Gelled Liquid Crystal Nanocarriers for Improved Antioxidant Activity of Resveratrol

As many natural origin antioxidants, resveratrol is characterized by non-suitable physicochemical properties for its topical application. To allow its benefits to manifest on human skin, resveratrol has been entrapped within liquid crystal nanocarriers (LCNs) made up of glyceryl monooleate, a penetration enhancer, and DSPE-PEG 750. The nanosystems have been more deeply characterized by using dynamic light scattering and Turbiscan Lab® Expert optical analyzer, and they have been tested in vitro on NCTC 2544. The improved antioxidant activity of entrapped resveratrol was evaluated on keratinocyte cells as a function of its concentration. Finally, to really propose the resveratrol-loaded LCNs for topical use, the systems were gelled by using two different gelling agents, poloxamer P407 and carboxymethyl cellulose, to improve the contact time between skin and formulation. The rheological features of obtained gels were evaluated using two important methods (microrheology at rest and dynamic rheology), before testing their safety profile on human healthy volunteers. The obtained results showed the ability of LCNs to improve antioxidant activity of RSV and the gelled LCNs showed good rheological profiles. In conclusion, the results confirmed the potentiality of gelled resveratrol-loaded nanosystems for skin disease, mainly related to their antioxidant effects.

Perspective use of bio-adhesive liquid crystals as ophthalmic drug delivery systems

The success of many drugs in ophthalmic treatments is hindered by their physico-chemical properties and the limited precorneal retention time. Here, lyotropic liquid crystals are proposed as a new ophthalmic drug delivery system. Acyclovir was chosen as model drug for its solubility and its controlled release from cubic phase was achieved. We demonstrated the effortless application of lamellar phase on corneal surface and its ability to convert itself in cubic phase in situ. While the complex viscosity of lamellar phase was affected by temperature (5.1 ± 1.4 kPa·s at 25 °C and 0.12 ± 0.001 Pa·s at 35 °C, respectively), the cubic phase shown no changes in viscosity values and shear thinning behaviour at both temperatures and even in presence of the drug The degradation kinetic of drug-loaded cubic phase was slightly slower than the empty formulation, recording 27.92 ± 1.43% and 33.30 ± 3.11% of weight loss after 8 h. Ex vivo studies conducted on porcine eyeballs and isolated cornea confirmed the instantaneous transition to cubic phase, its ability to resist to gravity force, and forced dripping of simulated tear fluid. Histopathological investigation showed how treated cornea did not report changes in epithelial and stroma structures. In summary, lyotropic liquid crystals could represent an advantageous ophthalmic drug delivery system.

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.

A comparison between silicone free and silicone-based emulsions: technological features and in vivo evaluation

Objective

Nowadays, the use of silicones in cosmetic formulation is still controversial, given that “natural” or “biodegradable” components are preferred. Often, the exclusion and/or the discrimination of these excipients from cosmetic field are unmotivated because all things cannot be painted with the same brush. Hence, we want to bring to light and underline the advantages of including silicones in cosmetic emulsions, refuting and debunking some myths related to their use.

Methods

Silicone‐free and silicone‐based emulsions were obtained within an easy homogenization process. Droplet size distribution was assessed by laser diffraction particle size analyser Mastersizer 2000™, and by optical microscopy. The long‐time stability profiles were investigated thanks to the optical analyser Turbiscan® Lab Expert. Diffusing wave spectroscopy (DWS) by Rheolaser Master™ and frequency sweep measurements by Kinexus® Pro Rotational Rheometer were carried out to assess a full rheological characterization. In vivo studies were carried out by the evaluation of Trans Epidermal Water Loss (TEWL) over time on healthy human volunteers. A skin feeling rating was collected from the same volunteers by questionnaire.

Results

From size distribution analysis, a better coherence of data appeared for silicone‐based emulsion, as the size of the droplets was kept unchanged after 1 month, as well as the uniformity parameter. Morphological investigation confirmed a homogenous droplet distribution for both samples. Silicones enhanced the viscosity, compactness and strength of the cream, providing a suitable stability profile both at room temperature and when heated at 40°C. The solid‐like viscoelastic behaviour was assessed in the presence of dynamic oscillatory stresses. The monitoring of TEWL over time demonstrated non‐occlusive properties of emulsions containing silicones, the values of which were comparable to the negative control. Silicone‐based emulsions gained higher scores from the volunteers in silkiness, freshness and softness features, while lower scores were obtained in greasiness compared to silicone‐free emulsions. No cases of irritation were recorded by the candidates.

Conclusion

The presence of specific silicones inside a cosmetic product improved its technological characteristics. The rheological identity and the stability feature showed the real suitability of prepared emulsion as a cosmetic product. Moreover, this study demonstrated that silicone‐based emulsions are safe for the skin and did not cause skin occlusion. Improved skin sensations are registered by potential consumers when silicones are included in the formulation.

Ammonium Glycyrrhizinate and Bergamot Essential Oil Co-Loaded Ultradeformable Nanocarriers: An Effective Natural Nanomedicine for In Vivo Anti-Inflammatory Topical Therapies

Bergamot essential oil (BEO) and Ammonium glycyrrhizinate (AG), naturally derived compounds, have remarkable anti-inflammatory properties, thus making them suitable candidates for the treatment of skin disorders. Despite this, their inadequate physicochemical properties strongly compromise their topical application. Ultradeformable nanocarriers containing both BEO and AG were used to allow their passage through the skin, thus maximizing their therapeutic activity. Physicochemical characterization studies were performed using Zetasizer Nano ZS and Turbiscan Lab^®. The dialysis method was used to investigate the release profile of the active compounds. In vivo studies were performed on human healthy volunteers through the X-Rite spectrophotometer. The nanosystems showed suitable features for topical cutaneous administration in terms of mean size, surface charge, size distribution, and long-term stability/storability. The co-delivery of BEO and AG in the deformable systems improved both the release profile kinetic of ammonium glycyrrhizinate and deformability properties of the resulting nanosystems. The topical cutaneous administration on human volunteers confirmed the efficacy of the nanosystems. In detail, BEO and AG-co-loaded ultradeformable vesicles showed a superior activity compared to that recorded from the ones containing AG as a single agent. These results are promising and strongly encourage a potential topical application of AG/BEO co-loaded nanocarriers for anti-inflammatory therapies.