⚠️ Auto-extracted by Claude on 2026-05-23 — not yet verified against full PDFs. Canonical identifiers (PubChem CID 71226339, CAS 1419401-88-9, MW 322.4 Da, IUPAC) cross-checked against PubChem; mechanism + regulatory + human-evidence claims sourced from PubMed abstracts of the sponsor RCTs + EU SCCS opinion. Quantitative claims (λmax, ε, in-vivo PPD reductions, gene-expression deltas in Marionnet 2022) require full-PDF cross-check before relying.
Mexoryl 400 (MCE)
INCI: methoxypropylamino cyclohexenylidene ethoxyethylcyanoacetate IUPAC: 2-ethoxyethyl (2Z)-2-cyano-2-[3-(3-methoxypropylamino)cyclohex-2-en-1-ylidene]acetate PubChem CID: 71226339 · CAS: 1419401-88-9 · MW: 322.4 g/mol · Formula: C₁₇H₂₆N₂O₄
Mexoryl 400 (trade name; abbreviated MCE in the published literature) is a topical organic UV filter developed by L’Oréal R&D and BASF, designed to fill the 380–400 nm ultra-long UVA-I “gap” left open by conventional broad-spectrum sunscreen filters. λmax ≈ 385 nm; molar extinction ε ≈ 63,052 M⁻¹cm⁻¹ in ethanol (0.02 mM) per Marionnet et al. 2022 1. It is the differentiating active in La Roche-Posay’s Anthelios UVMune 400 sunscreen line — see uv-protection for the underlying photoprotection framework.
Why 380–400 nm matters
Conventional UVA-I filters drop off in absorption above ~370 nm:
| Filter | λmax | Coverage at 385 nm |
|---|---|---|
| Avobenzone | 357 nm | Weak |
| Tinosorb S | 343 nm | Weak |
| Uvinul A Plus | 354 nm | Weak |
| Mexoryl SX | 345 nm | Weak |
| Mexoryl XL | 303 + 344 nm | Weak |
| MCE / Mexoryl 400 | 385 nm | Strong |
Ground-level solar UV at temperate latitudes contains substantial irradiance in the 380–400 nm band (the long tail of UVA-I merging into visible violet). This radiation penetrates to the deep dermis and drives:
- ROS-mediated indirect DNA damage (8-OHdG, single-strand breaks)
- Mitochondrial dysfunction in dermal fibroblasts
- MMP-1/3/9 induction via AP-1 and NF-κB (the fisher-1996-photoaging-ap1-mmp cascade, band-agnostic at the dose level)
- Photoimmunosuppression (Langerhans cell loss, contact-hypersensitivity attenuation)
- Persistent pigment darkening (PPD) and immediate pigment darkening (IPD)
MCE addition to an SPF50+ formula extends spectral absorption from ~370 nm to 400 nm without substantially altering UVB coverage, providing the deepest UVA-I gap-fill available in the cosmetic-filter inventory as of 2026.
Mechanism
MCE is a small-molecule organic absorber: a conjugated cyclohexenylidene-cyanoacetate chromophore stabilized by methoxypropylamino + ethoxyethyl substituents. Absorption at 385 nm dissipates the photon’s energy through internal conversion + non-radiative decay (heat) rather than re-emission, with no photoisomerization or photolysis at typical formulation concentrations. The filter is photostable in finished products and does not require co-photostabilizers (unlike avobenzone, which requires octocrylene or similar). High molecular weight (322 g/mol) + lipophilicity place MCE in the stratum corneum + upper epidermis at use concentrations; dermal penetration is low.
Regulatory status
| Region | Status |
|---|---|
| EU | SCCS Opinion S87 (Dec 2019); authorized ≤3% in dermal sunscreens by Commission Regulation (EU) 2020/1684 (Nov 2020) as Annex VI entry. Inhalable/spray applications excluded (no inhalation tox data submitted). |
| Australia (TGA) | Compositional guideline published; permitted in listed therapeutic-goods sunscreens. |
| Canada (Health Canada) | Approved as a cosmetic UV filter (not on Hotlist). |
| United States (FDA) | Not GRASE. Not in 21 CFR §352 monograph. No Time and Extent Application (TEA) pending publicly. Products containing MCE cannot be sold as US sunscreens. |
Human evidence
All published efficacy studies as of May 2026 are L’Oréal-sponsored intra-individual hemiface or hemibody RCTs comparing an SPF 50+ formula with MCE against the same base without MCE. No independent replication. No biopsy endpoints. No long-term photoaging hard outcomes.
| Study | Design | n | Key result |
|---|---|---|---|
| Marionnet 2022 1 | RHE + in-vivo intra-individual RCT (NCT04865094) | 19 (in-vivo arm); Fitzpatrick III–IV | MCE-enriched SPF50+ reduced UVA-I-induced fibroblast loss, MMP1/IL-1RA/IL-6/IL-8/GM-CSF release, and 27+24 fibroblast/keratinocyte gene dysregulations at 50 J/cm² UVA-I in RHE; PPD ΔL* attenuated in-vivo vs SPF-matched reference |
| Flament 2024 2 | Outdoor intra-individual RCT, 8 wk | 113 women (Brazil + China, phototype III–V) | SPF50 + 3% MCE vs SPF50 base: smaller pigmentation increase + better expert-panel skin-aging severity scores on MCE side |
| Mercurio 2025 3 | Outdoor intra-individual RCT, 4 wk | 52 Brazilian women (phototype I–III) | SPF50 + 1% MCE vs SPF50 base: expert-panel superiority for upper-lip wrinkles, crow’s feet, pigmentation endpoints (all p<0.0001), vascular abnormalities, ptosis (p<0.01) |
| Zhang 2024 4 | Open single-arm, 4 wk | 60 Chinese adults (30 sensitive + 30 normal) | Mexoryl 400-containing sunscreen: melanin ↓13.49% (p<0.001), redness ↓9.84%, sebum ↓22.70%, hydration ↑38.44%. No comparator — MCE contribution not isolable. |
What’s missing from this evidence base:
- No independent (non-L’Oréal) efficacy replication.
- No human biopsy data on CPD, 6-4PP, 8-OHdG, or MMP-1 IHC with vs without MCE.
- No photo-immunosuppression endpoints (Langerhans cell density, contact-hypersensitivity).
- No head-to-head against a top-tier non-MCE EU stack (e.g., Tinosorb S + Mexoryl SX/XL + Uvinul A Plus + avobenzone) — comparators in all RCTs are the same base minus MCE.
- No long-term outdoor photoaging RCT with histology (the Hughes 2013 / Krutmann 2021 standard).
no-independent-replication · no-biopsy-endpoint · needs-head-to-head-top-stack
Safety
- EU SCCS dossier (S87, Dec 2019) reviewed acute, repeat-dose, dermal absorption, sensitization, photo-sensitization, mutagenicity, reproductive tox — concluded safe ≤3% dermal. Inhalation excluded.
- No published carcinogenicity, reproductive, or endocrine concerns beyond standard SCCS review at use concentrations.
- First independent human adverse event: Loretan 2024 5 reported a single case of allergic contact dermatitis (Type IV hypersensitivity) — 59-yo woman, atopic dermatitis history, 1-yr chronic facial dermatitis traced to Anthelios UVMune 400 SPF50+; ++ patch test to MCE 1% at 48 + 96 h; 12 atopic controls negative; clinical resolution within ~1 wk of cessation. Case report only — not a population-level allergy signal but the first documented human sensitization to MCE.
- Dermal absorption appears minimal based on filter physicochemistry (MW 322, log P moderate) — but no Matta-style FDA pharmacokinetic study has been performed publicly (the FDA’s maximal-use PK protocol 6 7 has not been applied to MCE because MCE is not under FDA jurisdiction).
Product availability
| Product line | Manufacturer | Region | MCE in line? |
|---|---|---|---|
| La Roche-Posay Anthelios UVMune 400 (all 5 SKUs) | L’Oréal | EU / UK / CA / AU / Asia | Yes |
| L’Oréal Revitalift Clinical SPF 50+ | L’Oréal | EU / select | Yes |
| Vichy Capital Soleil UV Age Daily | L’Oréal | EU | Yes |
| CeraVe AM Facial Moisturizing Lotion (EU formulation) | L’Oréal | EU | Some SKUs |
| Anything else | — | — | No as of May 2026 — MCE is L’Oréal-proprietary |
US-market Anthelios formulations (Melt-In Milk, Mineral SPF 30/50, etc.) do not contain MCE — they use US-GRASE filters only (avobenzone + homosalate + octisalate + octocrylene, or ZnO/TiO₂ in mineral SKUs).
Cross-references
- uv-protection — parent intervention page (filter sits in § Chemical filters → ultra-long UVA-I subsection)
- triasorb — competing 380+ nm filter (Pierre Fabre / Avène)
- fisher-1996-photoaging-ap1-mmp — mechanistic anchor (AP-1/NF-κB/MMP cascade driven by sub-erythemogenic UV)
- krutmann-2017-skin-aging-exposome — exposome framework calling for expanded-spectrum protection
- genomic-instability — UV-induced CPD/6-4PP/8-OHdG burden
- loss-of-proteostasis — MMP-driven dermal collagen/elastin degradation
- chronic-inflammation — UV-NF-κB cytokine induction
- skin-aging — primary photoaging endpoint
Footnotes
Footnotes
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doi:10.1016/j.xjidi.2021.100070 · Marionnet C, Tricaud C, Stocker L, et al. · JID Innov 2022;2(1):100070 · in-vitro RHE + in-vivo intra-individual RCT (NCT04865094) · n=19 in-vivo arm, Fitzpatrick III–IV · MCE λmax 385 nm; MW 322.41 g/mol; ε≈63,052 M⁻¹cm⁻¹ (ethanol, 0.02 mM); MCE-enriched SPF50+ reduced UVA1-induced fibroblast loss + MMP1/IL-1RA/IL-6/IL-8/GM-CSF release + dysregulation of 27 fibroblast + 24 keratinocyte genes at 50 J/cm² UVA1; in-vivo PPD ΔL* attenuated · COI: all authors L’Oréal employees · no-fulltext-access ↩ ↩2
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doi:10.1111/jdv.19486 · Flament F, Bourokba N, Nouveau S, et al. · J Eur Acad Dermatol Venereol 2024;38(1):214–222 · rct (intra-individual, outdoor, 8 wk) · n=113 women (Brazil + China, phototype III–V) · SPF50 + 3% MCE vs same SPF50 base on hemiface + contralateral forearm; chromametry showed smaller sun-induced pigmentation increase on MCE side; expert-panel skin-aging severity scores decreased on MCE side, unchanged/worsened on reference; naïve-panel radiance + homogeneity superior on MCE side · COI: all L’Oréal/La Roche-Posay ↩
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doi:10.1111/phpp.13020 · Mercurio DG, Wagemaker TAL, Passeron T, et al. · Photodermatol Photoimmunol Photomed 2025;41(1):e13020 · rct (intra-individual, outdoor, 4 wk) · n=52 Brazilian women (phototype I–III) · SPF50 + 1% MCE vs SPF50 alone hemiface · expert-panel significant superiority of MCE side: upper-lip wrinkles (p<0.0001), crow’s feet (p<0.0001), upper-lip pigmentation (p<0.0001), vascular abnormalities (p<0.0001), mouth-contour texture (p=0.001), lower-face ptosis (p=0.003), lateral facial pigmentation (p=0.005), whole-face pigmentation (p=0.01) · COI: all L’Oréal · no-fulltext-access ↩
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doi:10.1002/hsr2.1923 · Zhang Y, Steel A, et al. · Health Sci Rep 2024;7(2):e1923 · single-center open trial, no comparator · n=60 Chinese adults (30 sensitive + 30 normal) · 4-wk daily Mexoryl 400-containing sunscreen · melanin ↓13.49% (p<0.001), redness ↓9.84%, sebum ↓22.70%, hydration ↑38.44% at d28 · MCE contribution not isolable (no comparator arm) · COI: Steel L’Oréal-affiliated ↩
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doi:10.1111/cod.14700 · Loretan C, Piletta P, Rossel JB · Contact Dermatitis 2024;92(1):80–81 · case report · n=1 + 12 atopic controls · 59-yo woman, 1 yr chronic facial dermatitis traced to UVMune 400 SPF50+; patch test ++ to MCE 1% (50/50 aq/alc) at 48 + 96 h; 12 atopic controls negative; resolution within ~1 wk of cessation · first independent (non-L’Oréal) human MCE publication ↩
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doi:10.1001/jama.2019.5586 · Matta MK, Zusterzeel R, Pilli NR, et al. (FDA OCP) · JAMA 2019;321(21):2082–2091 · maximal-use plasma PK · n=24 · 4 chemical filters; all exceeded 0.5 ng/mL plasma threshold; referenced here only for the comparator framework (MCE not tested) · no-fulltext-access ↩
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doi:10.1001/jama.2019.20747 · Matta MK, Florian J, Zusterzeel R, et al. (FDA) · JAMA 2020;323(3):256–267 · maximal-use plasma PK · n=48 · expanded panel including homosalate, octisalate, octinoxate; persistence through day 21 · referenced here only for comparator framework · no-fulltext-access ↩