Inhibition of melanin production and promotion of collagen production by the extract of Kuji amber

Molecular understanding of the therapeutic potential of melanin inhibiting natural products

With the development of society and the improvement of people's living standards, there is an increasing demand for melanin-inhibiting products that prioritize health, safety, and efficacy. Therefore, the development of natural products that can safely and efficiently inhibit melanin synthesis is of great social significance and has significant market potential. In this paper, by reviewing the literature reported in recent years, we summarized the natural products with inhibition of melanin synthesis effects that have been put into or not yet put into the market, and classified them according to the chemical groups of their compounds or the extraction methods of the natural products. Through the summary analysis, we found that these compounds mainly include terpenoids, phenylpropanoids, flavonoids and so on, while the natural product extracts mainly include methanol extracts, ethanol extracts, and aqueous extracts. Their main inhibition of melanin synthesis mechanisms include: (1) direct inhibition of tyrosinase activity; (2) down-regulation of the α-MSH-MC1R, Wnt, NO, PI3K/Akt and MAPK pathways through the expression of MITF and its downstream genes TYR, TRP-1, and TRP-2; (3) antioxidant; (4) inhibition of melanocyte growth through cytotoxicity; (5) inhibition of melanosome production and transport. This paper provides an in-depth discussion on the research progress of whitening natural products and their market value. The aim is to offer guidance for future research and development of natural skin whitening products.

Protective Effect of Amber Extract on Human Dopaminergic Cells against 6-Hydroxydopamine-Induced Neurotoxicity

Parkinson’s disease (PD) is the second most common progressive neurodegenerative disease, after Alzheimer’s disease. In our previous study, we found that amber—a fossilized plant resin—can protect cells from apoptosis by decreasing the generation of reactive oxygen species (ROS). In this study, we focused on the effect of amber on 6-hydroxydopamine-induced cell apoptosis in the human neuroblastoma cell line SHSY5Y (one model for PD). Initially, we determined the protective effect of amber on the PD model. We found that amber extract has a protective effect against 6-hydroxydopamine-induced cell apoptosis. The decrease in ROS, cleaved caspase-3, pERK, and extracellular signal-regulated kinase (ERK) protein levels confirmed that amber extract decreases apoptosis via the ROS-mediated ERK signaling pathway. Furthermore, we determined the effects of amber extract on autophagy. The results showed that amber extract increased the levels of LC3II and Beclin-1, suggesting that amber extract can protect neuronal cells against 6-hydroxydopamine-induced cell apoptosis by promoting autophagy.

Anti-inflammatory activities of amber extract in lipopolysaccharide-induced RAW 264.7 macrophages

Amber is a type of fossil tree resin with several bioactive properties and has been traced in traditional medicines used in Russia and China. However, its anti-inflammatory activities are poorly characterized. Here, the anti-inflammatory effects of the extract of amber mined from Kaliningrad, Russia was investigated in lipopolysaccharide (LPS)-induced RAW 264.7 cells. The effect of the amber extract on cell viability was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay. Further, its effects on the production of intracellular reactive oxygen species (ROS), NO, and inflammatory cytokines were assessed by 2',7'-dichlorodihydrofluorescein diacetate staining, Griess test, and cytokine enzyme-linked immunosorbent assays, respectively. Western blotting and real-time reverse transcription-polymerase chain reaction analysis were performed to assess the mRNA and protein expression levels of the inflammatory cytokines, including tumor necrosis factor-alpha (TNF-α) interleukin-6 (IL-6), cyclooxygenase-2 (COX-2), and inducible nitric oxide synthase (iNOS). The translocation of the nuclear factor-kappa B (NF-κB) p65 subunit was observed by immunofluorescent staining. Amber extract negatively regulated the LPS-induced differentiation of RAW 264.7 cells to dendritic-like cells and reduced the LPS-induced increase in ROS and NO levels. It also reduced the level of mRNA and protein expressions of TNF-α, IL-6, COX-2, and iNOS in LPS-induced RAW 264.7 macrophages, in a dose-dependent manner. Furthermore, amber extract suppressed the nuclear translocation of the NF-κB p65 subunit. These findings suggest that the potent anti-inflammatory effect of the amber extract is mediated by the inhibition of the NF-κB p65 signaling pathway. Collectively, this study renders amber extract as a potential pharmacological alternative to treat inflammation-related diseases.

Role of amber extract in protecting SHSY5Y cells against amyloid β1-42-induced neurotoxicity

Alzheimer disease (AD) is an irreversible, progressive brain disease. Amyloid β plays a critical role in AD development. Some Chinese traditional medicines, such as the fossilized plant resin, amber, have been applied as mental stabilizers. However, the effects of amber on AD pathogenesis remain unknown. Therefore, we aimed to determine the potential of amber extract for treating AD by evaluating its effects on amyloid-β (1-42) (Aβ (1-42))-induced neuronal cell death. We measured levels of ROS, Bcl-2, and Bax mRNA, and found that amber extract decreased Aβ (1-42)-induced cell apoptosis via the reactive oxygen species (ROS)-mediated mitochondrial pathway. Amber extract also decreased β-site amyloid precursor protein cleaving enzyme 1 (BACE1) and increased microtubule-associated proteins 1A/1B light chain 3B (LC3II) and Beclin 1. These findings suggested that amber extract protects neuronal cells against Aβ (1-42)-induced cell apoptosis by upregulating autophagy and downregulating BACE1.