The aim of this study was to clarify the melanogenesis-inhibitory and
antioxidant activity of Thai breadfruit's heartwood extract for application as a skin-lightening agent. The heartwood of breadfruit (Artocarpus incisus ) grown in Phitsanulok Province, Thailand, was extracted by using
diethyl ether or
methanol. The amount of
artocarpin, a major component of A. incisus extract, was determined by using the HPLC method. The
artocarpin content found in
ether extract was 45.19 +/- 0.45% w/w, whereas that in
methanol extract was 19.61 +/- 0.05% w/w. The
ether extract was then evaluated for
tyrosinase-inhibitory, melanogenesis-inhibitory, and
antioxidant activities. The
tyrosinase-inhibitory activity was tested in vitro by monitoring the inhibition of the extract against the formation of
DOPAchrome by
tyrosinase enzyme. The results showed that the
tyrosinase-inhibitory activity of the extract was in a dose-dependent manner. The obtained IC50 value was 10.26 +/- 3.04 microg/ml, while
kojic acid, a well-known
tyrosinase inhibitor, provided an IC50 of 7.89 +/- 0.18 microg/ml. Melanocyte B16F1
melanoma cells (ATCC No. CRL-6323) were then used for determination of the melanogenesis-inhibitory activity of the extract, comparing it to
hydroquinone,
kojic acid, and purified
artocarpin. The amount of
melanin produced by the cells was monitored by measuring an absorbence at 490 nm. The obtained results indicated that A. incisus extract at a concentration of 2 to 25 microg/ml was able to decrease the
melanin production of the melanocyte B16F1 cells. The obtained micrograph also confirmed that the extract did not change the cell morphology but reduced the
melanin content by inhibiting
melanin synthesis, whereas the purified
artocarpin at a concentration of 4.5 microg/ml caused changes in cell morphology. Additionally, the extract exhibited
antioxidant activity in a dose-dependent manner at an EC50 of 169.53 +/- 9.73 microg/ml, according to DPPH assay. The obtained results indicated that the
ether extract of A. incisus 's heartwood has the potential of acting as a skin-lightening agent for application in
cosmetics.