Quick Comparison
| Alpha Arbutin | Kojic Acid | |
|---|---|---|
| Typical Concentration | Concentrations: 1-2%. Apply morning and/or night. Can be combined with vitamin C and niacinamide for enhanced brightening. Results visible at 8-12 weeks. More effective when combined with acids or retinoids that increase cell turnover. | Concentrations: 1-4%. Kojic dipalmitate is a more stable ester form but less potent. Apply once or twice daily. Often combined with other brightening agents (arbutin, vitamin C, niacinamide). Results visible at 4-8 weeks. |
| Application | Topical (serum, cream). Water-soluble. Apply before oils/occlusives. | Topical (serum, cream). Store in airtight, opaque packaging. Discard if the product turns brown. |
| Research Papers | 10 papers | 10 papers |
| Categories |
Mechanism of Action
Alpha Arbutin
Alpha arbutin (4-hydroxyphenyl-alpha-D-glucopyranoside) is a glycosylated hydroquinone with glucose bound to the para position. Alpha-glucosidase and other glycosidases slowly hydrolyze the bond, releasing hydroquinone in controlled low concentrations—avoiding peak levels that cause irritation and ochronosis. Released hydroquinone inhibits tyrosinase by competing with tyrosine and through copper chelation at the catalytic center, reducing L-DOPA to dopaquinone conversion. The alpha anomer provides greater stability and skin penetration than beta arbutin. May also inhibit melanosome maturation. Gradual release creates sustained low-dose tyrosinase inhibition that brightens over 8-12 weeks with minimal side effects.
Kojic Acid
Kojic acid (5-hydroxy-2-hydroxymethyl-4H-pyran-4-one) inhibits tyrosinase through copper chelation—tyrosinase is a type-3 copper enzyme requiring two copper ions to catalyze tyrosine to L-DOPA and L-DOPA to dopaquinone. By sequestering copper, kojic acid renders tyrosinase inactive. May also inhibit tyrosinase-related protein-1 (TRP-1). Exhibits direct antioxidant activity, scavenging superoxide and hydroxyl radicals. Relatively unstable—oxidizes with air and light, forming brown degradation products that lose activity; opaque, airtight packaging and low pH improve stability. Kojic dipalmitate is a more stable ester but requires enzymatic cleavage, reducing potency. Contact sensitization can develop with prolonged use.
Risks & Safety
Alpha Arbutin
Common
Very well-tolerated. Occasionally mild irritation.
Serious
None documented at cosmetic concentrations.
Rare
Allergic contact dermatitis.
Kojic Acid
Common
Contact sensitization (developing an allergy over time with repeated use), redness, irritation.
Serious
Contact dermatitis in sensitized individuals.
Rare
Paradoxical darkening in very sensitive skin types.
Full Profiles
Alpha Arbutin →
A naturally derived tyrosinase inhibitor extracted from bearberry, cranberry, and blueberry plants. Alpha arbutin slowly releases hydroquinone in a controlled manner within the skin to lighten hyperpigmentation safely. It is significantly gentler than direct hydroquinone application while providing meaningful brightening over time. One of the safest and most effective brightening ingredients available.
Kojic Acid →
A natural brightening agent produced as a byproduct of sake and soy sauce fermentation. Kojic acid inhibits tyrosinase by chelating copper, which is required for the enzyme's active site. It is one of the most effective OTC alternatives to hydroquinone for treating hyperpigmentation, melasma, and age spots, though it is less stable in formulation and can cause contact sensitization over time.