Benefits of combinations of vitamin A, C and E derivatives in the stability of cosmetic formulations

Alpha-Tocopherol-Infused Flexible Liposomal Nanocomposite Pressure-Sensitive Adhesive: Enhancing Skin Permeation of Retinaldehyde

Retinaldehyde (RAL), or retinal, is a vitamin A derivative that is widely used for several skin conditions. However, it is light sensitive and has low water solubility, limiting its efficiency in transdermal delivery. This study developed a novel delivery system for retinal (RAL) using flexible liposomes (FLPs) infused with α-tocopherol succinate (α-TS) to improve stability, and enhance skin permeability. The RAL-FLPs were embedded in pressure-sensitive adhesive (PSA) hydrogels, creating a delivery platform that supports prolonged skin residence and efficient permeation of RAL. The stability and skin permeation as well as human skin irritation and adhesion capabilities were assessed to determine the formulation's safety and efficacy. Our findings suggested that the addition of α-TS could improve liposomal stability and RAL chemical stability. Moreover, the skin permeation and fluorescence microscopic-based studies suggested that the addition of α-TS could enhance skin permeability of RAL through hair follicles. The RAL-FLP was embedded in PSA hydrogels fabricated from 25% GantrezTM S-97 (GT) and 1% hyaluronic acid (Hya) with aluminum as a crosslinker. The PSA hydrogel exhibited desirable peeling and tacking strengths. The developed hydrogels also demonstrated greater skin deposition of RAL compared with its aqueous formulation. Additionally, the RAL-FLP-embedded PSA hydrogels showed no skin irritation and maintained better adhesion for up to 24 h compared to commercial patches. Hence, the developed hydrogels could serve as a beneficial platform for delivering RAL in treating skin conditions.

Ascorbic Acid (Vitamin C) as a Cosmeceutical to Increase Dermal Collagen for Skin Antiaging Purposes: Emerging Combination Therapies

Ascorbic acid (AA) is an essential nutrient and has great potential as a cosmeceutical that protects the health and beauty of the skin. AA is expected to attenuate photoaging and the natural aging of the skin by reducing oxidative stress caused by external and internal factors and by promoting collagen gene expression and maturation. In this review, the biochemical basis of AA associated with collagen metabolism and clinical evidence of AA in increasing dermal collagen and inhibiting skin aging were discussed. In addition, we reviewed emerging strategies that have been developed to overcome the shortcomings of AA as a cosmeceutical and achieve maximum efficacy. Because extracellular matrix proteins, such as collagen, have unique amino acid compositions, their production in cells is influenced by the availability of specific amino acids. For example, glycine residues occupy 1/3 of amino acid residues in collagen protein, and the supply of glycine can be a limiting factor for collagen synthesis. Experiments showed that glycinamide was the most effective among the various amino acids and amidated amino acids in stimulating collagen production in human dermal fibroblasts. Thus, it is possible to synergistically improve collagen synthesis by combining AA analogs and amino acid analogs that act at different stages of the collagen production process. This combination therapy would be useful for skin antiaging that requires enhanced collagen production.

Advantages of Hyaluronic Acid and Its Combination with Other Bioactive Ingredients in Cosmeceuticals

This study proposes a review on hyaluronic acid (HA) known as hyaluronan or hyaluronate and its derivates and their application in cosmetic formulations. HA is a glycosaminoglycan constituted from two disaccharides (N-acetylglucosamine and D-glucuronic acid), isolated initially from the vitreous humour of the eye, and subsequently discovered in different tissues or fluids (especially in the articular cartilage and the synovial fluid). It is ubiquitous in vertebrates, including humans, and it is involved in diverse biological processes, such as cell differentiation, embryological development, inflammation, wound healing, etc. HA has many qualities that recommend it over other substances used in skin regeneration, with moisturizing and anti-ageing effects. HA molecular weight influences its penetration into the skin and its biological activity. Considering that, nowadays, hyaluronic acid has a wide use and a multitude of applications (in ophthalmology, arthrology, pneumology, rhinology, aesthetic medicine, oncology, nutrition, and cosmetics), the present study describes the main aspects related to its use in cosmetology. The biological effect of HA on the skin level and its potential adverse effects are discussed. Some available cosmetic products containing HA have been identified from the brand portfolio of most known manufacturers and their composition was evaluated. Further, additional biological effects due to the other active ingredients (plant extracts, vitamins, amino acids, peptides, proteins, saccharides, probiotics, etc.) are presented, as well as a description of their possible toxic effects.

Quality Control of Vitamins A and E and Coenzyme Q10 in Commercial Anti-Ageing Cosmetic Products

Vitamins A and E and coenzyme Q10 are common ingredients in anti-ageing cosmetic products. Within this study, we evaluated the quality of commercial cosmetics with vitamin A (35 products), vitamin E (49 products), and coenzyme Q10 (27 products) by using validated HPLC–UV methods. Vitamin A was determined as retinol, retinyl palmitate, retinyl propionate, β carotene, and hydroxypinacolone retinoate in concentrations ranging from 950 ng/g to 19 mg/g. Total vitamin A contents, expressed with retinol equivalents, ranged from 160 ng/g to 19 mg/g, and were above the maximum concentration recommended by the SCCS in six of the 35 tested cosmetics. The content-related quality control of 10 cosmetics with specified vitamin A content revealed significant deviations (between 0% and 400%) of the label claim. Vitamin E was determined as both tocopherol and tocopheryl acetate in concentrations between 8.5 µg/g and 16 mg/g. Coenzyme Q10 was determined as ubiquinone in 24 tested cosmetics, which labelled it, in concentrations between 4.2 µg/g and 100 µg/g. Labelling irregularities were observed in all three active compound groups, resulting in a significant share (42%) of improperly labelled cosmetic products. The results of this study reveal the need for stricter cosmetics regulation and highlight the importance of their quality control, especially by evaluating the contents of the active compounds, in their efficacy and safety assurance.

Retinoid stability and degradation kinetics in commercial cosmetic products

BACKGROUND

Retinoids as dermatological agents are effective against acne, psoriasis, skin aging, and other skin conditions. However, their susceptibility to degradation is a limiting factor for their widespread use.

OBJECTIVES

Within this study, we aimed to provide comprehensive and evidence-based information on retinoid stability and degradation kinetics in commercial cosmetics, focusing on different factors affecting their stability.

METHODS

A validated HPLC-UV methodology was utilized for determination of the most common retinoids in cosmetics (retinol, retinyl palmitate, β-carotene) and a newer promising retinoid (hydroxypinacolone retinoate). The stability of 16 retinoid derivatives in 12 commercial cosmetics was evaluated within 6 months of long-term and accelerated stability testing in addition to a one-week photostability study. Retinoid degradation in the tested formulations followed first-order kinetics, which was further applied to shelf-life prediction.

RESULTS

Long-term and accelerated stability testing revealed retinoid instabilities in almost all products, resulting in a 0%-80% decline after 6 months at 25°C and a 40%-100% decline at 40°C, which were kinetically evaluated. Light degradation was more pronounced than temperature-induced degradation. Among the studied retinoids, the stability of the newer hydroxypinacolone retinoate was the most prominent. This study also identifies correlations between retinoid concentrations, price, formulation, and their stability in cosmetics.

CONCLUSIONS

Retinoid instabilities were formulation-dependent and associated with lower contents than declared in some cosmetics. Retinoid chemical stability and physical stability in topical formulations need to be evaluated by real-time stability studies, instead of the more frequently used accelerated stability studies.

Quality control of retinoids in commercial cosmetic products

BACKGROUND

Retinoids are widely used in different cosmetic products because of general improvement of skin appearance. However, retinoid concentration in cosmetics is restricted, and one particular form-retinoic acid, is banned in cosmetics due to safety reasons.

AIMS

Within this study, we aimed to examine the quality of a considerable number of commercial retinoid cosmetic products in terms of their content and labeling, including also screening for the presence of retinoic acid.

METHODS

An appropriate analytical methodology, based on HPLC-UV for the simultaneous determination of common retinoids, along with a screening method for retinoic acid, was developed and validated. Structural identity confirmation of the newer retinoid-hydroxypinacolone retinoate, was performed by LC-MS.

RESULTS

Retinol and retinyl palmitate were most often found, in concentrations mostly below 0.3%, and up to 1.3% retinol equivalents. Determined contents deviated significantly from the quantitatively declared ones in seven products (0%-130%). In more than half of the tested products, inconsistencies between the contained and labeled retinoid were noticed. These products, as well as 14 additional anti-age cosmetics, were screened for retinoic acid, which was detected in two products.

CONCLUSIONS

The obtained results from retinoids assay in commercial cosmetic products confirmed that the proposed method is appropriate for their routine analysis. The presence of retinoic acid in two products and determined retinoid contents above the Scientific Committee on Consumer Safety recommendations in 20% of the tested cosmetics reveal the need for their more strict regulation and quality control to ensure their efficacy and safety.

Influence of vegetable oils in the rheology, texture profile and sensory properties of cosmetic formulations based on organogel

OBJECTIVE

The knowledge about how ingredients in formulation can influence the texture profile is an important factor on the development of a cosmetic product. In this context, the aim of this work was to evaluate the effect of vegetable oils in the texture profile, rheological and sensorial properties of cosmetic formulations based on organogel.

METHODS

Four organogel-based emulsions were developed and supplemented or not with sunflower, macadamia or olive oils. Analyses of rheological behaviour, texture profile and sensory properties were performed.

RESULTS

The vegetable oils added to formulation did not alter the pseudoplastic rheological behaviour, but increased the area of hysteresis and reduced the work of shear of the formulations. In addition, the sunflower seed oil increased the consistency index and all texture parameters while the macadamia oil reduced firmness and consistency. The cosmetic formulation based on organogel containing the sunflower seed oil showed the highest score on sensory evaluation.

CONCLUSION

The vegetable oils affected the rheology behaviour, texture profile and sensory properties of the formulations under study. However, the influence of sunflower oil in organogel-based cosmetic formulation was more pronounced considering texture profile and the response perceived by subjects in the sensorial analysis.

Application of Factorial Design and Rheology to the Development of Photoprotective Formulations

A sunscreen should form a stable and homogeneous film over the skin surface, which can improve its photoprotective activity and avoid adverse effects. For this purpose, the definition of the appropriate vehicle is of fundamental importance since emulsifying agents are known to directly influence the stability, sensorial properties and surface tension of sunscreens, modulating their film-forming performance. In this context, the objective of the present study was to systematically develop formulations with UVB/UVA protection and evaluate the effect of wax concentration on the rheological behaviour. A 2-level full factorial design was applied for the development of four formulations. Two categorical factors were evaluated, glyceryl stearate plus PEG-75 stearate (Wax 1) and methyl glucose sesquistearate (Wax 2). Rheological behaviour was determined in triplicate and rheograms were analysed using the Ostwald model. Rheological parameters were correlated by the Spearman rank correlation test and effects were evaluated by Pareto chart and surface response methodology (SRM). It was possible to identify the pseudoplastic and thixotropic behaviour of all formulations exhibiting a thinning effect on higher shear stress. Factorial analysis showed that both waxes significantly influenced consistency and thixotropic behaviour. The effect of Wax 2 concentration in thixotropy was positive and of higher magnitude and a synergistic effect was also observed. Spearman correlation coefficient of consistency index and apparent viscosity was significantly strong and positive. Finally, factorial analysis allowed the determination of the effects of waxes on the rheological parameters of the formulations. A quantitative relationship between wax concentration and significant responses was established, permitting the prediction of desirable rheological properties for improved sunscreen efficacy.

Vitamin C: One compound, several uses. Advances for delivery, efficiency and stability

Vitamin C (Vit C) is a potent antioxidant with several applications in the cosmetic and pharmaceutical fields. However, the biggest challenge in the utilization of Vit C is to maintain its stability and improve its delivery to the active site. Several strategies have been developed such as: controlling the oxygen levels during formulation and storage, low pH, reduction of water content in the formulation and the addition of preservative agents. Additionally, the utilization of derivatives of Vit C and the development of micro and nanoencapsulated delivery systems have been highlighted. In this article, the multiple applications and mechanisms of action of vitamin C will be reviewed and discussed, as well as the new possibilities of delivery and improvement of stability.

Protective effect of neglected plant Diplocyclos palmatus on quorum sensing mediated infection of Serratia marcescens and UV-A induced photoaging in model Caenorhabditis elegans

Plants are considered to be a leading source for possible human therapeutic agents. This holistic study has investigated the anti-quorum sensing (anti-QS), anti-infection, antioxidant and anti-photoaging properties of neglected plant Diplocyclos palmatus. The results showed that D. palmatus methanolic leaf extract (DPME) effectively inhibited the quorum sensing (QS) regulated virulence factor production as well as biofilm formation in Serratia marcescens. The transcriptomic analysis revealed that DPME significantly downed the expression of QS-regulated genes such as fimA, fimC, flhC, bsmB, pigP and shlA in S. marcescens, which supports the outcome of in vitro bioassays. Further, the docking study revealed that the presence of active compounds, namely tocopherols and phytol, DPME exhibited its anti-QS activity against S. marcescens. In addition, DPME treatment extended the lifespan of S. marcescens infected C. elegans by the action of dropping the internal accumulation. Further, qPCR analysis clearly revealed that DPME treatment significantly up-regulated the expression of the lifespan-related gene (daf-16) and immune-related genes (clec-60, clec-87, lys-7 and bec-1) in S. marcescens infected C.elegans. On the other hand, DPME extensively reduced the UV-A induced ROS stress, thereby, extended the lifespan in UV-A photoaged C. elegans. Further, the qPCR analysis also confirmed the up-regulation of daf-16, clec-60, clec-87 and col-19 genes which advocated the improvement of the lifespan, healthspan and collagen production in UV-A photoaged C. elegans. Further bioassays evidenced that that the lifespan extension of photoaged C. elegans was accomplished by the actions of antioxidants such as tocopherols and phytol in DPME.

Physical-Mechanical characterization of cosmetic formulations and correlation between instrumental measurements and sensorial properties

OBJECTIVE

The correct choice of raw materials in the development of cosmetic formulations is essential for obtaining stable and pleasant skin care products. Therefore, rheological, texture and sensory analyses are important to understand the behaviour and stability of the formulations. In this context, the aim of this study was to develop cosmetic formulations containing or not (vehicle) UV filters and chicory root extract, to evaluate their stability as well as to characterize their physical and texture properties and correlate them with the sensory attributes.

METHODS

Four formulations containing organic UV filters and chicory extract, each alone or in combination, were developed and evaluated for 180 days with a cone and plate rheometer, a texture analyzer and consumer's sensorial analysis. Thus, the data obtained were correlated to observe the different influences.

RESULTS

The developed formulations remained stable after 180 days regarding macroscopic aspects, organoleptic characteristics and pH values. The addition of the UV filters alone and in combination with the active substance resulted in significant increases in rheology properties, viscosity and consistency. The formulation with the active ingredient showed significant decreases in the texture parameters after 180 days, mainly due to its polysaccharide inulin. All formulations obtained high scores in sensorial parameters. A strong correlation was mainly found between spreadability and work of shear, and between the texture parameters.

CONCLUSION

The raw materials strongly influenced the physical, texture and sensorial parameters. Finally, the UV filters showed a greater influence on the results of the formulations than the chicory root extract. In conclusion, the association of the mentioned methods allows the correct choice of ingredients and their combinations.

Rheological and physical parameters correlations in formulations with pinhão derivatives stability study: building up an analytical route

This study focuses on the correlation investigation between rheological and physical parameters and how it can contribute to optimize the topical formulations development. A gel and an emulgel containing pinhão derivatives, and their respective controls, were analyzed along six months of storage. A flowchart of analyses was proposed to use in topical formulation development when a benchmark is the goal or when it is necessary to change some raw material. All formulations were stable over the storage time and the formulations containing pinhão starch and coat extract presented similar properties to those of the control formulations. Correlations between rheological and physical data, as moisture content and particle size, were determined using Pearson's correlation coefficient. A moderate positive correlation was verified between particle size distribution and flow index, and a strong positive correlation between particle size and flow index. It was also found that the higher the moisture content, the higher the consistency index, quality factor, and apparent viscosity. The correlation analyses applied in this study contributed to build up an analytical route for topical formulation development, saving time and costs.

Cichorium intybus root extract: A "vitamin D-like" active ingredient to improve skin barrier function

During the aging process, the human skin suffers many alterations including dryness, skin barrier function damage. The skin barrier function is important to the prevention of skin alterations and maintenance of homeostasis. So, the objective of this study was to assess the clinical efficacy on skin barrier function of Cichorium intybus root extract in cosmetic formulations with or without UV filters. Fifty women, aged between 45 and 60 years, were divided into two groups. One group received vehicle formulations containing UV filters, and the other group received formulations without UV filters. Both groups received a formulation containing the extract and the vehicle. The formulations were applied twice daily to the upper arms after washing with sodium lauryl sulphate. Transepidermal water loss (TEWL) and skin microrelief were evaluated before and after a 14- and 28-day period of treatment. The control regions and regions where the vehicles were applied showed an increase in the TEWL. For the formulations containing the extract, decreased TEWL and improved microrelief were observed when compared to the vehicle and control areas after a 28-day period. In conclusion, Cichorium intybus root extract showed protective and restructuring effects on the skin and stands out as an innovative ingredient to improve skin barrier function.

Pinhão starch and coat extract as new natural cosmetic ingredients: Topical formulation stability and sensory analysis

The objective of this study was to use pinhão derivatives, starch and coat extract, as new natural ingredients to develop cosmetic formulations. Two types of formulation, gel and emulgel, and their controls were developed. The formulations were characterized by stability studies using thermal stress. The parameters analyzed were resistance to centrifugation, pH, spreadability, rheology, content of phenolic compounds and antioxidant activity. Sensory analysis was also performed to verify the acceptability of the ingredients to potential consumers. The pH was kept the same after heating/freezing cycles for all formulations, and the formulations showed stability by resistance to centrifugation. The formulations did not induce any skin irritation or cutaneous pH alteration. The pinhão starch addition improved spreadability stability and increased viscosity when compared with control formulations. The pinhão coat extract used in these formulations is a good source of phenolic compounds and antioxidant activity. Moreover, sensory analysis indicates that the emulgel formulation is the best vehicle for adding pinhão starch and pinhão coat extract.

Multifunction hexagonal liquid-crystal containing modified surface TiO2 nanoparticles and terpinen-4-ol for controlled release

Multifunctional products have been developed to combine the benefits of functional components and terpinen-4-ol (TP) delivery systems. In this way, p-toluene sulfonic acid modified titanium dioxide (TiO2) nanoparticles and TP, an antioxidant, have been incorporated in liquid-crystalline formulations for photoprotection and controlled release of the TP, respectively. By X-ray powder diffraction and diffuse reflectance spectroscopy, we noted that using p-toluene sulfonic acid as a surface modifier made it possible to obtain smaller and more transparent TiO2 nanoparticles than those commercially available. The liquid-crystalline formulation containing the inorganic ultraviolet filter was classified as broad-spectrum performance by the absorbance spectroscopy measurements. The formulations containing modified TiO2 nanoparticles and TP were determined to be in the hexagonal phase by polarized light microscopy and small-angle X-ray scattering, which makes possible the controlled released of TP following zero-order kinetics. The developed formulations can control the release of TP. Constant concentrations of the substance have been released per time unit, and the modified TiO2 nanoparticles can act as a transparent inorganic sunscreen.

Efficacy evaluation of a multifunctional cosmetic formulation: the benefits of a combination of active antioxidant substances

This study presents the association of active antioxidants substances in a multifunctional cosmetic formulation with established efficacy against signs of aging. A multifunctional cosmetic formulation containing an association of UV filters and antioxidant substances (liposoluble vitamins A, C and E, Ginkgo biloba and Phorphyra umbilicalis extracts) was evaluated. This formulation was submitted to a clinical efficacy study using biophysics techniques and skin images analysis (digital photography imaging systems, 20 MHz ultrasound, and reflectance confocal microscopy). The volunteers applied the formulation containing the UV filters and antioxidant substances during the day and the formulation with antioxidant substances and without the UV filters at night, for 90 days. The formulation increased the hydration and protected the skin barrier function after a single application. At the long term assessment the formulation provided an improvement in skin barrier function and skin hydration to the deeper layers of the epidermis, leading to an improvement in skin appearance by reducing wrinkles and skin roughness. The multifunctional cosmetic formulation studied can be suggested to preventing signs of aging and improving skin conditions. In addition, this study presents the benefits of associating different active antioxidants substances in a single cosmetic formulation to prevent skin aging.

Stability of sunscreens containing CePO4: proposal for a new inorganic UV filter

Inorganic UV filters have become attractive because of their role in protecting the skin from the damage caused by continuous exposure to the sun. However, their large refractive index and high photocatalytic activity have led to the development of alternative inorganic materials such as CePO4 for application as UV filters. This compound leaves a low amount of white residue on the skin and is highly stable. The aim of this study was to evaluate the physical and chemical stability of a cosmetic formulation containing ordinary organic UV filters combined with 5% CePO4, and, to compare it with other formulations containing the same vehicle with 5% TiO2 or ZnO as inorganic materials. The rheological behavior and chemical stability of the formulations containing these different UV filters were investigated. Results showed that the formulation containing CePO4 is a promising innovative UV filter due to its low interaction with organic filters, which culminates in longer shelf life when compared with traditional formulations containing ZnO or TiO2 filters. Moreover, the recognized ability of CePO4 to leave a low amount of white residue on the skin combined with great stability, suggests that CePO4 can be used as inorganic filter in high concentrations, affording formulations with high SPF values.

Moisturizing effect of a cosmetic formulation containing pequi oil (Caryocar brasiliense) from the Brazilian cerrado biome

Caryocar brasiliense, popularly known in Brazil as “pequi”, is a species widely distributed in the Brazilian Cerrado. The seeds are surrounded by a woody endocarp coated with a yellow fleshy mesocarp rich in oil and vitamin A, whose oil has a useful role in the treatment of skin aging and protection of human skin against UV-induced damage and skin hydration. The aim of this study was to evaluate the effect of cosmetic formulations containing pequi oil (Caryocar brasiliense) on skin hydration, after a single application. Hydration effect assessment was performed by applying the formulations under study (Control – no formulation, vehicle, and vehicle + pequi oil) onto forearm skin of 30 human volunteers. Skin capacitance and Transepidermal Water Loss (TEWL) measurements were analyzed before, and at 1, 2 and 3 hours after, a single application. Evaluation results of a single application of the vehicle containing pequi oil showed an increase in stratum corneum water content, indicating a skin moisturizing effect. Results of the evaluation of immediate effects of TEWL demonstrated that the vehicle containing pequi oil significantly increased skin moisture during the 3 h evaluation period. The formulations containing pequi oil showed clinical efficacy, increasing stratum corneum water content and enhancing skin barrier function.

Stability of a cosmetic multiple emulsion loaded with green tea extract

Multiple emulsions are excellent and exciting potential systems for the delivery of useful cosmetic agents. The work describes stability of a multiple emulsion for cosmetic purpose, loaded with extract of Camellia sinensis L. (Theaceae) in concentration of 5%. The formulation constitutes of cetyl dimethicone copolyol and polyoxyethylene (20) cetyl ether as emulsifiers and was characterised and monitored for various physicochemical aspects. Centrifugation has no devastating effect on physical destabilization/phase separation observed for 30 days. Mean globule sizes of multiple droplets were found in the range of 10.29 ± 4.4 μm to 12.77 ± 5.1 μm and of inner droplets were in the range of 0.8 ± 0.4 μm to 1.6 ± 0.8 μm. All samples exhibited shear thinning behavior with increase in shear stress. The results of the present study indicate that multiple emulsions can be used as carrier of 5% Camellia sinensis L. extract to enhance desired effects. The developed physically and chemically stable system is an effective system for targeting skin layers; however, long-term stability at elevated temperatures may be needed with suitable modifications, if required.