Prevention of the photodamage in the hairless mouse dorsal skin by kojic acid as an iron chelator

Topical Iron Chelator Therapy: Current Status and Future Prospects

Systemic iron chelation therapy has long been used for iron overload, providing a role in returning iron levels to proper homeostatic concentrations. Recently, topical iron chelation therapy has emerged as a potential strategy for treating skin damage. This narrative review explores the current status and future prospects of topical iron chelation therapy for treating ultraviolet (UV) and non-UV skin damage, as well as its potential application in wound healing. The review was conducted through a literature search across PubMed, Web of Science, and EMBASE databases, spanning publications from 1990 to 2023. The selection of articles was focused on primary research studies, either experimental or clinical, that explored the implications and formulations of topical iron chelators used alone or in conjunction with another therapeutic agent. The search strategy employed a combination of terms, including "topical iron chelation", "topical deferoxamine", "UV", "wound healing", "skin inflammation", "radiation-induced fibrosis", and "skin cancer". Relevant studies, including methods, intervention strategies, measured outcomes, and findings, are summarized. The review also considered the potential challenges in translating research findings into clinical practice. Results indicate that topical iron chelators, such as deferoxamine, are effective in mitigating UV-induced skin damage, reducing tumorigenesis, and decreasing oxidative damage. In addition, the use of these agents in radiation-induced fibrosis has been shown to significantly increase skin elasticity and reduce dermal fibrosis. Several studies also highlight the use of topical iron chelators in difficult-to-treat chronic wounds, such as diabetic neuropathic ulcers and sickle cell ulcers. In conclusion, topical iron chelation therapy represents a novel and promising approach for skin protection and wound healing. Its potential makes it a promising area of future research.

Ultraviolet Light Protection: Is It Really Enough?

Our current understanding of the pathogenesis of skin aging includes the role of ultraviolet light, visible light, infrared, pollution, cigarette smoke and other environmental exposures. The mechanism of action common to these exposures is the disruption of the cellular redox balance by the directly or indirectly increased formation of reactive oxygen species that overwhelm the intrinsic antioxidant defense system, resulting in an oxidative stress condition. Altered redox homeostasis triggers downstream pathways that contribute to tissue oxinflammation (cross-talk between inflammation and altered redox status) and accelerate skin aging. In addition, both ultraviolet light and pollution increase intracellular free iron that catalyzes reactive oxygen species generation via the Fenton reaction. This disruption of iron homeostasis within the cell further promotes oxidative stress and contributes to extrinsic skin aging. More recent studies have demonstrated that iron chelators can be used topically and can enhance the benefits of topically applied antioxidants. Thus, an updated, more comprehensive approach to environmental or atmospheric aging protection should include sun protective measures, broad spectrum sunscreens, antioxidants, chelating agents, and DNA repair enzymes.

Cyclic voltammetric studies of electron transfer reactions associated with bioactive iron-KA complexation at different biological pH

This study explores electrochemical interactions of a pharmaceutical drug; Kojic acid (5-hydroxy-2-hydroxymethyl-4H-pyran-4-one; KA) with bioactive iron; Fe(III) at different pH systems by cyclic voltammetric technique. For this study, buffers relevant to the physiological pH of blood and digestive system have been selected. Buffers of pH 4.0, 5.5, 6.0, 6.7, 7.0 and 7.4 have been used for this study. Present study shows that concurrent ingestion of the Kojic acid can cause marked changes in the bioavailability of Fe(III) ions. Bioactive iron was found to form an electroactive complex; [Fe(III)L3] in the presence of Kojic acid, at all the studied pH values whereas electrochemical behavior of Kojic acid was also changed by complex formation. The number of electrons (n) involved in the redox process of [Fe(III)L3] complex was determined at all studied pHs and it was found to be in the range of 0.998 to 1.005. This electrochemical investigation reveals that under the experimental conditions, [Fe(III)L3] complex undergoes a diffusion controlled, one electron redox process which is quasi-reversible in nature. It was also found that [Fe(III)L3] complex undergoes coupled chemical reaction according to EC mechanism, and this interaction is pH dependent. Cyclic voltammetric data was also used to extract information about heterogeneous kinetics related to the [Fe(III)L3] complex. Heterogeneous electron transfer rate constant (k0) was determined by three different methods that are modified Nicholson & Shain method, Gileadi method, and the Kochi method. The standard heterogeneous rate constant was found to be in the range of 10-3 to 10-5 cm/s.

Burn injury induces elevated inflammatory traffic: the role of NF-κB

A burn insult generally sustains a hypovolemic shock due to a significant loss of plasma from the vessels. The burn injury triggers the release of various mediators, such as reactive oxygen species (ROS), cytokines, and inflammatory mediators. Damage-associated molecular patterns (DAMPs) and pathogen-associated molecular patterns (PAMPs), stemming from foreign microbial discharge and damaged tissue or necrotic cells from the burn-injured site, enter the systemic circulation, activate toll-like receptors (TLRs), and trigger the excessive secretion of cytokines and inflammatory mediators. Inflammation plays a vital role in remodeling an injured tissue, detoxifying toxins, and helps in the healing process. A transcription factor, nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), contributes to a variety of physiological and pathological conditions, including immune response, cell death, cell survival, and inflammatory processes. During the pathogenesis of a burn wound, upregulation of various cytokines and growth factors lead to undesirable tissue inflammation. Thus, NF-κB, a dominant moderator of inflammation, needs to be altered to prove beneficial to the treatment of burns or other inflammation-associated diseases. This review addresses the relationship between NF-κB and elevated inflammation in a burn condition that could potentially be altered to induce an early wound-healing mechanism of burn wounds.

Light-triggered release of photocaged therapeutics - Where are we now?

The current available therapeutics face several challenges such as the development of ideal drug delivery systems towards the goal of personalized treatments for patients benefit. The application of light as an exogenous activation mechanism has shown promising outcomes, owning to the spatiotemporal confinement of the treatment in the vicinity of the diseased tissue, which offers many intriguing possibilities. Engineering therapeutics with light responsive moieties have been explored to enhance the bioavailability, and drug efficacy either in vitro or in vivo. The tailor-made character turns the so-called photocaged compounds highly desirable to reduce the side effects of drugs and, therefore, have received wide research attention. Herein, we seek to highlight the potential of photocaged compounds to obtain a clear understanding of the mechanisms behind its use in therapeutic delivery. A deep overview on the progress achieved in the design, fabrication as well as current and possible future applications in therapeutics of photocaged compounds is provided, so that novel formulations for biomedical field can be designed.

Biodegradable Kojic Acid-Based Polymers: Controlled Delivery of Bioactives for Melanogenesis Inhibition

Kojic acid (KA) is a naturally occurring fungal metabolite that is utilized as a skin-lightener and antibrowning agent owing to its potent tyrosinase inhibition activity. While efficacious, KA's inclination to undergo pH-mediated, thermal-, and photodegradation reduces its efficacy, necessitating stabilizing vehicles. To minimize degradation, poly(carbonate-esters) and polyesters comprised of KA and natural diacids were prepared via solution polymerization methods. In vitro hydrolytic degradation analyses revealed KA release was drastically influenced by polymer backbone composition (e.g., poly(carbonate-ester) vs polyester), linker molecule (aliphatic vs heteroatom-containing), and release conditions (physiological vs skin). Tyrosinase inhibition assays demonstrated that aliphatic KA dienols, the major degradation product under skin conditions, were more potent then KA itself. All dienols were found to be less toxic than KA at all tested concentrations. Additionally, the most lipophilic dienols were statistically more effective than KA at inhibiting melanin biosynthesis in cells. These KA-based polymer systems deliver KA analogues with improved efficacy and cytocompatible profiles, making them ideal candidates for sustained topical treatments in both medical and personal care products.

Novel functionalized monomers based on kojic acid: snythesis, characterization, polymerization and evalution of antimicrobial activity

Two novel acrylate monomers, [5-(benzyloxy)-4-oxo-4H-pyran-2-yl]methyl acrylate and {1-[(5-(benzyloxy)-4-oxo-4H-pyran-2-yl)methyl]-1,2,3-triazol-4-yl}methyl acrylate were synthesized by the reaction of 5-benzyloxy-2-(hydroxymethyl)-4H-pyran-4-one and 5-(benzyloxy)-2-{[4-(hydroxymethyl)-1,2,3-triazol-1-yl]methyl}-4H-pyran-4-one with acryloyl chloride in the presence of triethylamine, respectively. These monomers were polymerized using 2,2^′-azobisisobutyronitrile (AIBN) as the initiator in N,N-dimethylformamide:14-dioxane (10:1) solution. The thermal behavior of the polymers was investigated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The synthesized compounds were evaluated for their antibacterial and antifungal activites aganist bacteria and fungi using the disk diffusion method. The results indicated that some of these compounds demonstrated moderate to good antibacterial and antifungal activities.

A multifunctional, light-activated prochelator inhibits UVA-induced oxidative stress

UVA radiation can damage cells and tissues by direct photodamage of biomolecules as well as by initiating metal-catalyzed oxidative stress. In order to alleviate both concerns simultaneously, we synthesized a multifunctional prochelator PC-HAPI (2-((E)-1-(2-isonicotinoylhydrazono)ethyl)phenyl (trans)-3-(2,4-dihydroxyphenyl)acrylate) that contains a trans-(o-hydroxy)cinnamate ester photocleavable protecting group that is cleaved upon UVA exposure to release a coumarin, umbelliferone, and an aroylhydrazone metal chelator, HAPI (N'-[1-(2-hydroxyphenyl)ethyliden]isonicotinoylhydrazide). While the prochelator PC-HAPI exhibits negligible affinity for iron, it responds rapidly to UVA irradiation and converts to an iron-binding chelator that inhibits iron-catalyzed formation of reactive oxygen species and protects cells from UVA damage.

Safety Evaluation and Anti-wrinkle Effects of Retinoids on Skin

Retinoids have many beneficial effects on dermatological applications. But, retinoids cause skin irritation. In this study, the safety of retinoids was clarified via both primary skin irritation test in rabbits and sensitization study using an integrated model for the differentiation of chemical-induced allergic and irritant skin reaction (IMDS) , an alternative method to sensitization test. The effects of retinoids on the change of ultraviolet A (UVA) -induced matrix metalloproteinase-1 (MMP-1) in human skin fibroblasts and the modulation of type-1 pN collagen synthesis in hairless mice were examined to clarify the anti-wrinkle effects. All-trans retinol (t-ROL) and its derivative, all-trans retinoic acid (t-RA) , showed mild skin irritation but did not induce the sensitization. t-ROL and t-RA exerted anti-wrinkle effects by inhibiting the UVA-induced MMP-1 in human skin fibroblasts and increasing the type-1 pN collagen synthesis in hairless mice. These findings suggest that retinoids do not induce the allergy, and show anti-wrinkle effects by decreasing MMP-1 activation and increasing collagen synthesis.

Design and synthesis of hydroxypyridinone-L-phenylalanine conjugates as potential tyrosinase inhibitors

A range of hydroxypyridinone-L-phenylalanine conjugates were synthesized starting from kojic acid. Their tyrosinase activity was determined, and it was found that one of the compounds ((S)-(5-(benzyloxy)-1-octyl-4-oxo-1,4-dihydropyridin-2-yl)methyl 2-amino-3-phenylpropanoate, 5e) showed potent inhibitory effect against mushroom tyrosinase, the IC50 values for monophenolase and diphenolase activities being 12.6 and 4.0 μM, respectively. It was also demonstrated that these conjugates are mixed-type inhibitors, suggesting they could bind to both the free enzyme and the enzyme-substrate complexes. MTT assay indicated that 5e was nontoxic to three cell lines. This compound may find applications in food preservation and cosmetics.

Microwave-Assisted Condensation of Kojic Acid with Aldehydes

Kojic acid derivatives have been prepared in excellent yield by the condensation of two molecules of kojic acid and one molecule of an aldehyde using sodium carbonate as a base under microwave irradiation.

Kojic acid-induced IL-6 production in human keratinocytes plays a role in its anti-melanogenic activity in skin

BACKGROUND

Kojic acid is a fungal metabolite widely used in medicinal and cosmetic formulations as a skin-lightening agent based on its de-pigmenting activity. Although in human clinical studies kojic acid has been shown to be effective in the treatment of hyper-pigmentation disorders such as melasma, the reasons for its apparent lack of anti-melanogenic activity in cultured mammalian melanocytes are unclear.

OBJECTIVES

This study was aimed to elucidate pharmacological mechanisms of the in vivo anti-melanogenic activity of kojic acid in human skin.

METHODS

A primary human melanocyte and keratinocyte co-culture system was used to evaluate whether kojic-acid-induced changes in keratinocytes were associated with anti-melanogenic activities in melanocytes. The cytokine secretion profiles in response to kojic acid were analyzed.

RESULTS

Kojic acid increased interleukin (IL)-6 and IL-8 production in melanocyte/keratinocyte co-cultures; however, IL-6 directly inhibited melanogenesis whereas IL-8 did not. In melanocyte monocultures, kojic acid did not increase IL-6 production whereas in keratinocyte monocultures it significantly up-regulated IL-6 gene and protein expression. Therefore, the up-regulation of IL-6 in melanocyte/keratinocyte co-cultures seems to be originated from kojic acid-induced changes in keratinocytes. Anti-IL-6 antibody treatment antagonized the anti-melanogenic effect of kojic acid on the co-cultures.

CONCLUSIONS

The pharmacological mechanism of kojic acid to explain clinically effective anti-melanogenic activity on hyper-pigmented skin is associated with the kojic acid-induced IL-6 production in keratinocytes. The cross-talk between melanocytes and keratinocytes should be determined in future studies on the pharmacological mechanisms of clinically effective dermatological drugs acting on the epidermis.

Inhibitory activity of novel kojic acid derivative containing trolox moiety on melanogenesis

A novel kojic acid derivative containing a trolox moiety, (±)-5-hydroxy-4-oxo-4H-pyran-2-yl methyl 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylate (3a), was synthesized. The two biologically active compounds, namely, kojic acid and trolox, were conjugated via an ester bond as they are expected to behave synergistically. The antioxidant activity and the tyrosinase inhibitory activity of this novel kojic acid derivative on melanogenesis were evaluated. Compound 3a exhibited potent tyrosinase inhibitory activity and radical scavenging activity. Limited structure-activity relationship (SAR) investigations indicated that the tyrosinase inhibitory activities may originate from the kojic acid moiety, and the radical scavenging activity may be due to the phenolic hydroxyl group of trolox. Compound 3a also exhibited potent depigmenting activity in a cell-based assay. The limited SAR investigations revealed that the depigmenting activity of 3a may be due to the synergistic activities of kojic acid and its trolox moiety.

Advances in iron chelation: an update

INTRODUCTION

Oxidative stress (caused by excess iron) can result in tissue damage, organ failure and finally death, unless treated by iron chelators. The causative factor in the etiology of a variety of disease states is the presence of iron-generated reactive oxygen species (ROS), which can result in cell damage or which can affect the signaling pathways involved in cell necrosis-apoptosis or organ fibrosis, cancer, neurodegeneration and cardiovascular, hepatic or renal dysfunctions. Iron chelators can reduce oxidative stress by the removal of iron from target tissues. Equally as important, removal of iron from the active site of enzymes that play key roles in various diseases can be of considerable benefit to the patients.

AREAS COVERED

This review focuses on iron chelators used as therapeutic agents. The importance of iron in oxidative damage is discussed, along with the three clinically approved iron chelators.

EXPERT OPINION

A number of iron chelators are used as approved therapeutic agents in the treatment of thalassemia major, asthma, fungal infections and cancer. However, as our knowledge about the biochemistry of iron and its role in etiologies of seemingly unrelated diseases increases, new applications of the approved iron chelators, as well as the development of new iron chelators, present challenging opportunities in the areas of drug discovery and development.

Apurinic/apyrimidinic endonuclease/redox effector factor-1(APE/Ref-1): a unique target for the prevention and treatment of human melanoma

Management of melanoma is a growing and challenging public health issue requiring novel and multidisciplinary approaches to achieve more efficient prevention and therapeutic benefits. The aim of this article is to show the critical role of APE/Ref-1 on melanomagenesis and progression. APE/Ref-1 serves as a redox-sensitive node of convergence of various signals as well as a DNA-repair enzyme, and its activation protects melanocytes and melanoma cells from chronic oxidative stress and promotes cell survival via mediation of downstream pathways. APE/Ref-1 is a strong candidate as a potential drug-treatable target for the prevention and treatment of human melanoma. Lead compounds exhibiting inhibitory effects on APE/Ref-1 are also reviewed. We anticipate potential clinical benefit in the future through inhibition of APE/Ref-1 and/or Ref-1-mediated signaling.

Vibrational spectroscopic studies and ab initio calculations of Goniothalamin, a natural product

5,6-Dihydro-6-styryl-2-pyrone (Goniothalamin), is isolated from the leaves of Goniothalamus wightii and identified by spectral analysis and X-ray diffraction studies. FT-IR spectroscopy has also been used to characterize the vibrational bands. The vibrational wavenumbers and corresponding vibrational assignments are examined theoretically using the Gaussian03 set of quantum chemistry codes. Predicted IR and Raman intensities are reported.

Oak leaf extract as topical antioxidant: free radical scavenging and iron chelating activities and in vivo skin irritation potential

The topical application of antioxidants may be beneficial for the protection of the skin against UV damage. An extract of Quercus robur leaves was prepared and evaluated considering its putative application as topical antioxidant. The solvent and extractive method selection was monitored by 1,1-diphenyl-2-picryl hydrazyl (DPPH) free radical scavenging activity and polyphenols extraction (measured by the Folin Ciocalteu assay). Iron chelating activity and the phenolic composition (HPLC/DAD) were assessed on the extract obtained under optimized conditions. Skin irritation potential was investigated by performing an in vivo patch test in 19 volunteers. The extraction solvent which resulted in the highest activity was ethanol:water (4:6) and thus it was selected for further preparation of this extract. The IC50s for the iron chelation and DPPH scavenging assays were 153.8 +/- 26.3 microg x mL-1 and 7.53 +/- 0.71 microg x mL-1 (mean +/- SD), respectively. The total phenolic content was found to be 346.3 +/- 6.7 mg gallic acid equivalents (GAE)/g extract (mean +/- SD). Three phenolic compounds were identified in the extract namely: ellagic acid, rutin and hyperoside. The major identified component was ellagic acid. The patch test carried out showed that the extract can be regarded as safe for topical application.

Anti-wrinkling effects of the mixture of vitamin C, vitamin E, pycnogenol and evening primrose oil, and molecular mechanisms on hairless mouse skin caused by chronic ultraviolet B irradiation

BACKGROUND

Naturally occurring antioxidants were used to regulate the skin damage caused by ultraviolet (UV) radiation because several antioxidants have demonstrated that they can inhibit wrinkle formation through prevention of matrix metalloproteinases (MMPs) and/or increase of collagen synthesis.

OBJECTIVE

We examined the effect of oral administration of the antioxidant mixture of vitamin C, vitamin E, pycnogenol, and evening primrose oil on UVB-induced wrinkle formation. In addition, we investigated the possible molecular mechanism of photoprotection against UVB through inhibition of collagen-degrading MMP activity or through enhancement of procollagen synthesis in mouse dorsal skin.

METHODS

Female SKH-1 hairless mice were orally administrated the antioxidant mixture (test group) or vehicle (control group) for 10 weeks with UVB irradiation three times a week. The intensity of irradiation was gradually increased from 30 to 180 mJ/cm2. Microtopographic and histological assessment of the dorsal skins was carried out at the end of 10 weeks to evaluate wrinkle formation. Western blot analysis and EMSA were also carried out to investigate the changes in the balance of collagen synthesis and collagen degradation.

RESULTS

Our antioxidant mixture significantly reduced UVB-induced wrinkle formation, accompanied by significant reduction of epidermal thickness, and UVB-induced hyperplasia, acanthosis, and hyperkeratosis. This antioxidant mixture significantly prevented the UVB-induced expressions of MMPs, mitogen-activated protein (MAP) kinase, and activation of activator protein (AP)-1 transcriptional factor in addition to enhanced type I procollagen and transforming growth factor-beta2 (TGF-beta2) expression.

CONCLUSION

Oral administration of the antioxidant mixture significantly inhibited wrinkle formation caused by chronic UVB irradiation through significant inhibition of UVB-induced MMP activity accompanied by enhancement of collagen synthesis.

Topical application of plant extracts containing xanthine derivatives can prevent UV-induced wrinkle formation in hairless mice

BACKGROUND

Plants are the source of important products with nutritional and therapeutic value. Topical or oral administration of some plant extracts has been shown to reduce photodamage. Cacao bean and cola nut are popular edible plants that contain polyphenols and xanthine derivatives. These plant extracts possess protective effects against UV-induced erythema when taken orally, and an H(2)O(2)-scavenging effect.

METHODS

Plant extracts containing xanthine derivatives and three xanthine derivatives were topically applied to the dorsal skin of hairless mice, and the mice were exposed to a resemblance of solar ultraviolet irradiation at a dose of 13.0 J/cm(2) (UVA) for 15 weeks, five times a week on weekdays. After the final irradiation, histological, and analytical studies were performed.

RESULTS

Topical application of plant extracts (cacao beans, cola nuts) and caffeine, theobromine, and theophylline markedly prevented photodamage including wrinkle formation and histological alterations. A significant increase in total hydroxyproline content caused by UV irradiation was observed. In contrast, topical application of plant extracts and xanthine derivatives reduced total hydroxyproline and pepsin-resistant hydroxyproline content in comparison with that of the control (vehicle, UV-irradiation group). Moreover, naphthol AS-D chloroacetate esterase staining and diaminobenzidine staining suggested that leukocytes including neutrophils increased in the UV-exposed skin. In contrast, weak staining was observed in skin treated with xanthine derivatives.

CONCLUSION

Topical application of plant extracts and xanthine derivatives suppressed wrinkle formation, dermal connective alteration, and collagen accumulation. It is suggested that xanthine derivatives prevented neutrophil infiltration caused by UV-irradiation.

From miso, saké and shoyu to cosmetics: a century of science for kojic acid

This article reviews the curious history of kojic acid, discovered as a fungal natural product in 1907. It was one of the first secondary metabolites to have its biosynthetic pathway studied by the isotope tracer technique, and, more recently, has been of interest as a skin lightening agent. There are 112 references.

Iron chelators may help prevent photoaging

For years, cosmetic ingredients for anti-aging treatments have attracted consumers. Skin aging is accelerated by reactive oxygen species (ROS), generated by exposure to solar ultraviolet radiation (UVR), in a process known as photoaging. Because cutaneous iron catalyses ROS generation, it is thought to play a key role in photoaging. Iron is essential to almost all forms of life. However, excess iron is potentially toxic as its catalytic activity induces the generation of ROS. Iron-catalysed ROS generation is involved in numerous pathological conditions, including cutaneous damage. When skin is directly exposed to UVR, cutaneous intracellular catalytic iron levels increase because of the release of iron from iron-binding proteins such as ferritin. Consequently, the subsequent ROS generation may overwhelm cutaneous defense systems such as the cellular iron sequestration and ROS scavenging capacity. The harmful role of excess cutaneous iron implies that there may be a potential for topical iron chelator treatments. We now consider cutaneous photodamage skin photoaging as the result of iron-catalysed ROS generation and discuss preventative strategies based on iron chelators.

Photoaging: Mechanisms and repair

Aging is a complex, multifactorial process resulting in several functional and esthetic changes in the skin. These changes result from intrinsic as well as extrinsic processes, such as ultraviolet radiation. Recent advances in skin biology have increased our understanding of skin homeostasis and the aging process, as well as the mechanisms by which ultraviolet radiation contributes to photoaging and cutaneous disease. These advances in skin biology have led to the development of a diversity of treatments aimed at preventing aging and rejuvenating the skin. The focus of this review is the mechanism of photoaging and the pathophysiology underlying the treatments specifically designed for its prevention and treatment.

LEARNING OBJECTIVES

At the conclusion of this learning activity, participants should be familiar with the mechanism of photoaging, the treatments for photoaging, and the data that supports the use of these treatments.

The effects of a novel synthetic retinoid, seletinoid G, on the expression of extracellular matrix proteins in aged human skin in vivo

BACKGROUND

Although retinoids have potential efficacy in aged skin, their side effect (skin irritation) remains a clinical problem. We designed a novel synthetic retinoid, seletinoid G, by using computer-aided molecular modeling, and investigated its effects on the expression of extracellular matrix proteins in human skin in vivo.

METHODS

Twenty-three subjects were tested on the buttocks using 4-day occlusive application of seletinoid G and all-trans retinoic acid (tRA). Skin irritation after topical application was quantified by the degree of erythema and cutaneous blood flow. The expression of extracellular matrix proteins and interstitial collagenase (MMP-1) in skin biopsies was investigated by immunohistochemical staining and Western blotting.

RESULTS

The topical application of seletinoid G under occlusion induced no skin irritation in contrast to tRA, which caused severe erythema. The topical treatment with seletinoid G increased the expressions of type I procollagen, tropoelastin, and fibrillin-1, and reduced MMP-1 in old skin in vivo. Seletinoid G was found to inhibit not only the UV-induced decrease of type I procollagen but the UV-induced increase of MMP-1 and c-Jun protein in young skin in vivo.

CONCLUSIONS

Seletinoid G is a novel synthetic retinoid, which has little the side effect of skin irritation after topical application. Seletinoid G can repair altered connective tissue in old skin and inhibit UV-induced collagen deficiency in young skin.

Probing the interaction of kojic acid antibiotics with iron(III) chloride by using electrospray tandem mass spectrometry

Kojic acid, 5-hydroxy-2-(hydroxymethyl)-4H-pyran-4-one, has been used extensively as a clinical iron-chelating drug although the nature of the complexes of iron and kojic acid has not been established. In this article we demonstrate the complexation of kojic acid with iron(III) chloride by using electrospray ionization mass spectrometry (ESI-MS). The ESI-MS analysis revealed different reactions between iron(III) chloride and kojic acid (M), and the mass spectrum exhibited four complexes: [Fe+2(M-H)]+, [Fe+3(M-H)+H]+, [Fe2+4(M-H)+Cl]+, and [Fe2+5(M-H)]+. All these proposed complexes and the presence of chloride ion in one of the dinuclear complexes have been confirmed by isotopic patterns and fragmentation studies by means of tandem mass spectrometry (MSn).

Ergocalciferol promotes in vivo differentiation of keratinocytes and reduces photodamage caused by ultraviolet irradiation in hairless mice

BACKGROUND

Ergocalciferol (VD(2)) is usually administered orally and it is metabolized to produce its biologically active metabolites in the liver and kidney. Active vitamin D is a well-known potent regulator of cell growth and differentiation.

PURPOSE

Active vitamin D such as 1,25-dihydroxyvitamin D(3) (1alpha,25(OH)(2)D(3)) prevents photodamage, including wrinkles and morphologic alterations. However, its clinical and cosmetic use is limited because of its potent, associated effect on calcium metabolism. We examined the efficacy of vitamin D analogues with few adverse effects for preventing skin photodamage.

METHOD

Topical application of VD(2) to hairless mouse dorsal skin, and exposure to solar-simulating ultraviolet (UV) radiation at a dose of 10.8 J/cm(2) (UVA) were performed for 15 weeks, five times a week on weekdays. At the end of the final irradiation, histological and analytical studies were performed.

RESULTS

Topical application of VD(2) significantly prevented wrinkle formation and abnormal accumulation of extracellular matrix components. In addition, VD(2) suppressed excessive secretion of IL-6 induced by UV irradiation in cultured human normal keratinocytes, in a dose-dependent manner.

CONCLUSION

VD(2) promoted keratinocytes differentiation in the epidermis and showed diverse physiological effects, the same as the active form of VD(3). The results suggested that the suppression of skin photodamage involved the promotion of keratinocytes differentiation and suppression of IL-6 secretion induced by exposure to UV. Topical application of VD(2) may become an effective means to suppress solar UV-induced human skin damage.

Downregulation of NF-kappaB activation in human keratinocytes by melanogenic inhibitors

BACKGROUND

Exposure of skin cells, particularly keratinocytes to various nuclear factor-kappaB (NF-kappaB) activators (e.g. tumor necrosis factor-alpha, interleukin-1, lipopolysaccharides, and ultraviolet light) leads to phosphorylation and degradation of the inhibitory protein, IkappaB. Liberated NF-kappaB is translocated into the nucleus where it can change or alter expression of target genes, resulting in the secretion of extracellular signaling molecules including melanotrophic factors affecting melanocyte.

OBJECTIVE

In order to demonstrate the possible role of NF-kappaB activation on the synthesis of melanotrophic factors from the keratinocytes, the activities of NF-kappaB induced by melanogenic inhibitors (MIs) were determined in human HaCaT keratinocytes transfected with pNF-kappaB-SEAP-NPT plasmid. Transfectant cells released the secretory alkaline phosphatase (SEAP) as a transcription reporter in response to the NF-kappaB activity and contain the neomycin phosphotransferase (NPT) gene for the dominant selection marker for geneticin resistance.

METHODS

MIs such as niacinamide, kojic acid, hydroquinone, resorcinol, arbutin, and glycolic acid were preincubated with transfectant HaCaT cells for 3 h and then ultraviolet B (UVB) was irradiated. NF-kappaB activation was measured with the SEAP reporter gene assay using a fluorescence detection method.

RESULTS

Of the MIs tested, kojic acid (IC(50)=60 microM) was found to be the most potent inhibitor of UVB-upregulating NF-kappaB activation in transfectant HaCaT cells, which is followed by niacinamide (IC(50)=540 microM). Pretreatment of the transfectant HaCaT cells with the MIs, especially kojic acid and niacinamide, effectively lowered NF-kappaB binding measured by electrophoretic mobility shift assay. Furthermore, these two inhibitors remarkably reduced the secretion level of IL-6, one of melanotrophic factors, triggered by UV-radiation of the HaCaT cells.

CONCLUSION

These observations suggest that MIs working at the in vivo level might act partially through the modulation of the synthesis of melanotrophic factors in keratinocyte.