Angelica acutiloba Root Extract Improves Hyperpigmentation via the Mechanism of Digestion of Melanosome Complexes

Melanosomes (MSs) are transferred to surrounding keratinocytes (KCs) to form melanin caps above their nuclei, where this process affects skin color. In normal KCs, MS complexes incorporated into lysosomes are degraded by lysosomal enzymes when KCs move to the skin surface through turnover. On the other hand, it has been reported that abnormal accumulation of large MS complexes in basal KCs is observed in senile lentigo. In studies on racial or skin color differences, it has been reported that MSs in KCs from light skin are more rapidly degraded than those from dark skin, and that the activity of cathepsin L2, one of the lysosomal enzymes, is higher in KCs from lightly pigmented, relative to darkly pigmented skins. Based on these reports, we hypothesized that enhancement of lysosome function as the digestive system in highly pigmented KCs could promote the digestion of MS complexes and the dispersion of melanin granules in KCs, leading to improved hyperpigmentation. As a result, we found that Angelica acutiloba root extract could be expected to improve hyperpigmentation via the mechanism of digestion of large melanosome complexes by promoting cathepsin activities.