FormalPara Key Summary Points

Facial aging is a multifactorial phenomenon due to poor skin hydration, deficient intercellular communication, collagen/elastin breakdown, and oxidative stress.

Optimal formulations to address this should include humectants, peptides, and antioxidants.

Fifty female subjects 35–65 years of age of all Fitzpatrick skin types with mild to moderate facial photoaging concerns (fine lines, wrinkles, sagging skin, tone and texture) were enrolled in this monadic study.

Improvement was seen in all parameters after 24 weeks of product use.

Introduction

Facial aging is a universal multifactorial phenomenon requiring complex formulations to result in appearance improvement. Skin aging occurs as a result of poor skin hydration, deficient intercellular communication, collagen/elastin breakdown, and oxidative stress [1,2,3]. Ingredients that address these mechanisms of aging ideally should be placed in a vehicle that optically smoothes the skin surface to create an immediate visual skin appearance improvement for the consumer followed by continued improvement based on ingredient alterations to counteract the aging phenomenon. Thus, antiaging formulations must be carefully constructed to meet these needs to deliver benefits. This research explored the value of a multimechanistic approach to formulation carefully combining both vehicle and combinations of active ingredients.

The vehicle for the formulation was built on a spreadable polymer backbone (polysilicone-11) to fill in the fine lines and dermatoglyphics of the face, thus physically creating a smooth skin surface and improving radiance/luminosity. This spreadable film was combined with a humectant blend of five variants of hyaluronic acid with varying molecular weights (sodium hyaluronate crosspolymer, high molecular weight sodium hyaluronate, medium molecular weight sodium hyaluronate, low molecular weight sodium hyaluronate, and acetylated hyaluronic acid) to hydrate and plump the skin [4]. The sodium hyaluronate crosspolymer largely remained as a film on the skin surface while the hydrolyzed hyaluronic acid more readily penetrated into the skin owing to its low molecular weight. High molecular weight sodium hyaluronate increased skin hydration, which led to an improvement in skin texture and radiance/luminosity [5]. Lastly, acetylated hyaluronic acid provided antioxidant-like benefits and has a decreased tendency to biodegrade, owing to its chemically modified structure.

Peptides were incorporated to facilitate intercellular communication [6]. The formulation contained a peptide cocktail (acetyl tripeptide-74 amide, acetyl tripeptide-54, palmitoyl sh-tripeptide-3 amide, and palmitoyl sh-tripeptide-1 amide). However, acetyl octapeptide-3 was also added, which is a peptide composed of the amino acids aspartic acid, glutamic acid, glutamine, and methionine. The peptide may act like a local neurotoxin in blocking neurotransmitters at the neuromuscular junction and reducing lines of facial expression, minimizing wrinkle depth, and improving skin roughness without systemic effects [7].

The rebuilding of collagen/elastin is a key endpoint for improvement of aging skin appearance. Growth factor-stimulating tripeptides (palmitoyl sh-tripeptide-3 amide, palmitoyl sh-tripeptide-1 amide, acetyl tripeptide-54 amide, and acetyl tripeptide-74 amide) support fibroblast growth and collagen deposition reducing the appearance of fine lines and wrinkles. Anigozanthos flavidus extract (kangaroo paw) was also included to promote collagen and elastin remodeling to improve laxity and the appearance of aging skin.

Since oxidative stress is a major contributor to aging, the formulation contained a variety of antioxidants. Tricholoma matsutake, a mushroom extract found in the Orient, is a potent antioxidant [8, 9] and was combined with bacillus ferment, created by fermenting Bacillus subtilis with yeast. The ferment has enzymatic activity and can exfoliate the skin surface [10]. Other components of the antioxidant blend included ergothioneine, which is a naturally occurring sulfur-containing amino acid, which can protect cells from UV-induced reactive oxygen species [11]. Finally, carnosine, which is a biomimetic peptide, was added for its antioxidant benefits and inhibition of UVA damage [12].

The objective of this research was to assess the efficacy of an antiaging prototype on the appearance of mild to moderate photoaged facial skin in all Fitzpatrick skin types after 24 weeks of use through clinical assessments.

Methods

Fifty female subjects 35–65 years of age of all Fitzpatrick skin types with mild to moderate facial photoaging concerns (fine lines, wrinkles, sagging skin, tone and texture) were enrolled in this monadic study to evaluate the effect of an antiaging formulation. Subjects who signed an informed consent (Allendale Institutional Review Board, Old Lyme, CT) and met all inclusion criteria and none of the exclusion criteria were enrolled at the baseline visit. The study documents, informed consent, and photography consent were approved by the Allendale Institutional Review Board (AIRB), Old Lyme, CT. The study was performed in accordance with the Helsinki Declaration of 1964 and its later amendments. The study was also conducted in accordance with Good Clinical Practices 21 CFR Part 50 guidelines. Pregnant and lactating subjects were excluded, as were subjects who had undergone any facial procedures in the past 6 months. Subjects who used any topical prescription or over-the-counter (OTC) facial products for 2 weeks prior to study entry or received any facial treatments in the past 6 months or were not willing to withhold all facial treatments during the course of the study including facial peels, dermabrasion, botulinum toxin, injectable fillers, energy-based treatments, or facial plastic surgery were not enrolled. Subjects who used any OTC or prescription retinoid facial products within the past 3 months were also excluded.

Subjects were asked to continue their self-selected cleanser and bland moisturizer they used without difficulty for the prior 30 days for the 24-week duration of the study unchanged. A marketed sunscreen (Neutrogena Clear Face Break-Out Free Liquid Lotion Sunscreen, Broad Spectrum SPF50, Johnson & Johnson, Skillman, NJ) was provided for sun protection. Subjects were asked to cleanse their face with a wipe (Kind to Skin Cleansing Wipes, Simple, Unilever) prior to any evaluations. The study product (PCA Skin Pro-Max Age Renewal Serum, Colgate-Palmolive Co. and PCA Skin, Piscataway, NJ) was applied in sufficient quantity twice daily to place a thin product film over a clean washed face and neck with applications recorded in a compliance diary. The study product composition is presented in Table 1.

Table 1 Multimechanistic antiaging composition
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The research dermatologist investigator visually completed baseline efficacy assessments (fine lines, wrinkles, skin evenness, radiance, plumping, texture/smoothness, sagging/firming/lifting, global appearance) and tolerability assessments (erythema, irritation, edema). All assessments were made on a 5-point ordinal scale (0 = none, 1 = minimal, 2 = mild, 3 = moderate, 4 = severe). The subjects completed a baseline tolerability assessment (itching, stinging, burning). The same 5-point ordinal scale was used. Noninvasive assessments of corneometry to evaluate skin hydration were taken from a target site on the left cheek with a pin probe (DermaLab, Cortex Technologies, Hadsund, Denmark). The corneometer measures moisture content in the stratum corneum by an electrical capacitance method. The measurement has no units, but is proportional to the dielectric constant of the surface layers of the skin, and increases as the skin becomes more hydrated. Elasticity measurements were taken from a target site on the right cheek (DermaLab, Cortex Technologies, Hadsund, Denmark). The instrument applied a vacuum to the skin and measured the skin’s elastic response. The probe was secured to the skin with double-sided tape. Negative vacuum pressure of 450 mbar was applied for 5 s and released for 10 s. The movement of the skin in and out of the probe was recorded during the application and release of the vacuum suction. The amount of extensibility, resiliency, and pure elasticity were recorded as VE (MPa), E (MPa), and retraction time (ms). Assessments were made at baseline, immediately after one application, week 1, week 2, week 4, week 8, week 12, week 16, week 20, and week 24.

Twenty investigator-selected subjects underwent photography of the front, right, and left face with standard, cross-polarized, and parallel-polarized lighting (Visia CR4.3, Canfield Scientific, NJ, USA). These subjects were selected randomly from within the various Fitzpatrick skin type groups enrolled in the study to ensure diversity in photographic documentation. Subjects were provided with a diary for compliance and the study product. Subjects applied the study product to the entire face after facial cleansing every morning and evening. The provided sunscreen was used after study product application every morning. Subjects recorded their applications in a compliance diary.

Results

Forty-seven of the 50 subjects successfully completed the 24-week study. The study enrolled all ethnicities to include 36 Caucasian, 2 Hispanic, 3 Asian, and 9 African-American women ages 37–64 years. All Fitzpatrick skin types were included. Oily, dry normal, and combination skin types were included. Two subjects discontinued at week 16 and one subject discontinued at week 20 for personal reasons unrelated to the study product.

The dermatologist investigator identified no tolerability issues in terms of erythema, irritation, or edema. Similarly, the subjects did not identify any sensory issues of stinging, itching, or burning. The subjects also assessed no odor or product stickiness issues.

Corneometry measurements were obtained from the left cheek at each visit to assess skin hydration. There was a statistically significant increase in skin moisturization immediately after product application of 54% (p < 0.001) that continued for the entire 24 weeks of the study. At the study conclusion, there was a 35% increase in skin moisturization (p < 0.001).

Elasticity measurements were taken with a negative pressure suction device on the right cheek. The elasticity was evaluated in terms of retraction time (RT), Young’s modulus (EM), and the calculated viscoelasticity. Retraction time is measured in milliseconds and represents a measurement of how long it takes for the skin to snap back to original conformation once it has been distended by the negative pressure vacuum pump. A decrease in retraction time means the skin is firmer. The retraction time decreased a statistically significant 16% at week 8 (p < 0.001). This statistically significant improvement continued for the remainder of the study increasing to 19% at week 24 (p < 0.001). This means the skin was 19% firmer at the end of the 24-week study. Viscoelasticity combines both the elevation and the retraction phase and is measured in megapascals. An improvement in viscoelasticity means the skin demonstrated less sagging or more lifting. The viscoelasticity demonstrated a statistically significant (p < 0.001) improvement of 22% at week 8, which persisted into week 24 with a 21% improvement. Thus, the skin demonstrated 21% less sagging or 21% more lifting after 24 weeks of study product application (Fig. 1).

Fig. 1
figure 1

Elasticity measurements. Results demonstrated a statistical improvement in firmness (a) and less sagging/more lifted skin (b) on the cheek

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The investigator assessed fine lines, wrinkles, skin evenness, radiance, plumping, texture/smoothness, sagging/firming/lifting, and global appearance. All assessments were made on a 5-point ordinal scale (0 = none, 1 = minimal, 2 = mild, 3 = moderate, 4 = severe). There was immediate statistically significant improvement in radiance (p < 0.001) and texture (p = 0.003). This improvement continued into week 1. By week 2, there was statistically significant improvement in radiance (p < 0.001), texture (p < 0.001), and evenness (p = 0.008), but also in overall appearance (p < 0.001). Cumulative improvement continued into weeks 12, 16, 20, and 24 when all evaluated criteria were statistically significant (p ≤ 0.001). By week 24, there was a 40% improvement in lines, a 23% improvement in wrinkles, a 42% improvement in evenness, a 64% improvement in radiance, a 58% improvement in plumping, a 65% improvement in texture, a 60% improvement in firmness, and a 45% improvement in overall appearance (Fig. 2). This investigator observational data is consistent with the noninvasive hydration and elasticity data. Representative before and after images are presented in Fig. 3.

Fig. 2
figure 2

Dermatologist investigator assessments. The investigator noted cumulative continuous improvement with continued use of the multimechanistic antiaging skin serum

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Fig. 3
figure 3

Photographs. Before and after photographs demonstrating overall facial appearance improvement in a subject with significant photoaging

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Discussion

Modern antiaging formulations must address the myriad of factors that have been identified to contribute to the appearance of aging skin. The current study examined a novel multimechanistic approach to product formulation. The basis of any facial cosmeceutical is the vehicle into which the antiaging ingredients are placed. The vehicle should increase skin water content through several mechanisms of moisturization. The current vehicle contained propanediol, glycerin, caprylyl glycol, butylene glycol, and pentylene glycol. Hyaluronic acid, the natural occurring water-holding substance in the dermis, was added in several different molecular weights to hold water in the superficial stratum corneum and viable epidermis. All of these substances are classified as humectants and can therefore hold water and increase skin hydration. However, the water is rapidly lost to the environment resulting in further dehydration if a hydrophobic film is not placed on the skin surface. To prevent this water loss, a film-forming polymer polysilicone-11 was added to temporarily restore the skin barrier while putting a smooth film over the skin surface to improve radiance/luminosity. These major ingredients form the foundation for a moisturizing appearance-enhancing vehicle that will produce immediate skin improvement upon application. The functioning of this ingredient combination was documented by an increase in skin plumping and hydration measured through dermatologist investigator assessment and corneometry.

Topical antiaging formulations are also valued by consumers for the smooth soft feel they impart to the skin. This is a temporary effect while the product is on the skin surface, but skin texture will improve as barrier repair occurs. Ingredients known as emollients are placed on the skin surface to provide friction reduction by smoothing down the desquamating corneocytes and creating a lubricious film. The emollient ingredients in this formulation included PPG-3 benzyl ether myristate and polymethylsilsesquioxane. This quality is known as emolliency and it is an important mechanistic component of antiaging cosmeceuticals. These ingredients provided for the improvement demonstrated in skin texture and smoothness.

Cellular communication along with the regeneration and production boosting of dermal proteins is necessary for optimally functioning skin [13]. The peptide cocktail, including growth factor-stimulating tripeptides, was key in delivering significant clinical improvements (reduction in fine lines and wrinkles, firmer/less sagging, more elastic skin) as per the dermatologist investigator assessment and retraction time and viscoelasticity measurements.

Perhaps the most cumulative damaging daily insult on skin is oxidative stress. This mechanistic concern requires a cocktail of antioxidants to counteract the effects of oxygen radicals [14]. Mushroom extract is capable of donating an electron to a reactive oxygen species. When combined with ergothioneine, a naturally occurring amino acid that is a thiourea derivative of histidine found in high concentration in the skin, an additive antioxidant effect was created [15]. Finally carnosine was added to function as a peptide antioxidant [16].

The limitation of this study is the inability to have a placebo control. There is no such thing as a placebo moisturizer, since even thickened water has an effect on the skin. Hence, it is difficult to isolate the individual added benefit of each ingredient and the skin effect produced by the moisturizer vehicle. The formulation must be evaluated as a whole for this reason.

The study antiaging formulation addressed many of the common causes of skin aging to include barrier damage, low skin water content, poor surface texture, and oxidative stress. The noninvasive mechanical data and investigator visual assessments support the value of a multimechanistic formulation in appearance improvement.

Conclusion

The antiaging serum combination of polymers, humectants, peptides, and antioxidants yielded excellent tolerability with visual and mechanistic skin improvement beginning at 1 week with cumulative continuing improvement through 24 weeks of use in terms of hydration, firmness, texture, radiance, plumping, evenness, wrinkles, and fine lines.