Polyglutamic Acid (PGA)

What is it?

Polyglutamic acid (PGA) is a naturally occurring biopolymer composed of repeating glutamic acid units linked by gamma-peptide bonds. Produced by bacterial fermentation (primarily Bacillus subtilis) and also found in the traditional Japanese fermented soybean food natto, PGA has gained significant attention in skincare for its extraordinary moisture-binding capacity — it can hold up to 5,000 times its weight in water, making it approximately four times more hydrating than hyaluronic acid on a weight-for-weight basis. PGA functions as a powerful humectant, drawing moisture from the environment and deeper skin layers to the stratum corneum. Beyond hydration, PGA inhibits the activity of hyaluronidase, the enzyme that breaks down hyaluronic acid in the skin, effectively prolonging the skin's natural HA levels. This dual action — both adding moisture directly and preserving the skin's own moisturizing molecules — makes PGA one of the most effective hydrating ingredients available. PGA also forms a smooth, transparent film on the skin surface that improves skin texture, reduces the appearance of fine lines, and creates a silky, primed canvas for subsequent product application. With a molecular weight range of 50–2,000 kDa depending on the formulation, PGA molecules are generally too large for deep dermal penetration but excel at surface hydration and barrier support.

How It Works

1. 1

   Binds Water (5000x Its Weight)

   Gamma-peptide bonds create an exceptional water-attracting matrix, drawing moisture to the skin surface far more effectively than HA.

2. 2

   Inhibits Hyaluronidase

   Blocks the enzyme that degrades the skin's natural hyaluronic acid, extending HA longevity — protecting the HA that PDRN-stimulated cells produce.

3. 3

   Forms Protective Film

   Creates a smooth, transparent film that reduces TEWL, improves texture, and may enhance retention of PDRN applied beneath.

4. 4

   Surface-Level Plumping

   Immediately smooths the appearance of fine dehydration lines by swelling the stratum corneum with retained moisture.

Role in PDRN

PGA and PDRN target hydration at completely different depths, making them a perfectly complementary pairing. PGA works at the skin surface — forming a hydrating film on the stratum corneum, reducing transepidermal water loss, and inhibiting hyaluronidase to preserve the skin's natural hyaluronic acid. PDRN works within the dermis — activating fibroblasts via the A2A receptor to increase glycosaminoglycan (GAG) production, collagen synthesis, and deep tissue hydration from within. The result is a comprehensive hydration strategy that addresses both surface dehydration and deep dermal moisture. PGA's film-forming property also creates an occlusive-like layer that may enhance the retention of PDRN applied beneath it, allowing PDRN's polynucleotide fragments more time to interact with dermal cells before evaporating. By inhibiting hyaluronidase, PGA also protects the hyaluronic acid that PDRN-stimulated fibroblasts produce, maximizing the hydrating returns of PDRN treatment.

Clinical Data

A 2013 study published in the Journal of Microbiology and Biotechnology demonstrated that gamma-PGA from Bacillus subtilis significantly increased skin moisture levels and reduced TEWL compared to hyaluronic acid at equivalent concentrations. Research in Biomaterials has confirmed PGA's ability to inhibit hyaluronidase activity, effectively extending the half-life of both endogenous and exogenous hyaluronic acid in the skin. A clinical trial comparing PGA to hyaluronic acid found that PGA provided superior hydration at lower concentrations and maintained moisture levels for longer periods. When used in conjunction with PDRN, PGA's surface hydration and HA-preserving effects amplify the deep dermal hydration PDRN stimulates, creating a synergistic multi-layer moisture system that patients report as significantly more effective than either ingredient alone.

Product Formats in the Wild

Common ways this ingredient is delivered in clinical and consumer products.