Olive Oil/Pluronic Oleogels for Skin Delivery of Quercetin: In Vitro Characterization and Ex Vivo Skin Permeability

In vitro diffusion of plant phenolics through the skin: A review update

OBJECTIVE

Excessive skin exposure to deleterious environmental variables results in inflammation as well as molecular and cellular impairments that compromise its functionality, aesthetic qualities, and overall well-being. The implementation of topical administration of antioxidants and other compounds as a method for preventing or reversing damage is a rational approach. Numerous phenolic compounds derived from plants have demonstrated capabilities such as scavenging free radicals and promoting tissue healing. However, the primary obstacle lies in effectively delivering these compounds to the specific place on the skin, and accurately forecasting their diffusion through the skin can assist in determining the most effective tactics. Hence, this article provides a comprehensive analysis of recent literature pertaining to the in vitro skin diffusion characteristics of plant phenolics. The aim is to gain a deeper understanding of their behaviour when present in various forms such as solutions, suspensions, and formulations.

METHOD

The data on plant extracts and isolated plant phenolic compounds in vitro skin diffusion assays published over the last six years were compiled and discussed.

RESULTS

Even though the gold standard Franz diffusion cell is the most commonly used in the assessment of in vitro plant phenolic skin diffusion profiles, a plethora of skin models and assay conditions are reported for a variety of compounds and extracts in different vehicles.

CONCLUSION

The presence of numerous models and vehicles poses a challenge in creating correlations among the existing data on plant phenolic compounds. However, it is possible to draw some general conclusions regarding molecular, vehicle, and skin characteristics based on the gathered information.

Technical Considerations, Applications, and Benefits of Organogels in Topical Drug Delivery Systems

Organogels represent semi-solid systems where an organic liquid phase is entrapped within a three-dimensional network formed by self-assembled, crosslinked, or entangled gelator fibers. These versatile materials find applications in a wide range of fields, including chemistry, pharmaceuticals, cosmetics, biotechnology, and food technology. Notably, in pharmacology, they serve as valuable platforms for drug and vaccine delivery, facilitating the transport of active ingredients through various routes such as transdermal, oral, and parenteral. However, their previous utility as drug delivery systems was hindered by the toxicity associated with the organic solvents used. The pharmacokinetics of medications delivered via organogels are primarily influenced by the distinctive properties of these materials, specifically their "high permeability and poor aqueous solubility," which can impact the bioavailability of the drugs. Organogels can be employed topically or for the controlled release of medications through cutaneous administration and percutaneous absorption, expanding their scope of application beyond conventional drug delivery methods. Organogels hold significant promise as drug delivery vehicles due to their biocompatibility, non-irritating properties, and thermoremanent characteristics. They enable the formulation of diverse drug delivery systems by incorporating both hydrophilic and hydrophobic bioactive compounds within the gel matrix. This comprehensive review offers an overview of organogels, encompassing their nature, synthesis, characterization, and properties. Special attention is directed towards cutting-edge technologies employed in designing organogels as potential controlled delivery systems, with a focus on their emerging therapeutic applications.

Exploring the potential of quercetin/aspirin-loaded chitosan nanoparticles coated with Eudragit L100 in the treatment of induced-colorectal cancer in rats

Growing evidence suggests quercetin and aspirin may have anticancer properties, notably in the case of colorectal cancer. The goal of this study was to create Pluronic F127 and polyethylene glycol4000 solid dispersion-loaded chitosan nanoparticles for colonic quercetin and aspirin delivery. In 1:1 polymeric stoichiometric ratio, solubility and complex formation were verified. Solid dispersion-loaded chitosan nanoparticles with a diameter of 244.45 ± 8.5 nm, a surface charge of 34.1 ± 3.3 mV, and encapsulation effectiveness of 76.3 ± 4.3% were generated under ideal conditions. In some cases, coating with Eudragit L100 resulted in a decrease in zeta potential and an increase in particle size. The coated formulation released the actives in a pH-dependent manner, considering their physicochemical features. Surprisingly, when compared to the actives' suspension and uncoated formulation, the coated formulation had greater anti-inflammatory efficacy, with a substantial reduction of PGE2 and IL-8 production in colonic tissues (16.9 ± 7.9 ng/g tissue and 134.9 ± 10.1 pg/g tissue, respectively). It also reversed most of the dimethyl hydrazine-induced histological alterations in the colon. It also demonstrated a greater reduction in TNF expression in colonic tissues. As a result, Eudragit L100-coated QT/AS-loaded chitosan nanoparticles are suggested to provide a potential platform for colonic delivery of quercetin and aspirin.

Poloxamer-based nanogels as delivery systems: how structural requirements can drive their biological performance?

Poloxamers or Pluronics®-based nanogels are one of the most used matrices for developing delivery systems. Due to their thermoresponsive and flexible mechanical properties, they allowed the incorporation of several molecules including drugs, biomacromolecules, lipid-derivatives, polymers, and metallic, polymeric, or lipid nanocarriers. The thermogelling mechanism is driven by micelles formation and their self-assembly as phase organizations (lamellar, hexagonal, cubic) in response to microenvironmental conditions such as temperature, osmolarity, and additives incorporated. Then, different biophysical techniques have been used for investigating those structural transitions from the mechanisms to the preferential component's orientation and organization. Since the design of PL-based pharmaceutical formulations is driven by the choice of the polymer type, considering its physico-chemical properties, it is also relevant to highlight that factors inherent to the polymeric matrix can be strongly influenced by the presence of additives and how they are able to determine the nanogels biopharmaceuticals properties such as bioadhesion, drug loading, surface interaction behavior, dissolution, and release rate control. In this review, we discuss the general applicability of three of the main biophysical techniques used to characterize those systems, scattering techniques (small-angle X-ray and neutron scattering), rheology and Fourier transform infrared absorption spectroscopy (FTIR), connecting their supramolecular structure and insights for formulating effective therapeutic delivery systems.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12551-023-01093-2.

Development of Olive Oil Containing Phytosomal Nanocomplex for Improving Skin Delivery of Quercetin: Formulation Design Optimization, In Vitro and Ex Vivo Appraisals

The objective of the current work was to fabricate, optimize and assess olive oil/phytosomal nanocarriers to improve quercetin skin delivery. Olive oil/phytosomal nanocarriers, prepared by a solvent evaporation/anti-solvent precipitation technique, were optimized using a Box–Behnken design, and the optimized formulation was appraised for in vitro physicochemical characteristics and stability. The optimized formulation was assessed for skin permeation and histological alterations. The optimized formulation (with an olive oil/PC ratio of 0.166, a QC/PC ratio of 1.95 and a surfactant concentration of 1.6%), and with a particle diameter of 206.7 nm, a zeta potential of −26.3 and an encapsulation efficiency of 85.3%, was selected using a Box–Behnken design. The optimized formulation showed better stability at ambient temperature when compared to refrigerating temperature (4 °C). The optimized formulation showed significantly higher skin permeation of quercetin when compared to an olive-oil/surfactant-free formulation and the control (~1.3-fold and 1.9-fold, respectively). It also showed alteration to skin barriers without remarkable toxicity aspects. Conclusively, this study demonstrated the use of olive oil/phytosomal nanocarriers as potential carriers for quercetin—a natural bioactive agent—to improve its skin delivery.

Development and assessment of phospholipid-based luteolin-loaded lipid nanocapsules for skin delivery

Luteolin is an excellent flavone possessing several beneficial properties such as antioxidant and anti-inflammatory effects which are interesting for skin delivery. Development of an appropriate skin delivery system could be a promising strategy to improve luteolin cutaneous performance.So, the main aim of this work was to fabricate, characterize and evaluate phospholipid-based luteolin-loaded lipid nanocapsules for skin delivery. The influence of phospholipid/oil ratio, surfactant type and chitosan coating were investigated. The prepared formulations underwent in vitro assessment and the selected formulations were evaluated ex vivo and in vivo. The mean diameters of investigated formulations varied between 174 nm and 628 nm while zeta potential varied between -25.7 ± 4.8 mV and 6.8 ± 1.7 mV. Increasing in phospholipid/oil ratios resulted in decrease in particles size with little effect on zeta potential and drug encapsulation. Cremophor EL showed the lowest particle sizes and the highest drug encapsulation. Chitosan coating shifted zeta potential towards positive values. Structural analyses showed that luteolin is incorporated into lipid core of nanocapsules. Selected formulations (LNC4 and LNC13) exhibited sustained in vitro release and antioxidant activity. LNC13 (chitosan coated) showed higher flux (0.457 ± 0.113 µg/cm²/h), permeability (45.70 ± 11.66 *10^-5 cm²/h) and skin retention (121.66 ± 7.6 µg/cm² after 24 h) when compared to LNC4 and suspension. It also showed disordered the integrity of the stratum corneum, increased epidermal thickness and relieving most of inflammatory features in animal model. In conclusion, this study proves that lipid nanocapsules could effectively deliver luteolin into skin and then can be established as a potential system in the pharmaceutical and cosmeceutical horizons.

Salicornia ramosissima: A New Green Cosmetic Ingredient with Promising Skin Effects

This study aims to validate a new cosmetic ingredient from Salicornia ramosissima S J. Woods through in vitro and ex vivo assays. The halophyte extracts were obtained by subcritical water extraction (SWE) at different temperatures (110, 120, 140, 160 and 180 °C). The antioxidant/radical scavenging activities and the phenolic profile were screened for all extracts. The optimal extract was assessed in keratinocytes and fibroblasts, while permeation assays were performed in Franz cells. The inhibitory activity of hyaluronidase and elastase was also evaluated. The sample extracted at 180 °C presented the highest phenolic content (1739.28 mg/100 g of dry weight (dw)). Despite not being efficient in the sequestration of ABTS^•+, this extract scavenged the DPPH^• (IC₅₀ = 824.57 µg/mL). The scavenging capacity of superoxide (O₂^•-) and hypochlorous acid (HOCl) was also considerable (respectively, IC₅₀ = 158.87 µg/mL and IC₅₀ = 5.80 µg/mL). The cell viability assays confirmed the absence of negative effects on keratinocytes, while the fibroblasts' viability slightly decreased. The ex vivo permeation of rutin, quercetin and syringic acid after 24 h was, respectively, 11, 20 and 11%. Additionally, the extract showed a good elastase and hyaluronidase inhibitory activity. The results obtained support the S. ramosissima bioactivity as a cosmetic ingredient.

EthoLeciplex: A new tool for effective cutaneous delivery of minoxidil

This work designates EthoLeciplex, a vesicular system consisting of phospholipid, CTAB, ethanol and water, as an innovative vesicular system for cutaneous/transfollicular minoxidil delivery. Minoxidil loaded EthoLeciplex was fabricated by one-step fabrication process. Formulations were designed to study the effects of drug/phospholipid ratio, CTAB/phospholipid ratio, and ethanol concentration on vesicular size, PDI, surface charge and EE%. The optimized formulation was characterized by in vitro release, drug/excipient compatibility, ex vivo skin permeability and safety. A size of 83.6 ± 7.3 to 530.3 ± 29.4 nm, PDI of 0.214 ± 0.01 to 0.542 ± 0.08, and zeta potential of +31.6 ± 4.8 to +57.4 ± 12.5 mV were observed. Encapsulation efficiency was obtained in its maximum value (91.9 ± 16.2%) at the lowest drug/phospholipid ratio, median CTAB/phospholipid and the highest ethanol concentration. The optimized formulation was consisted of 0.3 as drug/lipid ratio, 1.25 as CTAB/lipid ratio and 30% ethanol concentration and showed responses' values in agreement with the predicted results. DSC studies suggested that EthoLeciplex existed in flexible state with complete incorporation of minoxidil into lipid bilayer. The cumulative amount of minoxidil permeated from EthoLeciplex, conventional liposome and ethanolic solution after 12h were 36.3 ± 1.5 µg/ml, 21 ± 2.0 µg/ml and 55 ± 4.0 µg/ml respectively. Based on the remaining amount, the amount of minoxidil accumulated in different skin layers can be predicted in descending order as follows; EthoLeciplex > conventional liposome > minoxidil solution. EthoLeciplex produced marked disorder in the stratum corneum integrity and swelling with no features of skin toxicity. This new cationic system is a promising carrier for cutaneous/transfollicular drug delivery.

Preparation and Characterization of Novel Oleogels Using Jasmine Floral Wax and Wheat Germ Oil for Oral Delivery of Curcumin

Oleogels (OGs) have gained a lot of interest as a delivery system for a variety of pharmaceuticals. The current study explains the development of jasmine floral wax (JFW) and wheat germ oil (WGO)-based OGs for oral drug (curcumin) delivery application. The OGs were made by dissolving JFW in WGO at 70 °C and cooling it to room temperature (25 °C). The critical gelation concentration of JFW that induces the gelation of WGO was found to be 10% (w/w). The OGs were characterized using various techniques such as Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), microscopic analysis, and mechanical test. XRD data indicated that JFW influences the crystallinity of the OGs. Among the prepared OGs, OG 17.5 showed higher crystallization in the series. Optical microscopic studies demonstrated the formation of fiber structures due to the entanglement of crystals whereas, polarized light micrographs suggested the formation of spherulites or clustered crystallite structures. The mechanical properties of the OGs increased linearly with the increase in the JFW concentration. Curcumin-loaded OGs were examined for their controlled release applications. In summary, the developed OGs were found to have the necessary features for modulating the oral delivery of curcumin.

Topical application of Aloe gel and/or olive oil combination promotes the wound healing properties of streptozotocin-induced diabetic rats

Diabetic wounds are characterized by a delayed closure rate due to the excess inflammation and the inhibition of angiogenesis. Natural products derived from Aloe vera have shown great promise due to their healing magnificent properties. Olive oil is another natural product with anti-microbial and anti-inflammatory properties that may contribute to the healing process. In the present investigation, we tried to evaluate the efficacy of topical application of Aloe gel and/or olive oil in the enhancement of diabetic wounds using histological and immunohistochemical analysis. Excisional wounds were created on the back skin of streptozotocin-induced diabetic rats. Topical treatments of Aloe gel and/or olive oil were applied separately and in a combination (AVO) daily for experimental groups. Macroscopic and microscopic observations of the excision wounds were monitored at time intervals (3, 6, 9, 14 days) post-wounding. Macroscopic observations of the AVO group exhibited almost complete healing at day 14, while other groups were still in progress. Similarly, immunohistochemical analysis of the AVO group showed a mild expression pattern of NF-κB.. While, the cell proliferation (Ki-67), and angiogenesis (CD34) markers were upregulated. Conclusively, the obtained results showed that the AVO combination effectively improved the healing process in diabetic excisional wounds with significant differences in the healing kinetics compared to wounds that received Aloe gel or olive oil separately.

Influence of Stabilizer on the Development of Luteolin Nanosuspension for Cutaneous Delivery: An In Vitro and In Vivo Evaluation

Luteolin is a natural drug used as an antioxidant and anti-inflammatory, but unfortunately, it possesses low water solubility, which hinders its delivery via the skin. The main objective of this study was to prepare a luteolin-loaded nanosuspension by the antisolvent precipitation/sonication technique and study the effects of four stabilizers (two nonionic stabilizers, Pluronic F127 and Tween 80, and two polymeric stabilizers, HPMC and alginate) on the physicochemical properties of the prepared formulations. The selected formulations were incorporated into a gel base to evaluate their skin permeability and anti-inflammatory efficacy. The particle size was in the nanosize range (in the range from 468.1 ± 18.6 nm to 1024.8 ± 15.9 nm), while the zeta potential was negative and in the range from −41.7 ± 6.3 mV to −15.3 ± 1.9 mV. In particular, alginate-stabilized nanosuspensions showed the smallest particle size, the highest zeta potential value, and excellent stability due to the dual stabilizing effects (electrostatic and steric effects). The DSC results revealed a less crystalline structure of luteolin in lyophilized NS2 and NS12. Formulations stabilized by 1% Pluronic (NS2) and 2% alginate (NS12) were incorporated into a carbopol 940 gel base and showed good organoleptic character (homogenous with no evidenced phase separation or grittiness). In vitro dissolution studies showed that NS12 enhanced luteolin release rates, indicating the effect of particle size on the drug release pattern. On the other hand, NS2 showed enhanced skin permeability and anti-inflammatory effect in a carrageenan-induced paw edema model, revealing the surface activity role of the stabilizers. In conclusion, while alginate increased the nanosuspension stability by means of dual stabilizing effects, Pluronic F127 improved the skin delivery and pharmacodynamic efficacy of luteolin.

EGFR and ERK activation resists flavonoid quercetin-induced anticancer activities in human cervical cancer cells in vitro

In the present study, due to the complex and numerous targets of Sarcandrae Herb (also known as Zhong Jie Feng), network pharmacology was performed to analyze its therapeutic effect on 2 cervical cancer cell lines, which could assist with the development of novel therapies. The results suggested that the natural flavonoid quercetin (Que), the effective antitumor ingredient in SH, which is widely present in a variety of plants, may depend on the target, EGFR. Previous studies have shown that EGFR serves a crucial role in the occurrence and development of cervical cancer, but its downstream molecules and regulatory mechanisms remain unknown. The anti-cervical cancer cell properties of Que, which are present in ubiquitous plants, were examined in vitro to identify the association between Que and its underlying pathway using MTT assays, flow cytometry, western blot analysis and Transwell assays. It was found that Que reduced cervical cancer cell viability, promoted G₂/M phase cell cycle arrest and cell apoptosis, as well as inhibited cell migration and invasion. The Tyr1068 phosphorylation site of EGFR and the corresponding ERK target were also examined and the 2 kinases were markedly activated by Que. Furthermore, the EGFR inhibitor, afatinib and the ERK inhibitor, U0126 blocked the increase of EGFR and ERK phosphorylation, and resulted in a notable enhancement of apoptosis and cell cycle arrest. Therefore, to the best of our knowledge, the current results provided the first evidence that EGFR and ERK activation induced by Que could resist Que-induced anticancer activities. On this basis, the present study determined the role of EGFR and the underlying signaling pathways involved in the anti-cervical cancer malignant behavior induced by Que and identified the negative regulatory association.