue, a light intensity gradient strategy was developed, which markedly improved the DHA and carotenoid content without reducing the oil yield. This strategy produced 30.16 g/L of microalgal oil with 15.11 g/L DHA, 221 µg/g astaxanthin, and 386 µg/g β-carotene. This work demonstrates that strain TZ209 is a promising DHA producer and provides an efficient strategy for the co-production of DHA oil together with carotenoids.

Oleic acid-based vesicular nanocarriers for topical delivery of the natural drug thymoquinone: Improvement of anti-inflammatory activity

The topical administration of a drug compound remains the first choice for the treatment of many local skin ailments. Many skin diseases can be treated by applying the active formulation directly to the skin, but unfortunately some drugs are unable to overcome the stratum corneum and exert their pharmacological action. An example is thymoquinone, a naturally derived drug obtained from Nigella sativa L. and potentially effective in the treatment of inflammatory and oxidative skin conditions. Since its physico-chemical properties are not suitable for overcoming the stratum corneum, we wanted to circumvent the problem by proposing new lipid-based nanovesicles called "oleoethosomes", made up of naturally derived ingredients, for its delivery. Among several formulations of oleoethosomes, the sample made up of 2% (w/w) oleic acid:PL90G 1:1 (molar ratio), and ethanol 15% showed the best physico-chemical characteristics and above all it showed the capacity to contain a suitable amount of thymoquinone (2 mg/ml). The formulation was tested in vitro on stratum corneum and viable epidermis membranes confirming its ability to induce the passage of thymoquinone through the human stratum corneum and to act as a permeation enhancer. In fact, it showed thymoquinone permeation values of 22.63 ± 1.49% regarding the applied drug amount. Oleoethosomes were compared with oleosomes, another kind of naturally derived nanosystems but free of ethanol. The experimental data confirmed that ethanol was an important component that enhanced the activity of the oleoethosomes when tested on the skin of healthy volunteers. The thymoquinone-loaded oleoethosome treatment demonstrated a significantly greater extent of anti-inflammatory activity than the treatment with thymoquinone-loaded oleosomes or the conventional dosage form of the drug. These in vivo results confirmed the synergic effect between oleic acid and ethanol on the lipid and protein compartments of the outermost skin layer, thus promoting a greater penetration capacity.

Vesicular Nanocarriers for Phytocompounds in Wound Care: Preparation and Characterization

The need to develop wound healing preparations is a pressing challenge given the limitations of the current treatment and the rising prevalence of impaired healing wounds. Although herbal extracts have been used for many years to treat skin disorders, due to their wound healing, anti-inflammatory, antimicrobial, and antioxidant effects, their efficacy can be questionable because of their poor bioavailability and stability issues. Nanotechnology offers an opportunity to revolutionize wound healing therapies by including herbal compounds in nanosystems. Particularly, vesicular nanosystems exhibit beneficial properties, such as biocompatibility, targeted and sustained delivery capacity, and increased phytocompounds’ bioavailability and protection, conferring them a great potential for future applications in wound care. This review summarizes the beneficial effects of phytocompounds in wound healing and emphasizes the advantages of their entrapment in vesicular nanosystems. Different types of lipid nanocarriers are presented (liposomes, niosomes, transferosomes, ethosomes, cubosomes, and their derivates’ systems), highlighting their applications as carriers for phytocompounds in wound care, with the presentation of the state-of-art in this field. The methods of preparation, characterization, and evaluation are also described, underlining the properties that ensure good in vitro and in vivo performance. Finally, future directions of topical systems in which vesicle-bearing herbal extracts or phytocompounds can be incorporated are pointed out, as their development is emerging as a promising strategy.