Cyclodextrin is made from potato starch, readily biodegradable and harvested from renewable and lasting sources.
Cyclodextrin is a host molecule (1) able to entrap an apolar guest molecule (2).
This creates a new entity also called inclusion compounds.
What are the benefits of cyclodextrin?
The entrapped molecule gains several traits and properties that can positively improve the cosmetic products and fragrances.
Cyclodextrin acts as:
- An active solubilizer.
CD solves difficulties with aqueous solubility. This is especially the case with retinol, liposoluble vitamins, vegetable oils, fatty acids and their esters, menthol, preservatives, etc. Looking closer at menthol, it is used as a cooling agent in cosmetics. CD enhances the solubility in aqueous form and avoids using alcohol.
- A defender.
By preventing the decomposition and oxidation of the embedded molecule due to light, heat, UV and chemicals, it is improving the shelf life of actives and fragrances.
Perfect match for molecule like oils, dyes, hydroquinone, natural tocopherol, kojic acid, etc. For retinol (used in topical anti-ageing and anti-wrinkles), CD prevents oxidation and formation of peroxidic toxic intermediates, while enhancing solubility in aqueous form.
- A stabilizer.
CD can improve the compatibility with the other components of the cosmetics formulations.
- A carrier.
It improves the release properties and increases the bioavailability of actives, it also reduces the volatility of the encapsulated molecules (especially perfumes).
- An odor neutralizer.
CD molecules are used to mask bad smells; helpful in formulations containing dihydroxyacetone, glutathione, mercaptan and to eliminate sweat malodor (body secretion like tiols, steroid, hexenal, octenal and nonenal, etc).
- A skin protector against irritation.
It decreases or prevents skin irritation from tea tree oil, limonene, p-cymene. Salicylic acid used in keratolytic and antibacterial products. CD enhances the solubility and reduces the irritant action.
How does cyclodextrin work?
Due to its toroidal shape structure, cyclodextrin allows the formation of molecular inclusion complexes with a wide variety of molecules by entrapping them entirely, or at least partially, both branched as well as unbranched.
Guest molecules are hydrophobic and have generally very low solubility in water. Only substrates that are less polar than water may form inclusion complexes with CDs.
Representation of molecular encapsulation possibilities
Depending on the size, the structural shape and the conformation of the guest molecules and the quantity of cyclodextrin, 2:1, 1:1 and 1:2 molecular inclusion complexes can be formed. It is noted that 1:1 molecular inclusion complexation is the most common form.
Cyclodextrin and hydroxypropyl cyclodextrin
The are two multifunctional types of CDs with specific functional benefits suited for different applications.
Cyclodextrin being a crystalline powder and having a very low solubility in cold water is adapted for dry powders formulas or dispersions: dry shampoos, deodorants in spray, fine perfumes, bath bomb / salt, soaps bar, etc.
Hydroxypropyl cyclodextrin being an amorphous powder, with a very high solubility in water as well as in ethanol-water blends, is adapted for liquid forms, emulsions and perfumes: toiletries, skin care, sun care, etc.
For all these possibilities, the cyclodextrin and hydroxypropyl cyclodextrin are already available and ready to use in hundreds of cosmetic products today : skin care, hair care, oral care, color cosmectics, fragrance, etc.