Lignin-Based Therapeutics: Targeting Mitochondrial Pathways in Osteosarcoma

Lignin is a natural product that holds significant potential in tumor treatment by inhibiting tumor growth and inducing apoptosis. However, its therapeutic efficacy is often constrained by challenges such as inconsistent bioavailability, structural complexity, and potential side effects. To address these challenges, we developed a series of lignin derivatives incorporating bioactive intermediate structures to enhance their antitumor activity. These derivatives efficiently induced apoptosis in osteosarcoma (OS) through a mitochondria-dependent pathway. Notably, lignin derivatives with amino groups demonstrated pronounced cytotoxicity, while those featuring benzylamine substituents exhibited strong therapeutic effects, achieving tumor inhibition rates of up to 48%. Mechanistic investigations revealed that these derivatives disrupt mitochondrial membrane permeability, leading to cytochrome C release and subsequent activation of the apoptotic cascade. This process was characterized by the upregulation of BAX, Cyto-c, cleaved CASP3, and CASP9 and downregulation of BCL2. Both <i>in vitro</i> and <i>in vivo</i> experiments confirmed that lignin derivatives significantly inhibited OS cell proliferation while maintaining a favorable biosafety profile. These results demonstrate the therapeutic potential of lignin derivatives in OS treatment by leveraging renewable resources to synthesize bioactive intermediates. This innovative approach not only enhances therapeutic efficacy but also establishes a sustainable paradigm for pharmaceutical development.