Lactoferrin Gene Expression and Antioxidant Activity in Tomato

Plant bioreactors offer low production costs, high biosafety, and facile scalability, making tomato an excellent platform for the expression of bioactive proteins. Lactoferrin (LF) possesses a wide range of biological activities; however, its production using microbial expression systems is limited by inherent drawbacks. These limitations can potentially be overcome through tomato-based heterologous expression. Nevertheless, studies investigating the biological activity of LF produced in tomato expression systems remain scarce, and validation using animal cell models has been relatively limited. In this study, the human lactoferrin (hLF) gene was codon-optimized, and the recombinant plasmid pSlhLF was constructed and introduced into tomato plants via Agrobacterium-mediated transformation to generate positive transgenic lines. Molecular analyses confirmed that hLF was expressed in all examined tomato tissues, with the highest expression level detected in fruits. Most transgenic lines exhibited significantly increased transcript levels of genes encoding antioxidant enzymes. Furthermore, in vitro cell assays demonstrated that tomato-derived hLF promoted the proliferation of H₂O₂-treated human fetal lung fibroblasts (HFL-1 cells) and reduced intracellular reactive oxygen species (ROS) accumulation. These findings suggest that hLF expressed in tomato may exert its antioxidant activity, at least in part, through the direct scavenging of ROS.