Ascorbyl Glucoside
Also known as Ascorbyl Glucoside, AA-2G, Ascorbic Acid 2-Glucoside, 2-O-alpha-D-Glucopyranosyl-L-ascorbic acid, Vitamin C Glucoside
“CIR Expert Panel says: safe as used in cosmetics.”
Ascorbyl Glucoside (AA-2G; CAS 129499-78-1) is a water-soluble, stable glycosylated derivative of L-ascorbic acid (vitamin C) used as an antioxidant and skin-conditioning active in cosmetics. The CIR Expert Panel published a dedicated safety assessment in 2025 (IJT 44(1_suppl):5S-16S, PMID 39513541) covering Ascorbyl Glucoside and Sodium Ascorbyl Glucoside, concluding both are safe in cosmetics in present practices of use and concentration — use data included leave-on applications up to 5% and rinse-off up to 2%. The compound functions as a tyrosinase inhibitor after enzymatic deglycosylation to free ascorbic acid by epidermal alpha-glucosidases, demonstrated to reduce solar lentigo pigmentation in a 24-week double-blind clinical trial. Stability studies confirm optimal preservation at pH 6.4, and dermal delivery research shows effective percutaneous absorption with conversion to ascorbic acid in vivo. No genotoxicity, carcinogenicity, phototoxicity, or significant irritation signals were identified in the safety assessment.
Superior stability vs. ascorbic acid: Ascorbyl Glucoside is stable across a wide pH range (optimal stability at pH 6.4), resistant to oxidation and color change, making it suitable for formulations that cannot accommodate the low-pH requirements of ascorbic acid
Water-soluble vitamin C derivative: compatible with aqueous, gel, and emulsion formulations; does not require anhydrous or oil-phase systems unlike lipophilic derivatives such as Tetrahexyldecyl Ascorbate
Tyrosinase inhibition and depigmentation: after enzymatic deglycosylation to ascorbic acid, inhibits tyrosinase by interacting with copper ions in its active site; 24-week double-blind clinical trial showed significant reduction in solar lentigo pigmentation scores and melanin index (Takada et al., 2024; PMID 39769217)
CIR Expert Panel concluded safe in present practices of use and concentration:5S-16S, 2025), covering 532 commercial formulations with leave-on concentrations up to 5% and rinse-off up to 2%, with no adverse genotoxic, carcinogenic, or phototoxic signals
Ascorbyl Glucoside is highly hydrophilic and only moderately penetrates the stratum corneum passively — more than 90% may remain at the skin surface at 6 hours under standard application; enhanced delivery methods (e.g., photoacoustic waves, microneedles) are under investigation
Functions as a prodrug: antioxidant and depigmenting activity requires in situ hydrolysis by epidermal alpha-glucosidases to release free ascorbic acid; interindividual variation in glucosidase expression may affect efficacy
CIR noted that functioning as a 'skin bleaching agent' is not a recognized cosmetic use in the US; the safety evaluation therefore covered only antioxidant and skin-conditioning functions, not depigmentation
CIR Quick Reference Table (December 2025) — Ascorbyl Glucoside row: Finding=S, Citation=IJT 44(Suppl. 1):5S-16S, 2025
“Ascorbyl Glucoside | S | IJT 44(Suppl. 1):5S-16S, 2025”— QRT-Update-Dec2025.pdf, p. 30