Common Name(s): Ergosterol,ergosterol,fungal provitamin d2,uv-activated skin-conditioning sterol
CAS Number: N/a
DESCRIPTION
What It Does: Provides sc-compatible sterol emolliency analogous to cholesterol for barrier integration, and uv-activation to vitamin d2 (ergocalciferol) — the plant/fungal equivalent of the skin's uvb-driven vitamin d3 synthesis.
Why It's Used: Ergosterol's uv-activation to vitamin d2 mirrors cholecalciferol synthesis from 7-dehydrocholesterol — both undergo [1,7]-sigmatropic photoisomerisation upon uvb exposure, providing photoactivated vitamin d from entirely different precursors.
How It Works: Uv-b photoisomerisation of ergosterol: ergosterol → pre-vitamin d2 (uvb 295-310 nm, [1,7]-sigmatropic rearrangement of the b-ring) → ergocalciferol (thermal isomerisation) → skin vdr activation. sc sterol: the ergostane ring geometry integrates into sc lamellar bilayers providing cholesterol-analogous barrier fluidity.
Typically Found In: Skin conditioning,vitamin d support
TECHNICAL DETAILS
Primary Category: Functional ingredient – emollient
Secondary Functions: Barrier sealing,softening
Application Areas:
Facial Skincare
Body Care
Hair Care
Beard Care
Color Cosmetics (Makeup)
Dietary/Oral Supplements
Typical Concentration Range: 0.1%–3%
SOURCING & ETHICS
Vegan Status: Conditional - supplier confirmation required
Halal Status: Unverified - supplier confirmation required
Source Notes: Plant-derived, synthetic or animal-derived. verify source. [audit 2026-07-29 rev2: the record's own source_notes does not assert a non-animal origin, or instructs the reader to verify with the supplier; "yes" asserts knowledge the record does not hold. determination requires shariah-panel sign-off.]
SKIN COMPATIBILITY
Irritancy Rating: 1/5 – very low
Comedogenicity Rating: 1/5 – low; formulation-dependent
Sensitivity Concerns: Non-irritating.
Safe for Sensitive Skin: Yes
SAFETY & COMPATIBILITY
Safety Profile: Excellent safety profile. ewg score: 1.
Works Well With: Humectants,ceramides,actives as carrier
Avoid Combining With: No significant incompatibilities
SCIENTIFIC NOTE
Ergosterol vs cholesterol in sc: ergosterol has an additional double bond (c22-c23) making the ring system slightly less flexible than cholesterol — the formulator should test barrier integration performance for each application as the chain-length difference may affect lamellar phase behaviour.
Last Verified: 2026-03-22
Primary Sources: Cosing database,ergosterol fungal provitamin d2 sc sterol review