Melanin protects the skin against UV damage, whereas excessive melanin accumulation causes abnormal pigmentation and even melanoma. It has been reported that Rosa rugosa exhibits antioxidant, anti-bacterial, anti-tumor, and anti-inflammation activities. The current study evaluated the melanogenesis-suppressing effect of R. rugosa extract and its solvent fractions (H2O, n-BuOH, 85% aq. MeOH, and n-hexane). The effect of R. rugosa on the extra/intra-cellular melanin and intracellular active tyrosinase levels, melanogenesis-related gene and protein expression, and PKA/CREB signaling pathway activation was investigated in α-MSH-induced B16F10 cells. The results showed that R. rugosa effectively suppressed melanin secretion and tyrosinase activity at non-cytotoxic concentrations. R. rugosa extract down-regulated the melanogenesis-related expression of genes and proteins of tyrosinase, microphthalmia-associated transcription factor (MITF), tyrosinase-related protein (TRP)-1, and TRP-2. Furthermore, R. rugosa effectively inhibited the phosphorylation of the PKA/CREB proteins. Finally, the total polyphenol content of R. rugosa crude extract and its H2O, n-BuOH, 85% aq. MeOH, and n-hexane solvent fractions were 1383.9 ± 44.5, 2004.7 ± 43.4, 7270.3 ± 54.5, 2064.1 ± 34.8, and 1091.1 ± 26.2 mg gallic acid equivalent/100 g extract, respectively. The anti-melanogenesis effect of R. rugosa was suggested to be exhibited by downregulating the PKA/CREB signaling pathway potentially due to a high content of polyphenols. Overall, R. rugosa crude extract and its solvent fractions could be considered sources of bioactive ingredients that can be used against hyperpigmentation.

Quercetin 3-O-galactoside (Q3G) is a common dietary flavanol that has been shown to possess several bioactivities, including anti-melanogenesis. However, how Q3G exerts its anti-melanogenic effect has not been studied. The current study, therefore aimed to investigate the anti-melanogenesis potential of Q3G and elucidate the underlying action mechanism in α-melanocyte-stimulating hormone (α-MSH)-induced hyperpigmentation model of B16F10 murine melanoma cells. Results showed that α-MSH stimulation significantly increased tyrosinase (TYR) and melanin production, which were significantly downregulated by Q3G treatment. The treatment with Q3G suppressed the transcriptional and protein expressions of melanogenesis-related enzymes TYR, tyrosinase related protein-1 (TRP-1), and TRP-2, along with the melanogenic transcription factor microphthalmia-associated transcription factor (MITF) in B16F10 cells. It was shown that Q3G downregulated MITF expression and suppressed its transcriptional activity by inhibiting the cAMP-dependent protein kinase A (PKA)-mediated activation of CREB and GSK3β. In addition, MAPK-regulated MITF activation signaling was also involved in the inhibition of melanin production by Q3G. The results suggest that the anti-melanogenic properties of Q3G rationalize further studies in vivo to confirm its action mechanism and consequent utilization as a cosmetic ingredient against hyperpigmentation.

Skin color is determined by melanin distributed in the skin, hair, eye, heart, and brain. Melanin protects the skin against ultraviolet and scavenges the cellular reactive oxygen species. However, the abnormal accumulation of melanin induces hyperpigmentation diseases such as melisma, freckles, etc. Recent studies have focused on discovering plant-origin whitening agents against hyperpigmentation with fewer side effects and higher biocompatibility. Salt marsh plants have unique functional secondary metabolites that are not present in land plants due to their special habitat conditions comprising mixed inorganic salts and organic substances. Artemisia littoricola is a halophyte classified as belonging to the division Magnoliophyta, class Magnoliopsida, order Asterales, family Asteraceae, and genus Artemisia. It is expected that by cultivating and collecting this plant, large amounts of raw material can be procured for the cosmetic industry. This study examines the crude extract and solvent-fractionated extracts of A. littoricola (H2O, n-butanol, 85% aq. MeOH, and n-hexane) and evaluates the inhibition of melanogenesis in B16F10 murine melanoma cells. The crude extract and solvent fractions of A. littoricola inhibited the oxidation of tyrosine and L-DOPA in a concentration-dependent manner, indicating an inhibitory effect on melanin production. All extracts also inhibited the expression of proteins responsible for melanin synthesis, namely TRP-1 and TRP-2. Results of the current study reveal the anti-melanogenic properties of A. littoricola and indicate the potential application as a natural source of cosmeceutical agents with skin-whitening effects.