The current study aimed to investigate the physicochemical properties of the natural eggshell membrane (NEM) and its protective effects against H₂O₂-induced oxidative stress in human chondrocytes (SW-1353). Bioactive components from NEM related to cartilage were profiled, consisting of 1.1 ± 0.07% hyaluronic acid, 1.2 ± 0.25% total sulfated glycosaminoglycans as chondroitin sulfate, 3.1 ± 0.33% collagen, and 54.4 ± 2.40% total protein. Protein was hydrolyzed up to 43.72 ± 0.76% using in vitro gastro–intestinal digestive enzymes. Peptides eluted at 9.58, 12.46, and 14.58 min using nano-LC-ESI-MS were identified as TEW, SWVE, and VYL peptides with an M/Z value of 435.1874, 520.2402, and 394.2336, respectively. Radical scavenging activity of NEM at 10 mg/mL using the ABTS assay was revealed to be 2.1 times higher than that of the positive control. NEM treatment significantly enhanced cellular SOD expression (p < 0.05). Pre-treatment with NEM (0.1, 1, and 10 mg/mL) dose-dependently reduced H₂O₂-induced ROS levels in SW-1353. Cell live imaging confirmed that NEM pre-treatment led to a significant reduction in apoptosis expression compared to control. Results from the present study suggest that NEM rich in cartilage protective components including hyaluronic acid, collagen, and chondroitin antioxidative peptides could be a potential therapeutic agent for osteoarthritis (OA) by scavenging oxidative stress.

The current study hypothesized that omega-3 fatty acids ω-3 FAs consumed with various tea extracts, which included green tea extract comprising 35% and 65% catechin (GTE35 and GTE65), naturally fermented green tea (Heukcha) extract (NFGT), and a complex of heat-treated green tea and enzymatically-modified isoquercitrin (1:1, w:w) (Adiphenon^TM) would enhance the digestive stability and intestinal absorption of ω-3 FAs. The digestive stability of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) co-digested with GTE65 using an in vitro digestion model system was improved by up to 20.76% and 23.22%, respectively, compared to ω-3 FAs. The oxidative stability, measured using peroxide values, was the lowest, whereas the DPPH radical scavenging capacity during digestion was the highest in Adiphenon™, showing 1.03 ± 0.25 meq O₂/kg oil and 1251.96 ± 26.03 µmol TE/g. The deviation in zeta potential was reduced when ω-3 FAs were co-treated with various tea extracts, indicating that the micelle of ω-3 FAs is stable. The intestinal absorption in Caco-2 cells increased by up to 34.53% for EPA and 60.23% for DHA with various tea extracts compared to ω-3 FAs alone. The co-treatment with GTE35 and Adiphenon™ did not alter the expression of P-glycoprotein (P-gp) compared to ω-3 FAs alone, which implies the efflux of tea polyphenols, such as catechins, could be limited due to the suppression of P-gp by ω-3 FA. The results from the current study suggest that the co-intake of ω-3 FAs with various tea extracts could increase the bioavailability of ω-3 FAs by preventing oxidation, stabilizing micelle structures, and minimizing intestinal efflux.