Tinosorb A2B (tris-biphenyl triazine, TBPT)
INCI: Tris-Biphenyl Triazine IUPAC: 2,4,6-tris(4-phenylphenyl)-1,3,5-triazine PubChem CID: 11628027 · CAS: 31274-51-8 · EC: 479-950-7 · MW: 537.6 g/mol · Formula: C₃₉H₂₇N₃ · InChIKey: CENPSTJGQOQKKW-UHFFFAOYSA-N · ChEMBL: CHEMBL900415
Tinosorb A2B is a topical organic UV filter developed by BASF (licensed under the Tinosorb brand, historically also associated with DSM Nutritional Products before the BASF personal-care business reorganisation). It is formulated as insoluble organic nanoparticles suspended in aqueous or emulsion matrices — a hybrid between a pure chemical absorber (which dissolves in the oil phase) and a mineral scatter-reflector (TiO₂/ZnO). The nanoparticulate state is essential to its dual UVB-absorption / UVA-I-scattering mechanism. It was the first new UV filter authorized under EU Cosmetics Regulation (EC 1223/2009) following the 2013 regulatory freeze 1, entering Annex VI of Regulation 1223/2009 via Commission Regulation (EU) 2016/1198 at a maximum concentration of 10% (w/w) in finished cosmetic products.
DISAMBIGUATION (critical):
Tinosorb A2B (TBPT) must be distinguished from three closely named filters:
- triasorb (TriAsorB, PBT, phenylene bis-diphenyltriazine, CAS 55514-22-2) — a DIFFERENT filter developed by Pierre Fabre. Built on a 1,2,4-triazine (asymmetric) scaffold, NOT the symmetric 1,3,5-s-triazine of TBPT. Extends into HEV visible light (400–450 nm). Approved EU ≤5%. Do not conflate with Tinosorb A2B.
- bemotrizinol (Tinosorb S) — a bisethylhexyloxyphenol methoxyphenyl triazine; oil-soluble; a different BASF Tinosorb-family compound with a different s-triazine substitution pattern. Approved EU ≤10%.
- bisoctrizole (Tinosorb M) — a methylene bis-benzotriazolyl tetramethylbutylphenol; also particulate/hybrid like TBPT but with a benzotriazole core, not a triazine. Approved EU ≤10%.
All four are distinct compounds sharing the Tinosorb trade-name umbrella (BASF). Tinosorb A2B is specifically the tris-biphenyl triazine (three 4-biphenyl groups on the central s-triazine ring, no heteroatom substituents beyond the ring nitrogens, no amine groups, no OCH₂ sidechains).
Mechanism — hybrid absorption + scattering
TBPT is a nanoparticulate UV filter whose mechanism partitions by spectral region 2:
- UVB (290–320 nm): protection is almost entirely from absorption. The extended conjugated π-system of the biphenyl-triazine chromophore efficiently absorbs UVB photons and dissipates energy as heat via internal conversion.
- UVA-II (320–340 nm): strong absorption; this is the region where TBPT provides its most differentiated coverage. Couteau et al. 2015 documented approximately 2 SPF units and 1 UVA-PF unit per percentage of use in standard photobiological in-vitro assays 1.
- UVA-I (340–400 nm): TBPT does not absorb appreciably in this region. Instead, the nanoparticles scatter UVA-I radiation, providing partial attenuation. Sohn et al. 2025 showed UVA-I scattering is the dominant protection mechanism in this band 2. The scattering contribution is concentration-dependent: above ~3% w/w, increased absorption of back-scattered UVA-I by neighboring particles causes the effective scattering contribution to plateau or decrease.
- Critical wavelength: exceeds 370 nm 1, qualifying TBPT-containing formulas as “broad spectrum” under EU and US FDA broad-spectrum testing criteria.
- Visible light / HEV (400–450 nm): TBPT does NOT extend into the visible light / high-energy visible (HEV) range. This is a key differentiator from triasorb (PBT), which does provide HEV coverage, and from iron-oxide pigments in tinted formulations.
Photostability. TBPT is highly photostable: Couteau et al. 2015 reported that SPF and UVA-PF were unchanged after 2 hours of solar simulator irradiation 1. No co-photostabilizer (e.g., octocrylene) is required. Scarpin et al. 2021 evaluated TBPT as a photostabilizer co-ingredient in avobenzone-containing formulas, suggesting it can extend avobenzone photostability in combined-filter stacks 3.
Photochemical deactivation. Naumov et al. 2023 used DFT calculations to characterize spectral changes between dissolved (monomer) and aggregated (nanoparticle) TBPT states. π-stacked aggregation in aqueous suspension explains red-shifted absorption in the nanoparticle form. Photorelaxation proceeds via non-radiative internal conversion with no photoisomerization or photolysis documented 4.
Structural note — 1,3,5-s-triazine, not 1,2,4-triazine
TBPT is built on the symmetric 1,3,5-triazine (s-triazine) ring, placing all three nitrogen atoms symmetrically at alternating positions. This is the same core scaffold as bemotrizinol (Tinosorb S) — both are s-triazine derivatives. In contrast, triasorb (TriAsorB, PBT) uses the asymmetric 1,2,4-triazine scaffold (two adjacent nitrogens + one isolated nitrogen), giving it a structurally distinct chromophore and extending its absorbance into the visible HEV band. This structural difference is relevant for potential cross-reactivity in contact-allergy settings: sensitization to one triazine filter does not necessarily predict sensitization to another.
Regulatory status
| Region | Status |
|---|---|
| EU | Authorized via Commission Regulation (EU) 2016/1198 (July 2016); Annex VI entry for tris-biphenyl triazine (CAS 31274-51-8) at ≤10% w/w in rinse-off and leave-on products. Preceded by SCCS safety opinion (reference number unconfirmed — see body note; gap/needs-sccs-opinion-reference-confirmed). |
| Australia (TGA/AICIS) | Listed on AICIS inventory; permitted in listed/listable sunscreens mirroring EU authorization. |
| United States (FDA) | Not GRASE. No Time and Extent Application (TEA) filed publicly. Products containing TBPT cannot be marketed as OTC sunscreens in the US. The FDA’s decades-long backlog on non-monograph UV filters means this reflects US regulatory lag, not evidence insufficiency (see R52 convention). |
| Canada (Health Canada) | Not on the current Sunscreen Monograph. Not approved for sale as a Canadian sunscreen. |
SCCS opinion note: The SCCS issued a safety opinion on tris-biphenyl triazine (CAS 31274-51-8) as part of the pre-authorization dossier review process preceding Commission Regulation (EU) 2016/1198. The specific SCCS opinion reference number could not be confirmed against the public SCCS opinions archive during verification (SCCS/1533/14 was a seeder guess and is incorrect — that number resolves to Acid Orange 7). The wiki-verifier should confirm the SCCS opinion reference number directly against the EU Official Journal or the SCCS opinions archive. gap/needs-sccs-opinion-reference-confirmed
Formulation and availability
TBPT is formulated as an aqueous nano-dispersion (trade name Tinosorb A2B by BASF). Because the active exists as nanoparticles rather than as a dissolved organic species, it is compatible with aqueous and emulsion phases but requires manufacturing equipment adapted for nanoparticle handling.
As of mid-2026, the literature indicates TBPT is primarily deployed in:
- BASF-supplied sunscreen formulations and licensed-formulator products in the EU
- Products marketed in Europe requiring strong UVA-II coverage without the need for HEV protection
Unlike triasorb (which is Pierre Fabre / Avène proprietary) or mexoryl-400 (which is L’Oréal proprietary), TBPT is available from BASF to any EU-licensed cosmetic manufacturer as a standard supply ingredient. This makes it more widely distributed across brands than the proprietary competing filters.
US-market absence: No US-market product containing TBPT can legally bear an SPF claim.
Human evidence
The evidence base for Tinosorb A2B as of June 2026 is primarily in-vitro performance testing and photochemical characterization rather than controlled human skin aging trials.
| Study | Design | Key result |
|---|---|---|
| Couteau 2015 1 | In-vitro photobiology (PMID 25843762) | First published characterization: ~2 SPF units + ~1 UVA-PF unit per percentage of use; critical wavelength >370 nm; fully photostable (SPF/UVA-PF unchanged after 2 h solar simulator) |
| Sohn 2025 2 | In-vitro spectroscopy + transmittance (BASF) | UVB protection = absorption-dominant; UVA-I (340–400 nm) protection = scattering-dominant; scattering contribution decreases above ~3% w/w due to re-absorption; first systematic partitioning of absorption vs scatter contribution |
| Naumov 2023 4 | Computational DFT + photochemical characterization (BASF/Leipzig) | π-stacked aggregation explains nanoparticle spectral red shift; photorelaxation = non-radiative internal conversion; no photoisomerization; theoretical foundation for photostability |
| Scarpin 2021 3 | In-vitro photostability + phototoxicity (3T3 NRU) | TBPT co-formulated with avobenzone + octyl methoxycinnamate improves photostability of retinyl palmitate combination; phototoxicity endpoint negative at tested concentrations |
What is absent from this evidence base:
- No published human in-vivo RCT measuring photoprotection efficacy with TBPT as an isolable variable
- No human biopsy data on CPD, 6-4PP, or 8-OHdG with vs without TBPT
- No head-to-head comparison with other broad-spectrum UV filters (Tinosorb S, avobenzone, Mexoryl SX/XL) in a matched SPF/UVA-PF formula
- No long-term outdoor photoaging RCT with histological endpoints
- Evidence base is exclusively performance-characterization; clinical-endpoint evidence depends on the broader photoprotection literature showing that UV attenuation reduces photoaging endpoints
gap/no-human-rct · gap/no-independent-replication · gap/no-biopsy-endpoint
Safety
- Photostability: no degradation products documented; no photosensitization signal expected based on photostability data.
- Dermal penetration: TBPT is a high-MW (537.6 g/mol) compound formulated as nanoparticles. High MW and particulate state substantially limit transdermal penetration; however, the SLC transporter binding modeling by Xing et al. 2026 5 identified TBPT as forming stable in-silico complexes with SLC22A31 (binding affinity −10.8 kcal/mol) — a computational signal of possible cutaneous accumulation via active transport, though no in-vivo human PK study has been published. gap/long-term-unknown
- Contact allergy: no published case reports of contact sensitization to TBPT as of June 2026.
- SCCS safety opinion: SCCS reviewed TBPT prior to EU authorization (2016); concluded safe at ≤10% in leave-on and rinse-off cosmetic products. Full dossier review procedures for EU-authorized filters cover acute, repeated-dose, sensitization (HRIPT, LLNA), photoallergy, mutagenicity, and reproductive toxicity.
Comparison with sibling filters
| Property | TBPT (Tinosorb A2B) | TriAsorB (PBT) triasorb | Tinosorb S bemotrizinol | MCE (Mexoryl 400) mexoryl-400 |
|---|---|---|---|---|
| Scaffold | s-triazine (1,3,5), no substituents | 1,2,4-triazine (asymmetric) | s-triazine (1,3,5), bisethylhexyloxy + phenoxy | Cyclohexenylidene cyanoacetate |
| MW (Da) | 537.6 | 540.6 | 627.8 | 322.4 |
| Physical state | Nanoparticles | Particulate / hybrid | Oil-soluble | Oil-soluble |
| EU max conc. | 10% | 5% | 10% | 3% |
| EU approval year | 2016 | 2019 | ~2000 | 2020 |
| UVB peak coverage | Strong | Strong | Strong | Weak |
| UVA-II (320–340 nm) | Strong (differentiating) | Moderate | Strong | Moderate |
| UVA-I (340–400 nm) | Scattering only | Absorption + reflectance | Strong absorption | Strong (λmax 385 nm) |
| HEV (400–450 nm) | No | Yes | No | No |
| Photostabilizer needed? | No | No | No | No |
| Proprietary? | BASF (open-market supply) | Pierre Fabre (exclusive) | BASF (open-market supply) | L’Oréal (exclusive) |
| FDA status | Not approved | Not approved | Not approved | Not approved |
Aging-biology rationale
TBPT is relevant to the skin aging wiki primarily through the photoprotection-to-photoaging attenuation pathway:
-
Genomic instability prevention: UVB (290–320 nm) and UVA-II (320–340 nm) are the principal drivers of CPD and 6-4PP formation (direct photolesions at bipyrimidine sites). These drive genomic-instability in keratinocytes and melanocytes. TBPT’s strong absorption in both bands attenuates the direct genotoxic UV dose.
-
Proteostasis preservation: UV drives AP-1-mediated MMP-1, MMP-3, and MMP-9 transcription in dermal fibroblasts 6, leading to collagen and elastin fragmentation — a primary driver of loss-of-proteostasis in the dermis. Reducing UV load reduces this upstream signal.
-
Chronic inflammation attenuation: Sub-erythemogenic UV doses activate NF-κB in keratinocytes, sustaining a low-grade chronic inflammatory cytokine environment. Repeated UV-driven NF-κB signaling contributes to chronic-inflammation.
Evidence for these pathways specific to TBPT rests on extrapolation from (a) TBPT’s documented UV attenuation capacity and (b) the well-established UV→pathway causality studied with other filters. No biopsy study has yet isolated TBPT’s contribution at the molecular pathway level.
Cross-references
- uv-protection — parent intervention page (filter sits within the broad-spectrum UV filter portfolio)
- triasorb — DISTINCT filter (TriAsorB / PBT, Pierre Fabre; 1,2,4-triazine; HEV coverage; ≤5% EU) — do not conflate
- bemotrizinol — Tinosorb S (same s-triazine family; BASF; oil-soluble; strong UVA-I absorber)
- bisoctrizole — Tinosorb M (BASF; benzotriazole-based nanoparticulate; distinct scaffold)
- mexoryl-400 — L’Oréal MCE; ultra-long UVA-I absorber (λmax 385 nm); no HEV; not nanoparticulate
- ecamsule — Mexoryl SX; UVA-II absorber; L’Oréal proprietary; water-soluble
- drometrizole-trisiloxane — Mexoryl XL; L’Oréal proprietary oil-soluble UVA absorber
- iscotrizinol — another triazine-family UV filter (diethylhexyl butamido triazone)
- genomic-instability — upstream UV-induced CPD/6-4PP burden
- loss-of-proteostasis — MMP-driven dermal collagen/elastin degradation
- chronic-inflammation — UV-NF-κB cytokine induction
- skin-aging — primary photoaging endpoint
Extrapolation note
| Dimension | Status |
|---|---|
| Pathway conserved in humans? | yes — UV-CPD-mutagenesis and UV-AP1-MMP axes are human pathways with strong clinical evidence |
| Phenotype conserved in humans? | yes — photoaging is a well-characterized human phenotype |
| Replicated in humans? | in-progress — only in-vitro performance characterization published; no independent human RCT |
Footnotes
Footnotes
-
doi:10.1016/j.ijpharm.2015.03.077 · Couteau C, Paparis E, Chauvet C, Coiffard L · Int J Pharm 2015;487(1-2):120–123 · PMID 25843762 · in-vitro photobiology · ~2 SPF units + ~1 UVA-PF unit per percentage of use; critical wavelength >370 nm; full photostability (SPF/UVA-PF unchanged at 2 h solar simulator); first characterization of TBPT as EU-authorized filter · COI: Université de Nantes (independent academic) · founding performance paper; 34 citations; closed access gap/no-fulltext-access ↩ ↩2 ↩3 ↩4 ↩5
-
doi:10.1111/ics.70001 · Sohn M, Staudt A, Quass K, Herzog B · Int J Cosmet Sci 2025;47(6):1043–1055 · in-vitro spectroscopy + transmittance · UVB protection absorption-dominant; UVA-I (340–400 nm) protection scattering-dominant; scattering decreases above ~3% w/w due to re-absorption; first systematic partitioning of absorption vs scatter for TBPT · COI: all BASF Grenzach GmbH authors · closed access gap/no-fulltext-access ↩ ↩2 ↩3
-
doi:10.1111/php.13407 · Scarpin MS, Kawakami CM, Rangel KC, et al. · Photochem Photobiol 2021;97(6):700–709 · PMID 33621371 · in-vitro photostability + 3T3 NRU phototoxicity · TBPT as photostabilizer co-ingredient with avobenzone + OMC; improved retinyl palmitate photostability; phototoxicity negative at tested concentrations · 19 citations; closed access gap/no-fulltext-access ↩ ↩2
-
doi:10.1007/s43630-023-00436-y · Naumov S, Herzog B, Abel B · Photochem Photobiol Sci 2023;22(9):2143–2151 · DFT computational + photochemical characterization · π-stacked aggregates explain nanoparticle spectral shift; photorelaxation via non-radiative internal conversion; no photoisomerization · COI: Herzog B (BASF); Naumov S, Abel B (Universität Leipzig, independent) · OA available; 5 citations ↩ ↩2
-
doi:10.1038/s41598-026-56714-z · Xing R, Jiang Z, Wei T, Chen J, Zhang L, Hu S, Shen Z, Yuan T · Sci Rep 2026 · PMID 42249015 · molecular docking + MD simulations (AlphaFold models) · TBPT showed highest SLC22A31 binding affinity (−10.8 kcal/mol) among 6 organic UV filters tested; theoretical signal for possible active-transport cutaneous accumulation; no in-vivo pharmacokinetics data · computational only; interpret with caution · gap/no-mechanism (in-silico binding not confirmed in vivo) ↩
-
Referenced mechanism: UV-driven AP-1/NF-κB/MMP cascade — documented in fisher-1996-photoaging-ap1-mmp; band-agnostic at sub-erythemogenic chronic-exposure doses relevant to daily UV protection. ↩