Apigenin (4′,5,7-trihydroxyflavone, flavonoid) is a phenolic compound that is known to reduce the risk of chronic disease owing to its low toxicity. The first study on apigenin analyzed its effect on histamine release in the 1950s. Since then, anti-mutation and antitumor properties of apigenin have been widely reported. In the present study, we evaluated the apigenin-mediated amelioration of skin disease and investigated its applicability as a functional ingredient, especially in cosmetics. The effect of apigenin on RAW264.7 (murine macrophage), RBL-2H3 (rat basophilic leukemia), and HaCaT (human immortalized keratinocyte) cells were analyzed. Apigenin (100 μM) significantly inhibited nitric oxide (NO) production, cytokine expression (interleukin (IL)-1β, IL6, cyclooxygenase (COX)-2, and inducible nitric oxide synthase [iNOS]), and phosphorylation of mitogen-activated protein kinase (MAPK) signal molecules, including extracellular signal-regulated kinase (ERK) and c-Jun N-terminal protein kinase (JNK) in RAW264.7 cells. Apigenin (30 μM) also inhibited the phosphorylation of signaling molecules (Lyn, Syk, phospholipase Cγ1, ERK, and JNK) and the expression of high-affinity IgE receptor FcεRIα and cytokines (tumor necrosis factor (TNF)-α, IL-4, IL-5, IL-6, IL-13, and COX-2) that are known to induce inflammation and allergic responses in RBL-2H3 cells. Further, apigenin (20 μM) significantly induced the expression of filaggrin, loricrin, aquaporin-3, hyaluronic acid, hyaluronic acid synthase (HAS)-1, HAS-2, and HAS-3 in HaCaT cells that are the main components of the physical barrier of the skin. Moreover, it promoted the expression of human β-defensin (HBD)-1, HBD-2, HBD-3, and cathelicidin (LL-37) in HaCaT cells. These antimicrobial peptides are known to play an important role in the skin as chemical barriers. Apigenin significantly suppressed the inflammatory and allergic responses of RAW264.7 and RBL cells, respectively, and would, therefore, serve as a potential prophylactic and therapeutic agent for immune-related diseases. Apigenin could also be used to improve the functions of the physical and chemical skin barriers and to alleviate psoriasis, acne, and atopic dermatitis.

Saponarin{5-hydroxy-2-(4-hydroxyphenyl)-6-[3,4,5-trihydroxy-6-(hydroxymethyl)oxan-2-yl]-7-[3,4,5-trihydroxy-6-(hydroxymethyl)oxan-2-yl]oxychromen-4-one}, a flavone found in young green barley leaves, is known to possess antioxidant, antidiabetic, and hepatoprotective effects. In the present study, the anti-inflammatory, anti-allergic, and skin-protective effects of saponarin were investigated to evaluate its usefulness as a functional ingredient in cosmetics. In lipopolysaccharide-induced RAW264.7 (murine macrophage) cells, saponarin (80 μM) significantly inhibited cytokine expression, including tumor necrosis factor (TNF)-α, interleukin (IL)-1β, inducible nitric oxide synthase, and cyclooxygenase (COX)-2. Saponarin (80 μM) also inhibited the phosphorylation of extracellular signal-regulated kinase (ERK) and p38 involved in the mitogen-activated protein kinase signaling pathway in RAW264.7 cells. Saponarin (40 μM) significantly inhibited β-hexosaminidase degranulation as well as the phosphorylation of signaling effectors (Syk, phospholipase Cγ1, ERK, JNK, and p38) and the expression of inflammatory mediators (tumor necrosis factor [TNF]-α, IL-4, IL-5, IL-6, IL-13, COX-2, and FcεRIα/γ) in DNP-IgE- and DNP-BSA-stimulated RBL-2H3 (rat basophilic leukemia) cells. In addition, saponarin (100 μM) significantly inhibited the expression of macrophage-derived chemokine, thymus and activation-regulated chemokine, IL-33, thymic stromal lymphopoietin, and the phosphorylation of signaling molecules (ERK, p38 and signal transducer and activator of transcription 1 [STAT1]) in TNF-α- and interferon (IFN)-γ-stimulated HaCaT (human immortalized keratinocyte) cells. Saponarin (100 μM) also significantly induced the expression of hyaluronan synthase-3, aquaporin 3, and cathelicidin antimicrobial peptide (LL-37) in HaCaT cells, which play an important role as skin barriers. Saponarin remarkably inhibited the essential factors involved in the inflammatory and allergic responses of RAW264.7, RBL-2H3, and HaCaT cells, and induced the expression of factors that function as physical and chemical skin barriers in HaCaT cells. Therefore, saponarin could potentially be used to prevent and relieve immune-related skin diseases, including atopic dermatitis.

Light plays vital roles in fungal growth, development, reproduction, and pigmentation. In Flammulina velutipes, the color of the fruiting body exhibits distinct changes in response to light; however, the underlying molecular mechanisms remain unknown. Therefore, in this study, we aimed to analyze the F. velutipes transcriptome under red, green, and blue light-emitting diode (LED) lights to identify the key genes affecting the light response and fruiting body color in this fungus. Additionally, we conducted protein–protein interaction (PPI) network analysis of the previously reported fruiting body color-related gene, Fvpal1, to identify the hub genes. Phenotypic analysis revealed that fruiting bodies exposed to green and blue lights were darker than those untreated or exposed to red light, with the color intensifying more after 48 h of exposure to blue light compared to that after 24 h of exposure. Differentially expressed gene (DEG) analyses of all light treatments for 24 h revealed that the numbers of DEGs were 17, 74, and 257 under red, green, and blue lights, respectively. Subsequently, functional enrichment analysis was conducted of the DEGs identified under green and blue lights, which influenced the color of F. velutipes. In total, 103 of 168 downregulated DEGs under blue and green lights were included in the enrichment analysis. Among the DEGs enriched under both green and blue light treatments, four genes were related to monooxygenases, with three genes annotated as cytochrome P450s that are crucial for various metabolic processes in fungi. PPI network analysis of Fvpal1 revealed associations with 11 genes, among which the expression of one gene, pyridoxal-dependent decarboxylase, was upregulated in F. velutipes exposed to blue light. These findings contribute to our understanding of the molecular mechanisms involved in the fruiting body color changes in response to light and offer potential molecular markers for further exploration of light-mediated regulatory pathways.

In nature; Flammulina velutipes, also known as winter mushrooms, vary in the color of their fruiting bodies, from black, yellow, pale yellow, or beige to white. The purpose of this study was to compare the genome sequences of different colored strains of F. velutipes and to identify variations in the genes associated with fruiting body color. Comparative genomics of six F. velutipes strains revealed 70 white-strain-specific variations, including single nucleotide polymorphisms (SNPs) and insertions/deletions (indels), in the genome sequences. Among them, 36 variations were located in the open reading frames, and only one variation was identified as a mutation with a disruptive in-frame deletion (ΔGCGCAC) within the annotated gene phenylalanine ammonia-lyase 1 (Fvpal1). This mutation was found to cause a deletion, without a frameshift, of two amino acids at positions 112 and 113 (arginine and threonine, respectively) in the Fvpal1 gene of the white strain. Specific primers to detect this mutation were designed, and amplification refractory mutation system (ARMS) polymerase chain reaction (PCR) was performed to evaluate whether the mutation is color specific for the F. velutipes fruiting body. PCR analysis of a total of 95 F. velutipes strains revealed that this mutation was present only in white strains. In addition, monospores of the heterozygous mutant were isolated, and whether this mutation was related to the color of the fruiting body was evaluated by a mating assay. In the mating analysis of monospores with mutations in Fvpal1, it was found that this mutation plays an important role in determining the color of the fruiting body. Furthermore, the deletion (Δ¹¹²RT¹¹³) in Fvpal1 is located between motifs that play a key role in the catalytic function of FvPAL1. These results suggest that this mutation can be used as an effective marker for the color-specific breeding of F. velutipes, a representative edible mushroom.

Ganoderma lucidum, a member of the Basidiomycetes family, is attracting attention for its medicinal potential due to its biological activity and the presence of numerous bioactive compounds. Although it is known that extracts of this mushroom inhibit melanin production, there are few reports on a single substance associated with this effect. In this study, we identified ganodermanontriol (GT), a novel compound from G. lucidum, that effectively inhibited melanin biosynthesis in B16F10 cells. GT inhibits melanin production by suppressing the expression of cellular tyrosinase proteins and microphthalmia-related transcription factor (MITF). Furthermore, GT affects the phosphorylation of cyclic adenosine monophosphate (cAMP) response element-binding protein (CREB) and mitogen-activated protein kinase (MAPK) signaling molecules, which are involved in melanogenesis in B16F10 cells. Finally, the biosynthesis of GT and other substances by G. lucidum was evaluated using HPLC analysis. Thus, this study revealed the mechanism by which GT in G. lucidum inhibits melanin production in B16F10 cells, and these findings will contribute to promoting the potential use of this mushroom in the future.

Flammulina velutipes is a widely cultivated edible mushroom in East Asia, recognized for its nutritional benefits and distinct morphology characterized by a long stipe and a compact, hemispherical pileus. The pileus not only plays a critical biological role in reproduction through spore formation but also serves as a key commercial trait influencing consumer preference and market value. Despite its economic importance, pileus development in F. velutipes is highly sensitive to environmental factors, among which carbon dioxide (CO₂) concentration is particularly influential under indoor cultivation conditions. While previous studies have reported that elevated CO₂ levels can inhibit pileus expansion in other mushroom species, the molecular mechanisms by which CO₂ affects pileus growth in F. velutipes remain poorly understood. In this study, we investigated the impact of CO₂ concentration on pileus morphology and gene expression in F. velutipes by cultivating fruiting bodies under two controlled atmospheric conditions: low (1000 ppm) and high (10,000 ppm) CO₂. Morphometric analysis revealed that elevated CO₂ levels significantly suppressed pileus expansion, reducing the average diameter by more than 50% compared to the low CO₂ condition. To elucidate the underlying genetic response, we conducted RNA sequencing and identified 102 differentially expressed genes (DEGs), with 78 being downregulated under elevated CO₂. Functional enrichment analysis highlighted the involvement of cyclin-dependent protein kinase regulatory pathways in this response. Two cyclin genes were found to be significantly downregulated under elevated CO₂ conditions, and their suppression was validated through quantitative real-time PCR. These genes, possessing conserved cyclin_N domains, are implicated in the regulation of the eukaryotic cell cycle, particularly in mitotic growth. These results indicate that CO₂-induced downregulation of cyclin genes may underlie cell cycle arrest, contributing to inhibited pileus development. This study is the first to provide transcriptomic evidence that elevated CO₂ concentrations specifically repress PHO80-like cyclin genes in F. velutipes, revealing a molecular mechanism by which CO₂ stress inhibits pileus development. These findings suggest that elevated CO₂ triggers a morphogenetic checkpoint by repressing PHO80-like cyclins, thereby modulating cell cycle progression during fruiting body development. This study provides the first evidence of such a transcriptional response in edible mushrooms and offers promising molecular targets for breeding CO₂-resilient strains and optimizing commercial cultivation conditions.