Science
Mechanism of Action
This ingredient functions as a potent antioxidant and radical scavenger, notably when incorporated into peptides like GHK, forming GthioHK. It actively prevents oxidative damage by inhibiting the formation of reactive oxygen and carbonyl species. Additionally, Thiohistidine effectively chelates redox-active metals such as Cu(II) and Fe(II), further reducing oxidative stress. As a histidine analogue, it may also contribute to metal regulation and potentially bolster skin barrier function and hydration.
Research
Clinical Evidence
Low confidenceN/A
Transparency
Dusting Analysis
Thiohistidine, particularly in its peptide-incorporated form, shows strong in vitro antioxidant potential. There is no current evidence to suggest it is overhyped or used in formulations at ineffective concentrations merely for marketing claims.
The Formula
Formulation
Stability
Solutions of thiohistidine-containing peptides demonstrate stability in buffered saline at physiological pH (around 7.2) for at least 48 hours at room temperature in the dark. Stability for similar histidine-containing structures typically ranges between pH 7.0-7.4, with destabilization observed below pH 6.8 due to imidazole ring protonation. Pure 2-thioHis may precipitate from aqueous solutions at pH 6.5, suggesting pH-dependent solubility, but its behavior in a formulated peptide context might be more stable within the optimal pH range.
Conflicts
- Harsh processing conditions (organic solvents, shear stress, temperature fluctuations)
- Certain excipients, particularly those containing impurities like formaldehyde (based on analogue histidine sensitivity)
- High temperature, humidity, and pressure during compression (similar to other sulfur-containing amino acids)
Safety
Safety Profile
No direct safety assessments for Thiohistidine as a cosmetic ingredient by regulatory bodies like CIR, SCCS, or FDA were found. While the safety of histidine has been studied, this does not directly extrapolate to its thio-analogue in topical applications. Therefore, its specific safety profile for cosmetic use remains largely undetermined.
Your Skin
Skin Compatibility
Our Assessment
Verdict
Thiohistidine demonstrates compelling in vitro antioxidant and radical scavenging potential, particularly when integrated into peptides, but further in vivo research and comprehensive safety assessments are required to fully establish its clinical efficacy and cosmetic utility.
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References
Sources