The Pigment-Making Process
Melanogenesis is the biochemical pathway by which melanocytes — specialised cells in the stratum basale — produce melanin pigment. It's the same process responsible for your natural skin tone, your ability to tan, and the dark spots that form after inflammation or UV damage.
The Tyrosinase Cascade
The key enzyme in melanogenesis is tyrosinase. The simplified pathway:
- L-Tyrosine (amino acid) → converted to DOPA by tyrosinase
- DOPA → converted to dopaquinone by tyrosinase
- Dopaquinone → spontaneously polymerises to form eumelanin (brown-black) or, in the presence of cysteine, phaeomelanin (yellow-red)
UV radiation dramatically upregulates tyrosinase activity — this is why tanning occurs and why unprotected UV exposure causes permanent pigmentation changes.
Why Pigmentation Becomes Uneven
Melanocytes produce pigment in organelles called melanosomes, which are then transferred to surrounding keratinocytes. Uneven pigmentation occurs when:
- Inflammation triggers excess tyrosinase activity (→ Post-Inflammatory Hyperpigmentation)
- Hormonal changes (oestrogen, progesterone) stimulate melanocyte activity (→ Melasma)
- Cumulative UV damage creates permanent tyrosinase upregulation (→ Solar lentigines, sun spots)
Ingredients That Target Melanogenesis
| Ingredient | Mechanism | Evidence |
|---|---|---|
| Kojic Acid | Tyrosinase inhibitor (chelates copper cofactor) | Strong |
| Niacinamide | Inhibits melanosome transfer to keratinocytes | Strong |
| Vitamin C (L-AA) | Reduces dopaquinone back to DOPA; antioxidant | Strong |
| Alpha Arbutin | Competitive tyrosinase inhibitor | Moderate-Strong |
| Tranexamic Acid | Inhibits plasmin-induced prostaglandin synthesis | Strong (melasma) |
| Hydroquinone (Rx) | Direct tyrosinase inhibitor + melanocyte cytotoxic | Very Strong (prescription) |
The most important rule in hyperpigmentation: Every brightening ingredient becomes futile without daily broad-spectrum SPF. UV triggers the tyrosinase cascade — if you treat without protecting, you're fighting against yourself every morning.
For clinical protocols for existing hyperpigmentation, see our full guide on Hyperpigmentation Treatment.