Octinoxate

Octinoxate (Octyl methoxycinnamate) is a thyroid hormone receptor agonist, reducing the levels of triiodothyronine (T3) and thyroxine (T4) and transcription levels of genes related to type II deiodinase (deio2) in Japanese Medaka. Octinoxate is commonly used as a safe ultraviolet (UV) filter used in the aquatic environment. Octinoxate inhibits CYP1A1 and CYP1B1 to regulate hyaluronan (HA) (HY-B0633A) metabolism in a PI3K pathway-dependent manner in human keratinocytes. Octinoxate also exhibits an anti-estrogenic and anti-androgenic effect in vitro and in vivo^{[1][2][3][4][5]}. In Vitro:Octinoxate (10 μM, 6 h) potentiates the ability of 6-formylindolo[3,2-b]carbazole (FICZ (HY-12451)) (10 nM, 6 h) and ultraviolet radiation (UVR) to activate the Aryl hydrocarbon Receptor (AhR) by elevating CYP1A1 and CYP1B1 mRNA levels in H1L1.1c2 cells and HaCaT cells^[3].
Octinoxate (10 μM, 24 h) decreases catalytic function of both CYP1A1 and CYP1B1 with IC₅₀ values of 1.0 μM and 586 nM respectively, weaker than α-NF in H1L1.1c2 cells^[3].
Octinoxate (30 μM or 50 μM, 24 h) significantly enhances the mRNA expression of the predominant hyaluronan (HA) metabolic enzyme HAS2 and HYAL1, but inhibits the mRNA expression of AQP3 in HaCaT keratinocytes^[4].
Octinoxate acts as a thyroid hormone receptor agonist in HepG2 cells^[5].
In Vivo:Octinoxate (0, 6.9 μg/kg, 96.0 μg/kg and 395.6 μg/kg, fed with pellets, twice a day for 6 weeks) downregulates dio2 and pax8a gene expression, but has no effect on thrα and thrβ expression in the cranial kidney of rainbow trout^[1].
Octinoxate (30 μM, 120 h) significantly decreases T3 and T4 concentrations in zebrafish larvae, upregulating transcriptions of trh, tshβ, tshr, tg, nis and deio2 genes and downregulating transcriptions of trαa, trβ and tpo genes^[2].