In vitroevaluation of sun protection factors of sunscreen agents using a novel UV spectrophotometric technique

Enhanced sun protection factor of octocrylene with green tea and bhringraj extracts

OBJECTIVES

The aim of this study of sun protection factor boosting effect sunscreen compositions with herbal extract and combination with octocrylene.

MATERIALS AND METHODS

The standardized herbal extracts procured and studied their sun protection Factors. Camellia Sinensis (Green tea) leaf Extract, Eclipta prostrata (bhringraj) leaf extract are selected for the development of the herbal sunscreen composition along with octocrylene as synthetic sunscreen. The developed sunscreen composition contains defined concentration of herbal extracts and octocrylene were evaluated for their different physicochemical properties and stability. Sun protection factor boosting effect of herbal extracts is studied combination with octocrylene.

RESULTS

Invitro SPF studied for herbal extract individually and combination with octocrylene. The results of Invitro SPF study revealed the presence of green tea extract and, Eclipta prostrata (bhringraj) leaf extract shows excellent sun protection factor (SPF) boosting value of sunscreen composition containing 5% concentration of herbal extract and octocrylene. The sunscreen formulation containing 5% herbal extracts are stable for 12 weeks in an oven (45 °C).

CONCLUSION

The findings of this in-vitro SPF study revealed a sun protection boosting capacity of green tea extract and bhringraj extract confirmed.

SUMMARY

The over exposure of human skin to Ultra-Violet Radiation (UVR) can trigger photodamage, UV burn, pigmentation, erythema, and enhance the chance of dermal carcinoma. UVR causes DNA damage, which leads to dermal cancer. Daily sunscreens protect the skin from the adverse effects of sun rays, especially UVB (290-320 nm) and UVA (320-400 nm). The ozone layer filters UVC (200-290 nm) radiation when it enters into atmosphere of the earth. UVB causes sunburn, photo damage and cause mutagenic changes in nucleic acids. UVA increases ROS (Reactive Oxygen Species) accumulation. ROS is responsible for cell repair which leads to carcinogenesis, and the cause of photodamage. Herbal extracts contain polyphenols, and flavonoids act as a natural sunscreen that will filter Ultra-Violet (UVB) light and contain antioxidant characteristics to modulate the photo-oxidative damage that results from UV-induced Reactive Oxygen Species production. The UVR protection of most herbal extracts are required to attain the higher UV protection in the sun care products. The approaches for preparing sun care products with higher Sun Protection Factor (SPF) possible through Oil in water formulation with herbal extract combinations of octocrylene. The developed sunscreen composition containing different concentration of herbal extracts were evaluated for their other physicochemical properties and stability. Invitro SPF was studied for Camellia Sinensis (Green tea) Leaf Extract and Eclipta prostrata (bhringraj) leaf extract individually and in combination with octocrylene. The results of the Invitro SPF study revealed the Camellia Sinensis (Green tea) Leaf Extract with octocrylene shows better Sun protection factor than Eclipta prostrata (bhringraj) leaf extract with octocrylene. The Sun Protection Factor (SPF) enhancement value of sunscreen compositions was compared to both sunscreen macroemulsion and nanoemulsion.

Expert Recommendations on the Evaluation of Sunscreen Efficacy and the Beneficial Role of Non-filtering Ingredients

A variety of non-filtering agents have been introduced to enhance sunscreen photoprotection. Most of those agents have only weak erythema protective properties but may be valuable and beneficial in supporting protection against other effects of UV radiation, such as photoimmunosuppression, skin aging, and carcinogenesis, as well as photodermatoses. The question arises how to measure and evaluate this efficacy since standard SPF testing is not appropriate. In this perspective, we aim to provide a position statement regarding the actual value of SPF and UVA-PF to measure photoprotection. We argue whether new or additional parameters and scales can be used to better indicate the protection conferred by these products against the detrimental effects of natural/artificial, UV/visible light beyond sunburn, including DNA damage, photoimmunosuppression and pigmentation, and the potential benefits of the addition of other ingredients beyond traditional inorganic and organic filters to existing sunscreens. Also, we debate the overall usefulness of adding novel parameters that measure photoprotection to reach two tiers of users, that is, the general public and the medical community; and how this can be communicated to convey the presence of additional beneficial effects deriving from non-filtering agents, e.g., biological extracts. Finally, we provide a perspective on new challenges stemming from environmental factors, focusing on the role of the skin microbiome and the role of air pollutants and resulting needs for photoprotection.

Fluorescent films based on PVDF doped with carbon dots for evaluation of UVA protection of sunscreens and fabrication of cool white LEDs

The ultraviolet-A (UVA) radiation from sunlight that reaches the earth's surface can induce premature aging, immunosuppression, and skin cancer. Commercial sunscreen products offer limited information regarding protection against UVA light. Therefore, proposing new and practical alternatives to evaluate the UVA protection capacity of commercial sunscreens is highly imperative. This work presents a novel methodology for evaluating the quality of sunscreens using polyvinylidene fluoride (PVDF) based films doped with plant derived photoluminescent carbon dots (CDs). The bluish white light emitting (under UVA exposure) PVDF/CD films were used to evaluate the UVA protection capacity of 8 different commercial sunscreens. The evaluation of UVA protection is based on the fluorescence attenuation observed with the films coated with sunscreens. In addition, visual evaluation of the UVA protection capacity of the sunscreens and commercial glasses, using the same films and a commercial UV lamp at 365 nm, has also been demonstrated. Two sunscreens with limited UVA protection were identified using the proposed simple evaluation mechanisms without conventionally used expensive instruments and complex methodologies. Additionally, the capacity of PVDF/CD material has been explored for the possible fabrication of WLEDs with cool light emission.

The Synergistic Behavior of Antioxidant Phenolic Compounds Obtained from Winemaking Waste's Valorization, Increased the Efficacy of a Sunscreen System

Grape pomace retains polyphenols in the peels and in the seeds after winemaking, which is indicative of the high valorization potential of this industrial waste. There is strong evidence that phenolics are robust antioxidants and confer photoprotection; thus, it is rational to apply these active compounds from winemaking waste to sunscreens, in order to increase UV protection. Despite the importance of this class of cosmetics to public health, more efficacious strategies are still needed to overcome the problems caused by the photoinstability of some UV filters. The hydroethanolic extract of Vitis vinifera L. grapes was obtained by percolation and then lyophilized. Six formulations were developed: Type I—cosmetic base and UV filters; Type II—cosmetic base and extract; and Type III—cosmetic base, extract and UV filters. Each formulation was prepared in the pHs 5 and 7. The antioxidant activities of the samples were measured by DPPH• and expressed in Trolox^® equivalents (TE), and their photostability and in vitro sun protection factor (SPF) were analyzed by diffuse reflectance spectrophotometry. The anti-radical efficiencies observed in the formulations with grape extract were: (II) 590.12 ± 0.01 μmol TE g⁻¹ at pH 5 and 424.51 ± 0.32 μmol TE g⁻¹ at pH 7; (III) 550.88 ± 0.00 μmol TE g⁻¹ at pH 5 and 429.66 ± 0.10 μmol TE g^−1, at pH 7, demonstrating that the UV filters, butylmethoxydibenzoyl methane, ethylhexyl methoxycinnamate and ethylhexyl dimethyl 4-aminobenzoic acid had no influence on this effect. The photoprotective efficacy and the photostability of formulation III containing the extract and UV filters at pH 5 suggested that a synergism between the active molecules provided an 81% increase in SPF. Additionally, this was the only sample that maintained a broad spectrum of protection after irradiation. These results confirmed that the grape pomace extract has multifunctional potential for cosmetic use, mainly in sunscreens, granting them superior performance.

Sensitive Synchronous Spectrofluorimetric Study of Certain Sunscreens Using Fluorescence Enhancers in Cosmeceutical Formulations

Synchronous spectrofluorimetric methods could be successfully adopted for simultaneous determination of Octinoxate (OMC), Avobenzone (AVO), Octyltriazone (OT), and Phenyl benzimidazole sulfonic acid (PBSA) in moisturizing sunscreen lotion, utilizing β-CD as fluorescence enhancer, and determination of Avobenzone (AVO), Homosalate, Tinosorb M and Phenyl benzimidazole sulfonic acid (PBSA) in presence of Octocrylene (OCR) in whitening sunscreen cream, using micellar medium of Sodium Dodecyl Sulfate (SDS) to enhance fluorescence intensity. For first product, zero order synchronous spectrofluorimetric method was used for determination of OMC and AVO, and derivative synchronous spectrofluorimetric technique was utilized for OT and PBSA in quaternary mixture. Linear calibration curves were obtained in a concentration range of 0.5-8 μg mL^- 1 for OMC and AVO, and in range of 0.05-3 μg mL^- 1 for OT and 0.001-5 μg mL^- 1 for PBSA, by measuring the fluorescence at 370, 405, 333.2 and 340.6 nm, respectively. For second product, first derivative synchronous fluorescence method was used for each UV-filter. A linear calibration curves were obtained in a concentration range of 0.5-8 μg mL^- 1 for AVO, in range of 0.1-8 μg mL^- 1 for Homosalate, 2-10 μg mL^- 1 for Tinosorb M and 0.001-5 μg mL^- 1 for PBSA, by measuring the fluorescence at 409.8, 373, 307.2 and 316.8 nm, respectively. The detection limits are well below the maximum admissible concentration. The proposed methods were validated according to ICH guidelines and successfully applied to determine sunscreens in pure form and in Cosmeceutical formulations. All the results obtained were compared with those of published methods, where no significant difference was observed.

A new hair follicle-derived human epidermal model for the evaluation of sunscreen genoprotection

Induction of skin cancer is the most deleterious effect of excessive exposure to sunlight. Accurate evaluation of sunscreens to protect the genome is thus of major importance. In particular, the ability of suncare products to prevent the formation of DNA damage should be evaluated more directly since the Sun Protection Factor is only related to erythema induction. For this purpose, we developed an in vitro approach using a recently characterized reconstituted human epidermis (RHE) model engineered from hair follicle. The relevance of this skin substitute in terms of UV-induced genotoxicity was compared to ex vivo explants exposed to solar-simulated radiation (SSR). The yield of bipyrimidine photoproducts, their rate of repair, and the induction of apoptosis were very similar in both types of skin samples. In order to evaluate the protection afforded by sunscreen against DNA damage, bipyrimidine photoproducts were quantified in tissue models following SSR exposure in the presence or absence of a SPF50+ formula. A rather high DNA protection factor of approximately 20 was found in RHE, very similar to that determined for explants. Thus, RHE is a good surrogate to human skin, and also a convenient and useful tool for investigation of the genoprotection of sunscreens.

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.

Quality by Design-Based Development of a Stability-Indicating RP-HPLC Method for the Simultaneous Determination of Methylparaben, Propylparaben, Diethylamino Hydroxybenzoyl Hexyl Benzoate, and Octinoxate in Topical Pharmaceutical Formulation

A stability-indicating RP-HPLC method has been developed and validated for the simultaneous determination of methylparaben (MP), propylparaben (PP), diethylamino hydroxybenzoyl hexyl benzoate (DAHHB), and octinoxate (OCT) in topical pharmaceutical formulation. The desired chromatographic separation was achieved on the Kinetex(TM) C18 (250 × 4.6 mm, 5 μm) column using gradient elution at 257 nm detection wavelength. The optimized mobile phase consisted of a buffer : acetonitrile : tetrahydrofuran (60 : 30 : 10, v/v/v) as solvent A and acetonitrile : tetrahydrofuran (70 : 30, v/v) as solvent B. The method showed linearity over the range of 0.19-148.4 μg/mL, 0.23-15.3 μg/mL, 1.97-600.5 μg/mL, and 1.85-451.5 μg/mL for MP, PP, DAHHB, and OCT, respectively. Recovery for all the components was found to be in the range of 98-102%. The stability-indicating capability of the developed method was established by analysing the forced degradation samples in which the spectral purity of MP, PP, DAHHB, and OCT, along with the separation of the degradation products from the analyte peaks, was achieved. The proposed method was successfully applied for the quantitative determination of MP, PP, DAHHB, and OCT in the lotion sample. The design expert with ANOVA software with the linear model was applied and a 2(4) full factorial design was employed to estimate the model coefficients and also to check the robustness of the method. Results of the two-level full factorial design, 2(4) with 20 runs including four centrepoint analysis based on the variance analysis (ANOVA), demonstrated that all four factors, as well as the interactions of resolution between DAHHB and OCT are statistically significant.

Teucrium polium L. extract adsorbed on zinc oxide nanoparticles as a fortified sunscreen

Introduction:

Zinc oxide nanoparticles (ZnOn) have been used as carriers and sun-protecting agents for Teucrium polium L. extract to enhance sun protection. ZnOn was synthesized by hydrolyzing zinc acetate using sodium hydroxide with mean particle diameter less than 500 nm.

Materials and Methods:

Top flowerings of T. polium L. were extracted by percolation method with petroleum ether, chloroform, and 80% methanol consecutively. Methanolic extract was lyophilized and used as a flavonoid-rich fraction. Sunscreen was prepared by the reconstitution of 0.5 g of the lyophilized extract in water and mixing with 0.5 to 2 g zinc-oxide (ZnO). Sun protection factor (SPF) of the aqueous extract of T. polium, the prepared gel, as well as the zinc oxide suspension alone and in combination with each other was determined spectrophotometrically based on a modified Transpore^® tape method.

Results and Conclusion:

Obtained results showed that the T. polium extract has a wide band of ultraviolet radiation (UV) spectrum absorption ranging from 250 nm to 380 nm. SPF of the combination product in the ultraviolet B (UVB) area was greater than 80, revealing a synergistic action between ZnO and T. polium. The adsorption of flavonoids of T. polium on Zinc-oxide nanoparticles (ZnOn) slowed down their release thereby lengthening their persistence on the skin and contributing to further duration of action.

Development and Validation of a Stability Indicating RP-HPLC Method for the Determination of Two Sun Protection Factors (Koptrizon and Tinosorb S) in Topical Pharmaceutical Formulations Using Experimental Designs

A novel, simple, validated stability indicating HPLC method was developed for determination of Koptrizon and Tinosorb S. Stability indicating power of the method was established by forced degradation study. The chromatographic separation was achieved with Waters X Bridge column, by using mobile phase consisting of a mixture of acetonitrile : tetrahydrofuran : water (38 : 38 : 24, v/v/v). The method fulfilled validation criteria and was shown to be sensitive, with limits of detection (LOD) and quantitation (LOQ) of 0.024 and 0.08 μg  for Koptrizon and 0.048 and 0.16 μg  for Tinosorb S, respectively. The developed method is validated for parameters like precision, accuracy, linearity, solution stability, specificity, and ruggedness as per ICH norms. Design expert with ANOVA software with linear model was applied and a 23 full factorial design was employed to estimate the model coefficients and also to check the robustness of the method. Results of the two-level full factorial design, 23 with 10 runs including two-centre-point analysis based on the variance analysis (ANOVA), demonstrated that all three factors, as well as the interactions between retention time of Koptrizon, Tinosorb S, and USP plate count for Koptrizon, are statistically significant.

In vitro evaluation of sunscreens: an update for the clinicians

Topical sunscreens contain molecules or molecular complexes that can absorb, reflect, or scatter UV photons. Evaluation of the efficacy of sunscreen products has been made through the Sun Protection Factor (SPF), a mean of quantitatively assessing in vivo the degree of protection offered by sunscreen products against solar radiation. In vivo evaluation of SPF has several drawbacks. First of all, this evaluation method is expensive in terms of money and time. Moreover, it raises several ethical issues concerning the potential damage to skin volunteers. Several in vitro techniques have been developed, but at present there is no broadly accepted method. In this paper, we will discuss some of the recent advances concerning the in vitro evaluation of sunscreens which would be acceptable for replacing in vivo assays.