Differential effects of topical vitamin E and C E Ferulic® treatments on ultraviolet light B-induced cutaneous tumor development in Skh-1 mice

The Effect of α-Arbutin on UVB-Induced Damage and Its Underlying Mechanism

Ultraviolet radiation can heighten tyrosinase activity, stimulate melanocyte production, impede the metabolism of numerous melanocytes, and result in the accumulation of plaques on the skin surface. α-Arbutin, a bioactive substance extracted from the arbutin plant, has been widely used for skin whitening. In this study, the whitening effect of α-arbutin by inhibiting tyrosinase activity and alleviating the photoaging effect induced by UVB are investigated. The results indicate that α-arbutin can inhibit skin inflammation, and its effectiveness is positively correlated with concentration. Moreover, α-arbutin can reduce the skin epidermal thickness, decrease the number of inflammatory cells, and down-regulate the expression levels of IL-1β, IL-6 and TNF-α, which are inflammatory factors. It also promotes the expression of COL-1 collagen, thus playing an important role in anti-inflammatory action. Network pharmacology, metabolomics and transcriptomics further confirm that α-arbutin is related to the L-tyrosine metabolic pathway and may interfere with various signaling pathways related to melanin and other photoaging by regulating metabolic changes. Therefore, α-arbutin has a potential inhibitory effect on UVB-induced photoaging and possesses a whitening effect as a cosmetic compound.

Evaluation of the effect of phenylpropanoids on the binding of heparin to human serum albumin and glycosylated human serum albumin concerning anticoagulant activity: A comparison study

The nonenzymatic advanced glycation end products (AGEs) and the accumulation of AGEs are the two main factors associated with the long-term pathogenesis of diabetes. Human serum albumin (HSA) as the most abundant serum protein has a higher fortuity to be modified by nonenzymatic glycation. In this study, the interaction of three phenylpropanoids (caffeic acid (Caf), p-coumaric acid (Cou), and cinnamic acid (Cin)) toward HSA and glycosylated HSA (gHSA) was analyzed by multiple spectroscopic techniques combined with molecular docking. The formation of fibrils in HSA and gHSA was confirmed by the Thioflavin T (ThT) assay. The phenylpropanoids have shown anti-fibrillation properties in vitro. The obtained thermodynamic parameters indicated that hydrogen bonding and van der Waals forces are the main forces in the binding interaction, and the quenching mechanism of the protein fluorescence is static. Molecular docking results, as well as the in vitro results, showed that Caf, Cou, and Cin exhibit more stable interactions with HSA, respectively. In addition, molecular docking analysis showed that Caf and Cou interact well with K199. Given the critical role of K199 in HSA glycosylation in diabetic patients, this process inhibits the interaction of stabilizer compounds and thus accelerates gHSA aggregation.

Ferulic Acid Activity in Topical Formulations: Technological and Scientific Prospecting

INTRODUCTION

Ferulic acid is a phenolic compound widely distributed in monocotyledons, with several applications, especially in pharmaceutical and dermo-cosmetic industries. It has proven antioxidant and anti- inflammatory activities, among others, which are mainly ascribed to its molecular structure. The main factor that can lead to serious skin damages like inflammation, dryness, wrinkles, and cancer is the exposure to UV radiation that is responsible for an increased level of radical oxygen species.

OBJECTIVE

This review aims to evaluate the application of ferulic acid in topical formulations and the technologies used to enhance its bioavailability and stability, as well as to get a clearer picture of its effects by in vivo and in vitro studies.

METHODS

It covers technological publications in the WIPO, EPO, INPI, and USPTO databases and scientific publications in the PubMed, Web of Sciences, and Science Direct databases, exploring the trend and application of this compound by country and year of publication.

RESULTS

Both the scientific and technological analyses showed the importance and tendency in the association of the Ferulic Acid and other vitamins and actives. The synergic effect certainly provides a better result, performance, and stability of the compounds, which cleared the great spectrum and applicability of the Ferulic Acid in topical formulations.

CONCLUSION

The present literature survey revealed that ferulic acid exerts an important activity in several formulations for topical application and improved the stability and bioavailability when combined with new technologies and methods, showing an open path to target the treatment of skin disorders.

Keratinocyte Carcinoma and Photoprevention: The Protective Actions of Repurposed Pharmaceuticals, Phytochemicals and Vitamins

Simple Summary

Keratinocyte carcinoma is the most common type of cancer. Sun exposure and ultraviolet radiation are significant contributors to the development of carcinogenesis, mediated by DNA damage, increased oxidative stress, inflammation, immunosuppression and dysregulated signal transduction. Photoprevention involves using different compounds to delay or prevent ultraviolet radiation-induced skin cancer. In this review, we look at new avenues for systemic photoprevention that are based on pharmaceuticals, plant-derived phytochemicals and vitamins. We also investigate the mechanisms underlying these strategies for preventing the onset of carcinogenesis.

Abstract

Ultraviolet radiation (UVR) arising from sun exposure represents a major risk factor in the development of keratinocyte carcinomas (KCs). UVR exposure induces dysregulated signal transduction, oxidative stress, inflammation, immunosuppression and DNA damage, all of which promote the induction and development of photocarcinogenesis. Because the incidence of KCs is increasing, better prevention strategies are necessary. In the concept of photoprevention, protective compounds are administered either topically or systemically to prevent the effects of UVR and the development of skin cancer. In this review, we provide descriptions of the pathways underlying photocarcinogenesis and an overview of selected photoprotective compounds, such as repurposed pharmaceuticals, plant-derived phytochemicals and vitamins. We discuss the protective potential of these compounds and their effects in pre-clinical and human trials, summarising the mechanisms of action involved in preventing photocarcinogenesis.

Comparison of Single and Combined Use of Ergothioneine, Ferulic Acid, and Glutathione as Antioxidants for the Prevention of Ultraviolet B Radiation-Induced Photoaging Damage in Human Skin Fibroblasts

Ultraviolet B (UVB) irradiation can cause human skin damage or skin aging and wrinkle formation through photochemical reactions. Antioxidative substances may ameliorate UV damage. In this study, the anti-photoaging activity of three antioxidants—ergothioneine, ferulic acid, and glutathione—was investigated after UVB irradiation of Hs68 human skin fibroblast cells. The cells treated with these three antioxidants appeared similar to unirradiated control cells. UVB irradiation decreased cell viability by 26% compared to that of unirradiated control cells. However, the addition of either single or combined antioxidants enhanced cell viability after UVB irradiation. These three antioxidants can inhibit the production of reactive oxygen species (ROS) induced by the UVB irradiation of the Hs68 cells. Ergothioneine showed a greater inhibitory effect on matrix metalloproteinase-1 (MMP-1) performance than the other two antioxidants. IL-1 alpha was not detected in the Hs68 cells after exposure to a radiation dose of 150 mJ/cm2. Ergothioneine showed better restoration of type 1 procollagen than either ferulic acid or glutathione. Based on these results, the addition of two antioxidants was expected to restore type Ι procollagen production. In summary, these results demonstrate that the three tested antioxidants protect the skin against UVB-induced damage. The single and combined use of ergothioneine, ferulic acid, and glutathione has the potential for development as anti-photoaging materials in cosmetic applications.

Dopamine Prevents Ultraviolet B-induced Development and Progression of Premalignant Cutaneous Lesions through its D2 Receptors

Although the role of dopamine (DA) in malignant tumors has been reported, its function in premalignant lesions is unknown. Herein we report that the stimulation of DA D₂ receptors in endothelial cells in ultraviolet B (UVB)-induced cutaneous lesions in mice significantly reduced the tumor number, tumor burden, and malignant squamous cell carcinoma in these animals. DA D₂ receptor agonist inhibited VEGFA-dependent proangiogenic genes in vitro and in vivo. However, the mice pretreated with selective DA D₂ receptor antagonist inhibited the actions of the agonist, thereby suggesting that the action of DA was through its D₂ receptors in the endothelial cells. To our knowledge, this study is the first to report DA-mediated regulation of pathogenesis and progression of UVB-induced premalignant skin lesions. PREVENTION RELEVANCE: This investigation demonstrates the role of dopamine and its D₂ receptors in UVB induced premalignant squamous cell skin lesions and how DA through its D₂ receptors inhibits the development and progression of these lesions and subsequently prevents squamous cell carcinoma of the skin.

Suppression of beta 2 adrenergic receptor actions prevent UVB mediated cutaneous squamous cell tumorigenesis through inhibition of VEGF-A induced angiogenesis

Although beta 2 adrenergic receptors (β2 ADR) are present in the keratinocytes, their role in cutaneous squamous cell tumorigenesis needs to be ascertained. For the first time, we report here that selective β2 ADR antagonists by inhibiting β2 ADR actions significantly retarded the progression of ultraviolet B (UVB) induced premalignant cutaneous squamous cell lesions. These antagonists acted by inhibiting vascular endothelial growth factor-A (VEGF) mediated angiogenesis to prevent UVB radiation-induced squamous cell carcinoma of the skin.

Topical application of a commercially available formulation of vitamin C stabilized by vitamin E and ferulic acid reduces tissue viability and protein synthesis in ex vivo human normal skin

BACKGROUND

Aqueous formulations of vitamin C stabilized by vitamin E and ferulic acid at low pH effectively protect skin against reactive oxygen species-induced damage. However, the effects of these formulations on human skin have not clearly been described. The aim of this study was to investigate whether topical application of two commercially available formulations of vitamin C alter human skin using an ex vivo model.

METHODS

Human skin explants were topically treated on alternate days with commercially available formulation 1 (15% vitamin C) at 100% (without dilution), 50%, or 10% diluted in saline or formulation 2 (20% vitamin C) at 100% (without dilution), 50%, or 10% diluted in saline. Only saline was applied to control skin explants.

RESULTS

Topical formulation 1 at 100%, 50%, or 10%, but not formulation 2 at 100%, 50%, or 10%, reduced the viability of ex vivo human skin compared to the control after 7, 10, and 13 days. In addition, compared to the control, ex vivo human skin treated with formulation 1 at 50%, but not formulation 2 at 50%, also decreased mRNA levels of actin and ribosomal protein L10 and gene expression of extracellular matrix components after 10 days. Furthermore, after 10 days, topical application of formulation 1 at 50%, but not formulation 2 at 50%, decreased the protein expression of proliferating cellular nuclear antigen, lysyl oxidase, β-actin, and glyceraldehyde-3-phosphate dehydrogenase compared to the control.

CONCLUSIONS

Topical formulation 1, but not formulation 2, may reduce the viability of and protein synthesis in ex vivo human skin. Those effects might be due to action of vehicle of formulation 1 on ex vivo human skin.

Ultraviolet A protective potential of plant extracts and phytochemicals

Chronic exposure to solar radiation is related to an increased incidence of various skin disorders, including premature skin aging and melanoma and non-melanoma skin cancers. Ultraviolet (UV) photons in particular are responsible for skin damage. Solar UV photons mainly belong to UVA wavebands, however UVA radiation has been mostly ignored for a long time. At the cellular level, UVA photons mainly provoke indirect oxidative damage to biomolecules via the massive generation of unstable and highly reactive compounds. Human skin has several effective mechanisms that forestall, repair and eliminate damage caused by solar radiation. Regardless, some damage persists and can accumulate with chronic exposure. Therefore, conscious protection against solar radiation (UVB+UVA) is necessary. Besides traditional types of photoprotection such as sunscreen use, new strategies are being searched for and developed. One very popular protective strategy is the application of phytochemicals as active ingredients of photoprotection preparations instead of synthetic chemicals. Phytochemicals usually possess additional biological activities besides absorbing the energy of photons, and those properties (e.g. antioxidant, anti-inflammatory) magnify the protective potential of phytochemicals and extracts. Therefore, compounds of natural origin are in the interest of researchers as well as developers. In this review, only studies on UVA protection with well-documented experimental conditions are summarized. This article includes 17 well standardized plant extracts (Camellia sinensis (L.) Kuntze, Silybum marianum L. Gaertn., Punica granatum L., Polypodium aureum L., Vaccinium myrtillus L., Lonicera caerulea L., Thymus vulgaris L., Opuntia ficus-indica (L.) Mill., Morinda citrifolia L., Aloe vera (L.) Burm.f., Oenothera paradoxa Hudziok, Galinsoga parviflora Cav., Galinsoga quadriradiata Ruiz et Pavón, Hippophae rhamnoides L., Cola acuminata Schott & Endl., Theobroma cacao L. and Amaranthus cruentus L.) and 26 phytochemicals.

2-Methoxyestradiol and Its Combination with a Natural Compound, Ferulic Acid, Induces Melanoma Cell Death via Downregulation of Hsp60 and Hsp90

Melanoma is an aggressive type of skin cancer with one of the highest mortality rates. Notably, its incidence in the last few decades has increased faster than any other cancer. Therefore, searching for novel anticancer therapies is of great clinical importance. In the present study, we investigated the anticancer potential of 2-methoxyestradiol, potent chemotherapeutic, in the A375 melanoma cellular model. In order to furthermore evaluate the anticancer efficacy of 2-methoxyestradiol, we have additionally combined the treatment with a naturally occurring polyphenol, ferulic acid. The results were obtained using the melanoma A375 cellular model. In the study, we used MTT assay, flow cytometry, and western blot techniques. Herein, we have evidenced that the molecular mechanism of action of 2-methoxyestradiol and ferulic acid is partly related to the reduction of Hsp60 and Hsp90 levels and the induction of nitric oxide in the A375 melanoma cell model, while no changes were observed in Hsp70 expression after 2-methoxyestradiol and ferulic acid treatment separately or in combination. This is especially important in case of chemoresistance mechanisms because the accumulation of Hsp70 reduces induction of cancer cell death, thus decreasing antitumour efficacy.

Phenylpropanoids and its derivatives: biological activities and its role in food, pharmaceutical and cosmetic industries

Phenylpropanoids and their derivatives are plant secondary metabolites widely present in fruits, vegetables, cereal grains, beverages, spices and herbs. They are known to have multifaceted effects which include antimicrobial, antioxidant, anti-inflammatory, antidiabetic, anticancer activities and as well as exhibits renoprotective, neuroprotective, cardioprotective and hepatoprotective effects. Owing to their antioxidant, antimicrobial and photoprotective properties, these compounds have wide application in the food (preservation, packaging films and edible coating), pharmaceutical, cosmetic and other industries such as textile (colorant), biofuel (antioxidant additive) and sensors (sensing biologically relevant molecules). Phenylpropanoids are present in commercially available dietary supplements and skin care products. In this review, we have presented the current knowledge on the biosynthesis, occurrence, biological activities of phenylpropanoids and their derivatives, along with the mechanism of action and their potential applications in various industries.

Safety Assessment of Tocopherols and Tocotrienols as Used in Cosmetics

The Cosmetic Ingredient Review (CIR) Expert Panel (Panel) assessed the safety of 14 tocopherols and tocotrienols and concluded these ingredients are safe as used in cosmetics. The tocopherols are reported to function in cosmetics as antioxidants or skin-conditioning agents; in contrast, tocotrienols are not reported to function as an antioxidants in cosmetics but as a light stabilizer, oral care agent, or skin-conditioning agent. The Panel reviewed the new and existing animal and clinical data to determine the safety of these ingredients and found it appropriate to extrapolate the existing information to conclude on the safety of all the tocopherols and tocotrienols.

Antioxidants in dermatology

The skin cells continuously produce, through cellular respiration, metabolic processes or under external aggressions, highly reactive molecules oxidation products, generally called free radicals. These molecules are immediately neutralized by enzymatic and non-enzymatic systems in a physiological and dynamic balance. In situations where this balance is broken, various cellular structures, such as the cell membrane, nuclear or mitochondrial DNA may suffer structural modifications, triggering or worsening skin diseases. several substances with alleged antioxidant effects has been offered for topical or oral use, but little is known about their safety, possible associations and especially their mechanism of action. The management of topical and oral antioxidants can help dermatologist to intervene in the oxidative processes safely and effectively, since they know the mechanisms, limitations and potential risks of using these molecules as well as the potential benefits of available associations.

Mitochondria-Targeted Vitamin E Protects Skin from UVB-Irradiation

Mitochondria-targeted vitamin E (MVE) is designed to accumulate within mitochondria and is applied to decrease mitochondrial oxidative damage. However, the protective effects of MVE in skin cells have not been identified. We investigated the protective effect of MVE against UVB in dermal fibroblasts and immortalized human keratinocyte cell line (HaCaT). In addition, we studied the wound-healing effect of MVE in animal models. We found that MVE increased the proliferation and survival of fibroblasts at low concentration (i.e., nM ranges). In addition, MVE increased collagen production and downregulated matrix metalloproteinase1. MVE also increased the proliferation and survival of HaCaT cells. UVB increased reactive oxygen species (ROS) production in fibroblasts and HaCaT cells, while MVE decreased ROS production at low concentration. In an animal experiment, MVE accelerated wound healing from laser-induced skin damage. These results collectively suggest that low dose MVE protects skin from UVB irradiation. Therefore, MVE can be developed as a cosmetic raw material.

Tocopherols in cancer: An update

Tocopherols exist in four forms designated as α, β, δ, and γ. Due to their strong antioxidant properties, tocopherols have been suggested to reduce the risk of cancer. Cancer prevention studies with tocopherols have mostly utilized α-tocopherol. Large-scale clinical trials with α-tocopherol provided inconsistent results regarding the cancer-preventive activities of tocopherols. This review summarizes our current understanding of the anticancer activities of different forms of tocopherols based on follow-up of the clinical trials, recent epidemiological evidences, and experimental studies using in vitro and in vivo models. The experimental data provide strong evidence in support of the anticancer activities of δ-tocopherol, γ-tocopherol, and the natural tocopherol mixture rich in γ-tocopherol, γ-TmT, over α-tocopherol. Such outcomes emphasize the need for detailed investigation into the cancer-preventive activities of different forms of tocopherols to provide a strong rationale for intervention studies in the future.

Disruption of redox homeostasis and carcinogen metabolizing enzymes changes by administration of vitamin E to rats

AIMS

A large meta-analysis of randomized clinical trials has seriously questioned chemoprevention based on vitamins including vitamin E (VE), and an increased risk for cancer among long-term users was actually seen. However, the mechanism underlying these findings still remain unknown. To clarify the mechanism, in an in vivo model we studied the putative disruption of redox homeostasis and the perturbation of carcinogen metabolizing enzymes determined by VE.

MAIN METHODS

Male Sprague-Dawley rats were treated ip with either 100 or 200mg/kg b.w. daily for 7 or 14 consecutive days. Controls received vehicle only. Cytochrome P450 (CYP) content, CYP-reductase, CYP-linked monooxygenases, as well as phase-II and the antioxidant enzymes catalase and

NAD(P)H

quinone reductase were investigated in both liver and kidney. Free radical species in tissue subcellular preparations were measured by electronic paramagnetic resonance (EPR) spectroscopy coupled to a radical probe technique.

KEY FINDINGS

No substantial changes of hepatic xenobiotic metabolism enzymes were determined by VE. Conversely, a powerful booster effect of various renal phase-I carcinogen bioactivating enzymes at both dosages and observational times was recorded. While no relevant changes of post-oxidative phase-II reactions were found in the liver, a significant inactivating effect was caused by VE in renal tissues. Antioxidant enzymes were found mainly downregulated by the treatment. In the kidney, a marked free radical over-generation linked to CYP induction was observed.

SIGNIFICANCE

This study proved that VE acts as a co-carcinogen and pro-oxidant agent. Such epigenetic mechanisms may contribute to explain the harmful outcomes observed in humans.

Chemopreventive mechanism of polypeptides from Chlamy Farreri (PCF) against UVB-induced malignant transformation of HaCaT cells

To investigate polypeptide from Chlamy Farreri (PCF)'s protective effect against skin cancer, we used a cellular model of ultraviolet B (UVB)-induced malignant transformation. The human keratinocyte cell line HaCaT was repeatly exposed to UVB (10 mJ/cm(2), 20 times) and malignant transformation was confirmed by Gimesa staining, cell cycle analysis and various assays [anchorage independent growth, matrix metalloproteinase-9 (MMP9) activity, plating efficiency]. The malignant transformation was found to be effectively prevented by PCF pretreatment (2.84mM for 2h prior to each UVB exposure). We investigated the mechanism of PCF-mediated action by determining its effect on DNA methylation status of the tumour suppressor genes [P16 and ras association domain family 1 A (RASSF1A)] in the UVB-transformed cells. Both genes were found to be hypermethylated by chronic UVB exposure. The expression levels of P16, RASSF1A, DNA methyltransferases (DNMTs) and DNA damage inducible protein a (GADD45a) were measured by reverse transcriptase-polymerase chain reaction and western blotting. While chronic UVB exposure was found to suppress the expression of P16 and RASSF1A, it enhanced the expression of DNMT3b. In the early phase of UVB-induced malignant transformation, the GADD45a expression was increased, however, it declined with a continued irradiation of the cells. The UVB-induced DNA hypermethylation of P16 and RASSF1A and subsequent gene silencing was reversed by PCF treatment. The inhibition of DNMTs expression suggested that PCF blocked DNA methylation and thereby the silencing of tumour suppressor genes. Furthermore, the PCF-mediated substantial increase in GADD45a expression indicated that PCF promoted demethylation of tumour suppressor genes via GADD45a induction.

Review of natural compounds for potential skin cancer treatment

Most anti-cancer drugs are derived from natural resources such as marine, microbial and botanical sources. Cutaneous malignant melanoma is the most aggressive form of skin cancer, with a high mortality rate. Various treatments for malignant melanoma are available, but due to the development of multi-drug resistance, current or emerging chemotherapies have a relatively low success rates. This emphasizes the importance of discovering new compounds that are both safe and effective against melanoma. In vitro testing of melanoma cell lines and murine melanoma models offers the opportunity for identifying mechanisms of action of plant derived compounds and extracts. Common anti-melanoma effects of natural compounds include potentiating apoptosis, inhibiting cell proliferation and inhibiting metastasis. There are different mechanisms and pathways responsible for anti-melanoma actions of medicinal compounds such as promotion of caspase activity, inhibition of angiogenesis and inhibition of the effects of tumor promoting proteins such as PI3-K, Bcl-2, STAT3 and MMPs. This review thus aims at providing an overview of anti-cancer compounds, derived from natural sources, that are currently used in cancer chemotherapies, or that have been reported to show anti-melanoma, or anti-skin cancer activities. Phytochemicals that are discussed in this review include flavonoids, carotenoids, terpenoids, vitamins, sulforaphane, some polyphenols and crude plant extracts.

Extended UVB Exposures Alter Tumorigenesis and Treatment Efficacy in a Murine Model of Cutaneous Squamous Cell Carcinoma

Epidemiological studies support a link between cumulative sun exposure and cutaneous squamous cell carcinoma (SCC) development. However, the presumed effects of extended ultraviolet light B (UVB) exposure on tumorigenesis in the sexes have not been formally investigated. We examined differences in ultimate tumorigenesis at 25 weeks in mice exposed to UVB for either 10 or 25 weeks. Additionally, we investigated the effect of continued UVB exposure on the efficacy of topical treatment with anti-inflammatory (diclofenac) or antioxidant (C E Ferulic or vitamin E) compounds on modulating tumorigenesis. Vehicle-treated mice in the 25-week UVB exposure model exhibited an increased tumor burden and a higher percentage of malignant tumors compared to mice in the 10-week exposure model, which correlated with increases in total and mutant p53-positive epidermal cells. Only topical diclofenac decreased tumor number and burden in both sexes regardless of UVB exposure length. These data support the commonly assumed but not previously demonstrated fact that increased cumulative UVB exposure increases the risk of UVB-induced SCC development and can also affect therapeutic efficacies. Our study suggests that cessation of UVB exposure by at-risk patients may decrease tumor development and that topical NSAIDs such as diclofenac may be chemopreventive.

Skin tumorigenic potential of benzanthrone: prevention by ascorbic acid

Benzanthrone (BA) exposed occupational workers have been found to exhibit toxicological manifestations in the skin, thus it is quite likely that long term exposure may lead to skin tumorigenicity. Thus, attempts were made to elucidate the tumor initiating and promoting potentials of pure (PBA) and commercial benzanthrone (CBA). Additionally, the preventive role of ascorbic acid (AsA) was also assessed. PBA showed tumor initiating activity while CBA demonstrated tumor initiating as well as promoting activities in two-stage mouse skin tumor protocol. Further, prior treatment of AsA to PBA and CBA followed by twice weekly application of 12-o-tetradecanoyl phorbal myristate acetate (TPA) resulted into delayed onset of tumor formation and similarly single application of 7,12-dimethylbenz [α] anthracene (DMBA) followed by twice weekly application of AsA and CBA showed an increase in the latency period. Thus, AsA showed a protective effect against CBA promoted skin tumor. Furthermore, the topical application of CBA significantly increased the levels of xenobiotic enzymes. The animals topically treated with AsA along with topical application of CBA, restored all the impairment observed in enzyme activities. Thus, this study suggested that AsA can be useful in preventing PBA and CBA induced skin tumorigenicity.