Abstract
Phyllostachys nigra var. henosis, a domestic bamboo species, has been attracting much attention; its bioactive compounds (especially in the leaf) show antioxidant, anti-inflammatory, and anti-obesity activities. Little information is available on the antioxidative and anti-melanogenetic activities of the bioactive compounds in bamboo stems. The anti-melanogenic and antioxidative activities of the EtOAc fraction (PN3) of a P. nigra stem extract were investigated in a cell-free system and in B16F10 melanoma cells. PN3 consisted of a mixture of flavonoids, such as catechin, chlorogenic acid, caffeic acid, and p-coumaric acid. The antioxidant activity (2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS)), and hydroxyl radical scavenging) was evaluated, as well as the inhibition of reactive oxygen species (ROS) produced by the Fenton reaction. PN3 showed in vitro tyrosinase inhibition activity with the half maximal inbihitory concentration (IC50) values of 240 μg/mL, and in vivo cytotoxic concentration ranges > 100 μg/mL. The protein expression levels and mRNA transcription levels of TYR, TRP-1, and MITF were decreased in a dose-dependent manner by the treatment with PN3. PN3 interfered with the phosphorylation of intracellular protein kinase A (PKA)/cAMP response element-binding protein (CREB), demonstrating potent anti-melanogenic effects. PN3 could inhibit PKA/CREB and the subsequent degradation of microphthalmia-associated transcription factor (MITF), resulting in the suppression of melanogenic enzymes and melanin production, probably because of the presence of flavonoid compounds. These properties make it a candidate as an additive to whitening cosmetics.
Highlights
Melanin, composed of pheomelanin and eumelanin, is synthesized in the melanosomes of melanocytes [1]
PN3 induced a significant suppression in mRNA expression levels of TYR and TRP-1 via microphthalmia-associated transcription factor (MITF) downregulation, which was caused by reduced intracellular cAMP levels. These results revealed that the inhibitory mechanism of PN3 on melanogenesis involves the cAMP–protein kinase A (PKA), and cAMP response element-binding protein (CREB)–MITF–TYR pathways
Phospho-PKA and phospho-CREB antibodies were provided by Cell Signaling (Danvers, MA, USA). α-Melanocyte-stimulating hormone (α-MSH), dimethyl sulfoxide (DMSO), sodium nitrite, and an antibody against β-actin were obtained from Sigma Aldrich
Summary
Melanin, composed of pheomelanin and eumelanin, is synthesized in the melanosomes of melanocytes [1]. Synthesized melanin is located in the skin, hair, and eyes, determines skin color and protects from UV damage. The abnormal synthesis of melanin causes skin conditions such as albinism, melasma, freckles, and post-inflammatory hyperpigmentation. In the first two steps of melanin biosynthesis, tyrosinase (EC 1.14.18.1) is the key enzyme in catalyzing the hydroxylation of L-tyrosine to 3,4-dihydroxyphenylalanine (DOPA) and the oxidation of DOPA to dopaquinone. The inhibition of tyrosinase activity may be considered as an important role in the development of whitening cosmetics. Many researchers have been trying to develop new whitening cosmetics with natural compounds including phytochemicals, such as polyphenol, flavonoids, Icnot.sJm. Meotil.cSsciw. I2t0h18n, 1a9t,u4r0a9l compounds including phytochemicals, such as polyphenol, flavonoids, oafn1d8 carotenoids. Mchoorleeostveerro,lbcaomnbteonot sitnemtheexfetrcaecstsofamraetsliotrreaateteddfawttiythliavehrigdhis-feaatsde iaent.dTihnecsreealsipedidt-hloewcheroilnegsteefrfoelcctsonwteenret iantttrhibeufteecdestoofthraetsinthreibatiteidonwoitfhcahohliegshte-fraotl daibets.orTphteiosne l[i3p]i.dF-luorwtheerirnmgoereff,ecthtsewaeceretyalctthroibliunteedcotonttehnet iinshhibigithioinn obfamchbooloesstteermolsa; bascoetrypltcihoonli[n3e]. iFs uarnthimerpmoortraen, tthneeuarcoettryalnchsmoliitnteercionntthenetchisohliingehrginic bnaemrvboouos sstyesmtesm; acoeftyvlecrhteoblirnaeteiss aanndimipnosertcatns t[n4e].urIontrtahnesmlaitstterfeinwthyeeachrso,lisnteurdgiiecsneornvotuhsesybsatmembooof vsetertmebrhaatvese abnedeninmseocststly[4]f.oIcnusthede laosnt fietws aynetaiorxs,idsatundt,iecshoonlesthteerobla-lmowboeorinstge,manhdavfeatb-ereednumcionsgtlyabfiolictuiesse.dToonoiutsr aknntoiowxlieddagnet,, chhoowleesvteerr,olt-hloerweearirnegn, aonrdepfaotr-trseodnuctihnegeafbfeiclittioefs.bTaomobuoroksnteomwleexdtgraec,thsocwonetvaeinr,itnhgermeaanrey nfloavroenpooirdtss ownitthhereesfpfeecctt toof bboathmabnotoiosxtiedmanetxatnrdacatsntcio-mntealianninoggemneasnisyaflcativvoitnieosid. sTwheirtheforersep, etchtistosbtuodthy aidnetinotxifiideasntthaendmaanjotri-mcoemlapnoougnedneasinsdacmtievcihtiaens.isTmheorfetfhoerea,nthtii-smsetuladnyogideennestiifis eesfftehcet omfaajobracmobmopoosutenmd aenxtdramcte.chanism of the anti-melanogenesis effect of a bamboo stem extract
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