Study finds improved method for formulating with vitamin E

A recent clinical study published in the International Journal of Cosmetic Science by Société Française de Cosmétologie has investigated a new delivery method for vitamin E (α-tocopherol) in skin care products.

Despite being a highly popular skin care ingredient, the antioxidant vitamin E is also known for its instability (heat, light, oxidation) and poor solubility that limits both its efficacy and formulation possibilities.

As such, the study, which was undertaken by researchers from Le Havre Normandie University explored encapsulating α-tocopherol (TOCO) within microcapsules (coacervates) made from fungal chitosan and gum Arabic.

The researchers used complex coacervation – a technique involving the interaction of oppositely charged polymers – to create the microcapsules.

High encapsulation efficiency and enhanced stability

The study found that the fungal chitosan and gum Arabic coacervation method achieved high encapsulation efficiency (87%) and loading (27.2% α-tocopherol).

The encapsulated TOCO also showed improved thermal stability up to 220°C, which the researchers said was a significant improvement over both pure TOCO and the carrier oil (diisopropyl adipate) used to dissolve it.

The study also found that the encapsulated TOCO degraded more slowly than pure TOCO during one month of ‘accelerated ageing’, when stored at a temperature of 40°C.

After two months, 63% of the encapsulated TOCO remained, compared to only 53.5% of the pure TOCO, which suggests a longer shelf life for products when using this encapsulation method.

Improved textural and rheological properties

The researchers found that incorporating the fungal chitosan and gum Arabic TOCO coacervates into oil-in-water emulsions significantly improved the emulsions' textural and rheological properties.

This included increased viscosity and enhanced viscoelasticity (a balance of liquid and solid properties important for spreadability and skin feel), as well as increased firmness and stickiness. This was most likely due to the interaction of the coacervates with the emulsion components.

The emulsions with coacervates also had a larger particle size distribution, which the researchers said could influence sensory perception.

What this means for vitamin E in skin care formulations?

The fungal chitosan and gum Arabic coacervation method provides a promising novel delivery system for TOCO, which addresses stability and solubility challenges. It could also potentially be used for other lipophilic actives.

As both fungal chitosan and gum Arabic are sustainable, non-animal-derived biopolymers, this could also address the growing consumer demand for natural and vegan beauty ingredients.

Meanwhile, the improved textural and rheological properties of the emulsions could offer better product aesthetics and a enjoyable sensory experience.

The enhanced stability of TOCO within the coacervates also suggested the formulation could have a longer product shelf life, as well as improved efficacy over time.

While these results were promising, the researchers concluded that further study is still needed to investigate the release kinetics of TOCO from the coacervates in topical applications, and to fully understand long-term stability, as well as any potential destabilisation mechanisms.