What is “Pullulan” and what is it used for?

Pullulan is a naturally derived polysaccharide obtained by fermenting sugars, such as glucose, sucrose, or starch, using the microorganism Aureobasidium pullulans. During this biotechnological process, the sugars are converted into long chains of repeating molecules, resulting in a water-soluble, neutral, and biodegradable polymer. Its production is therefore based on a controlled fermentation pathway, similar to the one used for certain other cosmetic ingredients, such as hyaluronic acid.

Structurally, pullulan is composed of maltotriose units, each corresponding to three glucose molecules linked together, which are connected by specific α-(1→6) glycosidic bonds. This organization gives it a flexible linear structure, different from that of many other, more highly branched polysaccharides. This particular feature notably explains its ability to form homogeneous, transparent films in aqueous solution while maintaining good affinity for water. Pullulan is therefore distinguished by physicochemical properties that are particularly suitable for cosmetic use: it is non-ionic, stable over a wide pH range, and compatible with many other ingredients, which facilitates its incorporation into various formulations.

Pullulan is mainly used in cosmetics for its film-forming and texturizing properties. Water-soluble and non-ionic, it forms a thin, uniform, and transparent film on the surface of the skin and hair, which can be perceived through an immediate tightening effect. This film acts as a physical barrier that limits transepidermal water loss, thereby helping to maintain skin hydration. In formulations, it also has a structural role: it increases viscosity, stabilizes emulsions, and promotes cohesion between different ingredients, including in the presence of surfactants. This versatility explains its use in many products (serums, masks, hair care), where it also contributes to a surface-smoothing and softening effect.

On the skin, this ability to form a film gives pullulan an immediate smoothing and tightening effect, purely physical in nature. It does not act in depth, but improves the appearance of the epidermis by evening out its surface and temporarily reducing the visibility of irregularities. In addition, this film can facilitate the gradual delivery of certain active ingredients by limiting their evaporation and maintaining a hydrated environment that is favorable to their activity. On the hair, pullulan is deposited along the hair fiber, where it helps sheath the cuticle, improve softness to the touch, and enhance shine, without weighing the hair down.

Beyond these surface effects, some studies suggest a potential role for pullulan in the process of wound healing.

An experimental study in rats evaluated the topical application of a pullulan gel on skin wounds. The results show a significant improvement in several biological markers involved in wound healing: increased collagen, protein, and DNA content, as well as faster wound contraction. The epithelialization time was cut in half, and histological analyses demonstrated better dermal regeneration, new blood vessel formation, and increased collagen synthesis. Although these results come from an animal model, they suggest that pullulan may help support skin repair.

In addition, photoprotective properties have also been investigated using exopolymers derived from Aureobasidium pullulans. In a murine model exposed to UVB for 15 weeks, topical application of these polymers helped limit oxidative stress induced by UV, notably by reducing the production of free radicals, preserving glutathione stores, an endogenous antioxidant, and inhibiting the activation of metalloproteinases, enzymes involved in collagen degradation. A decrease in pro-inflammatory cytokines and in keratinocyte apoptosis was also observed. These findings suggest a potential protective effect against photoaging, although clinical data in humans remain limited to date.

Finally, beyond its conventional use, pullulan is attracting growing interest for more advanced applications, particularly in the development of active delivery systems. Its ability to form solid, biocompatible structures is being leveraged in the manufacturing of dissolvable microneedles, used in dermatology to enhance the penetration of certain compounds. Although these technologies are still mostly investigated in a medical context, they highlight the potential of pullulan as a delivery vehicle, with possible translation into cosmetics.

Pullulan is considered an ingredient that is very well tolerated when applied topically. To date, the scientific literature has not reported any significant adverse effects associated with its use in cosmetic products. Its lack of marked chemical reactivity greatly limits the risk of skin irritation or sensitization. In addition, it does not penetrate deeply into the skin and acts mainly at the surface, which further reduces the likelihood of unwanted reactions. It should also be noted that, based on current knowledge, pullulan does not present any specific contraindications: it can be used in children, pregnant or breastfeeding women, as well as in people with sensitive skin or prone to skin conditions.

That said, as with any ingredient, tolerance can vary from one individual to another, which is why it is useful to perform a test when using a new cosmetic product for the first time.

• KANG S. J. & al. Inhibition of UVB-induced skin damage by exopolymers from Aureobasidium pullulans SM-2001 in hairless mice. Basic & Clinical Pharmacology & Toxicology (2015).

• MORGANTI P. & al. Pullulan for advanced sustainable body- and skin-contact applications. Journal of Functional Biomaterials (2020).

• DONNELLY R. F. & al. Pullulan-based dissolving microneedle arrays for enhanced transdermal delivery of small and large biomolecules. International Journal of Biological Macromolecules (2020).

• LONCHIN S. & al. Topical administration of pullulan gel accelerates skin tissue regeneration by enhancing collagen synthesis and wound contraction in rats. International Journal of Biological Macromolecules (2020).

• KENNEDY J. F. & al. Pullulan in pharmaceutical and cosmeceutical formulations: A review. International Journal of Biological Macromolecules (2023).