The stratum corneum (SC) is the outermost layer of the epidermis and plays an important role in maintaining skin moisture and protecting the skin from the external environment. Ceramide and natural moisturizing factor (NMF) are the major SC components that maintain skin moisture. In this study, we investigated whether the oral intake of enzymatically decomposed AP collagen peptides (APCPs) can improve skin moisture and barrier function by assessing changes in the ceramide and NMF contents in the SC after APCP ingestion with the aim to develop a skin functional food. Fifty participants orally ingested APCP (1000 mg) or placebo for 12 weeks, and then, skin hydration and skin texture were evaluated. SC samples were collected to analyze skin scaling, ceramide, and NMF contents. Participants in the APCP group exhibited improved skin moisture content by 7.33% (p = 0.031) and roughness by −4.09% (p = 0.036) when compared with those in the placebo group. NMF content; the amounts of amino acids (AA), including glycine and proline; and AA derivatives were significantly increased in the APCP group (31.98 μg/mg protein) compared to those in the placebo group (−16.01 μg/mg protein) (p = 0.006). The amounts of total ceramides and ceramide subclasses were significantly higher in the APCP group than in the placebo group (p = 0.014). In conclusion, our results demonstrate that APCP intake improves skin moisture and increase the ceramide and NMF contents in the SC, thereby enhancing the skin barrier function.

Eunkyoung Lee, Dong Kyu Ahn, Jong Hoon Kim, Sunghee Lee, Han Jo Kim, Hae Kwang Lee, and Jin Hee Shin. J. Microbiol. Biotechnol. 2025;35:1-11. https://doi.org/10.4014/jmb.2507.07008

Facial skin characteristics are complex traits determined by genetic and environmental factors. Because genetic factors continuously influenced facial skin characteristics, identifying associations between genetic variants [single-nucleotide polymorphisms (SNPs)] and facial skin characteristics may clarify genetic contributions. We previously reported a genome-wide association study (GWAS) for five skin phenotypes (wrinkles, pigmentation, moisture content, oil content, and sensitivity) conducted in 1079 subjects. In this study, face measurements and genomic data were generated for 261 samples, and significant SNPs described in previous papers were verified. We conducted a GWAS to identify additional genetic markers using the combined population of the previous study and current study samples. We identified 6 novel significant loci and 21 suggestive loci in the combined study with p-values < 5.0 × 10⁻⁸ (wrinkles: 4 SNPs; moisture content: 148 SNPs; pigmentation: 6 SNPs; sensitivity: 18 SNPs). Identifying SNPs using molecular genetic functional analysis is considered necessary for studying the mechanisms through which these genes affect the skin. We confirmed that of 23 previously identified SNPs, none were replicated. SNPs that could not be verified in a combined study may have been accidentally identified in an existing GWAS, or the samples added to this study may not have been a sufficient sample number to confirm those SNPs. The results of this study require validation in other independent population groups or larger samples. Although this study requires further research, it has the potential to contribute to the development of cosmetic-related genetic research in the future.

Polymorphous Light Eruption (PLE) is a prevalent UV-induced photodermatosis characterized by abnormal immune responses, oxidative stress, and cutaneous inflammation. Alpha-glucosylrutin (AGR), a chemically modified flavonoid widely used for its antioxidant and photoprotective effects, has shown clinical efficacy; however, its synthetic origin and classification as a potential skin sensitizer and aquatic toxin raise safety and environmental concerns. These limitations underscore the need for safer, naturally derived alternatives. In this study, we investigated the comparative efficacy of quercetin (QC) and hesperidin (HPN)—two plant-based flavonoids—against AGR in in vitro and ex vivo models of sun-induced skin damage. An optimized QC:HPN 8:1 (w/w) complex significantly restored antioxidant enzyme activities (SOD: 4.11 ± 0.32 mU/mg; CAT: 1.88 ± 0.04 mU/mg) and suppressed inflammatory cytokine production (IL-6: 155.95 ± 3.17 pg/mL; TNF-α: 62.34 ± 0.72 pg/mL) more effectively than AGR. β-hexosaminidase secretion, a marker of allergic response, was reduced to 99.02 ± 1.45% with QC:HPN 8:1, compared to 121.33 ± 1.15% with AGR. QC alone exhibited dose-dependent cytotoxicity at ≥10 μg/mL, whereas HPN maintained >94% cell viability at all tested concentrations. These findings highlight the QC:HPN 8:1 complex as a safe, natural, and effective alternative to synthetic AGR for preventing and managing PLE and UV-induced dermal inflammation. Further research should focus on clinical validation and formulation development for topical use.

Conventional treatments for androgenetic alopecia (AGA) are often limited by suboptimal efficacy and potential adverse effects, highlighting the need for alternative approaches. We aimed to evaluate the efficacy and safety of a multi-targeted cosmetic formulation containing TrinogeniX™, composed of synthetic small-molecule inhibitors of glycogen phosphorylase, the prostaglandin D₂ receptor, and 15-hydroxyprostaglandin dehydrogenase, developed using the artificial intelligence-driven platform DeepZema^®, in individuals with AGA. This 24-week, randomized, double-blind, placebo-controlled trial involved 56 participants, of whom 49 completed the study. Efficacy was assessed using phototrichogram analysis, visual evaluation by dermatologists, and subjective questionnaires. Safety was evaluated based on adverse event reports and dermatological examinations. The test group demonstrated a significant increase in hair density and thickness over 24 weeks (p < 0.05), whereas no significant changes were observed in the placebo group. Expert visual assessments confirmed greater improvements in the test group. Subjective evaluations revealed consistently greater perceived improvements in hair loss symptoms, hair richness, and front hairline conditions in the test group. No adverse events or clinically significant abnormalities were observed. The multi-targeted cosmetic formulation (Motifull hair tonic) significantly improved hair density, thickness, and overall hair condition without adverse effects, suggesting its potential as a safe and effective option for AGA. Clinical trial registration: CRIS No. KCT0010804: A double-blind, randomized, placebo-controlled clinical trial evaluating the efficacy and safety of “Motifull Hair Tonic” (tentative name) for the alleviation of hair loss symptoms.