The traditional use of tamarind and its health benefits while
the high phenolic content of its seed coat suggest it might be explored as a
skin lightener. For this, we focused on the possible role of the seed coat extract
in inhibiting melanogenesis. The seed coat of tamarind (Tamarindus indica
L.) was extracted with ethyl acetate, which among other solvents recovered highest
phenolic content (85.6±0.9 mg g-1 catechin equivalents-Folin-Ciocalteu
assay). B16-F1 melanoma cells were stimulated by α-melanocyte stimulating
hormone (α-MSH) for 48 h and the extract added after the first 24 h, it
dose-dependently inhibited melanin production by 20-32%. When MSH was added
24 h after the extract, the melanin reduction was about 42-59%. Kojic acid (50
μg mL-1), a well-known hypopigmenting agent had similar effects.
Cell viability and morphology were unaffected by any of the concentration used.
The extract also inhibited tyrosinase activity (IC50 = 152.1±10.2
μg mL-1). This is the first report shows that tamarind seed
coat can inhibit melanogenesis and suggests that further refinements may show
their benefit in hyperpigmentation improvement.