Inhibitory effect of CADI on melanin transfer in the B16F10-HaCAT cells co-culture system and anti-melanogenesis of CNCE in zebrafish

Establishment of an in vitro cell coculture model for investigating the whitening mechanism of Paeonia lactiflora Pall seeds oil

BACKGROUND

In vitro single-cell experiments may yield inconsistent results compared to clinical trials. To enhance the reliability of cosmetic active ingredient screening, a coculture model of B16F10-HaCaT cells was established in vitro based on the structural characteristics of human skin, thereby improving the credibility of experimental outcomes. Currently, most cosmetic whitening additives primarily target simple efficacy goals such as inhibiting tyrosinase activity or melanin transfer. Therefore, investigating novel and efficient whitening additives has become a prominent research focus.

OBJECTIVES

The aim is to establish an in vitro cell coculture model for more reliable experimental results and investigate the mechanism by which Paeonia lactiflora Pall seeds oil inhibits melanin production and transfer.

METHODS

The impact of different concentrations of Paeonia lactiflora Pall seeds oil on cocultured cell proliferation rate was assessed using cck8 assay. Tyrosinase inhibition ability in cocultured cells was tested using levodopa as a substrate. Melanin production inhibition ability in coculture cells was evaluated by lysing cells with sodium hydroxide. The effect of Paeonia lactiflora Pall seeds oil on dendrite-related gene expression levels was examined through qPCR analysis. Additionally, Western blotting was employed to study the effect of Paeonia lactiflora Pall seeds oil on dendrite-related protein expression levels.

RESULTS

Different concentrations of Paeonia lactiflora Pall seeds oil did not affect the proliferation activity of cocultured cells. A specific concentration of α-MSH increased cell tyrosinase activity, cellular melanin content, as well as Rac1, Cdc42, and PAR-2 gene and protein expression related to dendritic formation. Treatment with a certain concentration of Paeonia lactiflora Pall seeds oil resulted in decreased tyrosinase activity and melanin content in cells along with downregulated expression levels of Rac1, Cdc42, and PAR-2 genes and proteins associated with dendritic formation.

CONCLUSIONS

Paeonia lactiflora Pall seeds oil at specific concentrations exhibits the ability to inhibit tyrosinase activity, decrease melanin content, and possesses the potential to impede melanin transfer.

Melanogrit potentiates melanogenesis by escalating cellular tyrosinase activity and MITF levels via pERK inhibition

Vitiligo is characterized by the development of white patches on the skin either due to the loss of functional melanocytes or perturbations in the melanogenesis pathway. In the present study, we investigated the therapeutic potential of herbo-mineral formulation, Melanogrit in neutralizing the white patches in the skin. The study utilized UPLC/MS-QToF technique to determine the diversified phytochemical profile in Melanogrit. The murine B16F10 cells when treated with Melanogrit underwent morphological changes, including increased angularity, enlarged cell size, and greater dendritic protrusions. To establish an equivalent model to study melanogenesis, we carefully optimized the dosage of α-melanocyte stimulating hormone (αMSH) in B16F10 cells as an alternative to using melanocyte-keratinocyte cocultures. The study determined a sub-optimal dose of αMSH (0.2 nM) in B16F10 cells that does not manifest any measurable effects on melanogenesis. In contrast, Melanogrit when used in conjunction with 0.2 nM αMSH, induced a dose-dependent increase in extracellular and intracellular melanin levels. Melanogrit transcriptionally up-regulated the decisive genes of the melanogenesis pathway, MITF, TYR, and TRP1, which was evident from the increased cellular tyrosine activity. Our findings also demonstrated that Melanogrit ameliorated the MITF protein levels by inhibiting pERK; notably without involving GSK3β in the process. Taken together, our findings strongly suggest that Melanogrit has the potential to stimulate melanogenesis, making it a promising candidate for clinical applications in the treatment of white skin patches that develop in vitiligo patients.

Melanin interference toxicity or transgenerational toxicity of organic UV filter ethylhexyl salicylate on zebrafish

With the improvement of human health awareness, the production and usage of sunscreens have increased dramatically, and their active ingredients, organic ultraviolet (UV) filters (OUVFs), have the potential to induce melanin abnormalities in aquatic organisms due to their UV-absorbing properties as they enter the aquatic environment directly with the washing of skin during water activities. In this paper, the melanin interference toxicity or transgenerational toxicity effects of typical OUVFs ethylhexyl salicylate (EHS) on zebrafish (Danio rerio) were investigated based on transcriptomic sequencing technology. Results showed that EHS induced significant enrichment of the melanin-related pathway cAMP signaling pathway in parental skin tissue through UV absorption, with sensitive genes identified as melanocortin 1 receptor, protein kinase A catalytic subunit beta a, calcium/calmodulin-dependent protein kinase II delta 2, adenylate cyclase 1 and G protein subunit alpha I a. qRT-PCR verification results showed that EHS may inhibit the expression of the melanin master regulator microphthalmia-associated transcription factor a (mitfa) and its induced signaling cascade mitf-tyrosinase (tyr)-dopachrome tautomerase (dct)-tyrosinase related protein 1 (tyrp1) by inducing abnormal expression of the above sensitive genes, thereby reducing melanogenesis. After reproduction, the melanin interference effect of EHS on the parents can be carried over to offsprings through maternal inheritance of abnormally expressed mitfa and parental transfer of pollutants, as evidenced by significant enrichment of melanogenesis pathway, abnormal expression of sensitive genes mitfa, tyr, dct and tyrp1b and significant decreases in melanin content and spinal melanin area. These findings revealed the specific melanin interference toxicity of OUVFs with UV-absorbing properties, facilitating a comprehensive ecological risk assessment of OUVFs and providing scientific support for the management of new pollutants.