Melatonin reduces melanogenesis by inhibiting the paracrine effects of keratinocytes

Potent pigmentation inhibitory activity of incensole-enriched frankincense volatile oil-identification, efficacy and mechanism

BACKGROUND

Frankincense volatile oil (FVO) has long been considered a side product in pharmaceutical industry since frankincense of large molecular weight is the prime target. However, the volatile oil recycled in the extract process might contain a series of functional actives, serving as promising ingredients in the cosmetic field.

METHODS

Gas chromatography-mass spectrometer was utilized to determine the species and amount of active ingredients in FVO. Subsequently, zebrafish models were used to evaluate pigmentation inhibition, ROS elimination and neutrophil activation. In vitro DPPH test was also conducted to consolidate the anti-oxidation efficacy. Based on the test results, network pharmacology was incorporated, where GO and KEGG enrichment analyses were performed to discover the interrelations between active ingredients.

RESULTS

About 40 actives molecules were identified, including incensole, acetate incensole, and acetate incensole oxide. The FVO demonstrated great depigmentation activity by suppressing melanin synthesis, as well as providing free radical scavenging and anti-inflammation effect. In network pharmacology analysis, 192 intersected targets were identified. By enrichment analysis and network construction, a series of whitening signal pathways, and hub genes, containing STAT3，MAPK3，MAPK1 were identified.

CONCLUSION

The current study quantified the components of FVO, evaluated its efficacy in skin depigmentation, and give pioneering insights on the possible mechanism. The results confirmed that the FVO could serve as whitening agent in topical uses.

Phenolic acids in Panax ginseng inhibit melanin production through bidirectional regulation of melanin synthase transcription via different signaling pathways

Background

Our previous investigation indicated that the preparation of Panax ginseng Meyer (P. ginseng) inhibited melanogenesis. It comprised salicylic acid (SA), protocatechuic acid (PA), p-coumaric acid (p-CA), vanillic acid (VA), and caffeic acid (CA). In this investigation, the regulatory effects of P. ginseng phenolic acid monomers on melanin production were assessed.

Methods

In vitro and in vivo impact of phenolic acid monomers were assessed.

Results

SA, PA, p-CA and VA inhibited tyrosinase (TYR) to reduce melanin production, whereas CA had the opposite effects. SA, PA, p-CA and VA significantly downregulated the melanocortin 1 receptor (MC1R), cycle AMP (cAMP), protein kinase A (PKA), cycle AMP-response element-binding protein (CREB), microphthalmia-associated transcription factor (MITF) pathway, reducing mRNA and protein levels of TYR, tyrosinase-related protein 1 (TYRP1), and TYRP2. Moreover, CA treatment enhanced the cAMP, PKA, and CREB pathways to promote MITF mRNA level and phosphorylation. It also alleviated MITF protein level in α-MSH-stimulated B16F10 cells, comparable to untreated B16F10, increasing the expression of phosphorylation glycogen synthase kinase 3β (p-GSK3β), β-catenin, p-ERK/ERK, and p-p38/p38. Furthermore, the GSK3β inhibitor promoted p-GSK3β and p-MITF expression, as observed in CA-treated cells. Moreover, p38 and ERK inhibitors inhibited CA-stimulated p-p38/p38, p-ERK/ERK, and p-MITF increase, which had negative binding energies with MC1R, as depicted by molecular docking.

Conclusion

P. ginseng roots' phenolic acid monomers can safely inhibit melanin production by bidirectionally regulating melanin synthase transcription. Furthermore, they reduced MITF expression via MC1R/cAMP/PKA signaling pathway and enhanced MITF post-translational modification via Wnt/mitogen-activated protein kinase signaling pathway.

Natural Retinol Analogs Potentiate the Effects of Retinal on Aged and Photodamaged Skin: Results from In Vitro to Clinical Studies

INTRODUCTION

Plants are a source of natural ingredients with retinol-like properties that can deliver anti-aging benefits without the side effects typically associated with retinoid use. We hypothesized that by combining two such analogs, bakuchiol (BAK) and Vigna aconitifolia extract (VAE), with the potent retinoid retinal (RAL), the anti-photoaging potential of RAL could be enhanced without compromising its skin irritation profile. The purpose of this study was to demonstrate that BAK and VAE potentiate the anti-photoaging activity of RAL.

METHODS

Gene expression profiling of full-thickness reconstructed skin was first used to examine the impact of BAK or VAE in combination with RAL on skin biology. Next, the irritative potential of this combination, and its capacity to reverse key signs of photoaging in an ex vivo model was assessed. Finally, a proof-of-concept open label clinical study was performed to evaluate the anti-photoaging capacity and skin compatibility of a cosmetic formulation (tri-retinoid complex; 3RC) containing this complex in combination with other well characterized anti-photoaging ingredients.

RESULTS

In vitro profiling suggested that combining 0.1% RAL with BAK or VAE potentiates the effect of RAL on keratinocyte differentiation and skin barrier function without affecting its skin irritation profile. When formulated with other anti-photoaging ingredients, such as niacinamide and melatonin, 3RC reversed ultraviolet radiation-induced deficits in structural components of the dermal extracellular matrix, including hyaluronic acid and collagen. In vivo, it led to a reversal of clinical signs of age and photodamage, with statistically significant improvement to skin firmness (+5.6%), skin elasticity (+13.9%), wrinkle count (-43.2%), and skin tone homogeneity (+7.0%), observed within 28 days of once nightly use. Notably, the number of crow's feet wrinkles was reduced in 100% of subjects. Furthermore, 3RC was very well tolerated.

CONCLUSION

These data suggest that 3RC is a highly effective and well-tolerated treatment for photoaging.

Combine with RNA-seq Reveals the Effect of Melatonin in the Synthesis of Melanin in Primary Melanocytes of Silky Fowls Black-Bone Chicken

(1) Background: It was found that the melanin of black-bone chicken has various effects such as scavenging DPPH free radicals and anti-oxidation, and the synthesis of melanin is affected by various factors including hormones. In addition, several studies have found that melatonin affects the melanoma cell synthesis of melanin, which has not been reported in chicken primary melanocytes; so, relevant studies were conducted. (2) Methods: In this study, chicken primary melanocytes were isolated and characterized, and then melanocytes were treated with different concentrations of melatonin to investigate the effects of melatonin on melanin synthesis in chicken melanocytes in terms of melanin synthesis-related genes, melanin content, and tyrosinase activity, and combined with RNA seq to detect the change in gene expression level of chicken melanocytes after melatonin treatment. (3) Results: We isolated and characterized primary melanocytes, and indirect immunofluorescence assay results showed positive melanocyte marker genes. RT-qPCR results showed that melatonin decreased the expression of melanin synthesis-related genes. In addition, melatonin reduced the melanin content and decreased the tyrosinase activity of melanocytes in the treated group. A total of 1703 differentially expressed genes were screened by RNA-seq, and in addition, in the KEGG results, the signaling pathway associated with melanin synthesis, and the mTOR signaling pathway were enriched. (4) Conclusions: Melatonin could decrease the synthesis of melanin in chicken primary melanocytes.