A Mixture of Nicotinamide Mononucleotide, Decursin, and <scp>l</scp> -Cysteine Lowered Senescence-Associated Markers In Vitro and Was Effective Against 2,4-Dinitrochlorobenzene-Induced Atopic Dermatitis In Vivo: An Application of Network Pharmacology

Skin aging, accelerated by oxidative stress from environmental factors, results in the breakdown of collagen and elastin, causing visible signs like wrinkles and inflammation. Natural antioxidants such as nicotinamide mononucleotide (NMN), decursin, and l-cysteine have shown potential in combating oxidative damage and inflammation. This study explored the effects of a formulated mixture of these compounds on skin aging and atopic dermatitis (AD) through a combination of <i>in vitro</i>, <i>in vivo</i>, and <i>in silico</i> methods. Using human keratinocyte cells, we assessed cytotoxicity via a cell viability assay, confirming NMN and l-cysteine were nontoxic up to 100 µM, while decursin exhibited toxicity above 10 µM. The intracellular oxidative stress measurement demonstrated that mixtures A and B, composed of the same concentrations of decursin and l-cysteine but differing in NMN levels (low in mixture A and moderate in mixture B), significantly reduced oxidative stress levels induced by 2,2'-azobis(2-amidinopropane) dihydrochloride, whereas mixture C, which contained the highest NMN concentration, was ineffective. Mixture B further reduced senescence-associated heterochromatin foci formation under oxidative stress, while mixture C caused cell structure disruptions. In the dinitrochlorobenzene-induced AD model in BALB/c mice, both, mixture-L and mixture-H treatments reduced epidermal thickness, scratching behavior, and transepidermal water loss, with mixture-L also lowering dermal thickness and mast cell infiltration. Gene expression analysis confirmed that mixture B decreased proinflammatory cytokines like <i>TNF-α</i> and <i>IL-6</i>, while network pharmacology predicted key antioxidant pathways, validated through restored <i>NOS2</i> gene expression. Overall, the findings highlight the potential of these compound mixtures to mitigate oxidative stress and inflammation, offering a promising approach for skin aging and dermatitis management, though further validation is needed to optimize efficacy and safety.