Structure, Stratum Corneum Distribution, and Stratum Corneum Conditioning Mechanism of Capryloyl Salicylic Acid: Barrier Effects and Safety Evaluation
Structure, Stratum Corneum Distribution, and Stratum Corneum Conditioning Mechanism of Capryloyl Salicylic Acid: Barrier Effects and Safety Evaluation
Capryloyl salicylic acid is a derivative of salicylic acid produced through lipophilic structural modification. It retains the o-hydroxybenzoic acid structure while introducing an octanoyl group at the 5-position of the benzene ring, thereby altering the molecule’s lipid affinity, molecular weight, and steric volume.
Under the reported experimental conditions, these changes result in greater retention of capryloyl salicylic acid within the stratum corneum and relatively slower diffusion into tissues beneath the stratum corneum. Existing studies suggest that its effects are relatively concentrated in the outer stratum corneum and that it can promote superficial desquamation by influencing the adhesive structures between corneocytes.
The core mechanistic pathway discussed throughout this article is:
Introduction of an octanoyl group at the 5-position → increased lipid affinity, molecular weight, and steric volume → increased stratum corneum retention and slower diffusion into deeper layers under the reported experimental conditions → association with reduced integrity of outer corneodesmosomes and weakened corneocyte adhesion → promotion of superficial corneocyte shedding
1 Chemical Structure of Capryloyl Salicylic Acid
1.1 Ingredient Definition
The International Nomenclature of Cosmetic Ingredients name of capryloyl salicylic acid is Capryloyl Salicylic Acid. In the literature and skincare field, it is commonly referred to as lipohydroxy acid (LHA). Its chemical name is 2-hydroxy-5-octanoylbenzoic acid, its CAS number is 78418-01-6, its molecular formula is C₁₅H₂₀O₄, and its relative molecular mass is 264.32.[1]
Because of its structural similarity, capryloyl salicylic acid was initially included in a group safety assessment together with salicylic acid and salicylates. However, its actual structure is not an ester formed from salicylic acid and octanoic acid. The octanoyl group is connected to the 5-position of the salicylic acid benzene ring through a carbon–carbon bond, forming an aromatic ketone structure.[1]
The structures can be represented in simplified form as follows:
Salicylic acid:
Benzene ring position 1—COOH; position 2—OH
Capryloyl salicylic acid:
Benzene ring position 1—COOH; position 2—OH; position 5—CO—(CH₂)₆—CH₃
Here, —CO—(CH₂)₆—CH₃ is the octanoyl group. This group forms part of the stable molecular framework of capryloyl salicylic acid. Therefore, capryloyl salicylic acid is not a precursor ingredient that releases salicylic acid through ester-bond hydrolysis.
1.2 Structural Changes Introduced by the Octanoyl Group
Both salicylic acid and capryloyl salicylic acid contain a carboxyl group and an adjacent phenolic hydroxyl group. The additional C8 acyl side chain in capryloyl salicylic acid increases its hydrophobic surface area and raises its relative molecular mass from 138.12 to 264.32.
Comparison Item | Salicylic Acid | Capryloyl Salicylic Acid |
Chemical structure | 2-Hydroxybenzoic acid | 2-Hydroxy-5-octanoylbenzoic acid |
Relative molecular mass | 138.12 | 264.32 |
Side-chain characteristics | No long-chain hydrophobic group | Contains a C8 octanoyl group |
Lipid affinity | Has a certain degree of lipid solubility | The octanoyl group further increases its tendency to partition into lipid phases |
Diffusion through the stratum corneum | Can enter the stratum corneum and continue to diffuse downward | Relatively slower diffusion into deeper layers under experimental conditions |
Primary site of action | Depends on concentration and vehicle and may involve a relatively broad range of the stratum corneum | More concentrated in the outer stratum corneum |
The estimated acid dissociation constant, pKa, of capryloyl salicylic acid is approximately 2.68, whereas the pKa of the carboxyl group of salicylic acid is approximately 2.97.[1] Their acidities are therefore within a similar range. The more pronounced effect of the octanoyl group is its alteration of molecular partitioning, diffusion, and the site of retention within the skin.
2 How Molecular Structure Alters Skin Distribution
2.1 Stratum Corneum Partitioning and Penetration into Deeper Layers
The entry of a topical active ingredient into the skin involves two distinct processes:
Release from the formulation and entry into the stratum corneum → diffusion through the stratum corneum and entry into the underlying viable epidermis
The higher lipid affinity of capryloyl salicylic acid facilitates its partitioning into the intercellular lipids of the stratum corneum, but this does not mean that it crosses the entire stratum corneum more rapidly.
After entering the stratum corneum, capryloyl salicylic acid has a strong tendency to partition into the lipid environment. At the same time, its increased molecular weight and steric volume may be among the factors contributing to slower diffusion through the densely organized stratum corneum. Re-entry from the lipid-rich stratum corneum into the more water-rich viable epidermis also requires another phase-partitioning step.
Its skin distribution can be summarized as follows:
Greater partitioning into and retention within the stratum corneum → relatively slower diffusion into the viable epidermis
2.2 Results of Skin Penetration Studies
In an ex vivo human skin study using the same vehicle, approximately 6% of capryloyl salicylic acid penetrated below the stratum corneum after 16 hours of exposure, compared with approximately 58% of salicylic acid. A human tape-stripping study estimated that 17.1% of capryloyl salicylic acid was retained in the stratum corneum, compared with 9.7% of salicylic acid.[1,2]
These data support the tendency of capryloyl salicylic acid to be retained to a greater extent within the stratum corneum and to diffuse more slowly into deeper layers. It should be noted that the human tape-stripping study did not specify the number of participants or the experimental vehicle and did not provide complete distribution data for most of the applied dose. Therefore, these percentages are suitable only for illustrating skin-distribution trends under specific experimental conditions and should not be extrapolated to all concentrations, vehicles, and conditions of use.
2.3 Formulation Control of Actual Skin Exposure
Lipid affinity determines the type of environment into which an ingredient tends to partition, whereas the formulation determines how much of the active ingredient is released and in what physical state it is deposited on the skin surface.
The main factors affecting the actual activity of capryloyl salicylic acid include:
① Dissolution state of the ingredient: Capryloyl salicylic acid that is not adequately dissolved cannot provide stable and reproducible active exposure.
② Solvent capacity: Alcohols, glycols, and oil-phase ingredients affect ingredient solubility, release rate, and skin partitioning.
③ Formulation pH and ionization state: The pH affects the degree of carboxyl-group dissociation, thereby altering molecular partitioning and diffusion within the skin.
④ Oil-phase and aqueous-phase composition: If the active ingredient has excessively high affinity for the formulation vehicle, it may not be readily released from the formulation. If its affinity is too low, precipitation or crystallization may occur.
⑤ Product rheology and evaporation: Viscosity, wettability, and evaporation rate affect application thickness and the uniformity of surface deposition.
⑥ Physical state after drying: Crystallization or localized precipitation after solvent evaporation may result in uneven effective exposure and increase localized irritation.
Capryloyl salicylic acid has good compatibility with sebum and stratum corneum lipids, but this does not mean that a product will automatically spread uniformly over the skin surface. Uniformity is jointly determined by dissolution, release, application, and the physical state of the formulation after drying.
3 Core Mechanism of Stratum Corneum Conditioning
3.1 Desmosomes and Corneodesmosomes
Keratinocytes in the viable epidermis are interconnected through desmosomes. Desmosomes consist of transmembrane adhesion proteins, intracellular junctional proteins, and keratin intermediate filaments, and they maintain the mechanical strength of the epidermis.
As keratinocytes differentiate outward and become corneocytes, ordinary desmosomes are converted into corneodesmosomes. Corneodesmosomes are the principal intercellular adhesive structures within the stratum corneum. Their representative components include:
① Desmoglein 1;
② Desmocollin 1;
③ Corneodesmosin.
During normal desquamation, the extracellular regions of corneodesmosomes are progressively degraded by proteases. As the number of intercellular junctions decreases, adhesion between outer corneocytes weakens, and the cells are ultimately shed from the skin surface.
Corneodesmosome degradation is primarily regulated by kallikrein-related peptidases and their inhibitors and is also associated with the pH and hydration state of the stratum corneum.[4]
3.2 Effects of Capryloyl Salicylic Acid on Corneocyte Adhesion
Early histological and ultrastructural studies observed reduced integrity of corneodesmosomes in the outer stratum corneum and weakened adhesion between corneocytes following treatment with capryloyl salicylic acid.[2,3]
The process can be represented as follows:
Exposure of the outer stratum corneum to capryloyl salicylic acid → reduced integrity or number of outer corneodesmosomes → weakened corneocyte adhesion → shedding of individual corneocytes or small groups of corneocytes
These studies support the conclusion that intercellular junctional structures between corneocytes are affected. However, it has not been established which corneodesmosomal protein is directly bound by capryloyl salicylic acid, and there is no evidence that it is a specific activator of any particular kallikrein.
Local pH, stratum corneum hydration, and endogenous proteolytic processes may participate in this change, but the specific molecular pathway and direct targets remain to be verified.
3.3 Relationship to Physiological Desquamation
Physiological desquamation occurs primarily in the outer stratum corneum and depends on the progressive degradation of corneodesmosomes. Corneocytes are generally shed individually or in small groups.
The relatively slow diffusion of capryloyl salicylic acid into deeper layers is consistent with observations that its effects are relatively concentrated in the outer stratum corneum. Early observations found that, compared with salicylic acid treatment, capryloyl salicylic acid more readily produced dispersed shedding of corneocytes.[2,3]
This similarity is limited to the site and pattern of desquamation. Complete epidermal renewal also involves basal-cell proliferation, keratinocyte migration, keratin reorganization, filaggrin processing, intercellular lipid release, and natural moisturizing factor formation.
Capryloyl salicylic acid primarily affects cell adhesion and desquamation at the terminal stage of epidermal renewal and should not be regarded as reproducing the entire natural metabolic process of the skin.
4 Effects on Roughness and Follicular Keratinization
4.1 Surface Roughness and Fine Scaling
When degradation of corneodesmosomes in the outer stratum corneum is insufficient, corneocytes that are close to being shed remain attached to the skin surface, resulting in irregular accumulation and fine scaling. As microscopic surface unevenness increases, skin feel and light reflection also change.
By weakening adhesion between outer corneocytes, capryloyl salicylic acid can promote the shedding of abnormally retained corneocytes. Its principal effects occur at the surface of the stratum corneum and do not require substantial penetration into the dermis. The primary function of capryloyl salicylic acid is to regulate the shedding of surface corneocytes rather than to directly alter dermal structure.
4.2 Keratin Accumulation at Follicular Openings
Comedone formation is associated with abnormal shedding of keratinocytes in the follicular infundibulum, increased cell adhesion, and sebum accumulation. Corneocytes and sebum together form microcomedones, which may subsequently develop into closed or open comedones.
Capryloyl salicylic acid has a relatively high tendency to partition into lipid phases, which may facilitate its distribution within the sebum-rich environment of follicular openings. Its stratum corneum-conditioning effect may help reduce the continued accumulation of keratinous material within the follicular infundibulum.
5 Barrier Function, Transepidermal Water Loss, and Irritation Responses
5.1 Transepidermal Water Loss
Transepidermal water loss (TEWL) is the flux of water that diffuses through the epidermis and stratum corneum and subsequently evaporates. It is commonly used to evaluate the integrity of the stratum corneum water barrier.[8]
The effect of capryloyl salicylic acid on TEWL depends on the degree of stratum corneum conditioning. The following are possible barrier outcomes under different exposure conditions. They represent mechanistic analyses, and actual results also depend on the concentration used, the vehicle, and the complete formulation.
Exposure Condition | Changes in the Stratum Corneum | Possible Barrier Outcome |
Moderate activity | Primarily removes outer corneocytes that are close to natural shedding | Continuity of the underlying stratum corneum may be maintained, and TEWL may not increase significantly |
Excessive exposure | Reduced number of corneocyte layers and disruption of intercellular lipid organization | Reduced resistance to water diffusion and a possible increase in TEWL |
Complete moisturizing formulation | Contains humectants, lipids, or film-forming agents | TEWL may decrease, but this cannot be attributed solely to capryloyl salicylic acid |
The pathway of barrier alteration is:
Excessive corneocyte shedding → reduced continuity of the stratum corneum → lower resistance to water diffusion → increased TEWL → increased dryness and tightness
Currently available evidence is insufficient to demonstrate that capryloyl salicylic acid itself directly reduces TEWL. Changes in TEWL observed with products containing capryloyl salicylic acid should be evaluated in the context of the complete formulation.
5.2 Erythema Index, Stinging, and Redness
The erythema index is a measure of skin redness obtained through skin reflectance spectroscopy or colorimetric measurement. Its value is primarily influenced by hemoglobin absorption, superficial blood volume, vasodilation, melanin, and the optical scattering properties of the skin.
The relatively slow diffusion of capryloyl salicylic acid into the viable epidermis may reduce the peak short-term exposure of living cells and sensory nerve endings to acidic molecules. This provides one possible skin-distribution-based explanation for the relatively good tolerability of certain formulations.
The relationship can be represented as follows:
Relatively slower diffusion into deeper layers → potentially lower transient exposure of the viable epidermis → potentially reduced probability of acute stinging and irritant erythema
This mechanism is a reasonable explanation based on skin distribution and does not indicate that capryloyl salicylic acid has direct analgesic, anti-inflammatory, vasoconstrictive, or anti-redness effects.
Excessive use of capryloyl salicylic acid may still cause stinging, dryness, desquamation, and erythema. Individual cases of contact allergy associated with capryloyl salicylic acid have been reported, but the source of the reaction may involve the parent capryloyl salicylic acid, positional isomers, or the complete formulation.[1]
6 Research on Capryloyl Salicylic Acid and Filaggrin
6.1 Functions of Filaggrin
Filaggrin is encoded by the filaggrin gene (FLG), and its precursor is profilaggrin.
During the terminal differentiation of keratinocytes, profilaggrin is processed into filaggrin monomers. Filaggrin aggregates keratin intermediate filaments and assists in the compression and reorganization of the cytoskeleton, enabling keratinocytes to transform into flattened corneocytes.
Filaggrin is subsequently degraded into small molecules, including free amino acids, pyrrolidone carboxylic acid, and urocanic acid, which contribute to the formation of the natural moisturizing factor (NMF).[6]
The process is:
Profilaggrin processing → filaggrin-mediated aggregation of keratin fibers → corneocyte maturation → filaggrin degradation → formation of natural moisturizing factor-related small molecules
6.2 Capryloyl Salicylic Acid and Filaggrin
Early studies and conference abstracts reported an increase in the thickness of the filaggrin-positive layer following the use of a formulation containing 2% capryloyl salicylic acid.[2,7]
However, an increase in the thickness of the filaggrin-positive layer may result from several different changes:
① An overall increase in epidermal or granular-layer thickness;
② An increase in the number of cells expressing filaggrin;
③ Changes in the rate of filaggrin processing or degradation;
④ Changes in the amount of filaggrin within individual cells.
Existing evidence suggests that formulations containing capryloyl salicylic acid may affect epidermal renewal and the structure of differentiated epidermal layers. However, it is insufficient to demonstrate that capryloyl salicylic acid directly upregulates FLG expression, promotes filaggrin synthesis, or increases natural moisturizing factor production.
7 Key Priorities in Ingredient Research and Safety Evaluation
7.1 Mechanistic Research
Future research on capryloyl salicylic acid should focus on three areas:
① Site of action: Use sequential tape stripping, Raman imaging, or mass spectrometry imaging to determine its concentration–time distribution within the stratum corneum and hair follicles.
② Corneodesmosomal targets: Examine changes in desmoglein 1, desmocollin 1, corneodesmosin, and kallikrein-related peptidases.
③ Balance between efficacy and barrier function: Simultaneously assess corneodesmosome density, stratum corneum thickness, TEWL, hydration, erythema index, and stinging scores.
7.2 Impurities and Phototoxicity
The CIR safety assessment published in 2024 concluded that the available data were insufficient to determine the safety of capryloyl salicylic acid under its intended conditions of use in cosmetics. The principal data gaps concerned impurity composition and phototoxicity.[1] This conclusion indicates that the available information remains incomplete and does not mean that capryloyl salicylic acid has been demonstrated to be unsafe.
The assessment noted that, when one in vitro 3T3 Neutral Red Uptake phototoxicity study was reinterpreted according to current evaluation criteria, some results could be classified as indicating “possible phototoxicity.” However, this method is also prone to false-positive results, and further testing is therefore required for confirmation. Positional isomers that may be present in the ingredient, including 3-octanoylsalicylic acid, should also be included in impurity-control programs.[1]
Ingredient-quality research should focus on:
① Positional isomers and synthetic residues;
② Impurity profiles resulting from different purification processes;
③ Photochemical changes following ultraviolet irradiation;
④ Human tolerability under finished-product formulation conditions.
8 Classification and Research Applications of Chemicals Related to the Structure, Stratum Corneum Conditioning, and Barrier Effects of Capryloyl Salicylic Acid
Table 1. Core Capryloyl Salicylic Acid Ingredient, Parent-Structure Controls, and Octanoyl-Group Research Reagents
Classification | CAS No. | Aladdin Catalog No. | Name | Specification or Purity | Product Features and Applications |
Core lipohydroxy acid ingredient | 78418-01-6 | Capryloyl Salicylic Acid | ≥98% | Core research ingredient for capryloyl salicylic acid; used to investigate the 5-position octanoyl structure, lipid-phase partitioning, stratum corneum retention, corneocyte adhesion, and mechanisms of superficial desquamation. | |
Salicylic acid parent-structure control | 69-72-7 | Salicylic Acid | UltraBio™, ultrapure grade, ≥99% | Used to compare the salicylic acid parent structure with its octanoyl-modified derivative in terms of molecular weight, lipid affinity, skin distribution, stratum corneum conditioning, and irritation responses. | |
Salicylate-form control | 54-21-7 | Sodium Salicylate | Suitable for analysis, premium grade | Used to investigate the ionized form, dissolution behavior, and acid–base equilibrium of salicylic acid and as an analytical control under neutral or mildly acidic conditions. | |
Aromatic carboxylic acid parent-structure control | 65-85-0 | Benzoic Acid | Sublimed grade, ≥99% | Used to compare the effects of an ortho phenolic hydroxyl group on the acidity, intramolecular hydrogen bonding, lipid partitioning, and stratum corneum-conditioning properties of aromatic carboxylic acids. | |
Octanoyl-chain-segment control | 124-07-2 | n-Octanoic Acid | AR, ≥99% | Used to investigate C8 fatty-chain structure, hydrophobicity, oil-phase compatibility, and the structural origin of the octanoyl group. | |
Octanoylation reagent | 111-64-8 | Octanoyl Chloride | ≥99% | Used for octanoyl-group introduction, screening of acylation reaction conditions, and laboratory synthesis of capryloyl salicylic acid-related structural derivatives. |
Table 2. Hydroxy Acid Controls for Stratum Corneum Conditioning, Molecular Structure, and Tolerability
Classification | CAS No. | Aladdin Catalog No. | Name | Specification or Purity | Product Features and Applications |
Small-molecule α-hydroxy acid control | 79-14-1 | Glycolic Acid | Suitable for analysis, premium grade | Used to compare small, hydrophilic hydroxy acids with capryloyl salicylic acid in terms of stratum corneum diffusion, superficial desquamation, acidity, and skin irritation. | |
Lactic acid-type α-hydroxy acid control | 50-21-5 | DL-Lactic Acid | AR, 85–90% | Used in studies of stratum corneum conditioning, lactate equilibrium, associations with natural moisturizing factor, stratum corneum hydration, and formulation acidity. | |
Aromatic α-hydroxy acid control | 90-64-2 | DL-Mandelic Acid | AR, ≥99% | Used to compare the effects of aromatic-ring structure, molecular volume, and lipophilicity on the skin partitioning, follicular keratinization, and tolerability of hydroxy acids. | |
Polyhydroxy acid lactone control | 90-80-2 | D-(+)-Glucono-δ-lactone | PharmPure™, USP | Used in studies of lactone hydrolysis, polyhydroxy structures, gradual acidification, stratum corneum hydration, and mild stratum corneum conditioning. | |
Disaccharide acid-type polyhydroxy acid control | 96-82-2 | Lactobionic Acid | ≥97% | Used to investigate disaccharide acid-type polyhydroxy structures, hygroscopicity, chelating capacity, stratum corneum hydration, and hydroxy acid tolerability. | |
Polycarboxylic acid and acidity-regulating material | 77-92-9 | Anhydrous Citric Acid Powder | Anhydrous grade, UltraBio™, ≥99.5% (T) | Used for formulation pH adjustment, multistep acid dissociation, buffer-system design, and studies of capryloyl salicylic acid release and stability under different acidity conditions. |
Table 3. Products Related to Stratum Corneum Lipids, Natural Moisturizing Factor, and Filaggrin Metabolism
Classification | CAS No. | Aladdin Catalog No. | Name | Specification or Purity | Product Features and Applications |
Stratum corneum sterol lipid | 57-88-5 | Cholesterol, from Lanolin | PharmPure™, JP, BP, European Pharmacopoeia (Ph. Eur.), NF, ultrapure grade | Used to construct intercellular lipid models of the stratum corneum and to investigate the effects of cholesterol on lipid-phase behavior, barrier permeability, and capryloyl salicylic acid partitioning. | |
Long-chain saturated free fatty acid | 57-11-4 | Stearic Acid | Moligand™, C18: 98% | Used to investigate long-chain fatty acid composition, ordered lipid organization, phase-transition behavior, and barrier models of the stratum corneum. | |
Long-chain saturated free fatty acid | 57-10-3 | Palmitic Acid | Moligand™, C16: 98% | Used to investigate free fatty acid composition in the stratum corneum, chain-length effects, lipid-membrane structure, and active-ingredient partitioning. | |
Monounsaturated fatty acid control | 112-80-1 | Oleic Acid | European Pharmacopoeia (Ph. Eur.), ≥65% | Used as a control in studies of lipid unsaturation, stratum corneum lipid organization, membrane fluidity, and changes in percutaneous penetration. | |
Polyunsaturated fatty acid control | 60-33-3 | Linoleic Acid | Moligand™, ≥99% (GC) | Used in studies of essential fatty acids, acylceramide-related metabolism, the stratum corneum lipid barrier, and the follicular sebum environment. | |
Sphingoid-base research material | 554-62-1 | Glycolipid (D-ribo-Phytosphingosine) | ≥98% | Used to investigate the phytosphingosine skeleton, ceramide precursors, sphingolipid metabolism, and organization of intercellular lipids in the stratum corneum. | |
Nonpolar oil phase and sebum-model material | 111-01-3 | Squalane | ≥98% | Used in studies of nonpolar oil phases, sebum compatibility, capryloyl salicylic acid dissolution and partitioning, and the sensory properties of laboratory formulations. | |
Natural moisturizing factor PCA form | 98-79-3 | L-Pyroglutamic Acid | UltraBio™, ultrapure grade | Used to investigate the structure and acid–base equilibrium of pyrrolidone carboxylic acid, the composition of natural moisturizing factor, and stratum corneum hydration mechanisms. | |
Natural moisturizing factor PCA salt | 28874-51-3 | Sodium L-Pyrrolidone-5-carboxylate | Oily form, 50% | Used in natural moisturizing factor models and studies of stratum corneum hygroscopicity, water binding, and the hydration performance of capryloyl salicylic acid formulations. | |
Nitrogen-containing small molecule in natural moisturizing factor | 57-13-6 | Urea | UltraBio™, molecular biology grade, ≥99.5% (T) | Used to investigate natural moisturizing factor composition, stratum corneum hygroscopicity, keratin hydration, and barrier status following acid treatment. | |
Filaggrin metabolism-related amino acid | 71-00-1 | L-Histidine | UltraBio™, ≥99.5% (NT) | Used in studies of amino acids associated with filaggrin degradation, histidine-to-urocanic acid conversion, and natural moisturizing factor in the stratum corneum. | |
Histidine metabolism and acid mantle research material | 104-98-3 | 4-Imidazoleacrylic Acid | ≥98% | Used to investigate urocanic acid structure, histidine metabolism, the acidic environment of the stratum corneum, and ultraviolet-induced isomerization. | |
Stratum corneum hydration control | 56-81-5 | Glycerol | Anhydrous grade, UltraBio™, molecular biology grade, ≥99.5% (GC) | Used as a control in studies of stratum corneum hygroscopicity, water content, transepidermal water loss, and the moisturizing performance and tolerability of capryloyl salicylic acid formulations. |
Table 4. Products Related to Formulation Solubilization, Skin Partitioning, and Barrier-Irritation Models
Classification | CAS No. | Aladdin Catalog No. | Name | Specification or Purity | Product Features and Applications |
Volatile polar solvent | 64-17-5 | E130059 | Ethanol | Anhydrous grade, Moligand™, ≥99.5%, H₂O ≤0.005% | Used in studies of capryloyl salicylic acid dissolution, deposition after evaporation, vehicle release, and skin partitioning under different solvent conditions. |
Glycol solvent and humectant | 57-55-6 | 1,2-Propanediol | AR, ≥99% | Used for capryloyl salicylic acid solubilization and in studies of formulation moisturization, vehicle release, skin wetting, and percutaneous partitioning. | |
Glycol solvent and humectant | 504-63-2 | 1,3-Propanediol | ≥98% | Used in studies of capryloyl salicylic acid solvent systems, formulation water activity, application properties, and skin tolerability. | |
Lipophilic vehicle and penetration research material | 110-27-0 | Isopropyl Myristate | PharmPure™, European Pharmacopoeia (Ph. Eur.), NF | Used as an oil-phase vehicle and in studies of capryloyl salicylic acid dissolution and release, partitioning into stratum corneum lipids, and percutaneous penetration controls. | |
Standard irritation and barrier-damage model reagent | 151-21-3 | Sodium Dodecyl Sulfate (SDS) | Anhydrous grade, ACS, ≥99% | Used to establish experimental models of skin irritation, erythema, stratum corneum barrier damage, and increased transepidermal water loss. |
Note: The products listed above are representative Aladdin products related to scientific and formulation research. Additional product specifications, grades, and COA information can be searched on the Aladdin website using the product name, CAS number, or catalog number.
References
[1] Johnson W Jr, Bergfeld WF, Belsito DV, et al. Safety Assessment of Capryloyl Salicylic Acid as Used in Cosmetics. International Journal of Toxicology. 2024;43(Suppl 3):92S-108S. doi:10.1177/10915818241237794.
[2] Saint-Léger D, Lévêque JL, Verschoore M. The Use of Hydroxy Acids on the Skin: Characteristics of C8-Lipohydroxy Acid. Journal of Cosmetic Dermatology. 2007;6(1):59-65. doi:10.1111/j.1473-2165.2007.00296.x.
[3] Lévêque JL, Corcuff P, Gonnord G, et al. Mechanism of Action of a Lipophilic Derivative of Salicylic Acid on Normal Skin. Skin Research and Technology. 1995;1:115-122. doi:10.1111/j.1600-0846.1995.tb00030.x.
[4] Ishida-Yamamoto A, Igawa S. The Biology and Regulation of Corneodesmosomes. Cell and Tissue Research. 2015;360(3):477-482. doi:10.1007/s00441-014-2037-z.
[5] Levesque A, Hamzavi I, Seite S, Rougier A, Bissonnette R. Randomized Trial Comparing a Chemical Peel Containing a Lipophilic Hydroxy Acid Derivative of Salicylic Acid with a Salicylic Acid Peel in Subjects with Comedonal Acne. Journal of Cosmetic Dermatology. 2011;10(3):174-178. doi:10.1111/j.1473-2165.2011.00566.x.
[6] Hoober JK, Eggink LL. The Discovery and Function of Filaggrin. International Journal of Molecular Sciences. 2022;23(3):1455. doi:10.3390/ijms23031455.
[7] Piérard GE, Rougier A. Nudging Acne by Topical Beta-Lipohydroxy Acid (LHA), a New Comedolytic Agent. European Journal of Dermatology. 2002;12(4):XLVII-XLVIII.
[8] Green M, Kashetsky N, Feschuk A, Maibach HI. Transepidermal Water Loss (TEWL): Environment and Pollution—A Systematic Review. Skin Health and Disease. 2022;2(2):e104. doi:10.1002/ski2.104.
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