Phyllostachys nigra var. henosis, a domestic bamboo species, has been attracting much\nattention; its bioactive compounds (especially in the leaf) show antioxidant, anti-inflammatory,\nand anti-obesity activities. Little information is available on the antioxidative and anti-melanogenetic\nactivities of the bioactive compounds in bamboo stems. The anti-melanogenic and antioxidative\nactivities of the EtOAc fraction (PN3) of a P. nigra stem extract were investigated in a cell-free system\nand in B16F10 melanoma cells. PN3 consisted of a mixture of flavonoids, such as catechin, chlorogenic\nacid, caffeic acid, and p-coumaric acid. The antioxidant activity (2,2-diphenyl-1-picrylhydrazyl\n(DPPH), 2,2-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS)), and hydroxyl radical\nscavenging) was evaluated, as well as the inhibition of reactive oxygen species (ROS) produced by the\nFenton reaction. PN3 showed in vitro tyrosinase inhibition activity with the half maximal inbihitory\nconcentration (IC50) values of 240 �¼g/mL, and in vivo cytotoxic concentration ranges > 100 �¼g/mL.\nThe protein expression levels and mRNA transcription levels of TYR, TRP-1, and MITF were decreased\nin a dose-dependent manner by the treatment with PN3. PN3 interfered with the phosphorylation of\nintracellular protein kinase A (PKA)/cAMP response element-binding protein (CREB), demonstrating\npotent anti-melanogenic effects. PN3 could inhibit PKA/CREB and the subsequent degradation of\nmicrophthalmia-associated transcription factor (MITF), resulting in the suppression of melanogenic\nenzymes and melanin production, probably because of the presence of flavonoid compounds.\nThese properties make it a candidate as an additive to whitening cosmetics.
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