Evaluation of the cytotoxic and antitumor effect of the serigueleiro gum (Spondias purpurea L).

Arabinogalactans, the class to which serigueleiro gum (SG) belongs, are polysaccharides known for their antitumor effects in vivo, primarily attributed to their immunomodulatory properties. This study assessed the antitumor potential of SG through comprehensive in vitro and in vivo analyses. Cytotoxicity was determined via the MTT assay in HCT 116, SW480, CT26.WT, B16-F10, MCF-7, MDA-MB-231, 4 T1, SNB-19 and PC-3 cell lines. The antitumor effects and immuno-stimulatory interactions of SG were evaluated using a murine syngeneic CT26.WT colorectal cancer model to investigate tumor-immune system interactions in immunocompetent hosts. Tumor inhibition was quantified by measuring tumor weights. Additionally, hematological, biochemical, histopathological, MPO, qRT-PCR and Western Blotting analyses were performed to elucidate the underlying mechanisms of action. Despite limited cytotoxicity in vitro, SG inhibited tumor growth in vivo by 32.04% at the 50 mg/kg/day dose (SG50), compared to only 1.31% at 100 mg/kg/day. The SG50 dose showed the most favorable therapeutic profile with no biochemical or histopathological alterations, whereas the higher dose caused mild systemic stress. Furthermore, SG50-treated animals presented an increase in leukocyte counts and significant upregulation of Il1b, Tlr4, and Ifng genes. Importantly, Western blotting revealed an increase in IL-10, alongside unaltered TNF-α and IL-12β protein levels in the SG50 group, indicating a safely regulated, homeostatic feedback mechanism that prevents excessive inflammation. Collectively, these findings suggest that SG may mediate tumor suppression via controlled immunomodulation, underscoring its remarkable potential as a safe and effective immuno-stimulatory candidate.