NOS2 and neoplasm: FMN and calycosin reduced the secretion of TNF-α in the tumor area by inhibiting the expression of NOS2, and regulated amino acid metabolism, especially glutamic acid, ornithine, aspartic acid, proline and arginine, thereby increasing the cytotoxicity of TMZ on malignant glioma, inhibiting tumor growth and infiltration in C6 glioma rats, and reducing cell aggregation and GFAP expression in C6 glioma area (Li et al., 2022).