Ascorbyl coumarates as multifunctional cosmeceutical agents that inhibit melanogenesis and enhance collagen synthesis

Ascorbic Acid (Vitamin C) as a Cosmeceutical to Increase Dermal Collagen for Skin Antiaging Purposes: Emerging Combination Therapies

Ascorbic acid (AA) is an essential nutrient and has great potential as a cosmeceutical that protects the health and beauty of the skin. AA is expected to attenuate photoaging and the natural aging of the skin by reducing oxidative stress caused by external and internal factors and by promoting collagen gene expression and maturation. In this review, the biochemical basis of AA associated with collagen metabolism and clinical evidence of AA in increasing dermal collagen and inhibiting skin aging were discussed. In addition, we reviewed emerging strategies that have been developed to overcome the shortcomings of AA as a cosmeceutical and achieve maximum efficacy. Because extracellular matrix proteins, such as collagen, have unique amino acid compositions, their production in cells is influenced by the availability of specific amino acids. For example, glycine residues occupy 1/3 of amino acid residues in collagen protein, and the supply of glycine can be a limiting factor for collagen synthesis. Experiments showed that glycinamide was the most effective among the various amino acids and amidated amino acids in stimulating collagen production in human dermal fibroblasts. Thus, it is possible to synergistically improve collagen synthesis by combining AA analogs and amino acid analogs that act at different stages of the collagen production process. This combination therapy would be useful for skin antiaging that requires enhanced collagen production.

Combination of Glycinamide and Ascorbic Acid Synergistically Promotes Collagen Production and Wound Healing in Human Dermal Fibroblasts

The purpose of this study is to present a novel strategy to enhance collagen production in cells. To identify amino acid analogs with excellent collagen production-enhancing effects, human dermal fibroblasts (HDFs) were treated with 20 kinds of amidated amino acids and 20 kinds of free amino acids, individually at 1 mM. The results showed that glycinamide enhanced collagen production (secreted collagen level) most effectively. Glycine also enhanced collagen production to a lesser degree. However, other glycine derivatives, such as N-acetyl glycine, N-acetyl glycinamide, glycine methyl ester, glycine ethyl ester, and glycyl glycine, did not show such effects. Glycinamide increased type I and III collagen protein levels without affecting COL1A1 and COL3A1 mRNA levels, whereas transforming growth factor-β1 (TGF-β1, 10 ng mL−1) increased both mRNA and protein levels of collagens. Ascorbic acid (AA, 1 mM) increased COL1A1 and COL3A1 mRNA and collagen I protein levels. Unlike TGF-β1, AA and glycinamide did not increase the protein level of α-smooth muscle actin, a marker of differentiation of fibroblasts into myofibroblasts. The combination of AA and glycinamide synergistically enhanced collagen production and wound closure in HDFs to a level similar to that in cells treated with TGF-β1. AA derivatives, such as magnesium ascorbyl 3-phosphate (MAP), 3-O-ethyl ascorbic acid, ascorbyl 2-O-glucoside, and ascorbyl tetraisopalmitate, enhanced collagen production, and the mRNA and protein levels of collagens at 1 mM, and their effects were further enhanced when co-treated with glycinamide. Among AA derivatives, MAP had a similar effect to AA in enhancing wound closure, and its effect was further enhanced by glycinamide. Other AA derivatives had different effects on wound closure. This study provides a new strategy to enhance cell collagen production and wound healing using glycinamide in combination with AA.

Antioxidant Properties and Industrial Uses of Edible Polyporales

The content of antioxidant compounds varies within fungal species, and the Polyporales order has been recognized for this property. Numerous antioxidant compounds have been identified in Polyporales fungi, including phenolic compounds, β-glucans, ergosterol, ergothioneine, vitamin C, and tocopherols. Each compound contributes differently to the antioxidant potential of fungi. Besides the health benefits for rural communities caused by fungi consumption, their antioxidant composition attracts the food, cosmetic, and pharmaceutical industries’ interest. In this context, the present review compiles, analyzes, and discusses the bioactive composition of edible fungi of the Polyporales order and its contribution to total antioxidant capacity.

Advances in the Design of Genuine Human Tyrosinase Inhibitors for Targeting Melanogenesis and Related Pigmentations

Human tyrosinase (hsTYR) is the key enzyme ensuring the conversion of l-tyrosine to dopaquinone, thereby initiating melanin synthesis, i.e., melanogenesis. Although the protein has long been familiar, knowledge about its three-dimensional structure and efficient overexpression protocols emerged only recently. Consequently, for decades medicinal chemistry studies aiming at developing skin depigmenting agents relied almost exclusively on biological assays performed using mushroom tyrosinase (abTYR), producing a plethoric literature, often of little useful purpose. Indeed, several recent reports have pointed out spectacular differences in terms of interaction patterns and inhibition values between hsTYR and abTYR, including for widely used standard tyrosinase inhibitors. In this review, we summarize the last developments regarding the potential role of hsTYR in human pathologies, the advances in recombinant expression systems and structural data retrieving, and the pioneer generation of true hsTYR inhibitors. Finally, we present suggestions for the design of future inhibitors of this highly attractive target in pharmacology and dermocosmetics.

Up- or Downregulation of Melanin Synthesis Using Amino Acids, Peptides, and Their Analogs

Harmonious synthesis and distribution of melanin in the skin contribute to the expression of beauty and the maintenance of health. When skin pigmentary disorders occur because of internal or external factors or, when there is a need to artificially increase or reduce the pigmentation level of the skin for aesthetic or therapeutic purposes, various pharmacological therapies are applied but the results are not always satisfactory. Studies have been conducted to improve the efficacy and safety of these treatment strategies. In this review, we present the latest studies regarding peptides and related compounds that may be useful in artificially increasing or reducing skin melanin levels. Certain analogs of α-melanocyte stimulating hormone (MSH) and oligopeptides with the sequences derived from the hormone were shown to promote melanin synthesis in cells and in vivo models. Various amino acids, peptides, their analogs, and their hybrid compounds with other chemical moieties were shown to inhibit tyrosinase (TYR) catalytic activity or downregulate TYR gene expression. Certain peptides were shown to inhibit melanosome biogenesis or induce autophagy, leading to decreased pigmentation. In vivo and clinical evidence are available for some compounds, including [Nle⁴-_D-Phe⁷]-α-MSH, glutathione disulfide, and glycinamide hydrochloride. For many other compounds, additional studies are required to verify their efficacy and safety in vivo and in clinical trials. The accumulating information regarding pro- and antimelanogenic activity of peptides and related compounds will lead to the development of novel drugs for the treatment of skin pigmentary disorders.

The Role of Bioactive Compounds and other Metabolites from Mushrooms against Skin Disorders- A Systematic Review Assessing their Cosmeceutical and Nutricosmetic Outcomes

Bioactive compounds derived from mushrooms have been shown to present promising potential as cosmeceutical or nutricosmetic ingredients. Scientific data reviewed herein showed that extracts prepared from medicinal and edible mushrooms and their individual metabolites presented antiinflammatory, antioxidant, photoprotective, antimicrobial, anti-tyrosinase, anti-elastase, and anticollagenase activities. These metabolites can be utilised as ingredients to suppress the severity of Inflammatory Skin Diseases, offer photoprotection to the skin, and correct Hyperpigmentation. However, studies regarding the molecular mechanism behind the mentioned bioactivities are still lacking. Challenges associated with the use of mushroom extracts and their associated metabolites as cosmeceutical and nutricosmetic ingredients include several steps from the fruiting bodies to the final product: extraction optimization, estimation of the efficacy and safety claims, the use of micro and nanocarriers to allow for controlled release and the pros and cons associated with the use of extracts vs individual compounds. This systematic review highlights that mushrooms contain diverse biomolecules that can be sustainably used in the development of nutricosmetic and cosmeceutical formulations. Reports regarding stability, compatibility, and safety assessment, but also toxicological studies are still needed to be considered. Furthermore, some of the constraints and limitations hindering the development of this type of ingredients still require long-term studies to achieve major breakthroughs.

Exogenous p-Coumaric Acid Improves Salvia hispanica L. Seedling Shoot Growth

: p-Coumaric acid (p-CA) belongs to a family of natural esters of hydroxycinnamic acid compounds that have been shown to modulate plant growth and metabolism. In this study, we investigated the effect of exogenous p-CA on plant growth, reactive oxygen species (ROS)-induced oxidative damage, photosynthetic metabolism, osmolyte content and changes in superoxide dismutase (SOD) enzymatic activity. Exogenous p-CA improved Salvia hispanica (chia) growth by significantly enhancing shoot length, fresh and dry weights coupled with augmented levels of total chlorophyll and carotenoid contents. Furthermore, p-CA also triggered an induction in proline, glycine betaine (GB) and superoxide (O2∙-) levels while no changes were observed for hydrogen peroxide (H2O2) and downstream malondialdehyde (MDA) content. Also, no change in SOD activity was observed in the p-CA treatment relative to the control. Therefore, the results suggest that exogenous p-CA improves chia seedling growth possibly via activation of a ROS-signalling pathway involving O2∙- under the control of proline accumulation.

Natural and Bioinspired Phenolic Compounds as Tyrosinase Inhibitors for the Treatment of Skin Hyperpigmentation: Recent Advances

One of the most common approaches for control of skin pigmentation involves the inhibition of tyrosinase, a copper-containing enzyme which catalyzes the key steps of melanogenesis. This review focuses on the tyrosinase inhibition properties of a series of natural and synthetic, bioinspired phenolic compounds that have appeared in the literature in the last five years. Both mushroom and human tyrosinase inhibitors have been considered. Among the first class, flavonoids, in particular chalcones, occupy a prominent role as natural inhibitors, followed by hydroxystilbenes (mainly resveratrol derivatives). A series of more complex phenolic compounds from a variety of sources, first of all belonging to the Moraceae family, have also been described as potent tyrosinase inhibitors. As to the synthetic compounds, hydroxycinnamic acids and chalcones again appear as the most exploited scaffolds. Several inhibition mechanisms have been reported for the described inhibitors, pointing to copper chelating and/or hydrophobic moieties as key structural requirements to achieve good inhibition properties. Emerging trends in the search for novel skin depigmenting agents, including the development of assays that could distinguish between inhibitors and potentially toxic substrates of the enzyme as well as of formulations aimed at improving the bioavailability and hence the effectiveness of well-known inhibitors, have also been addressed.

p-Coumaric Acid as An Active Ingredient in Cosmetics: A Review Focusing on its Antimelanogenic Effects

Controlling unwanted hyperpigmentation is a major challenge in dermatology and cosmetology, and safe and efficacious antimelanogenic agents are deemed useful for this purpose. p-Coumaric acid is a natural metabolite contained in many edible plants, and its antioxidant activities in reducing oxidative stress and inflammatory reactions have been demonstrated in various experimental models. p-Coumaric acid has the optimal structure to be a competitive inhibitor of tyrosinase that catalyzes key reactions in the melanin biosynthetic pathway. Experimental evidence supports this notion as it was found to be a more potent inhibitor of tyrosinase, especially toward human enzymes, than other well-known tyrosinase inhibitors such as arbutin and kojic acid. p-Coumaric acid inhibited melanin synthesis in murine melanoma cells, human epidermal melanocytes, and reconstituted three-dimensional human skin models. Ex-vivo skin permeation experiments and in-vivo efficacy tests for p-coumaric acid confirmed its efficient transdermal delivery and functional efficacy in reducing erythema development and skin pigmentation due to ultraviolet radiation exposure. Human studies further supported its effectiveness in hypopigmentation and depigmentation. These findings suggest that p-coumaric acid has good potential to be used as a skin-lightening active ingredient in cosmetics. Future studies are needed to extensively examine its safety and efficacy and to develop an optimized cosmetic formulation for the best performance in skin lightening.

Cinnamic acid derivatives in cosmetics: current use and future prospects

Cinnamic acid derivatives are widely used in cosmetics and possess various functions. This group of compounds includes both naturally occurring and synthetic substances. On the basis of the Cosmetic Ingredient Database (CosIng) and available literature, this review summarizes their functions in cosmetics, including their physicochemical and biological properties as well as reported adverse effects. A perfuming function is typical of many derivatives of cinnamaldehyde, cinnamyl alcohol, dihydrocinnamyl alcohol and cinnamic acid itself; these substances are commonly used in cosmetics all over the world. Some of them show allergic and photoallergic potential, resulting in restrictions in maximum concentrations and/or a requirement to indicate the presence of some substances in the list of ingredients when their concentrations exceed certain fixed values in a cosmetic product. Another important function of cinnamic acid derivatives in cosmetics is UV protection. Ester derivatives such as ethylhexyl methoxycinnamate (octinoxate), isoamyl p-methoxycinnamte (amiloxiate), octocrylene and cinoxate are used in cosmetics all over the world as UV filters. However, their maximum concentrations in cosmetic products are restricted due to their adverse effects, which include contact and a photocontact allergies, phototoxic contact dermatitis, contact dermatitis, estrogenic modulation and generation of reactive oxygen species. Other rarely utilized functions of cinnamic acid derivatives are as an antioxidant, in skin conditioning, hair conditioning, as a tonic and in antimicrobial activities. Moreover, some currently investigated natural and synthetic derivatives of cinnamic acid have shown skin lightening and anti-ageing properties. Some of them may become new cosmetic ingredients in the future. In particular, 4-hydroxycinnamic acid, which is currently indexed as a skin-conditioning cosmetics ingredient, has been widely tested in vitro and in vivo as a new drug candidate for the treatment of hyperpigmentation.

Role of Vitamin C in Skin Diseases

Vitamin C (ascorbic acid) plays an important role in maintaining skin health and can promote the differentiation of keratinocytes and decrease melanin synthesis, leading to antioxidant protection against UV-induced photodamage. Normal skin needs high concentrations of vitamin C, which plays many roles in the skin, including the formation of the skin barrier and collagen in the dermis, the ability to counteract skin oxidation, and the modulation of cell signal pathways of cell growth and differentiation. However, vitamin C deficiency can cause or aggravate the occurrence and development of some skin diseases, such as atopic dermatitis (AD) and porphyria cutanea tarda (PCT). Levels of vitamin C in plasma are decreased in AD, and vitamin C deficiency may be one of the factors that contributes to the pathogenesis of PCT. On the other hand, high doses of vitamin C have significantly reduced cancer cell viability, as well as invasiveness, and induced apoptosis in human malignant melanoma. In this review, we will summarize the effects of vitamin C on four skin diseases (porphyria cutanea tarda, atopic dermatitis, malignant melanoma, and herpes zoster and postherpetic neuralgia) and highlight the potential of vitamin C as a therapeutic strategy to treat these diseases, emphasizing the clinical application of vitamin C as an adjuvant for drugs or physical therapy in other skin diseases.

Inhibitors of Melanogenesis: An Updated Review

Melanins are pigment molecules that determine the skin, eye, and hair color of the human subject to its amount, quality, and distribution. Melanocytes synthesize melanin and provide epidermal protection from various stimuli, such as harmful ultraviolet radiation, through the complex process called melanogenesis. However, serious dermatological problems occur when there is excessive production of melanin in different parts of the human body. These include freckles, melasma, senile lentigo, pigmented acne scars, and cancer. Therefore, controlling the production of melanin is an important approach for the treatment of pigmentation related disorderes. In this Perspective, we focus on the inhibitors of melanogenesis that directly/indirectly target a key enzyme tyrosinase as well as its associated signaling pathways.

Structural Requirements of Alkylglyceryl-l-Ascorbic Acid Derivatives for Melanogenesis Inhibitory Activity

l-Ascorbic acid has multifunctional benefits on skin aesthetics, including inhibition of melanin production, and is widely used in cosmetics. It, however, has low stability and poor skin penetration. We hypothesize that alkylglyceryl-l-ascorbic acid derivatives, highly stable vitamin C–alkylglycerol conjugates, would have similar anti-melanogenic activity with better stability and penetration. We test 28 alkylglyceryl-l-ascorbic acid derivatives (1–28) on theophylline-stimulated B16 melanoma 4A5 cells to determine if they inhibit melanogenesis and establish any structure–function relationships. Although not the most potent inhibitors, 3-O-(2,3-dihydroxypropyl)-2-O-hexyl-l-ascorbic acid (6, IC₅₀ = 81.4 µM) and 2-O-(2,3-dihydroxypropyl)-3-O-hexyl-l-ascorbic acid (20, IC₅₀ = 117 µM) are deemed the best candidate derivatives based on their inhibitory activities and low toxicities. These derivatives are also found to be more stable than l-ascorbic acid and to have favorable characteristics for skin penetration. The following structural requirements for inhibitory activity of alkylglyceryl-l-ascorbic acid derivatives are also determined: (i) alkylation of glyceryl-l-ascorbic acid is essential for inhibitory activity; (ii) the 3-O-alkyl-derivatives (2–14) exhibit stronger inhibitory activity than the corresponding 2-O-alkyl-derivatives (16–28); and (iii) derivatives with longer alkyl chains have stronger inhibitory activities. Mechanistically, our studies suggest that l-ascorbic acid derivatives exert their effects by suppressing the mRNA expression of tyrosinase and tyrosine-related protein-1.

Hydroxycinnamic Acids and Their Derivatives: Cosmeceutical Significance, Challenges and Future Perspectives, a Review

Bioactive compounds from natural sources, due to their widely-recognized benefits, have been exploited as cosmeceutical ingredients. Among them, phenolic acids emerge with a very interesting potential. In this context, this review analyzes hydroxycinnamic acids and their derivatives as multifunctional ingredients for topical application, as well as the limitations associated with their use in cosmetic formulations. Hydroxycinnamic acids and their derivatives display antioxidant, anti-collagenase, anti-inflammatory, antimicrobial and anti-tyrosinase activities, as well as ultraviolet (UV) protective effects, suggesting that they can be exploited as anti-aging and anti-inflammatory agents, preservatives and hyperpigmentation-correcting ingredients. Due to their poor stability, easy degradation and oxidation, microencapsulation techniques have been employed for topical application, preventing them from degradation and enabling a sustained release. Based on the above findings, hydroxycinnamic acids present high cosmetic potential, but studies addressing the validation of their benefits in cosmetic formulations are still scarce. Furthermore, studies dealing with skin permeation are scarcely available and need to be conducted in order to predict the topical bioavailability of these compounds after application.