Guinea Pig Skin Research Articles

Perbandingan Hipersensitivitas Tipe IV Akibat Paparan Remanium Gm800 Dan Stainless Steel 316L

Stainless steel and cobalt chromium is a metal that is used in dentistry. Stainless steel (SS) 316L has good corrosion resistance, but there are still many cases of hypersensitivity due to the use of such materials. Remanium GM800 is a cobalt-based alloy which is relatively mild with the advantages of having a high fracture resistance, high modulus of elasticity and resistance to corrosion. The research aims to know type IV hypersensitivity reactions for cobalt chromium GM800 applications compared with 316L Stainless steel. The research was conducted through the test GPMT (Guinea Pig Maximization Test). The pre-research phase does CoCr patch/SS/control application to 3 guinea pigs of each group with concentrations of 5%, 10%, 20%, 40%, and 80%. Primary research begins with intradermal induction on the backs of guinea pigs for 7 days with a suspension of A (50% FCA emulsion dan 50% Propylene glycol), B (SS/CoCr/blank dan Propylene glycol) and C (50% SS/CoCr/blank suspension and 50% FCA) on the left and right backs of guinea pigs. On the 8th day induction results topical concentration of 40% for 24 hours, then opened to see the reaction and closed again for 48 hours. After that, the research was continued with challenge phase by attaching patch 5% concentration for 14 days. On the 28th day was observed erythema and edema on the skin of guinea pigs followed by sacrifice in order to obtain specimen to do immunohistochemical staining by ED antibodies. The result showed 316L SS cause 40% of the samples sensitized that were grouped in moderate classification, while CoCr GM800 cause 20% of the samples sensitized so classified in the mild classification in triggering type IV hypersensitivity reaction. Histopathology examination showed that 42% of the visual field SS 316L specimen expressed macrophages, while only 28% expressed macrophages in CoCr GM800 specimen. The conclusion of this study CoCr GM800 trigger type IV hypersensitivity reaction is lower than SS 316L.

Sensitization Properties of Propolis and Balsam of Peru in Guinea Pig Maximization Test (GPMT)

Introduction: Propolis is used in Poland as an active ingredient of some drugs administered externally, dietary supplements and cosmetics. According to the literature, propolis is a non-toxic and safe substance, although it may cause allergic contact dermatitis. Aim: The aim of this study was to assess the allergenic properties of propolis and Balsam of Peru. Material and methods: The study was conducted according to the OECD Guideline for testing of chemicals-Skin sensitization with use of Guinea pig maximization test (GPMT). Guinea pigs have similar sensitivity to allergens as human body. Sensitization properties of propolis were tested in comparison with sensitization properties of Balsam of Peru because of the possibility of cross-reaction between those two substances. Results: The skin of guinea pigs in the propolis group showed no visible change compared to the control group during the first (48 h) and second observation (72 h). The skin of guinea pigs from Balsam of Peru group showed discrete erythema in only one case at the first observation (8.33% of the animals). During the second observation, no visible changes were observed compared to the control group. Conclusions: Guinea pig maximization test showed no sensitizing properties of propolis and weak sensitizing properties of Balsam of Peru in concentration of 5%.

Transdermal delivery of isoniazid and rifampin in guinea pigs by electro-phonophoresis

Electro-phonophoresis (EP) has been used as a drug delivery approach in clinical fields. The objective of the present study is to evaluate the skin permeability of isoniazid and rifampin in guinea pigs by EP to provide reference basis for clinical applications of such transdermal delivery system in the treatment of patients with superficial tuberculosis. Isoniazid and rifampin solutions were delivered transdermally with or without EP in health guinea pigs for 0.5 h. Local skin and blood samples were collected serially at 0, 1/2, 1, 2, 4, 6 and 24 h after dosing. Drug concentrations in local skin and blood were evaluated by high-performance liquid chromatography. Isoniazid concentrations in local skin of guinea pigs receiving isoniazid through EP transdermal delivery were significantly higher than in animals receiving only isoniazid with transdermal patch. However, for rifampin, patches alone group presented almost uniform concentration versus time curve with that of EP group, and both groups had concentrations much higher than the therapeutic concentration of the drug over sustainable time. After EP transdermal delivery, the mean peak concentrations of isoniazid and rifampin in skin were 771.0 ± 163.4 μg/mL and 81.2 ± 17.3 μg/mL respectively. Neither isoniazid nor rifampin concentration in blood could be detected (below the lower detection limit of 1 μg/mL) at any time point. The present study showed that application of EP significantly enhanced INH penetration through skin in guinea pigs, while RIF patch alone obtained therapeutic concentration in local skin. Our work suggests several possible medication approaches for efficient treatment of superficial tuberculosis.

Inhibitory effect of a genistein derivative on pigmentation of guinea pig skin

This study demonstrated the mechanisms of the inhibitory effects of GD against UVB-induced pigmentation in guinea pig skin.

Moraceae Plants with Tyrosinase Inhibitory Activity: A Review.

Hyperpigmentation is an abnormal darkening of the skin mostly derived from excessive melanin production. It is typical of skin disorders including melasma associated to pregnancy or age, freckles, sun freckles and photoaging, age spots, and actinic keratosis. These conditions can be uncomfortable for aesthetic reasons and specific depigmenting treatment is frequently requested. Tyrosinase (EC 1.14.18.1) is the rate-limiting enzyme of melanin synthesis and the main target of antihyperpigmentation remedies. Much interest is focused on compounds able to inhibit tyrosinase activity, particularly natural products, for which there is an increasing demand in the fields of cosmetics and pharmaceutical applications. This review concerns plants from the Moraceae family that have shown tyrosinase inhibition in vitro, including species from the genera Morus, Artocarpus, Maclura (Cudrania), Broussonetia, Milicia (Chlorophora), and Ficus. Compounds with remarkable tyrosinase inhibitory properties have been isolated from the wood and bark of different species, such as calchones, stilbenoids, flavonoids and diterpenes. Studies of structure-activity relationships have suggested that an unsubstituted resorcinol moiety is important for the acquirement of strong tyrosinase inhibition, but various exceptions have been reported. A few species, such as M. alba, A. heterophyllus, A. incisus, Maclura tricuspidata, and C. excelsa, have also shown inhibition of melanin biosynthesis on cultured melanoma cells. In addition, wood extract and the stilbene artocarpin from A. incisus have induced whitening effects on guinea pig skin, while an extract from A. lakoocha has hindered melanin formation in human volunteers. The complex of data indicates that Moraceae plants deserve attention for the development of natural and semi-synthetic tyrosinase inhibitors able to compete with, or outclass, currently available skin whitening drugs.

Deoxyarbutin Possesses a Potent Skin-Lightening Capacity with No Discernible Cytotoxicity against Melanosomes.

Safe and effective ingredients capable of removing undesired hyperpigmentation from facial skin are urgently needed for both pharmaceutical and cosmetic purposes. Deoxyarbutin (4-[(tetrahydro-2H-pyran-2-yl) oxy] phenol, D-Arb) is a glucoside derivative of hydroquinone. Here, we investigated the toxicity and efficacy of D-Arb at the sub-cellular level (directly on melanosomes) and skin pigmentation using in vivo and in vitro models to compare with its parent compound hydroquinone (1,4-benzenediol, HQ). At first, we examined the ultrastructural changes of melanosomes in hyperpigmented guinea pig skin induced by 308-nm monochromatic excimer lightand/or treated with HQ and D-Arb using transmission electron microscopy. The results showed that prominent changes in the melanosomal membrane, such as bulb-like structure and even complete rupture of the outer membranes, were found in the skin after topical application of 5% HQ for 10 days. These changes were barely observed in the skin treated with D-Arb. To further clarify whether membrane toxicity of HQ was a direct result of the compound treatment, we also examinedultrastructural changes of individual melanosomes purified from MNT1 human melanoma cells. Similar observations were obtained from the naked melanosome model in vitro. Finally, we determined the effects of melanosomal fractions exposed to HQ or D-Arb on hydroxyl radical generation in the Fenton reaction utilizing an electron spin resonance assay. D-Arb-treated melanosomesexhibit a moderate hydroxyl radical-scavenging activity, whereas HQ-treated melanosomessignificantly generate more hydroxyl free radicals. This study suggests that D-Arb possesses a potent ability in skin lightening and antioxidation with less melanosome cytotoxicity.

In vivo anti-Trichophyton Activities of Seed Oil Obtained from Caraganakorshinskii Kom.

Aim: The objective of this study was to evaluate the effects of seed oil of Caragana korshinskii Kom. against Trichophyton mentagrophytes on an in vivo guinea pig model of dermatophytosis. Methods: The skin of albino guinea pigs was infected with T. mentagrophytes, and the animals were divided into five groups: negative control (NC group), positive control (PC group), vehicle control, CK50% group (received topical 50% seed oil of C.korshinskii), and CK100% group (received topical 100% seed oil of C.korshinskii). Evaluation of clinical efficacy was performed 72 h after the completion of a 10-day treatment regimen. Skin biopsy samples were processed for histopathological examination. Results: The infected untreated control guinea pigs showed patches of hair loss and ulcerated or scaly skin. Lower clinical scores indicate improved efficacy compared with NC. The lesion scores significantly declined in the CK50%, CK100%, and PC groups in comparison with the NC group. The CK50% group (45.31%) and the CK100% group (75%) showed clinical efficacy compared with the PC group (78.13%). In addition, no fungal elements, inflammation, or tissue destruction was observed in any of the PAS-stained sections of the infected skin in the groups treated with CK100% or 1% terbinafine. Conclusion: Seed oil of C.korshinskii demonstrated high antifungal efficacy in experimental dermatophytosis.

Salidroside's Protection Against UVB-Mediated Oxidative Damage and Apoptosis Is Associated with the Upregulation of Nrf2 Expression.

Salidroside is the major active component of Rhodiola rosea, a traditional Chinese herbal medicine used for protection against ultraviolet (UV) radiation. This study investigated whether salidroside can protect skin from ultraviolet B (UVB)-induced oxidative damage in human immortalized HaCaT keratinocytes and the skin of guinea pigs. Using HaCaT cell models, the effects of salidroside on oxidative damage and possible regulatory factors [including NF-E2-related factor 2 (Nrf2), NAD(P)H-quinone oxidoreductase (NQO1), and heme oxygenase 1 (HO-1)] were examined. In addition, the regulatory effects of salidroside on apoptotic sunburn cells (SBCs) and 8-hydroxy-2'-deoxyguanosine (8-OHdG)-positive epidermal cells on UVB-exposed guinea pig skin were also investigated. We found that salidroside pretreatment upregulated Nrf2 translocation to the nucleus and transcription activity in HaCaT cells, as reflected by the increased nuclear accumulation of Nrf2 as well as the gene and protein expression of downstream Nrf2 antioxidants, including NQO1 and HO-1. In addition, we also found that pretreatment with salidroside reactive oxygen species (ROS) in irradiated HaCaT cells. The oral administration of salidroside (0.1% w/w) to guinea pigs inhibited the UVB-mediated formation of apoptotic SBCs and 8-OHdG-positive epidermal cells in the skin of guinea pigs. Our results show that UVB-induced oxidative damage can be prevented by salidroside with upregulation of nuclear Nrf2 expression.

Degradation of bradykinin by a metalloendopeptidase from Streptococcus pyogenes

ObjectivesStreptococcus pyogenes secretes streptococcal pyrogenic exotoxin B (SpeB), which cleaves kininogen to liberate bradykinin. In addition, this bacterium also has cell-associated bradykinin-degrading activity. Here, we characterized the bradykinin-degrading enzyme produced by S. pyogenes. MethodsThe effects of various peptidase inhibitors on bradykinin degradation by intact S. pyogenes and cell lysates were assessed. Cleavage of bradykinin and other peptides by a recombinant putative metalloendopeptidase (Sp-Pep) from S. pyogenes was analyzed by mass spectrometry. The enhancement of vascular permeability induced by bradykinin (before and after treatment with Sp-Pep) was evaluated in guinea pig skin. ResultsVarious S. pyogenes strains expressed Sp-Pep. Immunoadsorption of S. pyogenes with an anti-Sp-Pep antibody showed that 80% of the bradykinin-degrading activity in S. pyogenes was due to Sp-Pep. Recombinant Sp-Pep cleaved bradykinin, and cleavage caused a loss of its extravasation-inducing potential. Sp-Pep-mediated degradation of bradykinin was 40 times more efficient than degradation of substance P and angiotensin II. While S. pyogenes secreted mature SpeB in stationary phase, this bacterium produced Sp-Pep during all tested growth phases. ConclusionsS. pyogenes produces a cell-associated metalloendopeptidase that degrades bradykinin.

Development of a guinea pig cutaneous radiation injury model using low penetrating X-rays

Purpose: A guinea pig skin model was developed to determine the dose-dependent response to soft X-ray radiation into the dermis.Materials and methods: X-ray exposure (50 kVp) was defined to a 4.0 × 4.0 cm area on the lateral surface of a guinea pig using lead shielding. Guinea pigs were exposed to a single fraction of X-ray irradiation ranging from 25–79 Gy via an XRAD320ix Biological Irradiator with the collimator removed. Gross skin changes were measured using clinical assessments defined by the Kumar scale. Skin contracture was assessed, as well as histological evaluations.Results: Loss of dermal integrity was shown after a single dose of soft X-ray radiation at or above 32 Gy with the central 2.0 × 2.0 cm of the exposed site being the most affected. Hallmarks of the skin injury included moist desquamation, ulceration and wound contracture, as well as alterations in epithelium, dermis, muscle and adipose. Changes in the skin were time- and radiation dose-dependent. Full-thickness injury occurred without animal mortality or gross changes in the underlying organs.Conclusions: The guinea pig is an appropriate small animal model for the short-term screening of countermeasures for cutaneous radiation injury (CRI).

The Effects of Nanodiamonds at the Action of Colored Metal Ions on the Skin of Guinea Pigs

The protective effect of modified nanodiamonds (MND) under the action of cobalt and nickel ions on the skin of Guinea pigs was shown. At the action of chromium ions on the skin of animals, the protective effect of MND was not found. The differences are related to different adsorption properties of MND to the investigated colored metal ions. It is shown in vitro that MND can adsorb ions of cobalt and nickel and don’t bind ions of chromium from aqueous medium. The perspectives using of MND as a new drug for the prevention allergic dermatitis caused by action of bivalent ions of metals are discussed.

Anti-Melanogenic Potentials of Nanoparticles from Calli of Resveratrol-Enriched Rice against UVB-Induced Hyperpigmentation in Guinea Pig Skin

We already reported that genetically engineered resveratrol-enriched rice (RR) showed to down-regulate skin melanogenesis. To be developed to increase the bioactivity of RR using calli from plants, RR was adopted for mass production using plant tissue culture technologies. In addition, high-pressure homogenization (HPH) was used to increase the biocompatibility and penetration of the calli from RR into the skin. We aimed to develop anti-melanogenic agents incorporating calli of RR (cRR) and nanoparticles by high-pressure homogenization, examining the synergistic effects on the inhibition of UVB-induced hyperpigmentation. Depigmentation was observed following topical application of micro-cRR, nano-calli of normal rice (cNR), and nano-cRR to ultraviolet B (UVB)-stimulated hyperpigmented guinea pig dorsal skin. Colorimetric analysis, tyrosinase immunostaining, and Fontana-Masson staining for UVB-promoted melanin were performed. Nano-cRR inhibited changes in the melanin color index caused by UVB-promoted hyperpigmentation, and demonstrated stronger anti-melanogenic potential than micro-cRR. In epidermal skin, nano-cRR repressed UVB-promoted melanin granules, thereby suppressing hyperpigmentation. The UVB-enhanced, highly expressed tyrosinase in the basal layer of the epidermis was inhibited by nano-cRR more prominently than by micro-cRR and nano-cNR. The anti-melanogenic potency of nano-cRR also depended on pH and particle size. Nano-cRR shows promising potential to regulate skin pigmentation following UVB exposure.

Effect of exposure area on nerve agent absorption through skin in vitro

Diffusion cells are used to determine the penetration of chemicals through skin in vitro. The cells have a limited surface area defined by the edge of the donor chamber. Should the penetrant spread rapidly to this containment limit the penetration rate can be accurately quantified. For the hazard assessment of small droplets of toxic chemicals, such as cholinesterase inhibitors, limiting skin surface spread in vitro could lead to underestimation of percutaneous penetration and hence underestimation of systemic toxicity in vivo. The current study investigated the dependency of the percutaneous penetration of undiluted radiolabelled nerve agents (VX and soman (GD), 10μl) on skin surface spread (pig and guinea pig) using Franz-type glass diffusion cells with an area available for diffusion of either 2.54cm2 or 14.87cm2. Both VX and GD spread to the edge of the 2.54cm2 cells, but, not the 14.87cm2 cells over the study duration. Amounts of VX and GD penetrating pig and guinea pig skin in the 2.54cm2 cells were less than in the 14.87cm2 cells (except for GD under unoccluded conditions); however, penetration rates expressed per unit area were similar. Artificial limitation of skin surface spread in vitro does not impact percutaneous penetration in vitro as long as penetration is expressed in terms of mass per unit area.

Biocompatibility of a titanium dioxide-coating method for denture base acrylic resin.

Ease of denture cleaning is of paramount importance in geriatric patients and those with limited dexterity. We have previously investigated methods of coating dentures with titanium dioxide (TiO2 ) and reported the effects (self-cleaning and antibacterial) of such treatments in invitro studies. This study was to verify the biocompatibility of a TiO2 -coated acrylic resin produced by the new coating method with spray-coating technique. Specimens were prepared from denture base acrylic resin and polished up to grit #1000. The TiO2 -coating agent was sprayed onto the specimens using an airbrush gun. Specimens were then divided into 'polymethyl methacrylate (PMMA)', 'primer-coated PMMA' and 'TiO2 -coated PMMA' groups to be evaluated for biological safety using a hamster oral mucosa irritation test, a guinea pig skin sensitisation test and a rabbit intracutaneous test. The biological reaction was scored. Reaction scores were considerably <1.0, the acceptable limit set by the ISO, in all three tests. Indeed, in most samples, there was no deleterious effect at all. These results tested on animals demonstrate that denture base resin coated with TiO2 by this method does not cause irritation or sensitisation of the oral mucosa, skin or intracutaneous tissue and is therefore good biocompatibility for use in close proximity to oral mucosa and skin.

High intensity focused ultrasound as a potential new modality for the treatment of pigmentary skin disorder.

The clinical skin tightening benefits of high intensity focused ultrasound (HIFU) have been established, but its mechanism of action in pigmented skin disorders remains unknown. We macroscopically and histopathologically investigated dermatological changes after HIFU at different exposure doses in a UVB-induced guinea pig model of hyperpigmentation. We applied HIFU irradiation at 0.1 and 0.2J/cm(2) to UVB-induced spotty hyperpigmentation in guinea pig skin. The therapeutic effects of HIFU were judged based on gross appearance using photography, dermoscopy, and chromametry during a period of 3weeks after HIFU irradiation. Histological assessments were performed using Fontana-Masson staining 1day before and 3weeks after HIFU irradiation. Macroscopically, UVB-induced hyperpigmentation was significantly reduced 2weeks after HIFU with 0.2J/cm(2) , and 3weeks after HIFU with 0.1J/cm(2) . Histopathologically, the heavy deposition of melanin in the epidermis induced by UVB exposure was reduced 3weeks after HIFU irradiation. We confirmed that HIFU has a positive effect on UVB-induced hyperpigmentation as well as mechanical destructive activity. We suggest that HIFU may be useful as an alternative modality for human patients suffering from skin pigmentary conditions.

Topical delivery of leflunomide for rheumatoid arthritis treatment: evaluation of local tissue deposition of teriflunomide and its anti-inflammatory effects in an arthritis rat model

Objective: We investigated whether leflunomide can be delivered topically and metabolized into teriflunomide through the skin, and evaluated the therapeutic effect of topical leflunomide.Methods: Permeation of leflunomide across and formation of its active metabolite within the skin was examined ex vivo. Deposition of teriflunomide in micropig knee joints after applying topical and transdermal patches containing leflunomide was investigated by determining the plasma and joint tissue concentrations. Finally, the anti-inflammatory effects and inhibition of skin sensitization by topical leflunomide were evaluated in a rat adjuvant arthritis model and mice with delayed-type induced hypersensitivity.Results: We found that after topical application of leflunomide on freshly excised mouse, rat and guinea pig skin, ∼24% of the permeated drug existed as teriflunomide. In micropigs treated topically with leflunomide on the knee joint, significantly lower teriflunomide concentrations were found in plasma, but its concentrations in the knee joint were 3.4-fold to 54.6-fold higher than those after oral administration. In a rat arthritis model, the plasma concentration of teriflunomide after treatment with 10% leflunomide topical solution was 7.54-fold lower than that after 10 mg/kg oral leflunomide. However, topical leflunomide was nearly as effective as oral in inhibiting paw edema (37% versus 56%, respectively). The values for hypersensitized mouse ear weight after treatment with topical leflunomide decreased significantly by 26% compared to vehicle.Conclusion: These results demonstrate that topically applied leflunomide can be delivered effectively and deposited as teriflunomide in an arthritic joint, possibly allowing better compliance in rheumatoid arthritis patients by avoiding leflunomide’s side effects.

CAMP-dependent activation of protein kinase A as a therapeutic target of skin hyperpigmentation by diphenylmethylene hydrazinecarbothioamide.

cAMP as a second messenger stimulates expression of microphthalmia-associated transcription factor (MITF) or the tyrosinase gene in UVB-induced skin pigmentation. Diphenylmethylene hydrazinecarbothioamide (QNT 3-80) inhibits α-melanocyte-stimulating hormone (α-MSH)-induced melanin production in B16 murine melanoma cells but its molecular basis remains to be defined. Here, we investigated the mechanism underlying the amelioration of skin hyperpigmentation by QNT 3-80. We used melanocyte cultures with raised levels of cAMP and UVB-irradiated dorsal skin of guinea pigs for pigmentation assays. Immunoprecipitation, kemptide phosphorylation, fluorescence analysis and docking simulation were applied to elucidate a molecular mechanism of QNT 3-80. QNT 3-80 inhibited melanin production in melanocyte cultures with elevated levels of cAMP, including those from human foreskin. This compound also ameliorated hyperpigmentation in vivo in UVB-irradiated dorsal skin of guinea pigs. As a mechanism, QNT 3-80 directly antagonized cAMP binding to the regulatory subunit of PKA, nullified the dissociation and activation of inactive PKA holoenzyme in melanocytes and fitted into the cAMP-binding site on the crystal structure of human PKA under the most energetically favourable simulation. QNT 3-80 consequently inhibited cAMP- or UVB-induced phosphorylation (activation) of cAMP-responsive element-binding protein in vitro and in vivo, thus down-regulating expression of genes for MITF or tyrosinase in the melanogenic process. Our data suggested that QNT 3-80 could contribute significantly to the treatment of skin disorders with hyperpigmented patches with the cAMP-binding site of PKA as its molecular target.

Formulation and development of industry feasible proniosomal transdermal drug delivery system of granisetron hydrochloride

Proniosomes gel is semisolid liquid crystal products of nonionic surfactants, which converted into niosomes upon hydration. A proniosome based transdermal drug delivery system of granisetron hydrochloride (GRA HCL) developed by coacervation phase separation method. Formulation optimized by use of 32 full factorial design. Span 60 and cholesterol selected as independent variables, while entrapment efficiency (EE) and flux selected as dependent variables. Proniosomes evaluated for EE, in vitro permeation study, stability study, microscopial examination by photomicroscopy, scanning electron microscopy, particle size analysis. F5 batch containing 90 mg span 60, and 10 mg cholesterol show maximum entrapment (66.57 ± 0.20%) and flux (7.94 ± 0390 μg/cm2/h). Comparative in vitro drug release study of plain drug solution and drug in proniosomal gel form was carried out for 48 h on guinea pig skin. It was found that cumulative release and flux of proniosomal gel was nearly two times more than drug solution containing same drug concentration.The study demonstrated the effectiveness of proniosomal transdermal patch containing GRA HCL for effective management of chemotherapy induced nausea and vomiting. Key words: Factorial design, industry feasible, niosomes, proniosomes, stability, transdermal drug delivery

Toxicity and medical countermeasure studies on the organophosphorus nerve agents VM and VX.

To support the effort to eliminate the Syrian Arab Republic chemical weapons stockpile safely, there was a requirement to provide scientific advice based on experimentally derived information on both toxicity and medical countermeasures (MedCM) in the event of exposure to VM, VX or VM–VX mixtures. Complementary in vitro and in vivo studies were undertaken to inform that advice. The penetration rate of neat VM was not significantly different from that of neat VX, through either guinea pig or pig skin in vitro. The presence of VX did not affect the penetration rate of VM in mixtures of various proportions. A lethal dose of VM was approximately twice that of VX in guinea pigs poisoned via the percutaneous route. There was no interaction in mixed agent solutions which altered the in vivo toxicity of the agents. Percutaneous poisoning by VM responded to treatment with standard MedCM, although complete protection was not achieved.

Andrographolide suppresses melanin synthesis through Akt/GSK3β/β-catenin signal pathway

BackgroundTyrosinase (TYR) is the key enzyme controlling the production of melanin. Very few papers have reported that andrographolide can inhibit melanin content. ObjectiveTo investigate the effects of andrographolide on melanin synthesis. MethodsCell viability, melanin content, TYR activity, transcriptional and protein expression levels of TYR family and other kinds of proteins involved in melanogenesis were measured after the treatments of andrographolide. ResultsIt was found that andrographolide decreased melanin content, TYR activity and transcriptional and protein expression of TYR family and microphthalmia-associated transcription factor (MITF) in B16F10 melanoma cells. Data showed andrographolide also decreased melanin content and TYR content in ultraviolet B (UVB) irradiation induced brown guinea pigs. Moreover, we found that melanin content and TYR activity were effectively inhibited in Human Epidermis Melanocyte (HEM) treated with andrographolide at the medium concentrations without apparent effect on cell viability. Results in experiments treated with MG-132 or cycloheximide (CHX) showed that andrographolide lowered the content of β-catenin in cell nucleus resulting from accelerating the degradation of β-catenin. Phosphorylation of glycogen synthase kinase 3β (GSK3β) and Akt decreased simultaneously. 6-Bromoindirubin-3′-oxime (BIO, inhibitor of GSK3β) and insulin-like growth factors-1 (IGF-1, activator of Akt) could reverse the decline of β-catenin in B16F10 cells induced by andrographolide. ConclusionThese results demonstrate that andrographolide can effectively suppress melanin content and TYR activity in B16F10 cells, HEM cells and UVB-induced brown guinea pig skin by decreasing phosphorylation of GSK3β dependent on Akt, promoting the degradation of β-catenin, inhibiting β-catenin into the nucleus and decreasing the expression of MITF and TYR family. Data indicate that andrographolide may be a potential whiting agent which can have great market in cosmetics and in clinical such as curing hyperpigmentation disorders.