Purpose: To investigate the immunomodulatory activity of the alcohol extract of Terminalia chebula Retz (Combretaceae) dried ripe fruits at the cellular level.

Methods: For antioxidant study, the liver mitochondria were separated and used for the estimation of enzymes catalase (CAT) and superoxide dismutase (SOD) - as well as lipid peroxidation (LPO) and reduced glutathione (GSH); Melatonin secretion was characterized using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) while spleen lymphocyte proliferation assay was performed by measuring optical density at 570 nm using ELISA reader. The cytokines, namely, IL-2, IL-10 and TNF-α expression in spleen cells, were determined by real time polymerase chain reaction (RT-PCR )

Results: Terminalia chebula extract (100 mg/kg/p.o.) increased the level of liver mitochondrial enzymes CAT and SO) as well as GSH but decreased the level of LPO in the liver when compared to the vehicle, sheep red blood cells (SRBC) and cyclophosphamide-treated groups. Secretion of melatonin by pineal gland was enhanced by T. chebula treatment.  The extract also increased spleen lymphocyte proliferation. Based on RT-PCR analysis, the expression of cytokines, viz, IL-2, IL-10 and TNF-α, was more in T. chebula-treated than in vehicle- and cyclophosphamide- treated groups.

Conclusion: This study confirms the immunomodulatory activity of ripe T. chebula fruits as evidenced by increase in the concentration of antioxidant enzymes, GSH, T and B cells, the proliferation of which play important roles in immunity. This phenomenon also enhances the concentration of melatonin in pineal gland as well as the levels of cytokines, such as IL-2,IL-10  and TNF-α, which play  important roles in immunity.

Keywords: Terminalia chebula, Antioxidants, SDS-PAGE, Lymphocytes proliferation, Real-time PCR, Immunity