Polydeoxyribonucleotide (PDRN) has emerged as a potent bioactive compound with proven efficacy in wound healing, tissue regeneration, and anti-inflammatory applications and is predominantly derived from salmonid gonads. However, this study presents a groundbreaking advancement by successfully extracting and characterizing PDRN from microbial sources, specifically Lactobacillus rhamnosus, marking the first report to utilize microbial-, biome-, or Lactobacillus-derived PDRN (L-PDRN). The findings demonstrate the enhanced biological properties of L-PDRN over traditional salmon-derived PDRN across several assays. L-PDRN exhibited superior antioxidant activity, with significantly higher SOD-like and DPPH radical scavenging activities compared to PDRN, particularly at higher concentrations. In wound-healing assays, L-PDRN demonstrated superior efficacy in promoting cell migration and wound closure, even under inflammatory conditions induced by tumor necrosis factor (TNF-α). Additionally, L-PDRN demonstrated the potential for enhanced immunostimulatory effects under non-inflammatory conditions while maintaining anti-inflammatory properties under lipopolysaccharide (LPS) stimulation. Electrophoretic analysis revealed that L-PDRN consists of smaller DNA fragments (under 100 bp) compared to salmon-derived PDRN (200–800 bp), suggesting greater bioavailability and skin absorption. Mechanistic studies confirmed that L-PDRN activates the focal adhesion kinase (FAK) and protein kinase B (AKT) signaling pathway through the A2A receptor, similar to PDRN, while also engaging alternative pathways for p38 and ERK phosphorylation, highlighting its signaling versatility. This study underscores the potential of L-PDRN as a multifunctional and sustainable alternative to salmon-derived PDRN, offering enhanced bioactivity, scalability, and environmental benefits. The novel approach of utilizing microbial-derived PDRN opens new avenues for therapeutic applications in oxidative stress management, tissue regeneration, and immune modulation, paving the way for a paradigm shift in PDRN sourcing and functionality.

The process of skin aging is intricate, involving intrinsic aging, influenced by internal factors, and extrinsic aging, mainly caused by exposure to UV radiation, resulting in photoaging. Photoaging manifests as skin issues such as wrinkles and discoloration. The skin microbiome, a diverse community of microorganisms on the skin’s surface, plays a crucial role in skin protection and can be affected by factors like humidity and pH. Probiotics, beneficial microorganisms, have been investigated for their potential to enhance skin health by regulating the skin microbiome. This can be accomplished through oral probiotics, impacting the gut–skin axis, or topical applications introducing live bacteria to the skin. Probiotics mitigate oxidative stress, suppress inflammation, and maintain the skin’s extracellular matrix, ultimately averting skin aging. However, research on probiotics derived from human skin is limited, and there is no established product for preventing photoaging. The mechanism by which probiotics shield the skin microbiome and skin layers from UV radiation remains unclear. Recently, researchers have discovered Lactobacillus in the skin, with reports indicating a decrease in this microorganism with age. In a recent study, scientists isolated Lactobacillus iners KOLBM20 from the skin of individuals in their twenties and confirmed its effectiveness. A comparative analysis of genetic sequences revealed that strain KOLBM20 belongs to the Lactobacillus genus and closely relates to L. iners DSM13335(T) with a 99.20% similarity. Importantly, Lactobacillus iners KOLBM20 displayed anti-wrinkle properties by inhibiting MMP-1. This investigation demonstrated the inhibitory effect of KOLBM20 strain lysate on MMP-1 expression. Moreover, the data suggest that KOLBM20 strain lysate may prevent UVB-induced MMP-1 expression by inhibiting the activation of the ERK, JNK, and p38 signaling pathways induced by UVB. Consequently, KOLBM20 strain lysate holds promise as a potential therapeutic agent for preventing and treating skin photoaging.

Melanocytes, located in the epidermis’ basal layer, are responsible for melanin pigment production, crucial for skin coloration and protection against UV radiation-induced damage. Melanin synthesis is intricately regulated by various factors, including the Wnt signaling pathway, particularly mediated by the microphthalmia-associated transcription factor (MITF). While MITF is recognized as a key regulator of pigmentation, its regulation by the Wnt pathway remains poorly understood. This study investigates the role of Sfrp5pepD, a peptide antagonist of the Wnt signaling pathway, in modulating melanogenesis and its potential therapeutic implications for pigmentary disorders. To tackle this issue, we investigated smaller peptides frequently utilized in cosmetics or pharmaceuticals. Nevertheless, there is a significant scarcity of reports on peptides associated with melanin-related signal modulation or inhibiting melanin production. Results indicate that Sfrp5pepD effectively inhibits Wnt signaling by disrupting the interaction between Axin-1 and β-catenin, thus impeding downstream melanogenic processes. Additionally, Sfrp5pepD suppresses the interaction between MITF and β-catenin, inhibiting their nuclear translocation and downregulating melanogenic enzyme expression, ultimately reducing melanin production. These inhibitory effects are validated in cell culture models suggesting potential clinical applications for hyperpigmentation disorders. Overall, this study elucidates the intricate interplay between Wnt signaling and melanogenesis, highlighting Sfrp5pepD as a promising therapeutic agent for pigmentary disorders. Sfrp5pepD, with a molecular weight of less than 500 Da, is anticipated to penetrate the skin unlike SFRPs. This suggests a strong potential for their use as cosmetics or transdermal absorption agents. Additional investigation into its mechanisms and clinical significance is necessary to enhance its effectiveness in addressing melanin-related skin conditions.

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.