SH-Polypeptide-121: properties, uses, pros, cons, safety

SH-Polypeptide-121 is a single-chain recombinant human polypeptide produced biotechnologically by fermentation using Escherichia coli. The starting gene is synthetically designed to correspond to the human gene encoding the collagen type XXI alpha-1 chain (COL21A1), with possible adaptations for the production system.

It may comprise up to 957 amino acids, making it very different from cosmetic peptides composed of only a few amino-acid residues. It is a biomimetic protein produced without extracting collagen from human or animal tissues.

Its documented cosmetic functions are Film Forming and Skin Conditioning.

Description

Natural collagen XXI belongs to the FACIT collagen family (Fibril-Associated Collagens with Interrupted Triple helices), which is associated with extracellular-matrix structures.

SH-Polypeptide-121 is designed using the sequence of the human collagen XXI chain as its biological reference. However, the natural protein present in human tissues and the recombinant cosmetic ingredient should be clearly distinguished.

The cosmetic material is not obtained from the human body. The genetic information required for production is synthesized and introduced into the microbial production system, which generates the polypeptide during fermentation.

For this reason, it is commonly described commercially as a biomimetic collagen or a collagen produced through precision fermentation.

The INCI definition allows the polypeptide to contain disulfide bonds and/or glycosylation.

Manufacturing process

Production may include:

• definition of the target protein sequence;

• synthesis of the corresponding gene;

• optimization of the DNA sequence for expression in the production organism;

• introduction of the genetic construct into E. coli;

• controlled fermentation;

• production of the recombinant polypeptide;

• recovery of the protein fraction;

• separation from microbial biomass;

• purification;

• concentration;

• filtration;

• identity and purity testing;

• formulation as a powder or solution;

• stabilization and packaging.

Purification is a critical stage because the protein must be separated from components originating from the fermentation system.

Commercial grades may be supplied either as a concentrated powder or as a solution containing a defined proportion of SH-Polypeptide-121. The percentage of commercial raw material added to a formulation should therefore not be confused with the actual concentration of the polypeptide in the finished cosmetic.

Structure

SH-Polypeptide-121 is a defined protein macromolecule composed of standard amino acids rather than a generic collagen hydrolysate or botanical extract.

The reference human COL21A1 protein contains 957 amino acids. The cosmetic ingredient is designed around this sequence or an adapted sequence consistent with the INCI definition.

It should therefore not be considered equivalent to:

• Hydrolyzed Collagen;

• Collagen Amino Acids;

• short oligopeptides;

• animal collagen extracted from skin, bone, or cartilage.

This distinction is relevant both to manufacturing and to formulation behavior.

Identification data and specifications

Indicative physicochemical properties

Cosmetics

SH-Polypeptide-121 may be used in:

• anti-aging serums;

• facial creams;

• eye-area products;

• firming formulations;

• masks;

• moisturizing products;

• after-sun products;

• scalp formulations;

• shampoos;

• conditioners;

• technologically advanced skin-care products.

Its film-forming properties can contribute to a temporary improvement in surface smoothness, softness, and skin or hair feel.

The ingredient is particularly marketed as a biomimetic collagen. Data available for specific commercial grades suggest potential effects on parameters such as:

• appearance of wrinkles;

• firmness and elasticity;

• skin redness;

• extracellular-matrix-related markers.

These findings are of interest, but much of the ingredient-specific efficacy documentation currently available originates from raw-material manufacturers, while independent clinical evidence remains more limited.

It should therefore not be assumed solely from its similarity to human collagen XXI that the topically applied protein:

• replaces dermal collagen;

• becomes directly incorporated into collagen fibers;

• penetrates intact skin as a complete protein;

• structurally rebuilds the dermal extracellular matrix.

Its large molecular size makes penetration through an intact stratum corneum substantially less plausible than for small peptides. Any deeper biological effects should therefore be supported by evidence for the specific commercial grade and finished formulation.

Use with vitamin C

SH-Polypeptide-121 may be formulated together with vitamin C or vitamin C derivatives.

The combination can be technically interesting in products designed for skin firmness and appearance, but the two ingredients do not need to be used together.

Compatibility should be assessed according to:

• the form of vitamin C;

• formulation pH;

• protein stability;

• processing temperature;

• preservative system;

• storage conditions.

Highly acidic formulations containing substantial levels of L-ascorbic acid may require specific testing to confirm that the protein remains stable.

Pros

• Produced by biotechnology without extraction of collagen from human or animal tissues.

• Allows precise control of protein identity.

• Fermentation can provide greater batch consistency than many extracted biological materials.

• Provides useful film-forming properties.

• Can be used in both skin-care and hair-care formulations.

• Preliminary formulation and clinical data for specific commercial grades are favorable.

• Can potentially fit vegan-positioned formulations when the complete production process and processing aids meet the relevant criteria.

Cons

• Independent clinical evidence specific to SH-Polypeptide-121 remains limited.

• Many anti-aging claims are supported primarily by manufacturer data.

• Its large molecular size limits the plausibility of deep penetration of the intact protein.

• Proteins can be sensitive to heat, extreme pH, proteolysis, and aggregation.

• Quality depends strongly on fermentation and purification.

• The INCI name does not indicate the actual protein concentration in a commercial raw material.

• It should not be regarded as equivalent to natural dermal collagen simply because it is biomimetic.

Safety and regulation

No specific SCCS or CIR assessment dedicated exclusively to SH-Polypeptide-121 has been identified that establishes a universal maximum cosmetic concentration.

Safety should therefore be assessed using the actual commercial grade and the finished formulation.

Biotechnological and microbiological quality

Because the protein is produced using E. coli, purification and process control are especially important.

Relevant quality parameters may include:

• residual host-cell proteins;

• residual microbial DNA;

• bacterial endotoxins;

• fermentation-medium residues;

• bioburden;

• protein purity;

• aggregates;

• degradation products.

Use of E. coli as the production organism does not mean that the cosmetic contains live bacteria. The microorganism is part of the manufacturing system; the final ingredient is the purified protein.

Similarly, the expression “human polypeptide” refers to the reference amino-acid sequence, not to its material origin. SH-Polypeptide-121 is not extracted from human tissues.

Sensitization

As with other proteins, a theoretical immunological potential cannot be completely excluded.

However, SH-Polypeptide-121 is not currently identified as a specific regulated cosmetic allergen in the EU.

For leave-on products and innovative protein ingredients, specific data on the following are nevertheless useful:

• irritation;

• sensitization;

• skin compatibility;

• protein stability;

• process-related impurities.

EU Cosmetics Regulation provisions

No specific Cosmetics Regulation provisions are identified for SH-Polypeptide-121 under Annexes II–VI of Regulation (EC) No 1223/2009.

The ingredient is included in the current EU cosmetic ingredient glossary as:

25925 – sh-POLYPEPTIDE-121

Inclusion in the glossary establishes the accepted ingredient name for labeling purposes but does not itself constitute a safety or efficacy approval.

Raw-material control

For professional evaluation, it is advisable to obtain:

• updated SDS;

• Certificate of Analysis (COA);

• technical data sheet;

• protein identity;

• analytical method used for identity confirmation;

• actual concentration of SH-Polypeptide-121;

• protein purity;

• molecular profile;

• protein aggregates;

• residual host-cell proteins;

• residual DNA;

• endotoxins;

• microbiological specifications;

• carrier solvents or excipients;

• preservatives in the commercial solution;

• pH;

• thermal stability;

• pH stability;

• storage conditions;

• formulation compatibility;

• irritation and sensitization data.

A particularly important point is to distinguish the percentage of commercial raw material added to the formulation from the actual concentration of SH-Polypeptide-121.

Environment

Fermentation-based production avoids the direct use of animal tissues required for many conventional collagen sources.

Potential advantages include:

• traceability;

• standardization;

• non-animal sourcing;

• reduced dependence on animal by-products.

The actual environmental profile nevertheless depends on the entire production process, including:

• fermentation substrates;

• water consumption;

• energy use;

• sterilization;

• purification;

• management of microbial biomass;

• wastewater treatment;

• refrigeration and storage.

Biotechnological production should therefore not automatically be described as low-impact without supporting life-cycle data.

Conclusion

SH-Polypeptide-121 is an innovative biotechnology-derived cosmetic protein based on the sequence of the human collagen type XXI alpha-1 chain.

Its main advantages are the ability to obtain a highly controlled biomimetic material without extracting collagen from animal or human tissues and its useful film-forming and skin-conditioning properties.

Available data for specific commercial grades suggest interesting anti-aging potential, but independent clinical evidence remains less extensive than for long-established cosmetic ingredients.

No specific Cosmetics Regulation provisions are identified for this ingredient.

SH-Polypeptide-121 can be considered a promising and generally favorable cosmetic ingredient when the commercial grade is adequately characterized, with particular attention to actual protein concentration, purity, fermentation residues, endotoxins, stability, skin tolerability, and the quality of efficacy evidence for the specific grade used.