Abstract
Calocedrus formosana (Cupressaceae) is one of the five precious woods of Taiwan. In this study, we investigated the anti-melanogenic activity of C. formosana wood essential oil (CFEO) and its bioactive components in vitro. Initially, CFEO exhibited strong mushroom tyrosinase activity in the cell-free mushroom tyrosinase assay system with an IC50 value of 2.72 µg/mL. Next, treatment with CFEO significantly as well as dose-dependently reduced a combination of α-melanocyte-stimulating hormone and forskolin (α-MSH-FSK)-induced melanin synthesis in B16-F10 cells. Indeed, 80 μg/mL CFEO completely inhibited melanin production, which is similar to that of control cells. Further studies revealed that treatment with CFEO significantly inhibited melanogenesis regulatory proteins, including TRP-1, TRP-2, and MITF, whereas tyrosinase was unaffected by either α-MSH-FSK or CFEO. In addition, the composition of the CFEO was characterized. The major components of CFEO were α-terpineol (23.47%), shonanic acid (10.45%), terpinen-4-ol (12.23%), thymol (5.3%), piperitone (3.44%), berbenone (2.81%), thujic acid (1.65%), and chaminic acid (0.13%). Among them, shonanic acid (1), thujic acid (2), and chaminic acid (3) were uncommon constitutes in essential oils, which could be the index compounds of CFEO, and the structure of these compounds were confirmed by spectral analysis. Furthermore, we found that thymol is an active ingredient responsible for CFEO’s anti-melanogenic activity. Based on these results, we suggest that CFEO or thymol could be a potential candidate for the development of skin whitening products for cosmetic purposes.
Highlights
Melanin is a group of natural pigments found in most living organisms
Tyrosinase is a rate-limiting enzyme involved in melanin production
The reaction rate of tyrosinase that converts L-DOPA into DOPA quinone can be used to evaluate the activity of tyrosinase, which in turn can be used as a screening platform for anti-melanoof tyrosinase, which in turn can be used as a screening platform for anti-melanogenic genic agents
Summary
Cellular melanin is biosynthesized through a complicated process, called melanogenesis, which takes place in the melanosome, an intracellular organelle found within the melanocytes. The melanin-containing melanosomes are transported to the neighboring keratinocytes in the epidermis. Based on melanin concentration in the epidermis, skin color and shade were determined [1]. Regulating melanogenesis is one of the desirable strategies to control hyperpigmentary skin diseases and beauty-enhancing cosmetic purposes. The development of anti-melanogenic agents are important for curing hyperpigmentation for cosmetic, pharamaceutical, and medicinal purposes; this is effective in melanoma therapy, in which melanogenesis and the concentration of melanin level can affect chemo-/radiotherapies and the survival period of patients with melanoma [3]
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