The anti-wrinkle efficacy of argireline, a synthetic hexapeptide, in Chinese subjects: a randomized, placebo-controlled study

Peptides: Emerging Candidates for the Prevention and Treatment of Skin Senescence: A Review

One class of cosmetic compounds that have raised interest of many experts is peptides. The search for ingredients with good biocompatibility and bioactivity has led to the use of peptides in cosmetic products. Peptides are novel active ingredients that improve collagen synthesis, enhance skin cell proliferation, or decrease inflammation. Based on their mechanism of action, they can be classified into signal peptides, carrier peptides, neurotransmitter inhibitor peptides, and enzyme inhibitor peptides. This review focuses on the main types of peptides and their application in the cosmetic field, underlining their main limitations. One of the most significant drawbacks of cosmetic peptides is their poor permeability through membranes, which limits their delivery and effectiveness. As a result, this review follows the methods used for improving permeability through the stratum corneum. Increasing peptide bioavailability and stability for enhanced delivery to the desired site of action and visible effects have become central points for the latest research due to their promising features. For this purpose, several methods have been identified and described. Physical techniques include thermal ablation (radiofrequency and laser), electrical methods (electroporation, iontophoresis), mechanical approach (microneedles), and ultrasounds. As an alternative, innovative formulations have been developed in nano-systems such as liposomes, niosomes, ethosomes, nanoemulsions, and other nanomaterials to reduce skin irritation and improve product effectiveness. The purpose of this review is to provide the latest information regarding these noteworthy molecules and the reasoning behind their use in cosmetic formulations.

Cosmeceuticals in photoaging: A review

BACKGROUND

Photoaging is a process of the architecture of normal skin damaged by ultraviolet radiation. Topical cosmeceuticals have been used to treat this condition. The authors aimed to understand the mechanism and level of evidence of different commonly used cosmeceuticals used to treat photodamaged skin.

OBJECTIVE

A range of commonly used topical cosmeceuticals (botanicals, peptides, and hydroquinone) has been used in cosmetic medicine for many years to treat photodamaged skin. This review article compares their efficacy and level of evidence.

MATERIAL AND METHODS

This study was a systematic review to evaluate the efficacy of different topical cosmeceuticals. Keywords including "Photoaging," "Azelaic acid," "Soy," "Green Tea," "Chamomile," "Ginkgo," "Tea Tree Oil," "Resveratrol," "Cucumber," "Ginseng," "Centella asiatica," "Licorice Root," "Aloe Vera," "Peptides," "Argireline," "Hydroquinone," were typed on OVID, PUBMED, MEDLINE for relevant studies published on photoaging treatment.

RESULTS

Most of the evidence behind cosmeceuticals is of high-quality ranging from Level I to Level II. In particular, the evidence base behind peptides is the strongest with most studies achieving Level Ib status in the evidence hierarchy.

CONCLUSION

Topical cosmeceuticals like botanicals, peptides and hydroquinone can effectively treat photodamaged skin.

Public Interest in Acetyl Hexapeptide-8: Longitudinal Analysis

BACKGROUND

Acetyl hexapeptide-8, also known as Argireline, is a topical, short-acting, synthetic peptide that has recently gained popularity for its antiwrinkle effects. This agent has emerged as a more accessible alternative to botulinum neurotoxin.

OBJECTIVE

This study evaluates the public interest in acetyl hexapeptide-8 in the United States from 2013 to 2023, as described by search volume on Google, the most-used search engine.

METHODS

We analyzed the longitudinal relative monthly search volume from January 1, 2013, to January 1, 2023, for acetyl hexapeptide-related terms. We compared the internet search trends for "Botox" during this period to "Argireline."

RESULTS

The terms "Argireline" and "Botox in a Bottle" both had substantial increases in search volume in 2022. Although its search volume is drastically increasing, "Argireline" was less searched than "Botox," which had a stable, up-trending search volume over the past decade.

CONCLUSIONS

The increasing interest in acetyl hexapeptide-8 may be due to its cost-effectiveness and use as a botulinum neurotoxin alternative. Affordability, over-the-counter availability, and ease of self-application of the agent suggest its potential to enhance accessibility to cosmetic dermatologic care.

Peptide-containing nanoformulations: Skin barrier penetration and activity contribution

Transdermal drug delivery presents a less invasive pathway, circumventing the need to pass through the gastrointestinal tract and liver, thereby reducing drug breakdown, initial metabolism, and gastrointestinal discomfort. Nevertheless, the unique composition and dense structure of the stratum corneum present a significant barrier to transdermal delivery. This article presents an overview of the current developments in peptides and nanotechnology to address this challenge. Initially, we sum up peptide-containing nanoformulations for transdermal drug delivery, examining them through the lenses of both inorganic and organic materials. Particular emphasis is placed on the diverse roles that peptides play within these nanoformulations, including conferring functionality upon nanocarriers and enhancing the biological efficacy of drugs. Subsequently, we summarize innovative strategies for enhancing skin penetration, categorizing them into passive and active approaches. Lastly, we discuss the therapeutic potential of peptide-containing nanoformulations in addressing a range of diseases, drawing insights from the biological activities and functions of peptides. Furthermore, the challenges hindering clinical translation are also discussed, providing valuable insights for future advancements in transdermal drug delivery.

Investigating the effects of Argireline in a skin serum containing hyaluronic acids on skin surface wrinkles using the Visia® Complexion Analysis camera system for objective skin analysis

Objective

To analyze the effects of Argireline on skin surface wrinkles using the Visia® camera system developed by Canfield Scientific Inc., U.S.A., for facial image capture.

Method

Nineteen female participants were recruited from a plastic surgery clinic. Initial facial images captured the left, front, and right sides of the participants' faces, which were documented as timepoint one. Following this, the participants immediately began to apply a facial skin serum containing triple hyaluronic acids produced by CNC cosmetic GmbH, Philippsburg, Germany. The serum was applied once in the morning and once in the evening. Participants received two identical containers labeled L for left and R for right, with each container to be used on the corresponding facial side, particularly around the eye area. One container contained Argireline, a synthetic hexapeptide, which previously was deemed to be a biosafe alternative to botulinum neurotoxin. The study was conducted as double-blind; neither the participants nor researchers knew which of the two containers contained Argireline. Participants were allowed to use their own cosmetic products throughout the study. After four weeks, the participants returned to have their faces recaptured using the Visia® camera, which was documented as timepoint two. The absolute scores of the wrinkles were noted, and results on both sides of the face were calculated and compared. The "TruSkinAge®" measurement provided by the Visia® camera was reviewed for each face side. Results between both time points and both sides of the face were compared. After the data analysis was complete, the company was contacted to determine which container contained Argireline.

Results

Nineteen participants returned for facial image capture. There were no significant adverse events, allergic reactions, or skin irritations. The investigation revealed that the wrinkle score slightly decreased for the right and left side of the face following four weeks of serum application. However, this decrease was not significant (p>0.05) based on the Wilcoxon matched pairs tests for the wrinkle scores (right side p=0.060 and left side p=0.176) and Truskin Ages® results (right side p=0.096 and left side p=0.489).Comparing the data from the right side with that from the left side of the face revealed that neither demonstrated a significant reduction in wrinkle score (p=0.829) or Truskin Ages® results (p=0.804). Argireline was included in the serum applied to the right side of the face. However, no statistical significance was seen in the results on this side of the face indicating any possible effects.

Conclusion

Wrinkle scores and Truskin Ages® results were observed to decrease non-significantly following the application of a skin serum involving hyaluronic acid. The Visia® imaging method was used to analyze the data objectively. Differences between both sides of the face that were treated with and without Argireline were not statistically significant. Therefore, the effect of Argireline was not proven. While Argireline presented with low toxicity, its efficacy was found not to be significant. Therefore, it is not deemed to be an alternative treatment to botulinum toxin.

A nanohybrid synthesized by polymeric assembling Au(I)-peptide precursor for anti-wrinkle function

A major sign of aging is wrinkles (dynamic lines and static lines) on the surface of the skin. In spite of Botulinum toxin's favorable therapeutic effect today, there have been several reports of its toxicity and side effects. Therefore, the development of an effective and safe wrinkle-fighting compound is imperative. An antioxidant-wrinkle effect was demonstrated by the peptide that we developed and synthesized, termed Skin Peptide. Aiming at the intrinsic defects of the peptide such as hydrolysis and poor membrane penetration, we developed a general approach to transform the Skin Peptide targeting intracellular protein-protein interaction into a bioavailable peptide-gold spherical nano-hybrid, Skin Pcluster. As expected, the results revealed that Skin Pcluster reduced the content of acetylcholine released by neurons in vitro, and then inhibit neuromuscular signal transmission. Additionally, human experiments demonstrated a significant de-wrinkle effect. Moreover, Skin Pcluster is characterized by a reliable safety profile. Consequently, anti-wrinkle peptides and Skin Pcluster nanohybrids demonstrated innovative anti-wrinkle treatments and have significant potential applications.

Design and Evaluation of Complex Polypeptide-Loaded Dissolving Microneedles for Improving Facial Wrinkles in Different Areas

Wrinkles are one of the most intuitive manifestations of skin aging. Complex polypeptide-loaded dissolving microneedles (CP-DMNs) for facial wrinkles in different areas have been developed and evaluated for the first time. In optimizing formulations, we compared the differences in CP-DMNs heights on skin insertion depth and skin repair and healing. Furthermore, systemic safety experiments were carried out to provide a reference for clinical application. On this basis, an 84-day efficacy assessment based on the improvement of facial wrinkles in different areas and a comparison between CP-DMNs vs. placebo was performed on 30 healthy subjects. As a result, DMNs with a height of 300 μm presented sufficient strength to pierce the stratum corneum with minimized skin damage. In addition, CP-DMNs possessed excellent biological safety and skin compatibility for clinical application. Compared with placebo, CP-DMNs exhibited obvious improvements in wrinkles distributed in the corners of eyes, under-eyes, and nasolabial folds. Furthermore, after using CP-DMNs for 84 days, facial wrinkles in five different areas were smoothed. In short, the complex polypeptides showed apparent anti-wrinkle efficacy with the aid of DMNs technology, and CP-DMNs seemed to work better on deeper wrinkles, such as frown lines and nasolabial folds.

The Effect of Synthetic Acetylhexapeptide-8 (AH8) on Sebaceous Function

OBJECTIVE

This study aims to evaluate the in vitro and clinical effects of topical acetylhexapeptide-8 (AH8) on the appearance of oily skin.

METHODS

In vitro SEB-1 human sebocyte cell lines were exposed to different concentrations of AH8 , then the lipid content of the sebocytes was measured. For the randomized, controlled, split-face clinical study, participants received AH8 10% lotion formulated in Cetaphil Moisturizing Facial Lotion on one side of their face and the control vehicle lotion on the other side of their face. Facial oiliness was assessed by a trained physician using a 3-point grading system, high-resolution digital photographs, and a sebumeter (SM815). Participants also filled out self-assessments of their skin oiliness.

RESULTS

The in vitro experiments showed that sebocyte lipid content significantly decreased after AH8 treatment (p < 0.05 at 0.00005% AH8 , p=0.09 at 0.0005% AH8 , p < 0.05 at 0.005% AH8,and p < 0.001 at 0.025% AH8). In the clinical study, participants trended towards a 10% reduction (p=0.16) in sebum production after AH8 treatment in comparison to the vehicle treatment.

CONCLUSION

AH8 inhibits the accumulation of lipids in sebocytes in vitro without altering cell proliferation or SREBP-1 expression. Topical AH8 trended toward decreased sebum production in human participants. The use of AH8 may serve as a promising agent to reduce sebocyte lipid production and the appearance of oily skin.

Matrikines as mediators of tissue remodelling

Extracellular matrix (ECM) proteins confer biomechanical properties, maintain cell phenotype and mediate tissue repair (via release of sequestered cytokines and proteases). In contrast to intracellular proteomes, where proteins are monitored and replaced over short time periods, many ECM proteins function for years (decades in humans) without replacement. The longevity of abundant ECM proteins, such as collagen I and elastin, leaves them vulnerable to damage accumulation and their host organs prone to chronic, age-related diseases. However, ECM protein fragmentation can potentially produce peptide cytokines (matrikines) which may exacerbate and/or ameliorate age- and disease-related ECM remodelling. In this review, we discuss ECM composition, function and degradation and highlight examples of endogenous matrikines. We then critically and comprehensively analyse published studies of matrix-derived peptides used as topical skin treatments, before considering the potential for improvements in the discovery and delivery of novel matrix-derived peptides to skin and internal organs. From this, we conclude that while the translational impact of matrix-derived peptide therapeutics is evident, the mechanisms of action of these peptides are poorly defined. Further, well-designed, multimodal studies are required.

Analysis of Multi-Part Phenotypic Changes in Skin to Characterize the Trajectory of Skin Aging in Chinese Women

Purpose

As the human body’s largest organ exposed to the external environment, the skin suffers from internal and external aging factors, leading to wrinkles, loss of elasticity, sagging, and rough appearance. However, little is known of the characteristics of skin aging of different body parts in Chinese women. Here, we study the signs of extrinsic skin aging in different body parts to identify the knowledge map of manifestations of aging in Chinese women.

Patients and Methods

Wrinkle and texture phenotypes and collagen samples from the face, neck, hands, and arms of 326 Chinese women were collected. The correlations between phenotypes and ages and the differences in phenotypes by age were evaluated.

Results

The wrinkle and texture phenotypes around the eyes and mouth and of the hands were strongly correlated with age. Ages 32 and 58 showed the largest number of differentially changed aging phenotypes. The number of aging phenotypes increased sharply between the ages of 24 and 30, suggesting that the skin was undergoing rapid aging. Eye aging was the most rapidly changing phenotype between 19 and 30 years old. Wrinkles at the corner of the eyes showed a significant difference in the older group, suggesting an early onset and long-term effects.

Conclusion

This is the first study to be performed on the characteristics of skin aging among Chinese women that takes account of multiple areas of the body. It was found that 24 years old was the time point at which the skin begins to age in Chinese women. This provides important clues for aging-related research and personalized skin care.

Neurocosmetics in Skincare—The Fascinating World of Skin–Brain Connection: A Review to Explore Ingredients, Commercial Products for Skin Aging, and Cosmetic Regulation

The “modern” cosmetology industry is focusing on research devoted to discovering novel neurocosmetic functional ingredients that could improve the interactions between the skin and the nervous system. Many cosmetic companies have started to formulate neurocosmetic products that exhibit their activity on the cutaneous nervous system by affecting the skin’s neuromediators through different mechanisms of action. This review aims to clarify the definition of neurocosmetics, and to describe the features of some functional ingredients and products available on the market, with a look at the regulatory aspect. The attention is devoted to neurocosmetic ingredients for combating skin stress, explaining the stress pathways, which are also correlated with skin aging. “Neuro-relaxing” anti-aging ingredients derived from plant extracts and neurocosmetic strategies to combat inflammatory responses related to skin stress are presented. Afterwards, the molecular basis of sensitive skin and the suitable neurocosmetic ingredients to improve this problem are discussed. With the aim of presenting the major application of Botox-like ingredients as the first neurocosmetics on the market, skin aging is also introduced, and its theory is presented. To confirm the efficacy of the cosmetic products on the market, the concept of cosmetic claims is discussed.

Complications and Adverse Effects of Periocular Aesthetic Treatments

The popularity and variety of temporary and permanent periocular aesthetic treatments has increased over the past decade. Patients frequently present to eye clinics with ocular complications and side effects following these treatments, their severity ranging from ocular irritation from dry eyes to visual loss from vascular occlusion. A careful, thorough history is essential, as many patients may not associate aesthetic procedures with ocular complications, and some may be embarrassed to disclose this information. All ophthalmologists should understand the potential ocular sequelae of these treatments and be able to initiate treatment in sight-threatening cases. Wesummarises the current literature on ophthalmic complications of the most common periocular aesthetic treatments.

Argireline: Needle-Free Botox as Analytical Challenge

Argireline-containing cosmetics attract public interest due to their confirmed reduction of facial wrinkles. Argireline is a peptide that works by inhibiting the release of neurotransmitters in the neuromuscular junction, producing a botox-like effect. Therefore, it is used as a safe needle-free alternative to botox treatment. In this work we investigated the presence of Argireline in cosmetic creams and sera by application of reversed phase liquid chromatography and tandem mass spectrometry (RP-HPLC/MS and MS/MS). The analysis revealed the presence of argireline and its oxidized form in several different cosmetics. The methionine residue in Argireline sequence was indicated as oxidation point according to neutral loss MS studies. The developed sample preparation strategy minimizes and monitors methionine oxidation, bringing to our attention the question of impact of ingredients on the stability of cosmetic product.

Topical Over-the-Counter Antiaging Agents: An Update and Systematic Review

Over-the-counter antiaging formulations aim to prevent or minimize the signs of aging skin, and to maintain the benefits obtained from different cosmetic procedures. Even though a huge selection of such products is available on the market, evidence and good clinical practice of the data supporting their use are oftentimes lacking. In this systematic review, the authors reviewed scientific data available in the published literature on the most common ingredients used in antiaging cosmetics, with a particular focus on in vivo studies.

Geometrical optimisation of a personalised microneedle eye patch for transdermal delivery of anti-wrinkle small peptide

Acetyl-hexapeptide-3 (AHP-3) is a small peptide with good anti-wrinkle efficacy and safety profile. However, due to its hydrophilicity and high molecular weight, its skin permeation is generally poor. An innovative microneedle (MN) patch such as the curved, flexible or personalised MN patch is a viable avenue to deliver AHP-3. However, the well-researched geometrical relationship of MN on a flat MN patch cannot be assumed for these novel MN patches due to a complex mix of axial and shear forces. In this study, 3D printing was used for the fabrication of various MN patches with different MN geometries and curvatures. Both mechanical strength and skin penetration efficiency were used to determine the optimal MN geometry. The optimal MN geometry was then applied to the fabrication of a personalized MN patch (PMNP) for anti-wrinkle therapy, via 3D printing. In all, the general principles of MN geometrical effects on mechanical strength and skin penetration efficiency for a curved and a flat MN patch were similar. A MN height of 800 μm, tip diameter of 100 μm, interspacing of 800 μm and base diameter of 400 μm was observed to be the optimal MN geometry across all curvatures. In vitro skin permeation study demonstrated enhanced transdermal delivery of AHP-3 using the fabricated PMNP. Therefore, PMNP with optimized MN geometry can potentially be a novel approach to augment transdermal delivery of AHP-3 for effective wrinkle management.

Anti-Wrinkle Efficacy of Cross-Linked Hyaluronic Acid-Based Microneedle Patch with Acetyl Hexapeptide-8 and Epidermal Growth Factor on Korean Skin

Background

Hyaluronic acid (HA)-based microneedle patch has recently been studied for wrinkle improvement. Cross-linked HA (CLHA) is widely used in dermal fillers. Acetyl hexapeptide-8 (AHP-8) and epidermal growth factor (EGF) are used for cosmetic ingredients.

Objective

This study aimed to verify the efficacy of the CLHA/HA-based patch with microstructure (microneedle patch) containing AHP-8 or EGF.

Methods

A total of 52 Korean females were enrolled in a double-blind, randomized, controlled, split-face trial. The subjects were divided into 3 groups: (1) microneedle patch alone, (2) microneedle patch/AHP-8, and (3) microneedle patch/EGF. The treatment was applied on the periorbital and nasolabial fold area for 4 hours to completely dissolve the microstructures once per week for 29 days. Evaluations, including photodamage scoring, image analysis with Antera 3D® (Miravex, Ireland), skin hydration measurement, and adverse effect assessments, were performed at each visit.

Results

Fifty subjects (96.2%) completed this clinical study. On day 29 after application, statistically significant improvements in wrinkle and skin hydration were observed in all groups (p<0.01). Treatment with microneedle patch/AHP-8 and microneedle patch/EGF showed statistically significant improvements in wrinkle compared with microneedle patch alone (p<0.05). No serious adverse effects were noted.

Conclusion

Combination of CLHA-based microneedle patch and functional cosmetic ingredients can improve wrinkle with minimal discomfort.

Botulinum toxin (Botox) A for reducing the appearance of facial wrinkles: a literature review of clinical use and pharmacological aspect

Background: Botulinum toxin (Botox) consists of 7 types of neurotoxins; however, only toxins A and B are used clinically. Botox A is used for several disorders in the field of medicine, particularly in dermatology, for cosmetic purposes. It is produced by the bacterium Clostridium botulinum and can be used as a treatment to reduce the appearance of wrinkles in the upper areas of the face, elevate the eyebrows and treat problems such as hyperhidrosis, lichen simplex, pompholyx (dyshidrotic eczema) and acne vulgaris.

Objectives: This article provides a literature review regarding the general issue of Botox as a treatment for reducing facial wrinkle.

Discussion: Botox works by blocking the release of acetylcholine, resulting in paralysis of the local muscles, which usually occurs 24 hrs to two weeks following Botox injection. This effect will last three to six months. The optimal dose of cosmetic Botox in dermatology is 20 units. Botox is relatively safe and does not result in any adverse side effects. However, in certain circumstances, the effect of Botox will gradually resolve, resulting in reduced muscle paralysis over time.

Conclusion: Botox is good and safe medicine to reduce the appearance of facial wrinkles.

Identification of small peptides and glycinamide that inhibit melanin synthesis using a positional scanning synthetic peptide combinatorial library

BACKGROUND

Antimelanogenic peptides are potentially useful to treat hyperpigmentation, but many peptides have limited application because of high cost and/or low activity.

OBJECTIVES

To identify small and potent peptide inhibitors of cellular melanin synthesis that are useful for cosmetic and medical applications.

METHODS

A positional scanning synthetic tetrapeptide combinatorial library was used for screening of potentially active peptides. Antimelanogenic activities of the peptide pools and individual peptides were evaluated in B16-F10 melanoma cells and human epidermal melanocytes treated with alpha-melanocyte-stimulating hormone (α-MSH).

RESULTS

Predicted active tetrapeptide sequences were R-(F/L)-(C/W)-(G/R)-NH₂ . Of the individual tetrapeptides tested, D3 (RFWG-NH₂ ) and D5 (RLWG-NH₂ ) exhibited high antimelanogenic activities. Tetrapeptide D9 (FRWG-NH₂ ) with a sequence identical to that of a portion of α-MSH also showed antimelanogenic activity. Of the tripeptides tested, E5 (FWG-NH₂ ), E6 (LWG-NH₂ ) and E7 (RWG-NH₂ ) were relatively more active. Dipeptide F1 (WG-NH₂ ) and monopeptide G1 (G-NH₂ , glycinamide) retained activity, but G2 (Ac-G-NH₂ ) and G3 (glycine) did not. The antimelanogenic activities of peptides D3, E5, F1 and G1 were verified in α-MSH-stimulated human epidermal melanocytes. Commercially available G-NH₂ ·HCl suppressed the phosphorylation levels of cAMP-responsive element binding protein, protein levels of microphthalmia-associated transcription factor and tyrosinase, l-tyrosine hydroxylase activity of tyrosinase, and the melanin levels in stimulated cells.

CONCLUSIONS

Small peptides, including glycinamide and tryptophanyl glycinamide, are potent antimelanogenic agents with potential value for the treatment of skin hyperpigmentation.

Evaluation of sex-related changes in skin topography and structure using innovative skin testing equipment

BACKGROUND

Evaluation of skin condition on the basis of parametrization and objective measurements of the parameters has become obligatory. The aim of this study was to assess sex-related changes in skin topography and structure using the skin testing equipment.

MATERIALS AND METHODS

The study was carried out on the group of 40 volunteers (20 females and 20 males) of the mean age 24 ± 3 years. The skin parameters were measured using 3 devices: Visioscan^®  VC 98 (skin topography), Visioline^® VL 650 (skin macro relief) and Ultrascan UC22 (ultrasound imaging of the skin). All measurements were performed on the inner part of the left forearm.

RESULTS

The skin parameters measured revealed significant differences in skin surface and structure between females and males. The skin of all women subjects was more homogenous in its structure with the presence of more abundant superficial skin lines and wrinkles in comparison to male skin. The higher number of skin furrows in the skin of women is in agreement with literature reports claiming that men's skin has lower number of wrinkles which are deeper and more pronounced. Ultrasound imaging of the skin indicated greater thickness and lower density of the dermis of men subjects compared to those of females.

CONCLUSION

Non-invasive methods of skin testing using new and advanced equipment have provided a possibility of objective parametrization and evaluation of sex-related changes in skin topography and structure.

Analysis of spin in the reporting of studies of topical treatments of photoaged skin

BACKGROUND

Spin-reporting that distorts the interpretation of results-is not unusual within scientific literature.

OBJECTIVE

To appraise strategies of spin among placebo-controlled double-blind clinical trials of topical treatments for photoaged skin.

METHODS

A systematic review of the literature was performed to identify placebo-controlled double-blind clinical trials of topical treatments for photoaged skin. A survey of spin strategies was developed and applied to the cohort of identified studies.

RESULTS

The systematic review led to the identification of 20 studies in which various types of spin strategies, broadly classified as either inappropriate statistical analyses or inappropriate interpretation of results, were used. The most commonly used strategies included use of multiple primary outcomes (95%), inappropriate extrapolation of results from specific outcomes to global improvements (95%), focus on within-group comparisons (75%), and focus on interim analyses to give more weight to nonsignificant findings (65%).

LIMITATIONS

Classification of spin strategies was subjective and might not encompass all the methods used in the published literature.

CONCLUSION

Findings in this study inform efforts to reduce spin in the dermatologic literature.

Bioactive Peptides: Applications and Relevance for Cosmeceuticals

Peptides found in skin can act by different mechanisms of action, being able to function as epidermal or nervous growth factors or even as neurotransmitters. Due to the vast functionality of these compounds, there is growing research on bioactive peptides aimed at investigating their uses in products developed for stimulating collagen and elastin synthesis and improving skin healing. Thus, a literature search on applications of the most common bioactive peptides used in cosmeceuticals was carried out. There is a lack of proper reviews concerning this topic in scientific literature. Nine peptides with specific actions on body and facial dysfunctions were described. It could be noted while searching scientific literature that studies aimed at investigating peptides which prevent aging of the skin are overrepresented. This makes searching for peptides designed for treating other skin dysfunctions more difficult. The use of biomimetic peptides in cosmetic formulations aimed at attenuating or preventing different types of skin dysfunctions is a topic where information is still lackluster. Even though research on these compounds is relatively common, there is still a need for more studies concerning their practical uses so their mechanisms of action can be fully elucidated, as they tend to be quite complex.

Enhanced Skin Permeation of Anti-wrinkle Peptides via Molecular Modification

Wrinkles can have a negative effect on quality of life and Botox is one of the most effective and common treatments. Argireline (Arg0), a mimetic of Botox, has been found to be safer than Botox and effective in reducing wrinkles, with efficacies up to 48% upon 4 weeks of twice daily treatment. However, the skin permeation of Arg0 is poor, due to its large molecular weight and hydrophilicity. Arg0 exists in zwitterionic form and this charged state hindered its skin permeation. Chemical modification of the peptide structure to reduce the formation of zwitterions may result in increased skin permeability. We investigated a total of 4 peptide analogues (Arg0, Arg1, Arg2, Arg3), in terms of skin permeation and wrinkle reduction. The 4 peptides were dissolved in various propylene glycol and water co-solvents. Enhanced human skin permeation was demonstrated by both Arg2 and Arg3 in vitro. On the other hand, the abilities of the 4 analogues to reduce wrinkle formation were also compared using primary human dental pulp stem cells derived neurons. By measuring the inhibition of glutamate release from the neurons in vitro, it was shown that Arg3 was the most effective, followed by Arg1, Arg0 and Arg2.