How Does Collagen Tripeptide Act on the Skin: Stratum Corneum Delivery, Matrix Protection, and Regulation of Collagen Homeostasis

Introduction

Collagen is the principal structural protein of the dermal extracellular matrix (ECM). Intact collagen consists of three long polypeptide chains that form a triple helix and subsequently assemble into collagen fibrils and collagen fibers, providing the skin with tensile strength and mechanical support.[1]

Collagen tripeptide (CTP) is a low-molecular-weight collagen peptide ingredient produced through the enzymatic hydrolysis of collagen. It retains short amino acid sequences derived from collagen but no longer possesses the triple-helical and fibrous structures of intact collagen. Evidence regarding the effects of topical CTP can be divided into three levels: participation in hydration at the skin surface and within the stratum corneum; modulation of markers related to oxidation, glycation, and collagen degradation in in vitro models; and potential effects on fibroblasts and extracellular matrix metabolism, provided that certain bioactive short peptides achieve the required skin distribution and reach effective local concentrations.[1,2,4,5,9,10]

Keywords: collagen tripeptide (CTP); Gly–X–Y sequence; stratum corneum delivery; stratum corneum hydration; matrix protection; fibroblasts; extracellular matrix; collagen homeostasis.

1 Molecular Structure of Collagen Tripeptide

1.1 How Enzymatic Hydrolysis of Collagen Produces Short Peptides

Proteases cleave long collagen chains into peptide fragments of different lengths by hydrolyzing peptide bonds. Peptide bond hydrolysis can be represented in simplified form as:

R¹–CO–NH–R² + H₂O ──protease──→ R¹–COOH + H₂N–R²

After repeated hydrolysis of peptide bonds, collagen polypeptide chains can yield polypeptides, oligopeptides, tripeptides, dipeptides, and free amino acids. The collagen source, cleavage specificity of the enzyme, hydrolysis time, temperature, pH, and subsequent separation processes all influence the peptide-chain length and sequence composition of the final ingredient.[2]

In skincare ingredients, “collagen tripeptide” generally refers to a collagen hydrolysate containing a relatively high proportion of tripeptide components rather than a chemically homogeneous compound. The actual ingredient may also contain dipeptides, tetrapeptides, longer collagen peptides, and small amounts of free amino acids. When evaluating a CTP ingredient, the tripeptide content and peptide profile provide a more representative description of its composition than average molecular weight alone.[2]

1.2 Gly–X–Y Is the Characteristic Sequence of Collagen

The triple-helical region of collagen contains continuous repeating sequences of:

(Gly–X–Y)ₙ

Glycine (Gly) occurs at every third amino acid position, whereas the X and Y positions may be occupied by various amino acids, with proline (Pro) and 4-hydroxyproline (Hyp) being particularly common.[1]

The side chain of glycine consists of only one hydrogen atom, allowing it to occupy the narrow central region of the triple helix. Proline and hydroxyproline restrict the conformational freedom of the polypeptide chains and promote spatial conformations suitable for triple-helix assembly. The structural characteristics of collagen arise from the continuous arrangement of numerous Gly–X–Y units rather than from any single isolated tripeptide.[1]

1.3 Relationship Between Gly–Pro–Hyp and Collagen Tripeptide Ingredients

Gly–Pro–Hyp is a representative collagen-derived tripeptide composed of glycine, L-proline, and hydroxyproline linked sequentially by two peptide bonds. Its molecular formula is C₁₂H₁₉N₃O₅, and its relative molecular mass is 285.30.[3]

Gly–Pro–Hyp contains only three amino acid residues and therefore cannot form the continuous triple helix found in native collagen or self-assemble into collagen fibers that provide mechanical support. It retains short-sequence information derived from collagen rather than the higher-order structure of intact collagen.

The relationship between collagen tripeptide ingredients and Gly–Pro–Hyp is summarized below:

Name	Chemical Composition	Structural Characteristics
Intact collagen	Protein composed of three long polypeptide chains	Possesses a triple helix and fibrous assembly structure
Conventional hydrolyzed collagen	Mixture of collagen peptides with different chain lengths	Most of the triple-helical structure has been disrupted
Collagen tripeptide ingredient	Collagen hydrolysate containing a relatively high proportion of tripeptides	Contains multiple collagen-derived short peptides
Gly–Pro–Hyp	Single tripeptide with a defined sequence	Does not possess the higher-order structure of intact collagen

2 Differences in Topical Use Among Intact Collagen, Hydrolyzed Collagen, and CTP

Collagen hydrolysis not only reduces molecular weight but also alters solubility, film-forming ability, release from the formulation, and skin distribution.

Comparison Item	Intact Collagen	Conventional Hydrolyzed Collagen	Collagen Tripeptide
Molecular-weight range	Hundreds of kilodaltons	Typical average molecular weight of approximately 3–6 kDa, depending on the process	A single tripeptide is generally several hundred daltons
Triple helix	Present	Largely disrupted	Absent
Water solubility	Influenced by source and processing conditions	Generally high	Generally high
Surface film-forming ability	Relatively pronounced	Depends on peptide-chain length	Generally weaker than that of longer collagen peptides
Potential to enter the stratum corneum	Low	Higher than that of intact collagen	Molecular size is relatively favorable, but delivery remains limited by hydrophilicity and charge
Principal topical effects	Surface film formation, moisturization, and improvement in skin feel	Moisturization, film formation, and short-peptide effects	Hydration and potential sequence-dependent effects
Direct formation of dermal collagen fibers	No corresponding process	No corresponding process	No corresponding process

Longer peptide chains in conventional hydrolyzed collagen contain more continuous polar sites and can readily form a hydrophilic film on the skin surface. Because CTP has a shorter chain length, its surface film-forming persistence is generally weaker, whereas its water solubility, diffusivity, and sequence specificity may be more pronounced.[2]

Intact collagen, conventional hydrolyzed collagen, and CTP are not simply different-sized forms of the same ingredient. Intact collagen is characterized by its protein structure and film-forming properties; hydrolyzed collagen by the combined properties of peptide fragments with different chain lengths; and CTP by its low-molecular-weight short-peptide composition and potential biological activity.[1,2]

3 Stratum Corneum Barrier and Skin Delivery of CTP

3.1 Barrier Structure of the Stratum Corneum

The stratum corneum consists of corneocytes surrounded by intercellular lipids. These lipids mainly include ceramides, cholesterol, and free fatty acids, which form highly ordered lamellar structures. This lipid organization constitutes an important barrier that limits the entry of external substances into the skin and reduces the loss of water from the body.[4]

Molecular weight affects diffusion rate but cannot independently determine skin penetration. The distribution of CTP within the skin is also influenced by the following factors:

① Molecular hydrophilicity and lipophilicity;

② Ionization state and net charge;

③ Number of groups capable of forming hydrogen bonds;

④ Molecular conformation and hydrodynamic radius;

⑤ Ability to be released from the formulation matrix;

⑥ Interactions with stratum corneum lipids and keratin;

⑦ Hydration level and barrier integrity of the stratum corneum.

CTP contains peptide bonds, amino groups, carboxyl groups, and other polar groups and therefore has high water solubility. However, its ability to partition from the aqueous phase into the lipid regions of the stratum corneum may be limited. Reduced molecular size favors diffusion, whereas strong hydrophilicity represents an additional delivery constraint.[5]

3.2 Relationship Between Molecular Weight and Skin Distribution

The relative molecular mass of a single Gly–Pro–Hyp molecule is approximately 285.30, which is lower than that of many conventional collagen peptides. However, a lower molecular weight does not necessarily correspond to greater dermal exposure. Hydrophilicity, charge, binding within the formulation, and degradation by skin enzymes may all reduce the migration of intact short peptides into deeper skin layers.[3,5]

The following parameters should be distinguished when evaluating the skin delivery of CTP:

Parameter	Meaning
Formulation release	Release of CTP from an emulsion, gel, or carrier into the aqueous phase at the skin surface
Surface retention	Retention of CTP on the skin surface or within skin furrows
Stratum corneum retention	Entry of CTP into the stratum corneum without reaching the viable epidermis
Viable epidermal distribution	Entry of CTP into the viable epidermis beneath the stratum corneum
Dermal distribution	Entry of CTP or its active fragments into dermal tissue
Percutaneous flux	Amount of a substance passing through a defined skin area per unit time
Percutaneous permeation	Passage of a substance through intact skin into the receptor fluid in an in vitro or ex vivo model
Systemic absorption	Further entry of a substance into the blood or systemic circulation in vivo

3.3 Potential Skin Delivery Pathways of CTP

Based on studies of stratum corneum structure and the diffusion of hydrophilic small molecules, CTP may involve the following three skin delivery pathways. The actual contribution of each pathway to a specific CTP ingredient and formulation remains to be experimentally confirmed.

① Intercellular Lipid Pathway

Short peptides may diffuse through the tortuous lipid regions between corneocytes. Hydrophilic CTP encounters partitioning resistance when moving from the aqueous phase into the lipid phase. The efficiency of this pathway is therefore influenced by the composition of the formulation and the ionization state of the peptide.

② Transcorneocyte Pathway

Hydrophilic small molecules may enter hydrated regions within corneocytes or diffuse through local polar microdomains in the stratum corneum. Studies have proposed that the diffusion of amino acids, urea, and certain hydrophilic peptides through the stratum corneum may involve transcorneocyte routes and regions associated with corneodesmosomes.[6]

③ Follicular and Skin Appendage Pathway

Hair follicle openings can bypass portions of the continuous stratum corneum and form local reservoirs. The contribution of this pathway is influenced by anatomical site, follicle density, formulation rheology, method of application, and contact time.

Liposomes, flexible lipid carriers, stratum corneum hydration, and suitable penetration-enhancing systems may alter formulation release, stratum corneum retention, and epidermal distribution of short peptides. Whether a carrier increases dermal exposure must be confirmed through skin-layer distribution studies of the specific formulation.[5,6]

The effects of CTP on the skin involve surface hydration, potential skin distribution, and matrix-related effects at different levels. Its overall pathways and levels of evidence are illustrated in the figure below. The deeper effects shown in the figure are contingent on active short peptides reaching the relevant skin layers and achieving effective local concentrations.

4 Effects of CTP on the Skin Surface and Stratum Corneum

4.1 Polar Groups Participate in Skin Hydration

CTP molecules contain peptide-bond carbonyl groups, amide groups, terminal amino groups, and carboxyl groups. These polar groups can form hydrogen bonds or ion–dipole interactions with water molecules.

After topical application, CTP distributed on the skin surface and within the superficial stratum corneum may help maintain a locally hydrated environment together with water, glycerol, hyaluronic acid, and other components in the formulation. This effect does not depend on CTP entering the dermis and does not involve conversion of CTP into intact collagen.

4.2 Effects of Stratum Corneum Hydration on Skin Appearance

Water in the stratum corneum helps maintain keratin conformation, the dissolved state of natural moisturizing factors, and the mechanical flexibility of corneocytes. When the water content of the stratum corneum decreases, corneocyte flexibility declines, while surface roughness, scaling, and dry texture become more pronounced.

By participating in stratum corneum hydration, CTP may produce the following changes in appearance and sensory properties:

① Reduce dryness and tightness;

② Improve the flexibility of the stratum corneum;

③ Reduce roughness and scaling caused by dryness;

④ Temporarily improve superficial fine lines;

⑤ Improve skin feel after product application.

4.3 Differences in Surface Effects Between CTP and Longer Collagen Peptides

Longer collagen peptides contain more continuous peptide bonds and interaction sites and generally exhibit more pronounced surface film-forming ability. The principal characteristics of the shorter peptide chains in CTP can be summarized as follows:

① High water solubility;

② Small molecular size;

③ Generally favorable release from aqueous formulations, although subsequent diffusion through the skin remains limited by hydrophilicity, charge, and formulation composition;

④ Certain defined sequences may possess independent short-peptide activity.

Longer collagen peptides and CTP differ in their principal effects: the former are more strongly associated with surface film formation and immediate skin feel, whereas the latter are more closely associated with hydration, stratum corneum distribution, and sequence-related effects. Actual performance depends on the complete molecular-weight distribution of the ingredient and the finished formulation.

5 Effects of CTP on the Collagen-Damaging Environment

The state of dermal collagen depends on a dynamic balance among synthesis, maturation, degradation, and damage. Oxidative stress, glycation, and increased matrix metalloproteinase activity can all promote aging of the collagen network.

5.1 Oxidative Stress and Collagen Degradation

Ultraviolet exposure can increase reactive oxygen species (ROS) in the skin and activate cellular signaling associated with inflammation and matrix degradation. This is followed by increased expression of multiple matrix metalloproteinases (MMPs).

Matrix metalloproteinase-1 (MMP-1) can initiate the cleavage of fibrillar type I and type III collagen. Following collagen fragmentation, the mechanical connection between fibroblasts and intact collagen fibers is weakened, and intracellular oxidative stress and MMP-1 expression may increase further, creating a mutually reinforcing cycle of collagen fragmentation and oxidative stress.[7,8]

In in vitro cellular experiments using a specific CTP ingredient, researchers observed reductions in ROS- and MMP-related markers. These results suggest that the ingredient may modulate the collagen-damaging environment under the corresponding model conditions.[9]

5.2 Effects of Glycation on Collagen Structure

Glycation is a nonenzymatic reaction between reducing sugars or reactive carbonyl compounds and free amino groups in proteins. Using reducing aldoses such as glucose as an example, the process can be represented in simplified form as:

Protein–NH₂ + reducing sugar ⇌ Schiff base → Amadori product → advanced glycation end products

Advanced glycation end products (AGEs) comprise a structurally complex group of reaction products. Reactive dicarbonyl compounds such as glyoxal and methylglyoxal can also directly modify proteins and promote the formation of AGEs and related cross-linked products.

Because collagen has a relatively slow turnover rate, glycation modifications can accumulate over long periods. Collagen glycation can increase nonphysiological cross-linking, reduce fiber flexibility, alter matrix stiffness, impair collagen renewal, and affect interactions between fibroblasts and the extracellular matrix.[10]

The antiglycation activity of skincare ingredients may be reflected in reduced early-stage glycation reactions, lower reactive carbonyl stress, decreased AGE formation, or improved cellular status under glycating conditions. It does not mean that pre-existing collagen cross-links can be completely removed.

5.3 Current Research Findings on Topical CTP

A study published in 2022 included in vitro experiments in human fibroblasts using a specific CTP ingredient and a four-week pilot trial of topical application. In the in vitro experiments, CTP treatment was associated with reductions in ROS, AGE accumulation, denatured collagen, and MMP induction, together with an increase in type I collagen-related markers. The human component included 22 Asian women and reported changes in wrinkles, elasticity, skin density, and skin AGE-related parameters.[9]

The human study used a single-arm design, involved a small sample size, and did not include a vehicle control without CTP. The participants also used a complete formulation containing CTP rather than CTP alone. The results provide preliminary signals of antiglycation, antioxidant, and skin-condition improvement, but they do not establish that all observed changes were attributable solely to CTP. The study also did not directly measure the concentration of intact CTP in the human dermis.[9]

6 Effects of CTP on Fibroblasts and the Extracellular Matrix

6.1 Reciprocal Regulation Between Fibroblasts and the Collagen Matrix

Dermal fibroblasts synthesize type I and type III collagen, hyaluronic acid, proteoglycans, and other extracellular matrix components. Through integrins and other adhesion structures, fibroblasts connect to collagen fibers and sense the tension and integrity of the surrounding matrix.

Within a structurally intact collagen matrix, fibroblasts can spread fully and maintain matrix-synthetic functions. When collagen fibers undergo sustained fragmentation, cellular mechanical support is weakened, collagen synthesis decreases, and MMP-related degradative responses increase. Collagen protection and fibroblast status therefore form a mutually interacting cycle.[7,8]

6.2 Different Collagen-Derived Short Peptides Exhibit Different Cellular Activities

Collagen-derived short peptides do not constitute a group of molecules with identical effects. Peptide-chain length, amino acid sequence, position of hydroxyproline, terminal-group status, and spatial conformation can all influence peptide stability, enzymatic degradation, and cellular recognition.

The collagen-derived dipeptide Pro–Hyp has been observed to promote cell proliferation and hyaluronic acid synthesis in cultured human dermal fibroblasts and to increase expression related to hyaluronan synthase 2.[11] This finding was obtained from an in vitro experiment in which Pro–Hyp was applied directly to cultured cells and does not demonstrate that topical Pro–Hyp can achieve the same level of exposure in the human dermis.

6.3 Matrix-Signaling Properties of Collagen-Derived Short Peptides

Following proteolysis of extracellular matrix proteins, certain fragments may display biological activities distinct from those of the intact parent protein. Such fragments capable of regulating cell migration, proliferation, inflammation, angiogenesis, or matrix remodeling are known as matrikines.[12]

Certain collagen-derived short peptides with experimentally verified biological activity may function as biochemical information during extracellular matrix degradation and remodeling, but their effects are sequence-specific. Different fragments may support tissue repair or participate in inflammation and abnormal matrix degradation.[12]

For CTP to produce measurable cellular effects, the following sequential conditions must be met:

① The ingredient must contain peptide sequences with the corresponding activity;

② The active peptides must be released from the formulation;

③ The active peptides must enter the relevant skin layer;

④ The active peptides must remain sufficiently stable in the local environment;

⑤ Their actual tissue concentration must be sufficient to elicit a cellular response.

6.4 Differences Among Levels of Collagen-Related Markers

Common parameters used to investigate the effects of CTP on fibroblasts include:

① Fibroblast migration and proliferation;

② Expression of the collagen type I alpha 1 chain gene (COL1A1);

③ Type I procollagen content;

④ Type I collagen protein levels;

⑤ MMP expression or activity;

⑥ Hyaluronic acid and other extracellular matrix components.

These parameters correspond to different stages, including transcription, protein synthesis, secretion, and matrix formation. An increase in COL1A1 messenger RNA does not necessarily indicate an increase in mature collagen fibers. Likewise, an increase in intracellular collagen protein does not demonstrate that collagen has completed extracellular assembly and cross-linking.

7 Relationship Between CTP and Collagen Synthesis, Maturation, and Degradation

7.1 Collagen Synthesis Is Not the Direct Assembly of Short Peptides

CTP may be further degraded into dipeptides and free amino acids and enter general peptide and amino acid metabolism. Newly synthesized collagen is not formed by directly incorporating topically applied Gly–Pro–Hyp into existing collagen fibers.

Using fibril-forming collagens such as dermal type I and type III collagen as examples, collagen formation involves the following processes:

① Transcription of collagen genes;

② Translation of prepro-α chains;

③ Hydroxylation of proline and lysine residues;

④ Glycosylation of certain hydroxylysine residues;

⑤ Formation of the procollagen triple helix by three pro-α chains;

⑥ Secretion of procollagen into the extracellular space;

⑦ Removal of the N- and C-terminal propeptides;

⑧ Assembly of collagen molecules into fibrils;

⑨ Formation of stable intermolecular cross-links.[1,13]

CTP may modulate fibroblast status and collagen-related expression through specific short peptides, but it does not replace collagen synthesis, post-translational modification, or extracellular assembly.

7.2 Hydroxylation of Proline and Lysine

During procollagen synthesis, proline and lysine residues are hydroxylated by collagen prolyl hydroxylases and lysyl hydroxylases, respectively. Both enzyme classes are Fe²⁺- and 2-oxoglutarate (α-ketoglutarate)-dependent dioxygenases.[13]

The principal reactions can be represented in simplified form as:

Procollagen-Pro + 2-oxoglutarate + O₂

──collagen prolyl 4-hydroxylase, Fe²⁺──→ procollagen-4-Hyp + succinate + CO₂

Procollagen-Lys + 2-oxoglutarate + O₂

──lysyl hydroxylase, Fe²⁺──→ procollagen-Hyl + succinate + CO₂

Hyl denotes hydroxylysine. Vitamin C helps maintain the iron ion at the enzyme active site in its reduced state, reduces hydroxylase inactivation, and thereby supports hydroxylation reactions and normal collagen maturation.[13,14]

7.3 Overall Effects of CTP on Collagen Homeostasis

The topical effects of CTP can be summarized as:

① Skin-surface and stratum corneum effects: After release from the formulation, CTP may participate in hydration at the skin surface and within the stratum corneum, improving stratum corneum flexibility and dry texture.

② In vitro mechanistic evidence: In specific cellular models, CTP ingredients have been associated with changes in ROS-, AGE-, MMP-, and type I collagen-related markers.

③ Potential deeper effects: If short peptides with the relevant activity achieve sufficient distribution within the viable epidermis or dermis and reach effective local concentrations, they may influence fibroblasts and the balance between collagen synthesis and degradation.

Surface and stratum corneum hydration are comparatively achievable effects of conventional topical products. Effects involving the viable epidermis or dermal fibroblasts still require validation in relation to peptide sequence, release from the formulation, skin distribution, local stability, and effective concentration.[5,6,9]

8 Combination of CTP with Other Skincare Ingredients

8.1 CTP and Vitamin C

Vitamin C helps maintain the normal function of collagen prolyl hydroxylases and lysyl hydroxylases and supports procollagen hydroxylation, triple-helix formation, and collagen maturation.[13,14]

CTP and vitamin C act at different stages:

Ingredient	Principal Stage of Action
CTP	Stratum corneum hydration, modulation of the matrix-damaging environment, and potential cellular effects of short peptides
Vitamin C	Antioxidant activity and support for procollagen hydroxylation and collagen maturation

The two ingredients act at different stages and therefore have theoretically complementary mechanisms. The efficacy of the finished product is also influenced by the form of vitamin C, system pH, dissolved oxygen, metal ions, oxygen-barrier properties of the packaging, and CTP stability.[14]

8.2 CTP and Palmitoyl Tripeptide-5

Palmitoyl tripeptide-5 consists of a tripeptide moiety and a palmitoyl chain. The palmitoyl chain increases the hydrophobic portion of the molecule, resulting in formulation partitioning and interactions with skin lipids that differ from those of non-lipidated CTP.[15]

CTP favors the aqueous phase and is characterized by collagen-derived short peptides and stratum corneum hydration, whereas palmitoyl tripeptide-5 has a lipidated structure. The two may therefore display different characteristics in formulation release and skin retention.

Lipidation can increase lipid affinity and may also increase stratum corneum retention. The actual skin distribution and efficacy of formulations combining palmitoyl tripeptide-5 with CTP should be determined through finished-product stability testing, layer-specific delivery studies, and controlled human trials.

8.3 CTP and Moisturizing or Barrier-Supporting Ingredients

Glycerol, hyaluronic acid, panthenol, ectoine, and ceramide ingredients can improve the condition of the stratum corneum through mechanisms including humectancy, hydration, lipid supplementation, and barrier support.

Their combination with CTP is mainly intended to:

① Increase the water content of the stratum corneum;

② Reduce dryness and tightness;

③ Improve skin-surface texture;

④ Maintain a hydrated environment around hydrophilic short peptides;

⑤ Improve product tolerability and sensory properties.

Such combinations primarily reinforce effects at the skin surface and within the stratum corneum and do not directly indicate an increase in dermal collagen content.

8.4 CTP with Retinoids and Sunscreen Systems

Retinoids such as retinol and retinal can influence epidermal renewal and processes related to the dermal extracellular matrix. When CTP is combined with retinoids, moisturization and barrier support may help reduce the sensation of dryness during product use.

Ultraviolet radiation can promote ROS production, inflammatory signaling, and MMP expression and is an important external factor driving sustained collagen degradation.[7] By reducing ultraviolet exposure, sunscreen systems help limit the source of collagen damage and complement the hydration and matrix-protective effects of CTP.

9 Classification and Research Applications of Representative Chemicals Related to Collagen Tripeptide Structure, Skin Delivery, Matrix Protection, and Collagen Homeostasis Regulation

Table 1. Core Collagen Materials, Structural Units, and Representative Short Peptides

Classification	CAS No.	Aladdin Cat. No.	Name	Specification or Purity	Product Features and Applications
Denatured collagen structural control	9000-70-8	G108396	Gelatin	PharmPure™, USP, BP, European Pharmacopoeia (Ph. Eur.), gel strength ~240 g Bloom	Used to study structural differences between intact and denatured collagen, gel formation, surface film formation, hydration properties, and enzymatic hydrolysis of collagen.
Enzyme for collagen hydrolysis and matrix degradation	9001-12-1	C754914	Collagenase from Clostridium histolyticum	Sterile-filtered, Type IA-S, 0.5–5.0 FALGPA units/mg solid, ≥125 CDU/mg solid	Used for enzymatic hydrolysis of collagen, preparation of collagen-derived short peptides, extracellular matrix degradation models, and measurement of collagen-degrading activity.
Recombinant type III collagen research material	9007-34-5	rp335221	Recombinant Humanized Type III Collagen	Animal-origin-free, carrier-free, recombinant, ≥90% (SDS-PAGE), expressed in Nicotiana benthamiana	Used for type III collagen-related analysis, fibroblast extracellular matrix formation, collagen degradation, and comparative studies of collagen tripeptide effects.
Collagen backbone amino acid	56-40-6	G274229	Glycine	Moligand™, proteomics grade	Used to study collagen repeat sequences, amino acid composition, procollagen synthesis, and the structures of collagen-derived short peptides.
Collagen conformation-related amino acid	147-85-3	L476193	L-Proline	UltraBio™, ≥99.5%	Used to study collagen amino acid composition, proline-containing sequences, procollagen synthesis, and collagen-derived short-peptide composition.
Characteristic hydroxylated amino acid of collagen	51-35-4	H111005	L-Hydroxyproline	Moligand™, ≥99%	Used for characteristic amino acid analysis of collagen, collagen content determination, evaluation of hydroxylation levels, and detection of hydrolysis products.
Amino acid associated with collagen hydroxylation and cross-linking sites	56-87-1	L598932	L-Lysine	Moligand™, ≥98%, metals <500 ppm	Used to study collagen amino acid composition, hydroxylation of lysine residues in collagen chains, hydroxylysine glycosylation, intermolecular collagen cross-linking, and collagen maturation.
Characteristic collagen tripeptide	2239-67-0	H769205	Glycine-Proline-Hydroxyproline	Moligand™, ≥98%	Used to study the structure, stability, skin distribution, cellular uptake, and extracellular matrix regulation of a representative collagen tripeptide.
Collagen-derived Pro–Hyp dipeptide	18684-24-7	H332495	4-Hydroxy-1-L-prolyl-L-proline	≥98%	Used for Pro–Hyp sequence identification, peptide-chain order analysis, cellular uptake studies, and in vitro investigation of fibroblast matrix-related responses.
Lipidated tripeptide salt	623172-56-5	S304179	Palmitoyl Tripeptide-5 biTFA	≥98%	Used to compare lipidated tripeptides and hydrophilic collagen tripeptides in terms of formulation partitioning, stratum corneum retention, and collagen-related cellular responses.

Table 2. Products Related to Studies of Collagen Hydroxylation, Maturation, Degradation, and Signaling Pathways

Classification	CAS No.	Aladdin Cat. No.	Name	Specification or Purity	Product Features and Applications
Cofactor for collagen hydroxylation and antioxidant protection	50-81-7	L432793	L-Ascorbic Acid	Anhydrous, Moligand™, ACS, ≥99%	Used to study hydroxylation of proline and lysine residues in procollagen, protection against oxidative stress, and collagen-related markers in fibroblasts.
Dioxygenase cosubstrate	328-50-7	K105571	α-Ketoglutaric Acid	Moligand™, ≥98%	Used as a cosubstrate for collagen prolyl hydroxylases and lysyl hydroxylases and in studies of hydroxylation reactions and cellular metabolism.
Divalent iron source for dioxygenases	7782-63-0	I434044	Iron(II) Sulfate Heptahydrate	European Pharmacopoeia (Ph. Eur.), suitable for analysis, ACS, guaranteed reagent grade	Used to provide divalent iron for studies of collagen hydroxylase reactions, metal-ion dependence, and hydroxylation conditions.
Hydroxylation reaction product control	110-15-6	S108853	Succinic Acid	Moligand™, for cell culture, suitable for insect cell culture, ≥99% (T)	Used as a product control for 2-oxoglutarate-dependent hydroxylation reactions and in analyses of enzymatic systems and cellular metabolism.
Stable vitamin C derivative	86404-04-8	O159940	3-O-Ethyl-L-ascorbic Acid	Moligand™, ≥98% (HPLC) (T)	Used to compare the stability, antioxidant capacity, cellular utilization, and collagen-related markers of vitamin C derivatives.
Magnesium salt of vitamin C phosphate	113170-55-1	S160999	L-Ascorbic Acid 2-Phosphate Sesquimagnesium Salt Hydrate	Moligand™, ≥98% (HPLC)	Used to study the stability, cellular conversion, antioxidant activity, and collagen synthesis-related effects of vitamin C phosphate.
Vitamin C glycoside derivative	129499-78-1	O160006	2-O-α-D-Glucopyranosyl-L-ascorbic Acid	≥98% (HPLC)	Used to study the stability, hydrolytic release, antioxidant properties, and collagen-related cellular markers of vitamin C glycosides.
Sodium salt of vitamin C phosphate	66170-10-3	S304311	Trisodium L-Ascorbate 2-Phosphate	≥96%	Used to study water-soluble vitamin C phosphate, cellular utilization, oxidative protection, and collagen-related responses.
Broad-spectrum matrix metalloproteinase inhibitor	142880-36-2	G274767	GM 6001, Broad-Spectrum MMP Inhibitor	Moligand™, ≥98%	Used for inhibition of matrix metalloproteinase activity, collagen degradation models, and validation of enzyme-dependent mechanisms.
Transforming growth factor-β receptor pathway inhibitor	301836-41-9	S1371574-GMP	SB-431542	Moligand™, ≥99%	Used to block the transforming growth factor-β type I receptor pathway and to investigate fibroblast collagen expression and short-peptide signaling mechanisms.
Transforming growth factor-β downstream pathway inhibitor	521984-48-5	S276442	SIS 3 Hydrochloride	≥98%	Used to block downstream transforming growth factor-β signaling and to investigate collagen-related gene expression and extracellular matrix regulatory mechanisms.
Aldehyde form of a retinoid	116-31-4	A122355	All-trans-Retinal	Moligand™, ≥98%	Used to study retinoid metabolism, epidermal renewal, fibroblast responses, collagen expression, and matrix degradation-related processes.
Alcohol form of a retinoid	68-26-8	V111674	Retinol	Moligand™, ≥95%	Used to study retinoid metabolic conversion, epidermal renewal, the balance between collagen synthesis and degradation, and combination formulations.

Table 3. Products Related to Studies of Glycation, Carbonyl Stress, and Oxidative Damage

Classification	CAS No.	Aladdin Cat. No.	Name	Specification or Purity	Product Features and Applications
Slow protein glycation model compound	50-99-7	D755713	D-(+)-Glucose	Anhydrous, UltraBio™, ≥99.5% (HPLC), sum of enantiomers	Used to study nonenzymatic glycation of collagen and other proteins and the formation of early glycation products and advanced glycation end products.
Accelerated protein glycation model compound	50-69-1	R104822	D-Ribose	Analytical standard, ≥99.5% (HPLC)	Used to accelerate collagen glycation and to evaluate cross-link formation, fluorescent glycation products, and antiglycation activity.
Dicarbonyl glycation model compound	107-22-2	G103130	Glyoxal Solution	Molecular biology grade, 40% in H₂O (8.8 M)	Used to study dicarbonyl stress, protein glycation, collagen cross-linking, and carbonyl-trapping capacity.
Reactive carbonyl glycation model compound	78-98-8	M109035	Methylglyoxal	Moligand™, 40% solution	Used in models of reactive carbonyl stress, advanced glycation end-product formation, collagen damage, and cellular glycation.
Positive control for glycation inhibition	2582-30-1	A111225	Aminoguanidine Bicarbonate	≥98.5%	Used as a positive control for reactive carbonyl trapping, inhibition of protein glycation, reduction of advanced glycation end products, and antiglycation activity.
Oxidative stress inducer	7722-84-1	H755825	Hydrogen Peroxide Solution	Suitable for microbiology, 3%	Used to establish oxidative stress model conditions and to evaluate increases in reactive oxygen species, collagen degradation signaling, and protective effects.
Thiol antioxidant control	616-91-1	A105421	N-Acetyl-L-cysteine (NAC)	PharmPure™, USP, Moligand™, European Pharmacopoeia (Ph. Eur.), ≥98.5%	Used as a thiol antioxidant control for reactive oxygen species scavenging, protection against oxidative damage, and studies of collagen degradation mechanisms.
Water-soluble antioxidant capacity control	53188-07-1	T137260	Trolox	≥98%, white	Used as a control in water-soluble antioxidant capacity measurements, free-radical scavenging assays, and protection against oxidative damage.

Table 4. Products Related to Stratum Corneum Hydration, Barrier Lipids, and Short-Peptide Delivery Studies

Classification	CAS No.	Aladdin Cat. No.	Name	Specification or Purity	Product Features and Applications
Basic humectant	56-81-5	G755728	Glycerol	Anhydrous, UltraBio™, molecular biology grade, ≥99.5% (GC)	Used to study stratum corneum hydration, the aqueous environment of short peptides, moisturizing performance of formulations, and skin barrier-related effects.
Phospholipid membrane material for liposomes	8002-43-5	P1456010	Phospholipids from Sunflower (Non-GMO)	Natural, with ≥60% phosphatidylcholine	Used for liposomal encapsulation of collagen-derived short peptides, membrane structure construction, formulation release, and skin delivery studies.
Stratum corneum lipid-disrupting and penetration-enhancing material	112-80-1	O1456057	Oleic Acid	European Pharmacopoeia (Ph. Eur.), ≥65%	Used to study stratum corneum lipid organization, percutaneous distribution of short peptides, penetration-enhancing conditions, and barrier changes.
Hyaluronate moisturizing material	9067-32-7	S774025	Sodium Hyaluronate	European Pharmacopoeia (Ph. Eur.)	Used to study stratum corneum hydration, water retention, film formation, rheological properties, and moisturizing combinations with collagen tripeptide.
Cholesterol quantification and lipid formulation control	57-88-5	C119727	Cholesterol Purity Reference Material	Analytical standard, ≥99.7%	Used for cholesterol quantification in stratum corneum lipids and liposomes, analytical method calibration, and content determination.
Hyaluronic acid parent material	9004-61-9	H131007	Hyaluronic Acid	Moligand™, from rooster comb	Used to study the acidic form of hyaluronic acid, hydration, viscoelasticity, film formation, and comparisons with sodium hyaluronate.
Cellular stress-protective ingredient	96702-03-3	E292674	Ectoine	≥99%	Used to study osmotic stress, oxidative damage, cellular protection, stratum corneum hydration, and the barrier microenvironment.
Moisturizing and barrier-supporting ingredient	81-13-0	P107368	D-Panthenol	≥98%	Used to study stratum corneum hydration, barrier recovery, skin condition after irritation, and combination formulations containing collagen tripeptide.

Note: The products listed above are representative Aladdin products related to scientific and formulation research. Additional product specifications, grades, and certificate of analysis information can be found on the Aladdin website by searching by product name, CAS number, or catalog number.

References

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[2] León-López A, Morales-Peñaloza A, Martínez-Juárez V M, Vargas-Torres A, Zeugolis D I, Aguirre-Álvarez G. Hydrolyzed Collagen—Sources and Applications. Molecules, 2019, 24(22): 4031. DOI: 10.3390/molecules24224031.

[3] National Center for Biotechnology Information. PubChem Compound Summary for CID 21252274, Gly-Pro-Hyp.

[4] van Smeden J, Janssens M, Gooris G S, Bouwstra J A. The Important Role of Stratum Corneum Lipids for the Cutaneous Barrier Function. Biochimica et Biophysica Acta—Molecular and Cell Biology of Lipids, 2014, 1841(3): 295–313. DOI: 10.1016/j.bbalip.2013.11.006.

[5] Mortazavi S M, Moghimi H R. Skin Permeability, a Dismissed Necessity for Anti-Wrinkle Peptide Performance. International Journal of Cosmetic Science, 2022, 44(2): 232–248. DOI: 10.1111/ics.12770.

[6] Neubert R H H. Mechanisms of Penetration and Diffusion of Drugs and Cosmetic Actives through the Stratum Corneum. European Journal of Pharmaceutics and Biopharmaceutics, 2024, 202: 114394. DOI: 10.1016/j.ejpb.2024.114394.

[7] Fisher G J, Quan T, Purohit T, et al. Collagen Fragmentation Promotes Oxidative Stress and Elevates Matrix Metalloproteinase-1 in Fibroblasts in Aged Human Skin. The American Journal of Pathology, 2009, 174(1): 101–114. DOI: 10.2353/ajpath.2009.080599.

[8] Cole M A, Quan T, Voorhees J J, Fisher G J. Extracellular Matrix Regulation of Fibroblast Function: Redefining Our Perspective on Skin Aging. Journal of Cell Communication and Signaling, 2018, 12: 35–43. DOI: 10.1007/s12079-018-0459-1.

[9] Lee Y I, Lee S G, Jung I, Suk J, Lee M H, Kim D U, Lee J H. Effect of a Topical Collagen Tripeptide on Antiaging and Inhibition of Glycation of the Skin: A Pilot Study. International Journal of Molecular Sciences, 2022, 23(3): 1101. DOI: 10.3390/ijms23031101.

[10] Zheng W, Li H, Go Y, Chan X H, Huang Q, Wu J. Research Advances on the Damage Mechanism of Skin Glycation and Related Inhibitors. Nutrients, 2022, 14(21): 4588. DOI: 10.3390/nu14214588.

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[12] Jariwala N, Ozols M, Bell M, et al. Matrikines as Mediators of Tissue Remodelling. Advanced Drug Delivery Reviews, 2022, 185: 114240. DOI: 10.1016/j.addr.2022.114240.

[13] Salo A M, Myllyharju J. Prolyl and Lysyl Hydroxylases in Collagen Synthesis. Experimental Dermatology, 2021, 30(1): 38–49. DOI: 10.1111/exd.14197.

[14] Boyera N, Galey I, Bernard B A. Effect of Vitamin C and Its Derivatives on Collagen Synthesis and Cross-Linking by Normal Human Fibroblasts. International Journal of Cosmetic Science, 1998, 20(3): 151–158. DOI: 10.1046/j.1467-2494.1998.171747.x.

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