Effective treatment for sensitive skin: 4-t-butylcyclohexanol and licochalcone A.

BACKGROUND: More than 50% of adults report to suffer from sensitive skin. This common condition is characterized by subjective sensations such as prickling, burning, skin tightness or pruritus, and is often accompanied by objective symptoms like inflammation and erythema. OBJECTIVE: The objective of this study was to develop an active ingredient concept for the treatment of sensitive skin. We tested compounds regarding their potential to (i) decrease the release of proinflammatory mediators, which among others induce erythema and (ii) counteract the hyperresponsiveness of nerve fibres and, thus, exert effects on cutaneous neurosensory dysfunction. METHODS: 4-t-butylcyclohexanol, licochalcone A and acetyl dipeptide-1 cetyl ester were analysed in vitro regarding their potential to (i) decrease the release of PGE2 and activation of NFκB and to (ii) inhibit TRPV1 activation or the release of neuronal CGRP. To assess subjective and objective symptoms of skin sensitivity in vivo, two controlled, single-blind, randomized studies were conducted with 4-t-butylcyclohexanol and the combination with licochalcone A. RESULTS: In vitro, 4-t-butylcyclohexanol significantly reduced TRPV1 activation, while acetyl dipeptide-1 cetyl ester had no effect on receptor activation. Licochalcone A significantly decreased NFκB signalling and PGE2 secretion, at lower concentrations than acetyl dipeptide-1 cetyl ester. A formulation containing 4-t-butylcyclohexanol showed a significant immediate anti-stinging/anti-burning effect in vivo, and a cream base containing a combination of 4-t-butylcyclohexanol and a licochalcone A-rich licorice extract reduced shaving-induced erythema. CONCLUSION: In vitro and in vivo data indicate that the combination of the TRPV1 antagonist 4-t-butylcyclohexanol and the potent anti-inflammatory licochalcone A provide an effective active ingredient concept for the treatment of sensitive skin, as the topical application resulted in an immediate relief from symptoms such as erythema and stinging.

4-n-butylresorcinol, a highly effective tyrosinase inhibitor for the topical treatment of hyperpigmentation.

BACKGROUND: Hyperpigmentary disorders like melasma, actinic and senile lentigines are a major cosmetic concern. Therefore, many topical products are available, containing various active ingredients aiming to reduce melanin production and distribution. The most prominent target for inhibitors of hyperpigmentation is tyrosinase, the key regulator of melanin production. Many inhibitors of tyrosinase are described in the literature; however, most of them lack clinical efficacy. METHODS: We were interested in evaluating the inhibition of skin pigmentation by well-known compounds with skin-whitening activity like hydroquinone, arbutin, kojic acid and 4-n-butylresorcinol. We compared the inhibition of human tyrosinase activity in a biochemical assay as well as inhibition of melanin production in MelanoDerm skin model culture. For some compounds, the in vivo efficacy was tested in clinical studies. RESULTS: Arbutin and hydroquinone only weakly inhibit human tyrosinase with a half maximal inhibitory concentration (IC(50)) in the millimolar range. Kojic acid is 10 times more potent with an IC(50) of approximately 500 µmol/L. However, by far the most potent inhibitor of human tyrosinase is 4-n-butylresorcinol with an IC(50) of 21 µmol/L. In artificial skin models, arbutin was least active with an IC(50) for inhibition of melanin production > 5000 µmol/L. Kojic acid inhibited with an IC(50) > 400 µmol/L. Interestingly, hydroquinone inhibited melanin production in MelanoDerms with an IC(50) below 40 µmol/L, probably due to a mechanism different from tyrosinase inhibition. Again, 4-n-butylresorcinol was the most potent inhibitor with an IC(50) of 13.5 µmol/L. In vivo efficacy of 4-n-butyl-resorcinol was confirmed in clinical studies. Subjects with age spots on the forearm treated twice daily two age spots with a formula containing 4-n-butylresorcinol and two control age spots with the corresponding vehicle. Within 8 weeks, 4-n-butylresorcinol reduced visibly the appearance of age spots, while the control spots showed no improvement. A second study showed that 4-butylresorcinol was more effective than 4-hexylresorcinol and 4-phenylethylresorcinol. CONCLUSION: The present in vitro and in vivo data prove the high inhibitory capacity of 4-n-butylresorcinol on human tyrosinase activity, exceeding by far the potency of hydroquinone, arbutin and kojic acid. The resulting clinical improvement of skin hyperpigmentations reveals 4-n-butylresorcinol as a very valuable active compound for the management of pigmentation disorders.

Effects of glyceryl glucoside on AQP3 expression, barrier function and hydration of human skin.

BACKGROUND/AIM: Aquaporins (AQPs) present in the epidermis are essential hydration-regulating elements controlling cellular water and glycerol transport. In this study, the potential of glyceryl glucoside [GG; alpha-D-glucopyranosyl-alpha-(1->2)-glycerol], an enhanced glycerol derivative, to increase the expression of AQP3 in vitro and ex vivo was evaluated. METHODS: In vitro studies with real-time RT-PCR and FACS measurements were performed to test the induction by GG (3% w/v) of AQP3 mRNA and protein in cultured human keratinocytes. GG-containing formulations were applied topically to volunteer subjects and suction blister biopsies were analyzed to assess whether GG (5%) could penetrate the epidermis of intact skin, and subsequently upregulate AQP3 mRNA expression and improve barrier function. RESULTS: AQP3 mRNA and protein levels were significantly increased in cultured human keratinocytes. In the studies on volunteer subjects, GG significantly increased AQP3 mRNA levels in the skin and reduced transepidermal water loss compared with vehicle-controlled areas. CONCLUSION: GG promotes AQP3 mRNA and protein upregulation and improves skin barrier function, and may thus offer an effective treatment option for dehydrated skin.

Stimulation of skin's energy metabolism provides multiple benefits for mature human skin.

As an organism ages, there is a decline in mitochondrial function and cellular energy balance. This decline is both accelerated by and can cause the formation of reactive oxygen species (ROS) that damage nuclear and mitochondrial DNA, lipid membranes as well as structural and catalytic proteins, especially those involved in energetic pathways of cells. Further, ROS have also been linked to some of the detrimental skin changes that occur as a result of photoaging. We have previously shown that levels of Coenzyme Q10 (CoQ10), a component of the respiratory chain in mitochondria, are reduced in skin cells from aging donors, and that topical supplementation can ameliorate processes involved in skin aging. Creatine is another important component of the cellular energy system and phosphocreatine, its phosphorylated form, functions as a reservoir for high energy phosphates. Unfortunately the creatine system and thus the energy storage mechanism in skin are negatively affected by aging and conditions of oxidative stress. This article reviews some of our in vivo data about the synergistic effects of combining a stabilized form of Creatine with CoQ10 and clearly depicts their beneficial effects as active ingredients in topical formulations.

Is vitamin D deficiency related to accumulation of advanced glycation end products, markers of inflammation, and oxidative stress in diabetic subjects?

OBJECTIVES: In diabetes accumulated advanced glycation end products (AGEs) are involved in the striking cardiovascular morbidity/mortality. We asked whether a hypovitaminosis D associates with an increased formation and toxicity of AGEs in diabetes. METHODS: In 276 diabetics (160 M/116 F, age: 65.0 ± 13.4; 43 type 1,T1DM, and 233 type 2 patients, T2DM) and 121 nondiabetic controls (60 M/61 F; age: 58.6 ± 15.5 years) routine biochemistry, levels of 25-hydroxyvitamin D3 (25-(OH)D), skin autofluorescence (SAF), plasma AGE-associated fluorescence (AGE-FL), N (ε) -(carboxymethyl)lysine (CML), soluble receptor for AGEs (sRAGE), soluble vascular adhesion protein-1 (sVAP-1), high sensitive C-reactive protein (hs-CRP), and renal function (eGFR) were determined. RESULTS: In the diabetics SAF and AGE-Fl were higher than those of the controls and correlated with age, duration of diabetes, and degree of renal impairment. In T2DM patients but not in T1DM the age-dependent rise of SAF directly correlated with hs-CRP and sVAP-1. 25-(OH)D levels in diabetics and nondiabetics were lowered to a similar degree averaging 22.5 ng/mL. No relationship between 25-(OH)D and studied markers except for sVAP-1 was observed in the diabetics. CONCLUSION: In diabetics hypovitaminosis D does not augment accumulation of AGEs and studied markers of microinflammation and oxidative stress except for sVAP-1.

Multidirectional interactions in vitro between lymphoid cells from Mls-disparate strains.

Chromosome 1 of the mouse carries a number of genes for alloantigens which can be recognized by T cells, among those the mixed lymphocyte stimulation (Mls) locus and the lymphocyte stimulating determinant (Lsd) locus have been described. The Relationship between the antigens coded for by these two loci has been further analyzed using a B10.BR anti C3H/Tif T cell clone E11. Segregation analysis was done with 167 individuals from backcrosses of (BALB/c (Mlsb, Lsd-) x DBA/2 (Mlsa, Lsd+] F1 animals into BALB/c mice. The analysis of the backcross data and of a limited number of recombinant inbred (RI) strains did not allow the segregated of the two loci, despite the fact that stable clusters were obtained in cluster analysis of the segregation data. The reasons for this failure are discussed. Parallel to the genetic analysis, we have studied the functional properties of the E11 T cell clone. First, there is the proliferation of the E11 T cells upon stimulation by macrophages or B cells of Mls-disparate stimulator strains. Second, there is an induction of differentiation of B cells of stimulator strains, requiring the direct interaction between E11 T and stimulator B cells. Third, there is an inhibitory influence of E11 T cells on the production of a mediator by Mls-disparate spleen cells presumably by their macrophages. We propose that the Mls antigen is a receptor regulating macrophage differentiation and transmitting a signal influencing the production of a mediator. This signal could be either the down regulation of the production of a stimulatory monokine or the induction of the production of an inhibitory monokine. Our presented data demonstrate that the anti Mls response is more complex than hitherto anticipated. It involves a multidirectional interaction between the Mls-disparate cell partners.

Results of photoprovocation and field studies on the efficacy of a novel topically applied antioxidant in polymorphous light eruption.

BACKGROUND: UVA-induced photooxidation is considered to play an essential role in the pathogenesis of polymorphous light eruption (PLE), and topical pretreatment of skin with alpha-glucosylrutin (AGR), a potent plant-derived antioxidant, has been shown to significantly suppress photoprovoked PLE eruption. AIM: In order to further elucidate the optimum pretreatment regimen and to investigate the efficacy and skin compatibility of topical preparations containing AGR under field conditions, two controlled clinical studies were conducted in PLE patients. METHODS: In the first study, photoprovocation of PLE was performed in 20 patients, using UVA irradiation (4 x 60-100 J/cm(2)), applied to four test sites at the individual areas of predilection. One site served as an untreated control. The remaining three sites received treatment with a SPF 15 sunscreen containing 0.25% AGR (Eucerin Gel Cream Phase 2) 30 minutes before irradiation. Two of these sites were additionally pretreated with the corresponding AGR-containing vehicle (Eucerin Gel Cream Phase 1) twice daily for 3 and 7 days, respectively. The second study was conducted as a controlled in-use-test in patients with PLE (n = 27) or acne aestivalis (n = 3), who had suffered from the disease during their last year's vacation. They were educated to apply the pre-sun preparation to the formerly affected skin areas twice daily for 1 week before their planned vacation and to use the SPF 15 sunscreen 30 minutes before each vacation sun exposure. Symptoms were recorded in patients' diaries throughout the vacation and documented by a physician after their return. RESULTS: In the first study, protection of skin with the SPF 15 sunscreen alone led to a significant prevention of PLE symptoms, especially itch, compared with the control area. Pretreatment further reduced the severity of PLE significantly and led to total prevention in 19 patients. In the second study, whereas 92.6% had reported severe and 7.4% mild PLE in the last year, there were currently only 7.4% severe cases, with 25.9% mild and 29.6% questionable cases; 37% had no symptoms at all. Also, two out of three acne aestivalis patients had diminished symptoms after treatment. CONCLUSION: The results confirm the prophylactic efficacy of the antioxidant AGR in PLE, applied as SPF 15 sunscreen alone or additionally to pretreatment with a corresponding pre-sun preparation, and also show an effect in acne aestivalis patients.

Coenzyme Q10, a cutaneous antioxidant and energizer.

The processes of aging and photoaging are associated with an increase in cellular oxidation. This may be in part due to a decline in the levels of the endogenous cellular antioxidant coenzyme Q10 (ubiquinone, CoQ10). Therefore, we have investigated whether topical application of CoQ10 has the beneficial effect of preventing photoaging. We were able to demonstrate that CoQ10 penetrated into the viable layers of the epidermis and reduce the level of oxidation measured by weak photon emission. Furthermore, a reduction in wrinkle depth following CoQ10 application was also shown. CoQ10 was determined to be effective against UVA mediated oxidative stress in human keratinocytes in terms of thiol depletion, activation of specific phosphotyrosine kinases and prevention of oxidative DNA damage. CoQ10 was also able to significantly suppress the expression of collagenase in human dermal fibroblasts following UVA irradiation. These results indicate that CoQ10 has the efficacy to prevent many of the detrimental effects of photoaging.

Alterations in the epidermal-dermal melanin axis and factor XIIIa melanophages in senile lentigo and ageing skin.

BACKGROUND: Senile lentigo (SL) is a pigmentation disorder that occurs predominantly on the dorsa of the hands, the forearms and the face; its incidence increases with age. Histological hallmarks of SL lesions are hyperpigmentation of the epidermis and elongation of the epidermal rete ridges. Various factors such as alpha-melanocyte-stimulating hormone, endothelin-1 or stem cell factor are involved in the onset and maintenance of the increased pigmentation. Alterations of the dermal compartment have not yet been analysed in detail in SL. OBJECTIVES: To study the occurrence and distribution of melanin in the dermis from SL and aged skin, biopsies from 12 subjects were morphologically analysed by light and electron microscopy in comparison with unaffected skin. METHODS: Punch biopsies of SL and adjacent skin from 12 male or female volunteers aged 52-81 years were prepared for light and electron microscopy and samples were analysed by morphological, morphometric, histochemical and immunohistochemical methods. RESULTS: The epidermis from SL revealed morphological features such as hyperpigmentation of basal keratinocytes and the formation of elongated rete ridges. S100+ melanocytes in the stratum basale were not markedly increased, indicating that the hyperpigmentation is predominantly due to changes in melanin synthesis, distribution or turnover. Quantification of epidermal cells expressing the proliferation marker Ki67 did not show an increase of this parameter in SL, indicating that at least in the established lesion cell proliferation is not enhanced. We further focused on the dermal compartment and observed granulated cells which were more abundant in SL. Electron microscopic and histochemical analysis revealed that the granulation of these cells is based on melanosomes, mostly present in large melanosomal complexes. Immunohistochemistry using antibodies to CD68 and factor XIIIa (FXIIIa) showed these melanophages to be predominantly FXIIIa+ dermal dendrocytes, which were about six times more abundant than CD68+ macrophages. CONCLUSIONS: In SL an increased number of melanophages was found compared with unaffected skin from the same subject. These melanophages were identified as FXIIIa+ dermal dendrocytes. Possible functional consequences of the massive melanin uptake by dermal dendrocytes are discussed.

A comparison of the IgG isotype expression in the so-called thymus-independent immune responses to alpha(1----3) and alpha(1----6) dextran.

This paper presents data on the IgG antibody response against two "thymus-independent" dextran (Dex) antigens from Leuconostoc mesenteroides, alpha(1----3) Dex B 1355S and alpha(1----6) Dex B 512F in BALB/c and C57BL/6 mice, which are considered to be responders or low responders to the respective antigen. The data point toward three common rules governing the two anti-Dex responses despite immunogenetic and antigenic disparities: (1) age dependency of the IgG isotype regulation of the response; (2) down-regulation of IgG isotype expression by T cells; and (3) individually determined preposition for IgG isotype formation in a given animal.

Regulation of the anti-alpha(1----3) dextran IgG antibody response of BALB/c mice by idiotype-specific T suppressor lymphocytes.

The immune response of BALB/c mice against the so-called thymus-independent bacterial Ag alpha(1----3) dextran (Dex) is restricted to the expression of few major idiotypes (Id). It is furthermore under the control of T lymphocytes which regulate the isotype expression in such a way that they prevent anti-Dex IgG antibody production upon immunization. At the same time these T cells are part of a regulatory system for Dex-specific B cell memory formation. The underlying Ts cell activity has previously been analyzed by using euthymic and athymic congenic animals. Now we have isolated CD4-positive Id-specific T cell lines and clones which by several criteria are representatives of the above Ts cells. They inhibit in vitro proliferation and antibody secretion of Dex-specific hybridoma B cells. They prevent Id-restricted in vivo IgG anti-Dex antibody formation in T cell-reconstituted BALB/c nu/nu mice. At the same time they enforce, again Id-specific, accumulation of Dex-specific B memory cells. As has been shown previously under the influence of splenic Ts cells, these B memory cells are arrested in the original host but can be expanded and activated for anti-Dex IgG antibody formation upon adoptive transfer into X-irradiated allotype congenic nonresponder BALB.Ighb mice. The data show that the regulatory influence of T cells on the anti-Dex response is Id specific. It can now be studied by means of cloned Ts cells.

The early phase of epidermal barrier regeneration is faster in patients with atopic eczema.

BACKGROUND: Altered epidermal barrier function as determined by transepidermal water loss (TEWL) is a typical feature in patients with atopic eczema (AE). OBJECTIVE: The purpose of this study was to assess the kinetics of epidermal regeneration after barrier perturbation induced by two different stimuli, namely acetone treatment (removal of stratum corneum lipids) and tape stripping (removal of the nonviable stratum corneum). METHODS: Fifteen patients with AE and 12 nonatopic healthy controls were investigated. An area of 9.0 cm2 of clinically normal skin of the forearm flexural side was treated by acetone or tape stripping in a way that an increase in TEWL of 3.5-4.0 times the pretreatment value was achieved. TEWL was recorded directly after perturbation (tO), after 15 min (tl), 3 h (t2), 6 h (t3), 24 h (t4), 48 h (t5), 72 h (t6) and 96 h (t7). RESULTS: The speed of epidermal regeneration was faster after acetone treatment, both in the patient and the control groups, with no significant difference between the two. However, after tape stripping at points t2, t5 and t6, TEWL values relative to tO were significantly lower in atopic skin as compared to normal skin (p < 0.05). CONCLUSION: The faster regeneration of barrier function after tape stripping in patients with AE may be the result of a persisting mild disturbance of barrier function. It may be speculated that repair mechanisms are permanently activated, and therefore barrier recovery is faster. However, a complete restoration of the epidermal barrier function is not achieved, perhaps because of the decreased content of ceramides in atopic skin.

Effects of topically applied antioxidants in experimentally provoked polymorphous light eruption.

BACKGROUND: Polymorphous light eruption (PLE) is the most common photodermatosis, with a prevalence of 10-20% in Western European countries and in the USA. Only few preventive measures for PLE exist, while its etiology and pathogenesis are still elusive. Recent theories on pathogenesis discuss the possible influence of oxidative stress. OBJECTIVE: The presented randomized, placebo-controlled, double-blind study examines for the first time the protective effect of 3 different topically applied antioxidative preparations in experimentally photo-induced PLE. METHOD: 30 patients with a history of PLE underwent photoprovocation after having had applied 3 different formulations with antioxidants and one formulation with the vehicle only to the extensor surface of their upper arms, representing the individual site of predilection, twice daily for 1 week prior to and during the consecutive week of photoprovocation. The antioxidants used were combinations of different concentrations of alpha-glycosylrutin, ferulic acid and tocopheryl acetate. RESULTS: Evaluation after the 4th photoprovocation revealed that the development and severity of PLE and concomitant pruritus were significantly reduced by the application of distinct combinations of antioxidants. CONCLUSION: The results offer a new insight into possible pathomechanisms of PLE and suggest a new approach for preventive and therapeutic measures.

Polymorphous light eruption (PLE) and a new potent antioxidant and UVA-protective formulation as prophylaxis.

BACKGROUND: Polymorphous light eruption (PLE) is the most common photodermatosis. While its etiology still remains elusive, pathogenesis seems to involve UVA-induced oxidative stress and subsequent deregulation of antioxidative immune responses. Only few and often ineffective prophylactic and therapeutic measures exist to date. METHODS: In our randomized, double-blind, placebo-controlled clinical study, we compared the efficacy of a new topical formulation, consisting of 0.25%alpha-glucosylrutin (AGR) (a natural, modified flavonoid), 1% tocopheryl acetate (vitamin E) and a broad-spectrum, highly UVA-protective sunscreen (SPF 15) in a hydrodispersion gel vehicle, to a sunscreen-only gel and vehicle. Thirty patients with a history of PLE were pretreated with either the above formulation, a similar preparation (with the same concentration for vitamin E and AGR, but a different UV filter system), placebo or a SPF 15 sunscreen-only gel, 30 min prior to daily photoprovocation with UVA irradiations of 60-100 J/cm(2) to 5 x 5 cm(2) areas on the upper arms. RESULTS: After 4 days, results revealed a statistically highly significant difference (P<0.001) between the antioxidant containing formulations and placebo, and sunscreen-only formulation, respectively, in experimentally eliciting PLE. While only one patient developed clinical signs of PLE with accompanying itch in the area treated with the new antioxidant UV-protective gel formulation, 62.1% of the placebo-treated areas and 41.3% of the sunscreen-only treated areas showed mild to moderate signs of PLE. CONCLUSION: Combining a potent antioxidant with a broad-spectrum, highly UVA-protective sunscreen is far more effective in preventing PLE than sunscreen alone or placebo and should thus be employed as the prophylaxis of choice for PLE.

[Modulation of oxidative stresses in human aging skin]. / Modulation des oxidativen Stresses in der humanen Altershaut.

Oxidative stress (UV irradiation, free radicals) plays a significant role in aging. Coenzyme Q10 (CoQ10) and exogenously applied antioxidants can significantly reduce the formation of oxidative stress with increasing age. In our in vitro and in vivo experiments concerning the parameters of ultraweak photon emission (UPE), intracellular thiol status, mitochondrial membrane potential and cell vitality, we demonstrated a diminished resistance in keratinocytes of old donors against UV irradiation. This reduced epidermal resistance against oxidative stressors, i.e. UV irradiation, can be improved by topical application of CoQ10 and antioxidants like alpha-glucosylrutin (15). Furthermore, our in vivo investigations show that wrinkles around the region of the eyes ("crow feet") could be reduced by long-term application of CoQ10.