Well tolerated in controlled skin irritation testing
Reduces inflammatory signaling linked to acne
Impairs acne causing bacteria's ability to form biofilms
Provides antioxidant support against environmental stress
Chestnut Leaf Extract Description
Chestnut Leaf Extract comes from Castanea sativa and owes much of its soothing reputation to a class of tannin compounds called ellagitannins, including one called castalagin, alongside supporting antioxidant compounds.
A controlled in vivo study testing the extract's irritation potential found it was well tolerated on skin, supporting its use as a gentle botanical antioxidant in sensitive skin formulas. More recent laboratory research testing both the whole leaf extract and isolated castalagin on skin cells infected with Cutibacterium acnes, the bacteria strain associated with acne, found both reduced the release of inflammatory signaling molecules and meaningfully impaired the bacteria's ability to form biofilms, a key step in how it colonizes skin.
This combination of documented low irritation potential and emerging anti inflammatory, anti biofilm activity gives chestnut leaf extract a role in both calming and blemish focused formulas.
Chestnut Leaf Extract References
In Vivo Skin Irritation Potential of a Castanea sativa (Chestnut) Leaf Extract, a Putative Natural Antioxidant for Topical Application, Basic and Clinical Pharmacology and Toxicology, 2008
Investigation into the Anti Acne Effects of Castanea sativa Mill Leaf and Its Pure Ellagitannin Castalagin in HaCaT Cells Infected with Cutibacterium acnes, International Journal of Molecular Sciences, 2024
Our team reviews ingredient research and uses up-to-date evidence to rate ingredients based on the categories below.
Best
Ingredients with the most rigorous and convincing evidence. These are the standouts backed by consistent findings across independent, peer reviewed clinical research.. When we call an ingredient Best, it has earned that distinction through genuine, reproducible proof that it improves skin.
Good
Reliable, well tolerated ingredients that do their job without complaint. They may not carry the headline benefits of a Best rated active, but they hydrate, stabilize a formula, or support the ingredients around them in ways that make a real difference in how a product performs and feels.
Average
Ingredients that are perfectly safe and serve a clear function, typically as an emollient, thickener, or filler, but do not offer any meaningful skin benefit beyond that basic job. Not a red flag, just not a reason to choose one product over another.
Bad/Worst
Ingredients with documented potential to irritate skin, disrupt the barrier, or trigger sensitization in some users, often synthetic fragrance, drying forms of alcohol, or certain essential oils. Not automatically a dealbreaker for every skin type, but worth knowing about before you commit to a product.
