F Bonté

LVMH Recherche, Lutetia Parisorum, Île-de-France, France

Are you F Bonté?

Claim your profile

Publications (60)123.34 Total impact

  • Source
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: IntroductionIn our continued efforts to contribute to the general knowledge on the chemical diversity of orchids, we have decided to focus our investigations on the Aeridinae subtribe. Following our previous phytochemical study of Vanda coerulea, which has led to the identification of phenanthrene derivatives, a closely related species, Aerides rosea Lodd. ex Lindl. & Paxton, was chosen for investigation.Objective To identify new secondary metabolites, and to avoid isolation of those already known, by means of the combined systems HPLC–DAD(diode-array detector) with high-resolution tandem mass spectrometry (HRMS/MS) and HPLC–DAD–MS–SPE(solid-phase extraction)–UV–NMR.MethodsA dereplication strategy was developed using a HPLC–DAD–HRMS/MS targeted method and applied to fractions from A. rosea stem extract. Characterisation of unknown minor compounds was then performed using the combined HPLC–DAD–MS–SPE–UV–NMR system.ResultsThe dereplication method allowed the characterisation of four compounds (gigantol, imbricatin, methoxycoelonin and coelonin), previously isolated from Vanda coerulea stem extract. The analyses of two fractions permitted the identification of five additional minor constituents including one phenanthropyran, two phenanthrene and two dihydrophenanthrene derivatives. The full set of NMR data of each compound was obtained from microgram quantities.Conclusion Nine secondary metabolites were characterised in A. rosea stems, utilising HPLC systems combined with high-resolution analytical systems. Two of them are newly described phenanthrene derivatives: aerosanthrene (5-methoxyphenanthrene-2,3,7-triol) and aerosin (3-methoxy-9,10-dihydro-2,5,7-phenanthrenetriol). Copyright © 2014 John Wiley & Sons, Ltd.
    Phytochemical Analysis 07/2014; · 2.48 Impact Factor
  • Source
    Frédéric Bonté, Marc Dumas, Patrick Barré, Alain Meybeck
    [Show abstract] [Hide abstract]
    ABSTRACT: Prunella vulgaris extracts have been shown to increase the keratinocytes differentiation in culture. The increase of the transglutaminase activity is one of the possible mecanisms involved in the activity.
    Acta botanica Gallica: bulletin de la Société botanique de France 04/2013; 144(4):485-488. · 0.24 Impact Factor
  • Source
    Marc Dumas, Frédéric Bonté, Alain Meybeck
    [Show abstract] [Hide abstract]
    ABSTRACT: Prunella vulgaris and Azadirachta indica extracts were shown to inhibit type I and II phospholipase A2 activity. These enzymes, involved in the biosynthesis of inflammation and allergy mediators and in the differentiation process of keratinocytes, are suitable for the screening of substances with a potent pharmacological activity.
    Acta botanica Gallica: bulletin de la Société botanique de France 04/2013; 144(4):481-484. · 0.24 Impact Factor
  • Frédéric Bonté
    [Show abstract] [Hide abstract]
    ABSTRACT: The 11(th) Annual LVMH Recherche Scientific Symposium was held in London on October 27(th), into the warmth of the distinguished British Library, with nearly 150 industry and research attendees. The meeting organized by LVMH Recherche was centered on the theme of skin rejuvenation. The current state of play for rejuvenation research was summarized, and then advances in the science of skin aging and rejuvenation therapies were discussed in detail. Personalized genomics and current and prospective translational therapies were presented, followed by a clever linking of multiple global theories towards a cohesive plan for future goals in rejuvenation research.
    European journal of dermatology: EJD 05/2012; 22(3):432-6. · 1.95 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Eucomic acid [(2R)-2-(p-hydroxybenzyl)malic acid)] (1) and three new glucopyranosyloxybenzyl eucomate derivatives, vandaterosides I (2), II (3), and III (4), were isolated and identified from the stems of Vanda teres. Their cellular antiaging properties were evaluated in a human immortalized keratinocyte cell line (HaCaT) by monitoring their effect on cytochrome c oxidase activity, implicated in mitochondrial respiratory function and cellular energy production. Eucomic acid (1) and vandateroside II (3) increased cytochrome c oxidase activity and/or expression, without enhancing cellular mitochondrial content. These two V. teres biomarkers apparently contributed to stimulate respiratory functions in keratinocytes. Since aging and its pathologies may be ascribed to a decline in mitochondrial functions, these biomarkers have the potential to become new natural ingredients for antiaging preparations to remedy age-related disorders such as skin aging.
    Journal of Natural Products 05/2011; 74(5):949-55. · 3.95 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The family of the orchids to date is poorly studied as a potential source of molecules with biological activity. The phytochemical analysis of extracts of Vanda coerulea stems (Orchidaceae), the isolation and the purification of the secondary metabolites realized by CLHP followed with high-resolution mass spectrometry and mono and two-dimensional nuclear magnetic resonance made it possible to identify the joint presence in an orchid of three stilbenoïds i.e, imbricatin, methoxycoelonin and gigantol. By flow cytometry, it is shown that the replicative senescence of human normal skin fibroblasts involves a reduction in the number of cells in phase S. A proteins chips technology dedicated to cell cycle proteins makes it possible to correlate this decrease of the number of cells in phase S to a decrease in cyclin E and cyclin dependant kinase 2, cdk2. The treatment by an ethanolic extract of stems of Vanda coerulea titrated in the three stilbenoids restores the percentage at an equivalent rate to that of young cells and the rate of cyclin E and, cdk2, thus bringing a beginning of explanation of their mechanism. These activities let predict an interesting potential as active ingredients to fight against the visible signs of cutaneous ageing.
    Annales Pharmaceutiques Françaises 05/2011; 69(3):177-81.
  • F Bonté
    [Show abstract] [Hide abstract]
    ABSTRACT: The main function of the skin is to protect the body against exogenous substances and excessive water loss. The skin barrier is located in the outermost layer of the skin, called the stratum corneum, which is composed of corneocytes, originating from the keratinocytes differentiation process, embedded in organized complex lipid domains. Moisturizing of the skin is recognized as the first anti-aging skin care. Skin moisturization is essential for its appearance, protection, complexion, softness and the reinforcement of its barrier properties against deleterious and exogenous environmental factors. The intrinsic water binding capacity of skin is not only due to the complex natural moisturizing factor present in corneocytes, but also to hyaluronic acid and a regulated water transport within the skin. Recent data shows that the water movements between the cells at the different levels of the epidermis are due to dedicated water and glycerol transport proteins named aquaporins. Their role in the skin moisturization is completed by corneodesmosomes and tight junctions. Water and pH are now shown to be of prime importance in the regulation of the epidermal enzymes linked to corneocytes desquamation and lipid synthesis. Furthermore, the level of moisturization of the skin is important in its protection against repeated exposure to various irritant agents or phenomena such as very frequent washing with strong tensioactive materials.
    Annales Pharmaceutiques Françaises 05/2011; 69(3):135-41.
  • Planta Medica 08/2010; 76(12). · 2.34 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The purpose of this study was to assess the in vivo efficacy of a cosmetic formulation containing plant extracts including orchid extracts, compared to 3% vitamin C derivative formulated with the same excipient, in Japanese female adult volunteers with melasma and/or lentigo senilis. The ethics committee of Osaka National Hospital approved the protocol of the study. Before recruitment, selection and inclusion of a volunteer in this study, signed informed consent was obtained from each volunteer after she was given clear and precise information on the study, enabling her to appreciate the aim of the study and the consequences of her consent. Forty-eight female volunteers aged 30-60 years applied the plant extracts and vitamin C derivative to one side of the face. After repeated application for 8 weeks, efficacy was evaluated clinically by colorimetric measurements and subjectively using a questionnaire. After 8 weeks of treatment, both the clinical evaluations by a dermatologist and the questionnaire surveys by volunteers indicated that the cosmetic formulation containing plant extracts was significantly effective in improving the size, brightness, color intensity, clarity, visibility and global appearance of the pigmented spots, and also the luminosity complexion and skin clarity of the face. The good agreement between the results of clinical evaluations and those of questionnaire surveys showed that the orchid-rich plant extracts possess efficacy similar to vitamin C derivative in whitening the skin as well as melasma and lentigo senilis on the face of Japanese women.
    The Journal of Dermatology 06/2010; 37(6):522-30. · 2.35 Impact Factor
  • Planta Medica 07/2009; 75(09). · 2.34 Impact Factor
  • Planta Medica 07/2009; 75(09). · 2.34 Impact Factor
  • Planta Medica 07/2009; 75(09). · 2.34 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Survivin is a bi-functional member of inhibitor of apoptosis protein family, as it is able to both inhibit apoptosis and to regulate cell cycle. We investigated the role of survivin in human keratinocytes under normal conditions and during UVB irradiation. Survivin siRNA decreases proliferation and induces apoptosis in human keratinocytes, in a mode consistent with the mitotic catastrophe. Low doses UVB increase survivin expression at earlier times, while high doses down-regulate survivin level. Low doses UVB induce cell cycle arrest in G2/M, while high doses UVB cause apoptosis. Moreover, overexpression of survivin protects keratinocytes from UVB-induced apoptosis, and silencing of survivin renders keratinocytes more susceptible to UVB-induced cell death. Finally, survivin siRNA increases UVB-induced reduction of cell proliferation. Taken together, these results indicate that survivin plays a critical role in epidermal homeostasis in normal conditions and during UVB exposure, with possible implication in skin carcinogenesis.
    Experimental Dermatology 04/2009; 18(5):464-71. · 4.12 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Several aquaporins (AQPs) are expressed in mammalian skin. Some are directly involved in water transport, such as AQP5, which is involved in sweat secretion. In contrast, the physiological role of skin aquaglyceroporins, which permeate both water and glycerol, appears more and more complex. AQP3 is the most abundant skin aquaglyceroporin. Both water and glycerol transport by AQP3 appear to play an important role in hydration of mammalian skin epidermis. In addition, recent data suggest that glycerol transport by AQP3 is involved in the metabolism of lipids in skin as well as in the regulation of proliferation and differentiation of keratinocytes. Finally, AQP3 is also believed to be important in wound healing, as a water channel by facilitating cell migration, and as a glycerol transporter by enhancing keratinocyte proliferation and differentiation.
    Handbook of experimental pharmacology 02/2009;
  • Source
    Retrovirology 01/2009; · 4.77 Impact Factor
  • Frédéric Bonté, Marc Dumas, Alex Saunois, Alain Meybeck
    [Show abstract] [Hide abstract]
    ABSTRACT: An alkaloid fraction from Phellodendron amurense bark, inhibits phospholipase A 2 activity. Activity is linked to the alkaloid fraction mainly composed of phellodendrine and magnoflorine.
    Pharmaceutical Biology 09/2008; 37(1):77-79. · 1.34 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The neurotrophin (NT) family includes nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3) and NT-4/5. Keratinocytes synthesize and release all NTs. Keratinocytes express the low-affinity p75 receptor which binds all NTs, the high-affinity NGF receptor trkA and the NT-3 receptor trkC. By contrast, keratinocytes express only a truncated form of trkB, the BDNF high-affinity receptor. NT-3 stimulates keratinocyte proliferation. NTs other than NGF fail to protect keratinocytes from UVB-induced apoptosis. While NGF decreases upon UVB irradiation, NT-3 and NT-4 are upregulated. UVA dose dependently increases NT-3 levels. NT-3 and NGF stimulate each other release. Both fibroblasts and myofibroblasts synthesize and release all NTs, as well as their trk receptors except for trkC. p75 is more expressed in myofibroblast than in fibroblasts. NGF reduces secretion of collagen I in myofibroblasts. Myofibroblasts secrete more collagen I than fibroblasts. NGF reduces production of metalloproteinase 2 (MMP2) in myofibroblasts. Melanocytes synthesize and release all NTs. UVB irradiation upregulates the release of NT-3, while it downregulates the release of NT-4. Melanocytes express p75, which is downregulated by UVB. Melanocytes also express trkA and the extracellular domain of trkB. Taken together, these data indicate that a complex NT network exists in human skin with potential functions, partly to be determined.
    Experimental Dermatology 06/2008; 13(9):588 - 588. · 4.12 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The extent of changes with aging depends largely on how much the skin is exposed to sunlight and also on the genetic disposition of the individual. There are thus two main processes, extrinsic aging because of environmental stress, and intrinsic genetically programmed aging [1]. Hence, the processes of aging depends on a person's ethnic origin and the part of the world in which they live.Methods The present study investigates the influence of age and exposure to sunlight on the facial skin of 31 healthy Japanese women, aged 20–78 years old, living in Osaka city. Skin samples were obtained during plastic surgery from the face, from areas exposed to varying intensities of sunlight (forehead, cheek, nose, upper eyelid). Samples were fixed in formalin and embedded in paraffin. Sections (5–7 μm) were cut and stained with hematoxylin–phloxyn–safran, orcein or Masson's trichrome. Others were immunostained for p63, β1-integrin, type IV collagen CD1a and AQP3. Statistical analysis of quantitative and qualitative parameters were performed by analysis of variance (anova) with linear regressions, and the chi-squared test.Results and discussionEpidermis and dermal-epidermal junction: histological organizationWe confirmed that the whole living epidermis becomes thinner with increasing age, with an average decrease of about 5 μm per decade. This thinning is mainly because of a significant reduction in the number of keratinocyte layers. The thinning of the epidermis and the reduction of the keratinocytes layers in Japanese skin do not seem to be reflected in the thickness of the stratum corneum, which appears to remain constant whatever the age in the sample studied.The epidermal papillary structures also became flatter with age, associated with an increase in the thickness of the dermal–epidermal junction (DEJ). Thus, in addition to the loss of epidermal cells, the epidermis and dermis become less overlapped, so reducing the surface area for exchange between the two compartments. The DEJ also become thicker as Japanese ages and the expression of type IV collagen, the main constituent of the lamina densa and anchoring plaques is reduced in the most photoexposed skin areas. This accounts for the major changes in the function and molecular structure of DEJ components, as in aged Caucasian skin [2].Keratinocyte growth and differentiation –β1-integrin and p63There is no doubt that the rate of cell turnover decreases in the flat aged epidermis, as indicated by the smaller number of proliferative cells [3, 4]. This study focused on two key regulatory proteins. One was p63, that is involved in maintaining the proliferative potential of basal keratinocytes and blocking their calcium-induced differentiation [5]. The other was β1-integrin, an adhesion protein present in basal keratinocytes and linked to their clonogenic potential [6].We found p63-positive cells in the basal layer of the epidermis and in the suprabasal layers (Fig. 1a), in agreement with others [7]. The used pan anti-p63 antibody suggest that other isoforms of the protein in addition to the major ΔNp63α mainly expressed in the basal cells, could take part to other functions like differentiation in the suprabasal layers [5]. The great interindividual variation in the staining intensity for p63 in the samples studied made it impossible to detect significant changes in the number of p63-positive cells with age. Only an increase of p63 was observed in photoexposed areas compared to others within this case, a possible relation to the epidermal thickening.Figure 1. Immunostaining of Japanese facial skin showing AQP3 expression at the plasma membrane of keratinocytes throughout the living epidermis (a) and the age-related change in AQP3 (b).Download figure to PowerPointβ1-integrin was detected only in the basal keratinocytes, and the staining intensity varied from one segment of the basal layer to another. We evaluated the length of immune-labeled epidermis and the intensity of labeling in each fragment, using an arbitrary colorimetric scale (0–5). We observed a significant decrease in the intermediate intensities (equal to 2 only) with age in the zone least exposed to sunlight. This is consistent with the loss of adhesive properties of freshly isolated epidermal cells in aged skin [2] and the existence of different pools of basal keratinocytes [6]. It suggests that the effect of aging could affect particularly on the transit amplifying cells containing intermediate quantities of β1-integrin.Osmotic and water homeostasis – aquaporin-3In addition to the stratum corneum (SC) that limits transepidermal water loss, the osmotic equilibrium inside the epidermis and hydration is controlled by the aquaglyceroporins 3 (AQP3) [8, 9]. Immunostaining for AQP-3 confirmed the presence of the protein in the plasma membranes of keratinocytes throughout the epidermis, together with AQP-3 cytoplasmic expression of the basal layer cells (Fig. 1a). There was no immunostaining in the SC (Fig. 1a) to retain water in the epidermis via the tight junction proteins [10], so maintaining the water-lipid barrier within the SC. The immunostaining for AQP3 decreased significantly with the skin age (Fig. 1b), but there was no significant difference between areas exposed to sunlight and those not exposed. This suggests that there is an overall reduction in the natural hydration potential as Japanese facial epidermis ages.The immune system – epidermal CD1a-positive cellsEpidermal dendritic cells, mainly Langerhans cells, control the skin immune system. These cells are CD1a positive (CD1a+). Immunostaining showed a major population of highly dendritic cells throughout the epidermis of all the Japanese skin samples. It also showed that the areas most exposed to sunlight (cheeks, forehead and nose) had significantly more CD1a+ cells than less exposed areas (upper eyelid) (Fig. 2a). This confirms previous findings on the wrinkling of area of Caucasian facial skin after chronic exposure to UV light [11]. The number of CD1a+ cells in less exposed areas of skin increased significantly with donor age (Fig. 2b). This shows that chronological aging and exposure to sunlight give rise to an epidermis which cellular immune homeostasis is perturbed.Figure 2. Immunostaining for CD1a in Japanese facial skin: numbers of CD1a-positive (CD1a+) epidermal cells per mm of dermal–epidermal junction (DEJ) in skin exposed to sunlight and skin from protected areas (a), and sun-protected area of facial skin from subjects of different ages (b).Download figure to PowerPoint
    International journal of cosmetic science 06/2008; 27(1):47 - 50.
  • [Show abstract] [Hide abstract]
    ABSTRACT: The biological effects of hormones on human melanocytes are still being investigated. Several kinds of hormones have mitogenic and/or melanogenic effects on human melanocytes. For example, melanotropic hormones, such as α-melanocyte-stimulating hormone (α-MSH) and adrenocorticotrophic hormone (ACTH), were shown to induce skin darkening some time ago, and more recently, the mechanism of up-regulation of tyrosinase activity in human normal melanocytes by melanotropins through the cyclic AMP (cAMP) signaling pathway has been reported. cAMP is now recognized to play a key role in the regulation of skin pigmentation. α-MSH is known to elevate intracellular cAMP levels through the melanocortin 1 receptor (MC1R) and this plays a critical role in the regulation of melanogenesis. Recently it has been recognized that cAMP elevating agents up-regulate transcription of the MITF gene that in turn stimulates expression of the tyrosinase gene via MITF binding to its M-box.Solar lentigo is a benign pigmented spot on sun-exposed skin especially on the back of the hands, arms and on the forehead. We have compared melanogenesis histological parameters in solar lentigo and in normal skin of Japanese women. We chose to analyze melanin distribution and expression of α-MSH as mediators of human pigmentation, in solar lentigo and normal skin biopsies of photo-exposed dorsal forearm. Punch biopsies were fixed with 4% formaldehyde and sections were stained with Fontana-Masson technique to evaluate melanin distribution. Immunohistochemistry was carried out to demonstrate α-MSH protein expression using rabbit polyclonal antibody anti-human α-MSH. Melanin distribution and relative expression of α-MSH were analyzed and quantified using semiquantitative computer-assisted image analysis. With this technique, we found that solar lentigo skin possessed 60% more α-MSH expression than normal skin (Fig. 1).Figure 1. Quantification of alpha MSH expression in solar lentigo and normal skin for 10 japanese subjects. Immunolocalization of alpha MSH in solar lentigo and normal skin. (a) Representative image of alpha MSH expression in solar lentigo. (b) Representative image of alpha MSH expression in normal skin. Alpha MSH expression was determined from the integrated intensity given areas of epidermis reported to the total surface of epidermis in each section. Four selected areas of each section were photographed and quantified. Statistical differences were evaluated using the paired Student's t-test. Data are presented as the mean of 10 biopsies.Download figure to PowerPointWhile it has been reported that human skin color is changed by castration or by injection of androgen and a recent in vitro study in contrast suggested that testosterone might reduce tyrosinase activities in human melanocytes through the decrease of the mRNA expression of MC1R, the precise mechanism involved in the regulation of skin pigmentation by androgens has remained unclear. To date, there have been few reports about the effects of androgens on human melanocytes. In a previous study, we demonstrated that human genital melanocytes are androgen target cells. Those melanocytes had androgen receptors (ARs) in their nuclei as detected by immunohistochemistry and they also had high levels of 5α -reductase activities, the enzyme that converts testosterone to its more active form, 5α-dihydrotestosterone (DHT). R1881 (methyltrienolone, a potent synthetic androgen) stimulated tyrosinase activity when melanocytes were cultured continuously with TPA, hydrocortisone and BPE and then were treated with FBS [1]. When melanocytes were deprived of FBS and BPE for a prolonged time, the effects of androgen on tyrosinase activity were reduced. Furthermore, when cultured without FBS, BPE or TPA, prolonged exposure to R1881 down-regulated tyrosinase activity when added together with FBS and BPE. These data suggest that FBS or BPE contain elements that inhibit tyrosinase activity when contacting melanocytes even if only briefly [2].Recent advances in the understanding of androgen signaling indicate the specific membrane-signaling pathway involved in Sex hormone-binding globulin (SHBG) as well as in the androgen-AR mechanism, a classical pathway. SHBG is a glycoprotein found in human plasma that possesses a high affinity for binding of sex hormones. It has been recognized that unbound, free steroids function on target cells through their intracellular receptors. Recently, it has been speculated that SHBG participates in steroid signaling pathways by binding to SHBG-receptors (RSHBG) located on the target cell membranes. SHBG that is bound to a steroid cannot bind to its receptor, but free SHBG that first binds to the RSHBG can subsequently bind steroids. Several studies on human tissues and cultured cells, such as prostate and breast cancer cells, have revealed that the SHGB–RSHBG complex is involved in the steroid-activated signal transduction pathway that results in the accumulation of intracellular cAMP. SHBG–RSHBG complexes on the cell membrane combine with some types of sex hormones and then induce the accumulation of intracellular cAMP in those tissues and cells. Further, some steroids antagonize the activation of SHBG–RSHBG induced by other steroids. FBS contains high endogenous levels of SHBG, which can confuse the study of steroid effects. We formed the hypothesis that androgen function in melanocytes is effected through the cell membrane signaling pathway via the SHBG–RSHBG complex. Immunohistochemistry was used to demonstrate the co-staining of SHBG and testosterone with specific monoclonal antibodies. There was a dramatic increase in positive staining following SHBG pre-treatment. Generally, staining for testosterone is much stronger when staining for SHBG is stronger. These immunohistochemical results strongly suggest the existence of the RSHBG on the surface of normal human melanocytes.The responses of intracellular levels of cAMP to various androgens and hydrocortisone were studied. After the saturation of RSHBG on the cell membranes by SHBG and then washing to remove excess SHBG, a decrease in intracellular cAMP levels within 30 min of incubation with testosterone was observed in a dose-dependent manner, but not in the absence of SHBG pre-treatment. Those findings suggest the possibility that normal human melanocytes might utilize the cell membrane transduction pathway of androgen via the SHBG–RSHBG complex to regulate intracellular cAMP. They further suggest that strong androgens, such as testosterone and DHT, might act as antagonists in this pathway. We have already reported that human melanocytes possess significant levels of 5α -reductase activities and that testosterone is predominantly metabolized to DHT, a stronger androgen. DHT might work as a negative feedback factor against cAMP accumulation via the SHBG–RSHBG complex, since the affinity of DHT to SHBG is higher than that of testosterone.Tyrosinase activity was decreased by the physiological concentration of testosterone after 4 days of treatment. As the decreases in tyrosinase activity coincided with decreases of intracellular cAMP, those intracellular cAMP levels (regulated through cell membrane signaling) might regulate tyrosinase activity influenced by androgens after treatment with SHBG. Tyrosinase activity was stimulated by R1881 when the melanocytes were cultured continuously in medium containing FBS and hydrocortisone. FBS and hydrocortisone that are endogenous in the medium might work against the effect of strong androgens that may be antagonists in the cell membrane signaling pathway, because high concentrations of unbound SHBG found in FBS can easily bind to the cell surface and high concentrations of hydrocortisone added to the culture medium might have already occupied the SHBG–RSHBG complex on the cell membrane.Further, we studied the expression of tyrosinase mRNAs by semi-quantitative RT-PCR. The expression of tyrosinase gene transcripts was not altered by the physiological concentration of testosterone in human plasma. No significant differences were also seen in tyrosinase mRNA expression between androgen treated cells and controls as measured by Northern blot analysis. While the classical androgen signal pathway (the androgen-AR complex) may possibly play a role in human melanocytes, this pathway might not directly regulate the transcriptional level of the tyrosinase gene. Western blot analysis also suggests that strong androgens have no significant effect on the levels of tyrosinase protein, even though its catalytic function is affected. Taken together, we speculate that strong androgens and SHBG might function as antagonists of intracellular cAMP accumulation via the SHBG–RSHBG complex signaling pathway on the cell membrane, and might also regulate tyrosinase activity at the post-transcriptional and/or post-translational levels.In conclusion, androgens may be another type of humoral hormone as well as α-MSH that controls melanin production and these hormones, along with other factors, may collaborate to regulate skin pigmentation. In solar lentigo, α-MSH may be a good mediator of human skin pigmentation. Sex hormones and α-MSH can be interesting target for whitening and anti-spot compounds.AcknowledgmentThe authors thank N. Lachmann and J. B. Grieu for their support, M. Juan, E. Noblesse and P. Gasser (Bio EC, Clamart, France) for assistance in the histological studies.References1. Tadokoro, T. et al. Human genital melanocytes as androgen target cells. J Invest Dermatol. 109, 513–517 (1997).2. Tadokoro, T. et al. The inhibitory effect of androgen and sex-hormone-binding globulin on the intracellular cAMP level and tyrosinase activity of normal human melanocytes. Pigment Cell Res. 16, 190–197 (2003).
    International journal of cosmetic science 06/2008; 27(1):56 - 59.

Publication Stats

712 Citations
123.34 Total Impact Points

Institutions

  • 1994–2014
    • LVMH Recherche
      Lutetia Parisorum, Île-de-France, France
  • 2011
    • University of Strasbourg
      Strasburg, Alsace, France
  • 2008
    • Università degli Studi di Modena e Reggio Emilia
      • Department of Biomedical, Metabolical and Neurosciences
      Modène, Emilia-Romagna, Italy
  • 2005
    • Charité Universitätsmedizin Berlin
      Berlín, Berlin, Germany
  • 2003
    • Claude Bernard University Lyon 1
      Villeurbanne, Rhône-Alpes, France