A Preliminary Study on the Effect and Mechanism of Antarctic Krill Peptides AKP on Alleviating UV-Induced Skin Photoaging by Regulating Estrogen Signaling Pathway

Chronic ultraviolet (UV) exposure is a primary driver of skin photoaging, yet safe and effective natural interventions remain limited. This study investigated the anti-photoaging potential and mechanism of Antarctic krill peptides (AKP), a low-molecular-weight oligopeptide mixture (Mw ~331 Da, with 82.82% < 500 Da) prepared by enzymatic hydrolysis and membrane fractionation. AKP exhibited excellent skin permeability in vitro. In UV-irradiated human dermal fibroblasts (HDF), AKP alleviated oxidative damage, restored superoxide dismutase activity, reduced malondialdehyde content, and promoted collagen I and XVII secretion, and inhibited matrix metalloproteinase-1 (MMP-1) expression. In a chronic UV-induced mouse photoaging model, topical AKP ameliorated epidermal thickening, dermal collagen loss, and macroscopic wrinkle formation. Skin proteomics revealed that AKP upregulated estrogen receptor Esr1 and androgen receptor Ar, activating the estrogen signaling pathway, which in turn corrected aberrant keratin (Krt5/14/19) and cell-cycle protein (Cdkn1a/Ccna2) expression. Immunohistochemical validation confirmed that AKP inhibited MMP-1/9 overexpression, elevated tissue inhibitor of metalloproteinase-1 (TIMP-1), and increased deposition of collagens I, III, and XVII, thereby restoring extracellular matrix homeostasis. Collectively, these findings demonstrate that AKP combats skin photoaging through estrogen-mediated regulation of matrix degradation and repair. This work fills a mechanistic gap for Antarctic krill-derived peptides and supports their development as natural marine-based anti-aging agents.