PDRN, Exosomes, Glutathione: What the Science Really Says

PDRN, exosomes, glutathione, kojic acid, postbiotics, tranexamic acid. These names are everywhere — on social media, in pharmacies, on packaging. But the line between genuinely innovative active ingredients, trendy but not new ones, and those whose promises outweigh the evidence, is rarely explained.

Here's what science actually says about each of them.

A trendy active ingredient is not necessarily an effective one. And an effective active ingredient is not necessarily new.

PDRN and Polynucleotides: The strongest active ingredient on the list

PDRN (polydeoxyribonucleotide) is extracted from salmon milt, whose DNA sequence shows approximately 85% homology with human DNA (the 95% figure sometimes cited actually refers to the product's purity, not its genetic similarity). It is not a new active ingredient — it has been used in regenerative medicine since the 1980s for healing chronic wounds and bedsores. What is new is its massive adoption in topical cosmetics, driven by the success of the injectable "Rejuran Healer" in South Korea starting in 2010.

Its mechanism is well documented. PDRN activates adenosine A2A receptors, stimulating fibroblast proliferation, collagen synthesis, and angiogenesis. It reduces inflammatory cytokines (TNF-alpha, IL-6) and accelerates tissue repair. A systematic review published in the Journal of Cosmetic Dermatology in 2025 (Lampridou et al.), analyzing 9 clinical studies on 219 patients, confirms significant results on wrinkle reduction, texture improvement, and elasticity when injected.

In topical cosmetics, the important nuance is that the skin penetration of DNA molecules highly depends on the formulation. Nano-encapsulations and biocompatible emulsions improve bioavailability, but clinical data for topical use remain less robust than for injectables. It is a promising active ingredient for topical use, with solid evidence for injectables and growing evidence in cosmetics.

Exosomes: Promising but early

Exosomes are extracellular vesicles naturally secreted by cells. They transport proteins, lipids, and nucleic acids, acting as intercellular messengers in tissue repair. In regenerative medicine, the data are real and promising, particularly in combination with microneedling or after laser procedures.

In topical cosmetics, two questions remain open. The penetration of exosomes through the intact skin barrier is not yet sufficiently documented. And the stability of formulations — exosomes are fragile biological structures — poses technical challenges that not all brands solve in the same way.

It is the most genuinely new active ingredient on this list, with the most limited evidence in cosmetics. To be continued, with honesty about what we know and what we don't yet know.

Glutathione: Effective but not in the way it's sold to you

Glutathione is the body's primary intracellular antioxidant. Its reputation in skincare is based on two documented properties: powerful antioxidant action against oxidative stress, and the ability to steer melanogenesis towards pheomelanin (lighter) rather than eumelanin (darker).

The problem lies in the route of administration. Topically, glutathione has limited percutaneous absorption — its large molecular size and sensitivity to oxidation compromise its effectiveness in crossing the skin barrier. Liposomal formulations improve bioavailability, but topical clinical studies are still insufficient to validate the brightening promises made by the majority of products.

Orally, the data are better. Several clinical studies show an improvement in skin radiance and a reduction in spots after 8 to 12 weeks of supplementation with reduced glutathione or S-acetyl glutathione. Its effectiveness is best documented as a dietary supplement, not as a topical serum.

Kojic acid: Effective, regulated, to be used with precision

Kojic acid is a fungal metabolite produced by the fermentation of Aspergillus oryzae. A documented tyrosinase inhibitor, it has been effective against hyperpigmentation since the 1990s. It is not a new active ingredient — it is one that has seen a resurgence in popularity on social media.

What few contents specify: the SCCS (European Scientific Committee on Consumer Safety) has revised its safety assessment. Following concerns about its potential endocrine-disrupting properties, the maximum authorized concentration in Europe has been lowered to 0.7% in the finished product, down from 1%. Use in combination with exfoliants, which increase percutaneous absorption, requires additional vigilance.

It remains effective at these concentrations. But a product that contained 1% kojic acid yesterday and 0.7% today is not identical. This is exactly the kind of detail that most consumers cannot read alone in an INCI list.

Tranexamic acid: The best documented underrated depigmenting agent

This is probably the least known active ingredient on this list to the general public, yet one of the best scientifically documented. Tranexamic acid inhibits keratinocyte plasminogen activator, thereby reducing melanocyte stimulation by prostaglandin and melanin production through a different pathway than tyrosinase.

Several randomized controlled studies show its effectiveness on melasma at concentrations between 2 and 5% topically, with a tolerability profile often superior to hydroquinone. A 2018 meta-analysis confirms the significant reduction in melasma severity by tranexamic acid, orally, topically, or injectably. It remains one of the best-documented depigmenting agents, particularly relevant for high phototypes.

Postbiotics: The real microbiome revolution

Postbiotics are preparations of inactivated microorganisms or their metabolites that provide a benefit to skin health. These include bacterial lysates, ferments, and cell wall fragments — stable biotechnological active ingredients that are easy to formulate, and whose efficacy is increasingly supported in the literature.

Lactobacillus lysates show anti-inflammatory and skin barrier repair effects documented in several independent publications, with an objective reduction in erythema and skin sensitivity in controlled clinical studies. Postbiotics represent the most concrete and advanced microbiome approach in cosmetic formulation today.

GHK-Cu: The copper peptide that deserves attention

GHK-Cu (glycyl-l-histidyl-l-lysine copper) is a peptide naturally present in human plasma, whose concentration decreases with age. It stimulates the synthesis of collagen, elastin, and glycosaminoglycans, promotes tissue repair, and exerts antioxidant and anti-inflammatory actions. It is one of the best-documented peptides in anti-aging cosmetics, with clinical studies published in A-rank journals since the 2000s.

The Paradermia approach

Our pharmacist integrates trendy active ingredients into protocols only when their level of evidence justifies it, at the correct concentration, and in a suitable formulation. A viral active ingredient in an improperly dosed formula or one incompatible with your skin will do nothing. Rigorous selection always takes precedence over trends.

Frequently asked questions

Can I find products with these active ingredients on Paradermia?
Some of these active ingredients are available in our selection when their formulation meets our rigorous criteria. Our pharmacist can guide you towards products that incorporate these active ingredients at relevant concentrations and in stable formulations.

Does topical PDRN work as well as injectable PDRN?
No, not equivalently. Injectable PDRN delivers the active ingredient directly into the dermis where it acts. Topical PDRN depends on the quality of the formulation to penetrate the skin barrier. Nano-encapsulated formulas are more effective than standard formulas. Both have their merits, but their levels of evidence and modes of action remain different.

Is kojic acid still authorized in Europe?
Yes, but at a maximum concentration of 0.7% in the finished product, following the SCCS revision. This limit is lower than what was previously authorized. Compliant products remain effective at this concentration — the important thing is to ensure that the product used complies with this current regulation.