The effect of vitamin C on oxidative stress indices and skin regimentation of vitiligo patients

It has been suggested that vitamin C is involved in suppressing stress oxidation signaling in vitiligo disease. However, the effect of vitamin C supplementation on stress oxidative factors has not been investigated in vitiligo subjects. This study was designed to examine the effects on vitamin C supplementation on serum levels of stress oxidative factors and regimentation in vitiligo patients. Forty-four vitiligo patients will be recruited in this study. After block matching for sex and number of phototherapy sessions, they will be randomly assigned to receive 1000 mg/d vitamin C or placebo for 8 weeks. The weight, height, and waist circumference of participants will be measured. Determination of serum stress oxidative indices (CAT, SOD, GPX, MDA, TOS, TAC) will be done at study baseline and at the end of the trial. Also, the regimentation will be determined using the VASI score. This is the first randomized controlled trial that will determine the effect of vitamin C supplementation on serum levels of stress oxidative indices and regimentation in vitiligo patients. The results of this trial will provide clinical evidence on the effectiveness of vitamin C supplementation in controlling oxidative stress in vitiligo patients. Trial registration number: This study is registered in the Iranian Registry of Clinical Trials website (available at http://www.irct.ir , identifier: IRCT20230123057193N1), Registration date: 2023/04/17.

Skin permeability, a dismissed necessity for anti-wrinkle peptide performance

The skin offers various benefits and potential for peptide delivery if its barrier performance can be reduced temporarily and reversibly. Since peptides possess high molecular weight, hydrophilic nature (in most cases), and ionizable groups in the structure, their skin delivery is highly challenging. Apart from this, they are susceptible to the proteolytic enzymes in the skin. Anti-wrinkle peptides, like other peptides, suffer from insufficient skin permeability, while most of them must penetrate deep in the skin to present their efficacy. Although the cellular studies indicate the effectiveness of such peptides, without the ability to permeate the skin sufficiently, this efficacy is useless. Poor skin permeability of anti-wrinkle peptides has led to ongoing research for finding feasible and noninvasive enhancement methods that would be desirable for consumers of cosmetic products. In this paper, the possibility of skin permeation of anti-wrinkle peptides as well as the chemical, physical, and encapsulation approaches that have been employed to date to increase permeability of these difficult molecules are thoroughly reviewed.

Bioactivities, Applications, Safety, and Health Benefits of Bioactive Peptides From Food and By-Products: A Review

Bioactive peptides generated from food proteins have great potential as functional foods and nutraceuticals. Bioactive peptides possess several significant functions, such as antioxidative, anti-inflammatory, anticancer, antimicrobial, immunomodulatory, and antihypertensive effects in the living body. In recent years, numerous reports have been published describing bioactive peptides/hydrolysates produced from various food sources. Herein, we reviewed the bioactive peptides or protein hydrolysates found in the plant, animal, marine, and dairy products, as well as their by-products. This review also emphasizes the health benefits, bioactivities, and utilization of active peptides obtained from the mentioned sources. Their possible application in functional product development, feed, wound healing, pharmaceutical and cosmetic industries, and their use as food additives have all been investigated alongside considerations on their safety.

Antioxidant and anti-aging potential of a peptide formulation (Gal2-Pep) conjugated with gallic acid

Skin is highly vulnerable to premature aging due to external stress, therefore, in this study, a peptide formulation, (galloyl)2-KTPPTTP (Gal2-Pep) was synthesized by combining TPPTTP peptide, and gallic acid (GA). All peptides were synthesized on 2-chlorotrityl chloride resin using solid-phase peptide synthesis (SPPS), and analyzed on an electrospray ionization (ESI)/quadrupole-time-of-flight (Q-TOF) tandem mass spectroscopy (MS) system. Initially, Gal2-Pep showed no toxicity below the concentration 100 μM with cell survival rate of 88% for keratinocytes and fibroblasts. The reactive oxygen species (ROS) scavenging activity of Gal2-Pep was more stable compared to GA alone; and after four weeks at room temperature, its ROS scavenging activity remained higher than 50%. Moreover, the peptide formulation, Gal2-Pep also exhibited elastase inhibitory effect in CCD-1064Sk fibroblast cells. Based on the results of RT-qPCR, it was proved in this study that Gal2-Pep increased the expression of PGC-1α to prevent oxidative stress, and validated its potential as an anti-aging agent through increasing the expression of type I collagen and by decreasing the expression of matrix metalloproteinase-1 (MMP1). The findings obtained reinforce the suggestion that the peptide formulation synthesized in this study could be used as a natural antioxidant and anti-aging agent for its cosmetic applications.

Vitamin C mesotherapy versus topical application for gingival hyperpigmentation: a clinical and histopathological study

OBJECTIVE

Vitamin C/Ascorbic acid inhibits tyrosinase enzyme causing melanin biosynthesis suppression. This study aimed to compare the efficacy of intra-mucosal injection (mesotherapy) with topical gel as non-surgical methods for managing gingival hyperpigmentation.

MATERIALS AND METHODS

Twenty healthy non-smokers with mild to severe hyperpigmented gingiva were randomly assigned for Mesotherapy (G1); intra-mucosal injection of ascorbic acid (1/week/3 weeks); or Gel (G2), topical ascorbic acid gel (1/day/3 months). Pigmentation index (DOPI), patient satisfaction, as well as histological analysis for Fontana-Masson-stained specimens were performed at baseline and after 6 months. Comparison between groups and changes by time were analyzed using Mann-Whitney and Friedman's tests, respectively.

RESULTS

The median DOPI significantly decreased after 1 month in G1 (P value < 0.001, r = 0.9) compared with non-significant change in G2. No pain experienced during or after treatment in both groups. G1 patients showed significantly higher satisfaction with treatment than G2. Mean area fraction of melanin forming cells was significantly reduced in both groups after 6 months, but the effect size was higher in G1 (r = 0.886) than in G2 (r = 0.797).

CONCLUSIONS

Vitamin C mesotherapy showed better and early effect than topical gel, and both techniques were not painful and esthetically satisfying in managing gingival hyperpigmentation.

CLINICAL RELEVANCE

Gingival melanin pigmentation causes esthetic concerns for significant number of patients. Investigating non-surgical depigmentation techniques to decrease postoperative complications and patient discomfort, pain and long healing period associated with surgical methods would be clinically significant.

Antioxidants as an Epidermal Stem Cell Activator

Antioxidants may modulate the microenvironment of epidermal stem cells by reducing the production of reactive oxygen species or by regulating the expression of extracellular matrix protein. The extracellular membrane is an important component of the stem cell niche, and microRNAs regulate extracellular membrane-mediated basal keratinocyte proliferation. In this narrative review, we will discuss several antioxidants such as ascorbic acid, plant extracts, peptides and hyaluronic acid, and their effect on the epidermal stem cell niche and the proliferative potential of interfollicular epidermal stem cells in 3D skin equivalent models.

The effect of Vitamin C on melanin pigmentation - A systematic review

Vitamin C, also known as ascorbic acid, is used as a treatment modality in depigmentation of hyperpigmented spots on the skin and gingiva. This systematic review discusses the studies conducted to assess the effect of Vitamin C on melanin pigmentation. The primary objective was to evaluate the effect of Vitamin C on melanin pigmentation. The secondary objective was to analyze the effect of Vitamin C administration on melanin pigmentation. An electronic database search was conducted from the following databases: PubMed, EBSCOhost, ScienceOpen, EMBASE and Google Scholar. Randomized controlled trials, experimental studies, case-control studies and cohort studies published in peer-reviewed journals in English language were included. Case reports, case series, animal model studies, in vitro studies, studies where Vitamin C was used along with other agents and unpublished research were excluded. Out of 22,580 studies, only 7 studies satisfied the selection criteria. Data extraction sheet was prepared, and the studies were analyzed. Out of the 7 studies analyzed, 1 was a randomized controlled trial and 6 were experimental studies. Vitamin C has been used widely as a depigmenting agent in dermatology. However, there are limited studies conducted on the use of Vitamin C for gingival depigmentation.

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.

Antiaging Activity of Peptide Identified from Fermented Trapa Japonica Fruit Extract in Human Dermal Fibroblasts

We have previously shown that Trapa japonica fruit extract (TJE) as well as its fermented extract (FTJ) can be potentially used to treat alopecia. In the current study, a newly synthesized peptide (PEP) was detected in an active compound isolated from FTJ. Several biological assays were conducted to verify the antiaging effects of TJE, FTJ, and PEP on the skin. We examined the effects of TJE, FTJ, and PEP on cell viability, collagen synthesis, and inhibition of mRNA expression of matrix metalloproteinases (MMPs), induced by tumor necrosis factor alpha (TNF-α), in human dermal fibroblasts (HDFs). In addition, a wound-healing assay of the human keratinocyte cell line (HaCaT) and a clinical study of antiaging activity were conducted. The findings confirmed that PEP exerted an effect on cell proliferation in a dose-dependent manner. Treatment with TJE, FTJ, and PEP increased collagen synthesis but inhibited TNF-α-induced mRNA expression of MMPs. Compared with TJE and FTJ, PEP promoted a significant level of wound recovery in HaCaT cells and also exhibited antiaging effect, as demonstrated by a clinical study. These results suggest that PEP shows potential as a skin antiaging cosmetic product.

A Strategy to Enhance Secretion of Extracellular Matrix Components by Stem Cells: Relevance to Tissue Engineering

The ability of cells to secrete extracellular matrix proteins is an important property in the repair, replacement, and regeneration of living tissue. Cells that populate tissue-engineered constructs need to be able to emulate these functions. The motifs, KTTKS or palmitoyl-KTTKS (peptide amphiphile), have been shown to stimulate production of collagen and fibronectin in differentiated cells. Molecular modeling was used to design different forms of active peptide motifs to enhance the efficacy of peptides to increase collagen and fibronectin production using terminals KTTKS/SKTTK/SKTTKS connected by various hydrophobic linkers, V₄A₃/V₄A₂/A₄G₃. Molecular dynamic simulations showed SKTTKS-V₄A₃-SKTTKS (P3), with palindromic (SKTTKS) motifs and SKTTK-V₄A₂-KTTKS (P5), maintained structural integrity and favorable surface electrostatic distributions that are required for functionality. In vitro studies showed that peptides, P3 and P5, showed low toxicity to human adipose-derived stem cells (hADSCs) and significantly increased the production of collagen and fibronectin in a concentration-dependent manner compared with the original active peptide motif. The 4-day treatment showed that stem cell markers of hADSCs remained stable with P3. The molecular design of novel peptides is a promising strategy for the development of intelligent biomaterials to guide stem cell function for tissue engineering applications.

Vitamin C enhances Nanog expression via activation of the JAK/STAT signaling pathway

Vitamin C (Vc), also known as ascorbic acid, is involved in many important metabolic and physiological reactions in the body. Here, we report that Vc enhances the expression of Nanog and inhibits retinoic acid-induced differentiation of embryonic stem cells. We investigated Vc regulation of Nanog through Janus kinase/signal transducer and activator of transcription pathway using cell signaling pathway profiling systems, and further confirmed by specific pathway inhibition. Using overexpression and knockdown strategies, we demonstrated that STAT2 is a new positive regulator of Nanog and is activated by phosphorylation following Vc treatment. In addition, site mutation analysis identified that STAT2 physically occupies the Nanog promoter, which was confirmed by chromatin immunoprecipitation and electrophoretic mobility shift assays. Taken together, our data suggest a role for Vc in Nanog regulation networks and reveal a novel role for STAT2 in regulating Nanog expression.

Action of ascorbic acid on the healing of malnourished rats'skin wounds

Objective: To evaluate the action of ascorbic acid on the healing of malnourished rats' cutaneous wounds compared with normal weight rats. Methods: We used 92 adult, male Wistar rats divided into four groups: 24 normal weight rats given only water and chow; 24 normal weight rats given vitamin C by gavage (340 mg/kg 12/12 hours); 22 malnourished rats given only water and chow; and 22 malnourished rats given vitamin C by gavage (340 mg/kg 12/12 hours). Malnutrition was induced by feeding the animals half of their daily energy requirement for 30 days. Two incisions were made, one sutured (healing by primary intention) and one left unsutured (healing by secondary intention). The rats were euthanized on the third, seventh, and fourteenth days of the experiment. Results: The following parameters differed significantly between the groups (p>0.05): granulation of the wound edge in the primary and secondary intention; extent of injuries on day 7 for primary intention and on day 3 for secondary intention; reepithelialization on day 7 for primary intention; fibrin-leukocyte scab on day 14 for primary intention; amount of neovascularization and concentration of macrophages, fibroblasts, and collagen fibers for primary and secondary intention. Conclusion: The use of vitamin C in malnourished and normal weight rats increases fibroblast proliferation and collagen deposition in the tissue, which helps to improve healing both by primary and secondary intention.

Collagen stimulating effect of peptide amphiphile C16-KTTKS on human fibroblasts

The collagen production of human dermal and corneal fibroblasts in contact with solutions of the peptide amphiphile (PA) C16-KTTKS is investigated and related to its self-assembly into nanotape structures. This PA is used in antiwrinkle cosmeceutical applications (trade name Matrixyl). We prove that C16-KTTKS stimulates collagen production in a concentration-dependent manner close to the critical aggregation concentration determined from pyrene fluorescence spectroscopy. This suggests that self-assembly and the stimulation of collagen production are inter-related.

Ascorbic acid increases the activity and synthesis of tyrosinase in B16F10 cells through activation of p38 mitogen-activated protein kinase

Ascorbic acid, a potential antioxidant, is known to inhibit melanogenesis. However, there are conflicting findings that ascorbic acid has very low stability and acts as a pro-oxidant, eventually increasing proliferation and melanin content in melanoma cells. In the present study, we explored the effects of ascorbic acid on the activity and expression of tyrosinase and melanin pigmentation in the presence and absence of α-melanocyte-stimulating hormone (α-MSH) using B16F10 melanoma cells. The mechanism by which ascorbic acid stimulated the expression of tyrosinase was also investigated. No inhibitory effect on melanin content was observed in ascorbic acid-treated cells, regardless of the presence of α-MSH. Ascorbic acid stimulated the activity and expression of tyrosinase and increased the expression of melanogenic regulatory factors, such as tyrosinase-related protein-1 (TRP-1), dihydroxyphenylalaminechrome tautomerase (TRP-2), and microphthalmia-associated transcription factor (MITF). Ascorbic acid also induced phosphorylation of p38 mitogen-activated protein kinase (MAPK). The inhibition of p38 MAPK pathway by SB203580 led to the suppression of tyrosinase, TRP-1, and TRP-2 expression in cells treated with ascorbic acid. Combined treatment with N-acetyl-L: -cysteine and/or desferrioxamine mesylate attenuated the stimulating effect of ascorbic acid on tyrosinase activation in the cells. Collectively, ascorbic acid stimulates tyrosinase activity and expression in B16F10 cells via activation of p38 MAPK signaling and subsequent up-regulation of MITF, tyrosinase, and TRP expression.