Phytosphingosine
Also known as 4-Hydroxy-D-ribo-sphinganine, 4-Hydroxysphinganine, Phytosphingosine
“No regulator has issued a verdict on this ingredient.”
Phytosphingosine (CAS 554-62-1) is a naturally occurring sphingoid base found in the stratum corneum. It was not present in the CIR Quick Reference Table (2018), indicating no CIR safety assessment has been published. The available peer-reviewed literature supports a favorable skin safety and activity profile: Kim et al. (J Invest Dermatol 2014, PMID 24177187) demonstrated that phytosphingosine and its derivatives suppress TPA-induced skin inflammation via NF-κB, JAK/STAT, and MAPK inhibition in keratinocytes and murine models, with derivatives engineered for lower cytotoxicity than the parent compound — implying native phytosphingosine has notable cytotoxic potential at high concentrations. Choi et al. (Arch Dermatol Res 2017, PMID 28936777) showed phytosphingosine upregulates filaggrin, caspase-14, and bleomycin hydrolase in keratinocytes, promoting NMF production and skin barrier hydration. Jang et al. (J Dermatol Sci 2017, PMID 28390782) demonstrated anti-melanogenic activity through dual suppression of MITF expression and ERK-mediated MITF degradation. Lee et al. (Arch Dermatol Res 2012, PMID 22566145) showed phytosphingosine-1-phosphate (a metabolite) protects human dermal fibroblasts from oxidative stress via PI3K/Akt signaling.
Anti-inflammatory: suppresses NF-κB, JAK/STAT, and MAPK inflammatory pathways in keratinocytes and in vivo skin models (Kim et al. 2014)
Skin barrier and moisturization: stimulates filaggrin biosynthesis and degradation pathway, increasing NMF production and skin hydration (Choi et al. 2017)
Anti-melanogenic: inhibits melanin synthesis via dual MITF suppression mechanisms, potential skin-brightening active (Jang et al. 2017)
Endogenous sphingoid base found naturally in human stratum corneum; replenishes ceramide-pathway precursor pool
- · No formal CIR safety assessment exists as of the 2018 QRT; long-term leave-on safety data at cosmetically-relevant concentrations is not well characterized in the reviewed literature
Kim et al. 2014 notes phytosphingosine derivatives were developed specifically to reduce toxicity relative to native phytosphingosine, suggesting concentration-dependent cytotoxicity is a concern at high doses