Molecular Weight Dependent Effects on the Immunomodulatory Antioxidant and Antihypertensive Activities of Collagen Peptides

Purpose – This study investigates the functional potential of tuna collagen peptides in promoting human health and providing new directions for health function development. It emphasizes their biological activities, including antioxidant and immunomodulatory properties, and explores how these peptides can support disease prevention and overall wellness. Design/Methodology/Approach – Based on methodology, three fractions—CP-I (<3 kDa), CP-II (3–15 kDa), and CP-III (>15 kDa)—were isolated from tuna collagen hydrolysates. Their DPPH antioxidant and ACE inhibitory (ACEI) activities were evaluated in vitro, and their immunomodulatory effects were examined using cyclophosphamide (CTX)-induced immunosuppressed mice. Findings – CP-I showed the strongest DPPH antioxidant (IC50 = 1.515 mg/ml) and ACEI (IC50 = 1.716 mg/ml) effects, followed by CP-II and CP-III. CP-I and CP-II significantly enhanced spleen and thymus indexes, leukocyte proliferation, cytokines (IFN-γ, TNF-α, IL-2, IL-4, IL-6, IL-10), and Ig (IgG, IgM) levels, and stimulated ConAinduced splenocyte proliferation. Research Implications – Lower MW fractions (CP-I, CP-II) showed superior in vitro antioxidant and immunomodulatory effects compared with CP-III, indicating that smaller peptides may possess higher bioactivity and better absorption potential. These findings provide strong evidence that tuna skin collagen peptides (TSCP) can serve as promising functional ingredients or adjuvants to support immune regulation and overall health. Their excellent biological activity suggests potential applications in functional foods, dietary supplements, and even pharmaceutical formulations aimed at enhancing immunity, preventing disease progression, and improving quality of life. This research also offers valuable scientific support for developing innovative health products and advancing nutritional science.