Chronic UVB exposure drives extrinsic skin aging through oxidative stress, inflammation, and collagen degradation. Although oral collagen peptides are promising photoprotective agents, most preparations lack defined composition and mechanistic validation. Here, we characterized CCAP1, a type I collagen-derived oligopeptide fraction (~1.7 kDa; 94.69% collagen-related components) prepared from Colla Corii Asini by dual-enzymatic hydrolysis and membrane fractionation. In UVB-irradiated mice, oral CCAP1 (100 and 200 mg/kg/d, 28 days) markedly alleviated UVB-induced epidermal hyperplasia, restored skin hydration and dermal collagen types I/III/IV, and suppressed MMP1. Untargeted skin metabolomics nominated AMPK signaling as the central node; Western blotting confirmed that CCAP1 activated the AMPK/Nrf2 axis while suppressing NF-κB phosphorylation, with elevated SOD activity and reduced MDA content. In UVB-injured HaCaT keratinocytes, CCAP1 restored cell viability and reduced intracellular ROS, and both effects were abolished by the AMPK inhibitor Compound C, establishing AMPK as a functionally required mediator. Collectively, CCAP1 is a composition-defined, orally bioavailable collagen peptide fraction that attenuates UVB-induced photoaging via an AMPK-dependent Nrf2/NF-κB regulatory program.

Background: Premature ovarian insufficiency (POI) is an intractable reproductive endocrine disease characterized by accelerated ovarian aging, accelerated follicle depletion and hormonal disorders, leading to secondary bone metabolic dysfunction and impaired long-term female health. Conventional hormone replacement therapy is the guideline-recommended first-line therapy for young women with POI, yet its long-term safety must be individualized; natural nutritional interventions are best viewed as complementary strategies. Donkey-hide gelatin (Ejiao), a natural food rich in bioactive collagen and amino acids, is commonly used for female reproductive care. Nevertheless, its systematic efficacy and molecular mechanisms against POI and related bone complications remain poorly defined. Methods: This study established a tripterygium glycosides (TG)-induced POI mouse model. Mice received low-dose (1.5 g/kg) and high-dose (3.0 g/kg) Ejiao treatment for 30 consecutive days. Reproductive organ morphology, estrous cycle, serum hormone levels, ovarian histopathology, bone microarchitecture and ovarian proteomic profiles were assessed. Results: Ejiao remarkably restored ovarian index and tended to improve uterine index (non-significant), corrected estrous cycle disturbance, and partially corrected the endocrine profile (E2, AMH, GnRH). It upregulated the ovarian reserve markers E2 and AMH and downregulated GnRH. Histological examination verified improved follicular development and reduced atresia. Furthermore, Ejiao alleviated POI-induced bone loss, optimized trabecular microstructure and rescued abnormal RANKL/OPG ratio to stabilize bone metabolism. Proteomic analysis revealed 313 differentially expressed proteins (DEPs) between Ejiao-treated and model groups, with enrichment in calcium signaling, cAMP, cGMP-PKG, and TGF-β/Smad pathways. Conclusions: As a natural bioactive food, Ejiao exerts dual protective effects against POI and concurrent bone metabolic dysfunction associated with modulation of multiple core signaling pathways and functional proteins (suggesting involvement of these pathways in its effects).

Objectives: Given that the structure-activity relationship between sturgeon chondroitin sulfate (S-CS) and the alleviation of osteoarthritis (OA) remains unclear, we characterized the structure of S-CS and explored the relationship between its structure and its effect in alleviating OA. Methods: Chondroitin sulfate was extracted from sturgeon cartilage by alcohol precipitation. Its structure was thoroughly characterized using infrared spectroscopy, pre-column derivatization, high-performance liquid chromatography with PMP (PMP-HPLC), nuclear magnetic resonance spectroscopy (NMR), and other techniques. A rat OA model was established to explore the mechanism underlying its alleviation of OA. In addition, 16S rRNA sequencing was performed to investigate the role of gut microbiota. Results: S-CS was identified as a sulfated polysaccharide with an average molecular weight of 68.81 kDa and a GlcUA-to-GalN molar ratio of approximately 1:1. NMR analysis confirmed its characteristic 6-/4-sulfation patterns. Oral administration of S-CS at 100 mg/kg/d significantly alleviated joint damage by inhibiting the NF-κB and p38 MAPK signaling pathways. Specifically, S-CS decreased the levels of p65 and p38 by 18.94% and 52.40% (p < 0.05), respectively, and decreased TNF-α concentration. Moreover, 16S rRNA sequencing showed that S-CS enhanced the diversity and richness of gut microbiota and reconstructed the microbial community structure. Conclusions: S-CS may be an effective supplement for OA.