Haiyue Pang

Background: Baeckea frutescens L. (BF) has been reported as a potential natural source for skin-whitening agents. However, its antimelanogenic activity and mechanisms remain unclear. Methods: The antimelanogenic effects of BF were evaluated in α-melanocyte-stimulating hormone (α-MSH)-stimulated B16F10 cells and in zebrafish embryos. Cell viability, intracellular tyrosinase activity and melanin content were measured. Western blot (WB) analysis was used to examine melanogenesis-related proteins. Network pharmacology and molecular docking were performed to predict potential targets and interactions of BF-derived metabolites. Results: The ethanolic extract of BF reduced intracellular tyrosinase activity and melanin content in cells without cytotoxicity. Western blot analysis showed decreased expression of microphthalmia-associated transcription factor (MITF) and its downstream melanogenic enzymes, including tyrosinase (TYR), tyrosinase-related protein-1 (TRP-1), and dopachrome tautomerase (DCT). In addition, BF reduced phosphorylation of protein kinase A (PKA), cAMP responsive element-binding protein (CREB) and extracellular signal-regulated kinase (ERK), suggesting potential suppression of PKA/CREB and ERK signaling pathways. These regulatory effects may contribute to MITF downregulation and subsequent inhibition of melanogenesis. BF reduced melanin accumulation in zebrafish embryos. Network pharmacology and molecular docking analyses further suggested that BF-derived metabolites, particularly bayogenin, may interact with multiple melanogenesis-related targets. Conclusions: BF may inhibit melanogenesis through coordinated modulation of multiple signaling pathways and may represent a promising skin-whitening candidate.

Dendrobium officinale exhibits hepatoprotective potential against acetaminophen-induced liver injury (AILI). Fermentation has been proposed as a strategy to enhance the utilization and efficacy of herbal medicines. However, whether yeast fermentation improves the hepatoprotective effects of D. officinale remains unclear. This study investigated whether fermentation of D. officinale flower extract with Saccharomyces cerevisiae (1002S) enhances its protective effects against AILI, compared with a nonfermented extract (DOFE). Hepatoprotective efficacy was evaluated in male C57BL/6 mice, which received 1002S or DOFE (500 mg/kg, oral gavage) for 7 days before an acute acetaminophen challenge. Untargeted metabolomics and network pharmacology analyses were used to characterize fermentation-associated metabolic alterations and to explore potential pathways related to the observed effects. Metabolomic profiling revealed distinct metabolic differences between 1002S and DOFE. Network pharmacology analysis indicated predicted targets of fermentation-associated metabolites were associated with the phosphoinositide 3-kinase (PI3K)/ protein kinase B (Akt) and Janus kinase (JAK)/signal transducer and activator of transcription proteins (STAT) signaling pathways. In vivo, 1002S more effectively alleviated hepatocellular necrosis and significantly reduced serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels. Increased expression of nuclear factor erythroid 2-related factor 2 (Nrf2), superoxide dismutase 2 (SOD2), solute carrier family 7 member 11 (SLC7A11) and glutathione peroxidase 4 (GPX4) was observed in liver tissues. Molecular docking suggested hemsleyanoside may contribute to these effects. Collectively, S. cerevisiae fermentation enhanced the antioxidant and hepatoprotective efficacy of D. officinale flower extract, supporting its potential development for AILI prevention.

L-Theanine, a natural amino acid found in green tea (Camellia sinensis) leaves, is known for its diverse psychotropic effects. This study aimed to evaluate the inhibitory effect of L-theanine on melanin production and uncover its regulatory mechanism. We evaluated the anti-melanogenic activities of L-theanine in vitro and in vivo. In B16F10 murine melanoma cells induced by α-melanocyte-stimulating hormone, melanin content and intracellular tyrosinase activity were determined, and melanogenesis-related protein expression and signaling pathways were analyzed by Western blotting. Melanin reduction was further assessed using the zebrafish (Danio rerio) test. L-Theanine reduced the intracellular tyrosinase activity and melanin content of B16F10 cells. It also attenuated the expression of melanogenesis-related proteins, such as microphthalmia- associated transcription factor, tyrosinase (TYR), TYR-related protein-1, and dopachrome tautomerase. L-Theanine modulated the protein kinase A (PKA), cAMP responder element binding protein (CREB), phosphorylation of/protein kinase B (Akt), glycogen synthase kinase-3β (GSK-3β), and β-catenin. The antimelanogenic activity of L-theanine (<2 mg/mL) was further confirmed using zebrafish larvae. L-Theanine inhibited melanogenesis by downregulating the PKA/CREB and Akt/GSK-3β/β-catenin signaling pathways. In summary, L-theanine shows potential as a skin-whitening compound, warranting further investigation for its possible applications in cosmetic and pharmaceutical products.

L-Theanine, a natural amino acid found in green tea (Camellia sinensis) leaves, is known for its diverse psychotropic effects. This study aimed to evaluate the inhibitory effect of L-theanine on melanin production and uncover its regulatory mechanism. We evaluated the anti-melanogenic activities of L-theanine in vitro and in vivo. In B16F10 murine melanoma cells induced by α-melanocyte-stimulating hormone, melanin content and intracellular tyrosinase activity were determined, and melanogenesis-related protein expression and signaling pathways were analyzed by Western blotting. Melanin reduction was further assessed using the zebrafish embryo test. L-Theanine reduced the intracellular tyrosinase activity and melanin content of B16F10 cells. It also attenuated the expression melanogenesis-related proteins, such as microphthalmia-associated transcription factor, tyrosinase (TYR), TYR-related protein-1, and dopachrome tautomerase. L-Theanine modulated the protein kinase A (PKA), cAMP responder element binding protein (CREB), phosphorylation of /protein kinase B (Akt), glycogen synthase kinase-3β (GSK-3β), and β-catenin. The antimelanogenic activity of L-theanine (<2 mg/mL) was further confirmed using in zebrafsh larvae. L-Theanine inhibited melanogenesis by downregulating the PKA/CREB and Akt/GSK-3β/β-catenin signaling pathways. In summary, the L-theanine can be considered as a skin-whitening compound for use in cosmetic and pharmaceutical products.

The fruit of Rosa laevigata Michx. (FR), a traditional Chinese herb utilized for the treatment of a variety diseases, has notably diverse pharmacological activities including hepatoprotective, anti-oxidant, and anti-inflammatory effects. Despite ongoing research on illustrating the underlying anti-inflammatory mechanism of FR, the principal mechanism remained inadequately understood. In this study, we investigated in depth the molecular mechanism of the anti-inflammatory actions of the ethanol extract of FR (EFR) and its potential targets using lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages in vitro. We showed that EFR effectively ameliorated the overproduction of inflammatory mediators and cytokines, as well as the expression of related genes. It was further demonstrated that LPS-induced activation of nuclear factor kappa B (NF-κB) and mitogen-activated protein kinases (MAPKs) were significantly inhibited by pretreatment with EFR, accompanied by a concomitant decrease in the nuclear translocation of the p65 subunit of NF-κB and activator protein 1 (AP-1). In addition, EFR pretreatment potently prevented LPS-induced decreased phosphorylation of adenosine monophosphate-activated protein kinase (AMPK). Our data also revealed that the activation of AMPK and subsequent inhibition of the mammalian target of the rapamycin (mTOR) signaling pathway was probably responsible for the inhibitory effect of EFR on LPS-induced inflammatory responses, evidenced by reverse changes observed under the condition of AMPK inactivation following co-treatment with the AMPK-specific inhibitor Compound C. Finally, the main components with an anti-inflammatory effect in EFR were identified as madecassic acid, ellagic acid, quinic acid, and procyanidin C1 by LC–MS and testified based on the inhibition of NO production and inflammatory mediator expression. Taken together, our results indicated that EFR was able to ameliorate inflammatory responses via the suppression of MAPKs/NF-κB signaling pathways following AMPK activation, suggesting the therapeutic potential of EFR for inflammatory diseases.

A polyphenol‐enriched fraction (PEF) from Acalypha wilkesiana, whose leaves have been traditionally utilized for the treatment of diverse medical ailments, was investigated for the anti‐inflammatory effect and molecular mechanisms by using lipopolysaccharide‐ (LPS‐) stimulated RAW 264.7 macrophages and acetaminophen‐ (APAP‐) induced liver injury mouse model. Results showed that PEF significantly attenuated LPS‐induced nitric oxide (NO) and prostaglandin E₂ (PGE₂) production and suppressed the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase (COX‐2) in RAW 264.7 macrophages. PEF also reduced the secretion of proinflammatory cytokines including tumor necrosis factor‐α (TNF‐α), interleukin‐ (IL‐) 1β, and IL‐6 in LPS‐stimulated RAW 264.7 macrophages. Moreover, PEF potently inhibited LPS‐induced phosphorylation of mitogen‐activated protein kinases (MAPKs) as well as the activation of nuclear factor‐κB (NF‐κB) by preventing the degradation of inhibitor κB‐α (IκB‐α). In vivo, PEF pretreatment ameliorated APAP‐induced liver injury and hepatic inflammation, as presented by decreased hepatic damage indicators and proinflammatory factors at both plasma and gene levels. Additionally, PEF pretreatment remarkably diminished Toll‐like receptor 3 (TLR3) and TLR4 expression and the subsequent MAPKs and NF‐κB activation. HPLC analysis revealed that two predominantly polyphenolic compounds present in PEF were geraniin and corilagin. These results indicated that PEF has an anti‐inflammatory effect, and its molecular mechanisms may be involved in the inactivation of the TLR/MAPK/NF‐κB signaling pathway, suggesting the therapeutic potential of PEF for inflammatory diseases.