The dorsal skin of animals was exposed to UVB radiation
(Spectronics Corporation XL-1000) three times a week (every other day)for 2 consecutive weeks.
The total energy dose of UVB was 1 J/cm2 per exposure.
The animals were then left for an additional week to allow the UVB-induced hyperpigmentation to stabilize.
Test samples were then topically applied daily to the hyperpigmented areas (2mg/cm2) for 4 successive weeks