Abstract
The development of antimelanogenic agents is important for the prevention of serious aesthetic problems such as melasmas, freckles, age spots, and chloasmas. In the course of screening for melanin synthesis inhibitors, we found that the culture broth from an insect morphopathogenic fungus, Beauveria bassiana CS1029, exhibits potent antimelanogenic activity. We isolated and purified an active metabolite and identified it as S-(−)-10,11-dihydroxyfarnesoic acid methyl ester (dhFAME), an insect juvenile hormone. To address whether dhFAME inhibits melanin synthesis, we first measured the size of the melanin biosynthesis inhibition zone caused by dhFAME. dhFAME also showed inhibitory activity against mushroom tyrosinase in Melan-a cells. Intracellular, dose-dependent tyrosinase inhibition activity was also confirmed by zymography. In addition, we showed that dhFAME strongly inhibits melanin synthesis in Melan-a cells. Furthermore, we compared levels of TYR, TRP-1, TRP-2, MITF, and MC1R mRNA expression by reverse-transcription polymerase chain reaction and showed that treatment of Melan-a cells with 35 μM dhFAME led to an 11-fold decrease in TYR expression, a 6-fold decrease in TRP-2 expression, and a 5-fold decrease in MITF expression. Together, these results indicate that dhFAME is a potent inhibitor of melanin synthesis that can potentially be used for cosmetic biomaterial(s).
Highlights
Melanin pigment, which contains a combination of melanins, is derived from tyrosine, which is converted to dihydroxyphenylalanine (DOPA), dopaquinone, and dopachrome by tyrosinase and other related enzyme systems [1]
In the course of screening natural compounds for inhibitors of melanin synthesis, we found that a culture broth of Beauveria bassiana CS1029 exhibited potent antimelanogenic activity as determined via an in vitro tyrosinase inhibition assay using B16F10 cells
In the course of screening for antimelanogenic agents, we interestingly found dihydroxyfarnesoic acid methyl ester (dhFAME), an insect juvenile hormone that is produced by Beauveria bassiana
Summary
Melanin pigment, which contains a combination of melanins, is derived from tyrosine, which is converted to dihydroxyphenylalanine (DOPA), dopaquinone, and dopachrome by tyrosinase and other related enzyme systems [1]. P-methoxyphenol, hydroquinone, and kojic acid have been examined as potential whitening agents, as they inhibit melanin synthesis. They are not widely used as, in addition to having weak biological activity, they have adverse effects that are lethal to skin epithelial cells [3]. As melanin pigment contains both types of melanin, the synthesis pathways for both eumelanin and pheomelanin must be inhibited. For efficient inhibition of melanin synthesis, several inhibitors targeting various steps in the synthesis pathway should be used [5]. This report provides evidence of the strong inhibitory activity of this metabolite against melanin synthesis via microphthalmia-associated transcription factor (MITF)-and/or tyrosinase-inhibiting machinery. We showed that dhFAME is a potent inhibitor of melanin biosynthesis
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