Evaluation of plant-based protein products: Tempeh derived from the local edible freshwater alga, Chara corallina Willdenow on immune function, toxicity and antioxidant activity

The findings demonstrated that a plant-based protein powder, tempeh derived from the freshwater alga Chara corallina (ATF-C), at 3.90–500 µg/mL showed no cytotoxicity, maintaining cell viability above 90%. It significantly promoted cell proliferation and upregulated mRNA expression of key antioxidant enzymes—superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase (CAT)—within 62.5–500 µg/mL (p<0.05). Moreover, ATF-C enhanced nitrite production and phagocytic activity in a dose-dependent manner. Gene expression profiling revealed marked induction of immune-related markers, including Lysozyme M, tumor necrosis factor-alpha (TNF-α), and interleukin-8 (IL-8), across the same concentration range (p<0.05). Collectively, these findings demonstrated that ATF-C is not only safe but also exhibits promising antioxidant and immunomodulatory properties. Its dual role as an immune enhancer and antioxidant is provided a strong foundation for future applications in human health, particularly in immunity regulation and oxidative stress management.