Determination Of Sun Protection Factor Research Articles

Physical Quality Evaluation and Determination of SPF (Sun Protection Factor) Value of Forest Coconut Oil Lotion (Pandanus julianettii Martelli) from Papua

Forest coconut fruit contains double-bonded fat or omega 3-6, tocopherol, or vitamin E. Vitamin E and some compounds such as flavonoids, tannins, and anthraquinone have potential as sunscreens. This study aims to evaluate the physical quality and determine the SPF value in forest coconut oil lotion analyzed in vitro. Physical quality evaluation includes organoleptic tests, homogeneity, spreadability, adhesion, pH, and the determination of SPF values by the UV-Vis spectrophotometry method. The results showed that each formula, namely FI (2%), FII (4%), and FIII (6%), was physically stable. The lotion preparation in each formula, namely FI (2%), FII (4%), and FIII (6%), has SPF values of 1.95, 1.57, and 1.19, respectively.

Effect of Ag and Ni-Doped Cerium Oxide Nanoparticles on the Formation of ROS and Evaluation as an Alternative Physical Sunscreen Material.

CeO2 nanoparticles (nanoceria) were proposed as an alternative physical sunscreen agent with antioxidant properties and comparable UV absorption performance. Green synthesis of nanoceria with Ag and Ni dopants resulted in doped nanoceria with lower catalytic activity and biologically-safe characteristics. The doped nanoceria was characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), Rancimat Instrument, and UV-Vis Spectrophotometer for SPF (Sun Protection Factor) determination. XRD and TEM analysis showed that nanoceria had been successfully formed in nanoscale-sized with a change in crystallite size due to the crystal defect phenomenon caused by dopant addition. While the Rancimat test and band gap energy analysis were conducted to evaluate the oxidative stability and reactive oxygen species formation, it was confirmed that dopant addition could decrease catalytic activity of material, resulting in Ni-doped Ce with a longer incubation time (11.81 h) than Ag-doped Ce (10.58 h) and non-doped Ce (10.30 h). In-vitro SPF value was measured using the thin layer technique of sunscreen prototype with Virgin Coconut Oil (VCO)-based emulsion, which yielded 10.862 and 5.728 SPF values for 10% Ag-doped Ce and 10% Ni-doped Ce, respectively. The dopant addition of nanoceria could reduce catalytic activity and give a decent in vitro UV-shielding performance test; thus, Ag and Ni-doped nanoceria could be seen as promising candidates for alternative physical sunscreen agents.

Formulation and optimization of phytosomes of ethanolic extract of Viola tricolor flowers using design of experiment (DOE) to evaluate in vitro photoprotective potential as sunscreen cream

Viola tricolor L. has many uses in treatment of various skin disorders, which attributed to their antioxidant-flavonoid compounds. The aim of this study was evaluation of photoprotection, cytotoxicity and phototoxicity of the ethanolic extract of Viola tricolor flowers (EE-Viola). At concentration of 0.2 mg/mL of EE-Viola, the sun protection factor (SPF) value was 15.3 ± 0.7. By evaluation of the survival of mouse fibroblast cells (3T3) in the presence and absence of UV light using MTT-based colorimetric assay, the calculated IC50 was found to be 30.79 µg/mL and 34.89 µg/mL, respectively. The phytosomes of EE-Viola (Phy&EE-Viola) were then prepared using thin-layer hydration technique and optimized by experimental design method. The optimum particle size (487.6 nm) and encapsulation efficiency (95.2%) of the prepared phytosomes obtained when ratio of extract amount to lecithin amount (3 to 1), experiment temperature of 50 °C, and bath sonication were used. The optimum prepared phytosome was characterized by scanning electron microscopy, Fourier-transform infrared spectroscopy, and differential scanning calorimetry. In the next step, Phy&EE-Viola was formulated in a cream base and its photoprotective potential was evaluated. Finally, the Phy&EE-Viola cream was evaluated for its pH, spread-ability, occlusivity, in vitro SPF determination, release and stability studies. The SPF value of the cream containing 4% of Phy&EE-Viola was equal to 14.0 ± 0.7. The results clearly indicated that the cream formulations exhibited a good stability at applied temperatures and good release profile. Therefore, the obtained cream of Phy&EE-Viola might be introduced as candidate as for sun protection which merit further investigations.

Sun protection factor and tyrosinase inhibitory activity of several plant secondary metabolites

Severe exposure to ultraviolet (UV) rays leads to skin damage, including hyperpigmentation, freckles, melanoma, age spots, and melasma, all of which are related to the skin pigment enzyme, tyrosinase. Prevention can be achieved by avoiding harsh UV rays and inhibiting tyrosinase catalytic activity. Many compounds have been developed for the treatment of such conditions; however, most come with unwanted side effects. The purpose of this study was to determine the sun protection factor (SPF) value and tyrosinase enzyme inhibitory activity of plant secondary metabolites with high antioxidant activity, namely rutin, catechin, niazirin, piperine, quercetin, and quercitrin, as potential alternatives. Both tests were carried out using UV-Vis spectrophotometry. SPF determination was performed by observing the absorbances across a wavelength range of 290 to 320 nm. The determination of anti-tyrosinase activity was conducted by measuring dopachrome at 490 nm after enzymatic reactions and calculating the IC50 value. In the SPF assay, benzophenone-3 was used as the standard, and piperine, rutin, quercetin, and quercitrin exhibited high protective abilities with SPF values above 30 at 500 µg/mL. In the tyrosinase inhibition assay, kojic acid as the standard showed a strong potential for inhibition with an IC50 of 33.65 µg/mL, while quercetin, rutin, and piperine exhibited weaker inhibitory potential with IC50 values of 178.44, 271.73, and 347.62 µg/mL, respectively. On the other hand, quercitrin and niazirin showed little to no tyrosinase inhibition activity. However, catechin demonstrated more catalytic activity towards the enzyme. In conclusion, quercetin, rutin, and piperine have the potential to be developed as active ingredients to protect the skin from UV-induced damage due to their satisfactory SPF values and tyrosinase inhibition activity.

Novel Researched Herbal Sunscreen Cream SPF Determination by In-Vitro Model

INTRODUCTION: Researchers' interest in creating novel cosmetic formulations has increased due to consumer interest in herbal cosmetics and increased patent activity. The rights of indigenous traditional knowledge and benefit sharing are also safeguarded under IPR.
 OBJECTIVE: To formulate and evaluate herbal sunscreen with determination of Sun Protection Factor (SPF) and anti-oxidant activity. To compare Sun Protection Factor of developed formulation with marketed formulation.
 METHOD: The formulation was developed according to the prepared formula. And multiple tests were done for evaluation i.e., physical observation, spreadability, extrudability, occlusion study, stability study and SPF determination. All the evaluations were found satisfactory. Characterisation of SPF was calculated according to the and UV-Vis Spectrophotometer (LABMAN Scientific instruments Pvt. Ltd.).
 RESULTS:The synergistic activity of all herbal compounds utilized in herbal sunscreen formulations, such as Cucumis sativus, Solanum Lycopersicon, and Aloe barbadensis Efficacy of photoprotection found in following order Marketed formulation > F3 > F2 > F1. For prepared formulation F3 provided better results in comparison to Formulation1 and Formulation 2. Formulation 3 was compared with marketed preparation and it showed good SPF value nearer to market preparation. Overall results were satisfactory. These results reveal that the prepared F3 herbal sunscreen have good SPF and good sun protection activity.
 CONCLUSION: Formulation 3, which consists of three formulations, has been found to be effective as sunscreen in every way. Since few people use sunscreen, there is a need to raise public knowledge of the risks associated with sun exposure as well as the advantages of using sun protection products on a regular basis to lessen these effects. This kind of research will be useful in offering consumers with an all-inclusive solution or product that will protect them from the damaging effects of sunlight.

Determination of Sun Protection Factor (SPF) of Malaysian Fruit and Vegetable Extracts Using UV–Visible Spectroscopy

Determination of Sun Protection Factor (SPF) of Malaysian Fruit and Vegetable Extracts Using UV–Visible Spectroscopy

Bioassay-Guided Skin-Beneficial Effects of Fractionated Sideritis raeseri subsp. raeseri Extract.

This study aimed to evaluate the potentials for skin-beneficial effects of the hydroethanolic extract of the aerial parts of ironwort (Sideritis raeseri Boiss. & Heldr. subsp. raeseri) and its fractions (petroleum ether, ethyl acetate, n-butanol and water). For these purposes, chemical analysis and in vitro antioxidant, anti-tyrosinase and antimicrobial assays, as well as determination of sun protection factor (SPF), were performed. The highest total phenolic content and quantity of individual flavonoids, chlorogenic acid and verbascoside were determined in the n-butanol fraction, which is in line with results obtained for antioxidant activity. The greatest antimicrobial activity against Staphylococcus aureus, Staphylococcus epidermidis and Pseudomonas aeruginosa, the most common causative agents of the skin infections in humans, was exhibited by the ethyl acetate fraction. The strongest anti-tyrosinase activity was shown by the hydroethanolic extract (52.64% of inhibition at 100 μg/mL). Almost all tested samples showed photoprotective activity with SPF higher than 6 obtained at a low concentration of 0.1 mg/mL, which was more than 15 for the butanol fraction. These findings revealed that the hydroethanolic extract of S. raeseri aerial parts could be a valuable ingredient in the formulation of cosmetic and medicinal products intended to overcome various skin disorders.

Salicin and Hederacoside C-Based Extracts and UV-Absorbers Co-Loaded into Bioactive Lipid Nanocarriers with Promoted Skin Antiaging and Hydrating Efficacy.

Conventional and herbal active principles can be combined in a beneficial harmony using their best features and compensating for the certain weaknesses of each. The study will answer the question, “how can willow bark extract (Wbe) or ivy leaf extract (Ile) influence the photoprotective, skin permeation and hydration properties of Bioactive Lipid Nanocarriers (BLN) loaded with UV-filters and selected herbals?”. BLN-Wbe/Ile-UV-filters were characterized for particle size, zeta potential, thermal behavior, entrapment efficiency and drug loading. The formulated BLN-hydrogels (HG) were subjected to in vitro release and permeation experiments. The in vitro determination of sun protection factors, as well as comparative in vitro photostability tests, rheology behavior and in vivo hydration status have been also considered for hydrogels containing BLN-Ile/Wbe-UV-filters. Photoprotection of BLN-HG against UVA rays was more pronounced as compared with the UVB (UVA-PF reached values of 30, while the maximum SPF value was 13). The in vitro irradiation study demonstrated the photostability of BLN-HG under UV exposure. A noteworthy cosmetic efficacy was detected by in vivo skin test (hydration effect reached 97% for the BLN-Wbe-UV-filters prepared with pomegranate oil). The research novelty, represented by the first-time co-optation of the active herbal extracts (Wbe and Ile) together with two synthetic filters in the same nanostructured delivery system, will provide appropriate scientific support for the cosmetic industry to design novel marketed formulations with improved quality and health benefices.

Functional composite hydrogels entrapping polydopamine hollow nanoparticles for highly efficient resistance of skin penetration and photoprotection

Living organisms tend to evolve various naturally photoprotective mechanisms to avoid photodamage. Among them, polydopamine (PDA) is an effective sunscreen, a mimic of melanin, which is the main functional component of the photoprotective system of human skin. However, the concerns of its dark color, skin penetration and photoprotective efficiency remain yet to be solved. Herein, we have constructed melanin-inspired nanocomposite hydrogels (CS-PDAh-GP-HA) for photoprotection, in which PDA was prepared as hollow nanoparticles (PDAh NPs) and entrapped in a physically cross-linked hydrogel (CS-GP-HA) formed by chitosan (CS) and hyaluronic acid (HA) using β-glycerophosphate (β-GP) as a modulator. The CS-PDAh-GP-HA hydrogels exhibit a shear-thinning flow behavior with an elastic modulus of 300 Pa with the gel-sol transition temperature maintained at about 37 °C simply by adjusting the β-GP content in the hydrogels. The CS-PDAh-GP-HA hydrogels also possess excellent resistance toward skin penetration. The photoprotective performances of CS-PDAh-GP-HA hydrogels were evaluated by the determination of sun protection factor (SPF) and in vitro UVA protection efficacy (UVAPE) along with UV–Vis spectroscopy. Compared with the TiO2 nanoparticles in CS-GP-HA hydrogel, the CS-PDAh-GP-HA hydrogels show stronger shielding ability in both UVA and UVB regions. When protected by the CS-PDAh-GP-HA hydrogels, the cell viability of NIH-3T3 fibroblasts increases to 96% while it was only 14% in the case of non-protecting group. These results suggest that the CS-PDAh-GP-HA hydrogels could efficiently shield the UV irradiation and protect the skin from photodamage. This work introduces PDA-based nanocomposite hydrogels with safe, biocompatible and photoprotective properties, and provides a melanin-mimicking photoprotection system for the application in sunscreens.

EBT3 Gafchromic® film as a new substrate for in vitro evaluation of sun protection factor.

There exist different methods for the determination of sun protection factor (SPF) values for sunscreens. We aimed to develop a new in vitro method using EBT3 Gafchromic® film as a substrate. The colour of EBT3 Gafchromic® film changes when exposed to UV light. Films were covered by sunscreen preparations of different SPF values ranging from 0 to 50. Uncovered and covered films were exposed to different solar light energies and their colour change was compared. Absorbance spectra of films was measured at 633nm using a UV-VIS spectrophotometer apparatus. The colour of the film darkens when ultraviolet energy increases, which means that absorbance increases with exposure time. However, when films are covered by sunscreens, the colour change is less visible and the absorbance significantly decreases with increasing SPF value. There is a linear correlation between the absorbance of EBT3 Gafchromic® film and SPF value of sunscreens covering the film. Statistical analysis demonstrated that the SPF value of a sunscreen can be predicted using EBT3 Gafchromic® film as a substrate. This is the first report of an in vitro method based on colour change of a substrate which takes into consideration exposure time, and relates more closely to conditions of real-life. Based on these parameters, this is a reliable in vitro method for SPF testing.

In Vitro Determination of Sun Protection Factor of Water Extract of Aerodramus fuciphagus from Central Kalimantan

Sunscreen is a cosmetic substance that has the ability to reflect or absorb sunlight actively. It can prevent skin irritation due to UV rays. One of the natural ingredients with a sunscreen effect is the Edible-nest swiftlet's (Aerodramus fuciphagus) nest (ESN). This study aimed to determine the value of the sun protective factor (SPF) of the ESN water extract. The ESN water extract solution with variation concentration, this is 2000, 2500, 5000, 6000, and 7000 ppm, were measured by spectrophotometric UV-Vis at wavelength 290-375 nm with 5 nm intervals to determine the value of SPF, percentage of erythema transmission (%Te), and percentage of pigmentation transmission (%Tp) of ESN water extract. The result showed that the ESN water extract's SPF values at the concentration 2000, 2500, 5000, 6000, and 7000 ppm were 7.80; 9.68; 18.75; 20.58; and 22.24. The value of %Te of each concentration were 15.60±0.19; 10.03±0.42; 1.24±0.04; 0.81±0.01 and 0.56±0.01. While the value of %Tp of each concentration was showed the sunblock category. In conclusion, the ESN water extract from Central Kalimantan at the concentration of 6000 ppm has potential in ultraviolet protection against the skin in the ultra category with sunblock category mechanism. Further, it can be developed into sunscreen cosmetics from natural ingredients.

Determination of sun protection factor and physical remanence of dermocosmetic emulgels formulated with Manilkara zapota (L.) fruit extract

Purpose: To develop a stable emulgel formulation from Manilkara zapota fruit extract (MZFE) and evaluate its sun-protective factor (SPF) and its physical retention on facial skin.
 Methods: Active test formulations containing MZFE and placebo (containing no active ingredients) were prepared by dispersing the primary emulsion into a gel phase. Both test and placebo emulgel formulations were subjected to physicochemical evaluation, stability studies, and assessment of possible photo-protective properties. The sun-protective factor (SPF) was determined in vitro by spectrophotometric analysis. Non-invasive in vivo skin bioengineering technique was used to assess the UV-quenching effects of the test and placebo emulgel formulations.
 Results: A stable and cosmetically acceptable emulgel formulation loaded with MZFE was obtained. The formulation and control exhibited optimum physicochemical stability in stress stability tests. The formulation exhibited promising photo-protective effects both in vitro (SPF = 14.215 ± 0.140) and in vivo (lasted for approximately 120 min).
 Conclusion: The developed MZFE-loaded test emulgel formulation possesses suitable photoprotection capability in vitro, and displays quenching effects against specific wavelengths of UV light, indicating a UV-filtering property

Determination of sun protection factor of vegetable and fruit extracts using UV–Visible spectroscopy: A green approach

Acute and chronic exposure to ultraviolet radiation leads to variety of changes in skin. For skin protection from deleterious effects of sunlight, sunscreen products are used in various forms having chemical and physical filters. These chemical formulations have adverse effects in chronic condition. Thus, involvement of herbal extracts could be of great choice owing to their specific radiation absorbing capacity. The rationale of this study was to determine the sun protection factor (SPF) of commonly consumed vegetables and fruits and compare it with that of a synthetic compound (Dibenzalacetone) and assess their efficacy as protecting ultraviolet (UV) radiations. Five vegetable samples namely Potato, Beetroot, Eggplant, Cucumber and Tomato and five fruit sample Banana, Papaya, Green Grapes, Black Grapes and Orange Fruits were examined for their SPF values at different temperature (7 °C, 25 °C, 45 °C) and pH (2, 7, 10) conditions. The photoprotective activity was recorded using spectrophotometric method and calculations were done using Mansur equation. Among all vegetable used the SPF of eggplant was found to be highest 14.37 at 25 °C and pH 7 while among fruits orange was found to be best at same conditions. It shows the possibility to use these extracts as a sunscreen in pharmaceutical preparations.

Electrohydrodynamic spray applicator for homogenous application and reduced overspray of sunscreen.

The recommended amount of sunscreen by hand application (2mg/cm2 ) is in reality not achieved, which decreases the homogeneity and thereby the effective sun protection factor (SPF). The homogeneity of sunscreen applied by a newly developed spray applicator using an electrostatically charged aerosol, for which a hand rubbing of the formulation is not necessary, is evaluated. In vivo experiments were performed on the volar forearms of human volunteers using the spray applicator compared to the standardized hand application according to ISO 24444. The distribution homogeneity was assessed qualitatively using in vivo laser scanning microscopy and quantitatively by absorption spectroscopy after tape stripping and by the standard deviation of multiple spatially displaced reflectance measurements for non-invasive SPF determination below the minimal erythemal dose, which showed a significantly higher homogeneity by 20.9% after spray application compared to hand application. Non-invasive SPF determination of multiple spatially displaced reflectance measurements was proven to be a suitable method for the non-invasive determination of the sunscreen distribution homogeneity. Electrostatically charged spray application increased the sunscreen distribution homogeneity on the skin and can reduce the amount of overspray.

Formulation and Determination of Sun Protection Factor In A Cream With Naturally Occurring Traditional Constituents

Formulation and Determination of Sun Protection Factor In A Cream With Naturally Occurring Traditional Constituents

Exploring the photo protective potential of solid lipid nanoparticle-based sunscreen cream containing Aloe vera.

Nowadays, the sunscreen creams are composed of mostly synthetic chemicals and other organic compounds which were found to enter into the blood stream on topical application raising concerns in the scientific community. The scientific community has now shifted their attention to herbal formulations due to toxicity of these synthetic molecules. Aloe vera is a xerophitic plant having excellent anti-oxidant properties. The permeation effect and drug stability of the drug candidate can be significantly enhanced by formulating it into solid lipid nanoparticles (SLN). The main objectives of the study were to formulate and evaluate Aloe vera-loaded SLN sunscreen cream and to determine its photoprotective potential. The Aloe vera-loaded SLNs were formulated by microemulsification technique. The developed SLNs were studied for its entrapment efficiency, poly dispersity index (PDI), zeta potential, particle size, and other characterization techniques. Finally, the optimized SLNs were incorporated into the sunscreen cream and evaluated for its spreadability, viscosity, extrudability, drug content, in vitro drug release, ex vivo permeation, determination of sun protection factor (SPF), skin irritation test, and accelerated stability studies. The in vitro SPF was found out to be 16.9 ± 2.44 and the in vivo SPF observed to be approximately 14.81 ± 3.81, respectively. Stability studies were performed under accelerated conditions and no appreciable changes in the parameters were noticed. The solid lipid nanoparticles of Aloe vera were incorporated into a cream and the SPF of the resultant sunscreen cream was found to be on par with the sunscreens that were currently available in the market.

Revisiting the Role of Irradiance in the Determination of Sunscreens' Sun Protection Factor.

The efficacy of a sunscreen tends to be associated with its sun protection factor (SPF) value, a figure determined in a test that relies on the independence of the SPF value to both UV radiation dose and irradiance. We probe these assumptions when photoinduced product degradation is present, and we estimate that the theoretical limit for their validity is when the sunfilter active molecule relaxation time is faster than ∼10 ns. While such threshold relaxation time should be compatible with the expected ultrafast relaxation mechanisms of sunfilter molecules (picoseconds), recent research on sunfilter photodynamics has identified the existence of much longer-lived molecular states. Such long lifetimes could compromise sunscreen performance and make the SPF value very different in natural sun irradiance conditions than in the solar simulated conditions typically used in SPF determination tests.

Anti-inflammatory / anti-oxidant activity of ingredients of sunscreen products? Implications for SPF.

ObjectiveThe Sun Protection Factor (SPF) of sunscreen products is derived from testing in vivo their ability to prevent erythema (“sunburn”). Recently, certain articles have raised concerns that sunscreen products may actively suppress erythema via anti‐inflammatory / anti‐oxidant (AI/AO) activity. These articles reason that this may result in a higher labelled SPF value than that provided by the efficacy of the UVR filters alone, giving consumers a “false sense of security”. On the other hand, since inflammatory processes are known to play a role in the mechanisms of photodamage / skin cancer induction and propagation, AI/AO activity may provide valuable incremental photoprotective benefit (provided that there is no interference with visible erythema). The objective of these studies, therefore, was to investigate the potential of AI/AO ingredients to suppress UVR‐induced erythemal response in human skin, in vivo.Methods In vivo studies with SPF30 sunscreen formulations containing a variety of AI/AO ingredients were performed according to the International Standard ISO24444:2010 method. While ISO24444:2010 requires assessment of erythema at 20 ± 4h post‐irradiation, an additional assessment at 5 h post‐irradiation was also used to determine potential delay in erythema development.ResultsNone of the formulations, containing a variety of AI/AO ingredients, influenced SPF determination in comparison to the vehicle formulation.ConclusionOur in vivo results demonstrate that commonly‐used AI/AO ingredients, at concentrations typically used in sunscreen products, neither influence SPF value nor delay erythemal response, i.e., the measured SPF reflects the true photoprotective capacity of the product.

PENENTUAN NILAI SPF EKSTRAK ETIL ASETAT DAUN MANGGA GEDONG MENGGUNAKAN SPEKTROFOTOMETRI UV - VIS

One way that is done to reduce the negative impact of sunlight is by using sunscreen. Sunscreen can protect the skin by spreading sunlight or absorbing sunlight radiation energy that is about the skin. Phenolic compounds especially flavonoid groups have the potential as a sunscreen because of the chromophore group (single conjugated double bond) capable of absorbing UV light both UV A and UV B, thus reducing the intensity of the skin. Flavonoids have three properties of photoprotektor that is UV absorption, antioxidant properties, and modulate some DNA signaling pathways. The potential of sunscreen can be expressed with Sun Protection Factor (SPF). SPF is designated as UV protection B and is not specifically intended to resist UV A and UV C. The purpose of this research is to know the value of SPF (Sun Protection Factor) of ethyl acetate extract of mango gedong leaves using UV-Vis spectrophotometry. Simplicia gedong mango leaves were extracted using ethyl acetate solvent by reflux. Gedong mango leaf extract identified flavonoid compound using 10% NaOH and H2SO4 (concentrated). Determination of SPF (Sun Protection Factor) value of med gedong leaf extract using UV-Vis spectrophotometry method. The concentration of ethyl acetate extract of mango gedong leaves used was 120 ppm, 240 ppm and 360 ppm. The SPF (Sun Protection Factor) values were analyzed using Mansur method. The result of identification of flavonoid compound showed that the extract of ethyl acetate of mango gedong leaves positively contain flavonoids, while the result of SPF (Sun Protection Factor) extract of ethyl acetate of mango gedong leaves was 5,556; 16,675 and 22,243. The SPF (Sun Protection Factor) extract of 5,556 muddy ethyl acetate leaves including moderate protection type, 16,675 and 22,243 including ultra-protection type when tested using UV-Vis spectrophotometry by Mansur method

The Effect of UVB Irradiation and Oxidative Stress on the Skin Barrier-A New Method to Evaluate Sun Protection Factor Based on Electrical Impedance Spectroscopy.

Sunlight is vital for several biochemical processes of the skin organ. However, acute or chronic exposure to ultraviolet radiation (UVR) has several harmful effects on the skin structure and function, especially in the case of the failing function of antioxidative enzymes, which may lead to substantial tissue damage due to the increased presence of reactive oxygen species (ROS). The aim of this work was to investigate the combined effect of ultraviolet B (UVB) irradiation and oxidative stress on the skin barrier integrity. For this, we employed electrical impedance spectroscopy (EIS) to characterize changes of the electrical properties of excised pig skin membranes after various exposure conditions of UVB irradiation, oxidative stress, and the inhibition of antioxidative enzymatic processes. The oxidative stress was regulated by adding hydrogen peroxide (H2O2) as a source of ROS, while sodium azide (NaN3) was used as an inhibitor of the antioxidative enzyme catalase, which is naturally present throughout the epidermis. By screening for the combined effect of UVB and oxidative stress on the skin membrane electrical properties, we developed a new protocol for evaluating these parameters in a simple in vitro setup. Strikingly, the results show that exposure to extreme UVB irradiation does not affect the skin membrane resistance, implying that the skin barrier remains macroscopically intact. Likewise, exposure to only oxidative stress conditions, without UVB irradiation, does not affect the skin membrane resistance. In contrast to these observations, the combination of UVB irradiation and oxidative stress conditions results in a drastic decrease of the skin membrane resistance, indicating that the integrity of the skin barrier is compromised. Further, the skin membrane effective capacitance remained more or less unaffected by UVB exposure, irrespective of simultaneous exposure of oxidative stress. The EIS results were concluded to be associated with clear signs of macroscopic tissue damage of the epidermis as visualized with microscopy after exposure to UVB irradiation under oxidative stress conditions. Finally, the novel methodology was tested by performing an assessment of cosmetic sunscreen formulations with varying sun protection factor (SPF), with an overall successful outcome, showing good correlation between SPF value and protection capacity in terms of skin resistance change. The results from this study allow for the development of new skin sensors based on EIS for the detection of skin tissue damage from exposure to UVB irradiation and oxidative stress and provide a new, more comprehensive methodology, taking into account both the influence of UVB irradiation and oxidative stress, for in vitro determination of SPF in cosmetic formulations.