Liposomal Incorporation of Lavandin Essential Oil by a Thin-Film Hydration Method and by Particles from Gas-Saturated Solutions

Thymus essential oil extraction, characterization and incorporation in phospholipid vesicles for the antioxidant/antibacterial treatment of oral cavity diseases

The aim of the work was to extract, characterize, and formulate Thymus capitatus (Tymbra capitata) essential oil in phospholipid vesicles: liposomes, glycerosomes and Penetration Enhancer-containing Vesicles (PEVs). The steam-distilled essential oil was mainly composed of carvacrol. The oil was mixed with lecithin and water to produce liposomes, or different ratios of water/glycerol or water/propylene glycol (PG) to produce glycerosomes and PG-PEVs, respectively. Cryo-TEM showed the formation of unilamellar, spherical vesicles, and light scattering disclosed that their size increased in the presence of glycerol or PG, which improved long-term stability. The formulations were highly biocompatible, and capable of counteracting oxidative stress and favouring wound repair in keratinocytes, thanks to enhanced uptake. The antibacterial activity of the oil was demonstrated against cariogenic Streptococcus mutans, Lactobacillus acidophilus, and commensal Streptococcus sanguinis. The combination of antioxidant and antibacterial activities of Thymus essential oil formulations may be useful for the treatment of oral cavity diseases.

Nanocharacterization of liposomes for the encapsulation of water soluble compounds from Cordyceps sinensis CS1197 by a supercritical gas anti-solvent technique

Nano-liposomes were designed for the sustained release of water soluble compounds from C. sinensis CS1197 using a supercritical gas anti-solvent (SC-GAS) method at various pressures, temperatures and Tween 80 concentrations. The SC-GAS method was compared to the Bangham method of liposome production in terms of mean diameter, coefficient of uniformity (C_u), encapsulation efficiency, morphology, viscosity and actual energy required for liposome formation. Liposome production via the SC-GAS method under optimized formulation conditions, i.e., 180 bar; 50 °C; 0.75% Tween 80; and a depressurization rate of 25 bar min⁻¹, yielded nano-liposomes exhibiting the lowest C_u value (1.10 ± 0.012) with a mean diameter of 0.072 ± 0.002 μm and better encapsulation efficiencies of 75.48 ± 2.5, 74.9 ± 2.1 and 70.23 ± 2.9% for adenosine, cordycepin and polysaccharides, respectively. Nano-liposomes were characterized using FTIR, XRD, DSC and TGA techniques. The stability indices and viscosities of the prepared liposome suspensions indicated good stability of up to 2 months and near-Newtonian behavior. The in vitro release of CS1197 water soluble compounds exhibited biphasic and sustained release patterns.

Nano-liposomes were designed for the sustained release of water soluble compounds from C. sinensis CS1197 using a supercritical gas anti-solvent (SC-GAS) method at various pressures, temperatures and Tween 80 concentrations.

Antimicrobial activity of free and liposome-encapsulated thymol and carvacrol against Salmonella and Staphylococcus aureus adhered to stainless steel

Antimicrobial activity of thymol, carvacrol and thymol/carvacrol liposomes (TCL) was evaluated against two bacterial pools, each one consisting of four strains of Staphylococcus aureus or Salmonella enterica. TCL were prepared using thin-film hydration, showing 270.20nm average diameter (polydispersity index of 0.33) and zeta potential of +39.99mV. Minimum inhibitory concentration (MIC) of thymol, carvacrol and TCL against S. aureus pool was 0.662mg/ml, while MIC for Salmonella pool was 0.331mg/ml for thymol and carvacrol, and for TCL was 0.662mg/ml. Bacterial pools (8.0logCFU/ml), allowed in contact on stainless steel AISI 304 coupons in UHT skim milk for 15min, resulted in adhered populations of 5.6-6.1logCFU/cm². Adhered S. aureus (±6.1logCFU/cm²) were inhibited after 1-min and 10-min treatments using thymol or carvacrol at MIC and 2.0 MIC. Reductions of 1.47-1.76logCFU/cm² and 1.87-2.04logCFU/cm² were obtained using 0.5 MIC of thymol and carvacrol, respectively. A 10-min contact with free (MIC and 2.0 MIC) and encapsulated (MIC) antimicrobials inhibited attached Salmonella (±6.0logCFU/cm²); however, after 1-min of contact, 2.0 MIC of thymol and carvacrol were not able to inactivate adhered Salmonella MIC of TCL inactivated S. aureus and Salmonella after 10min; however, after 1-min contact, adhered S. aureus and Salmonella populations were decreased in 1.62logCFU/cm² and 2.01logCFU/cm², respectively. Considering antimicrobial concentrations and contact times, thymol, carvacrol, and TCL could be employed in food-contact surfaces to prevent biofilm formation at early stages of bacterial attachment. Further investigations should be performed considering long-term antibacterial effects of TCL.

Using different natural origin carriers for development of epigallocatechin gallate (EGCG) solid formulations with improved antioxidant activity by PGSS-drying

Epigallocatechin gallate (EGCG) is the catechin with the highest antioxidant activity present in green tea.

Development of tea tree oil-loaded liposomal formulation using response surface methodology

The aim of this study is to prepare tea tree oil liposome (TTOL) and optimize the preparation condition by single factor experiment and statistical design. TTOL was prepared using a thin-film hydration with the combination of sonication method and the preparation conditions of TTOL were optimized with response surface methodology (RSM). The optimal preparation conditions for TTOL by response surface methodology were as follows: the mass ratio of PC and Cho 5.51, TTO concentration 1.21% (v/v) and Tween 80 concentration 0.79% (v/v). The response surface analysis showed that the significant (p < 0.05) second-order polynomial regression equations successfully fitted for all dependent variables with no significant (p > 0.05) lack of fit for the reduced models. Furthermore, the interaction of the mass ratio of PC/Cho and TTO concentration had a significant effect. The amounts of Tween 80 required were also reduced with RSM. Under these conditions, the experimental encapsulation efficiency of TTOL was 97.81 ± 0.33%, which was close with the predicted value. Therefore, the optimized preparation condition was very reliable. The increased entrapment efficiency would significantly improve the TTO stability and bioavailability.

Essential oils encapsulated in liposomes: a review

In the recent years there has been an increased interest toward the biological activities of essential oils. However, essential oils are unstable and susceptible to degradation in the presence of oxygen, light and temperature. So, attempts have been made to preserve them through encapsulation in various colloidal systems such as microcapsules, microspheres, nanoemulsions and liposomes. This review focuses specifically on encapsulation of essential oils into liposomes. First, we present the techniques used to prepare liposomes encapsulating essential oils. The effects of essential oils and other factors on liposome characteristics such as size, encapsulation efficiency and thermal behavior of lipid bilayers are then discussed. The composition of lipid vesicles membrane, especially the type of phospholipids, cholesterol content, the molar ratio of essential oils to lipids, the preparation method and the kind of essential oil may affect the liposome size and the encapsulation efficiency. Several essential oils can decrease the size of liposomes, homogenize the liposomal dispersions, increase the fluidity and reduce the oxidation of the lipid bilayer. Moreover, liposomes can protect the fluidity of essential oils and are stable at 4-5 °C for 6 months at least. The applications of liposomes incorporating essential oils are also summarized in this review. Liposomes encapsulating essential oils are promising agents that can be used to increase the anti-microbial activity of the essential oils, to study the effect of essential oils on cell membranes, and to provide alternative therapeutic agents to treat several diseases.

Nanostructuring molecular materials as particles and vesicles for drug delivery, using compressed and supercritical fluids

The structuring of synthetic and biological therapeutic actives as micro- and nano-particulate materials is a widely accepted formulation strategy to improve efficacy and reduce the toxicity of drugs. However, the development of efficient production platforms that enable the formulation of these nanomedicines at an industrial scale and with the quality requirements imposed by regulatory agencies remains a challenge. In this framework, compressed fluid-based methods are promising technologies for the controlled and reproducible preparation of uniform micro- and nano-particulate nanomedicines at a large scale. This review provides an overall but practical knowledge about what has been achieved so far in the field of compressed fluids applied to the preparation of solid micro- and nanoparticles and vesicles as drug delivery systems. In addition, recent examples of application of these technologies to the production of polymeric nanostructured microparticles highly loaded with gentamicin and to the preparation of uniform cholesterol-rich vesicular systems are explained.