PURPOSE: In the present study, phyllanthin isolated from Phyllanthus amarus was investigated for its immunosuppressive effects on various cellular and humoral immune responses in Balb/C mice.
METHODS: Male mice were treated daily at 20, 40 and 100mg/kg of phyllanthin for 14 days by oral gavage. The effects of phyllanthin on cellular immune responses in treated /non treated mice were determined by measuring CD 11b/CD 18 integrin expression, phagocytosis, nitric oxide (NO) production, myeloperoxidase activity (MPO), T and B cells proliferation, lymphocyte phenotyping, serum cytokines production by activated T-cells and delayed type hypersensitivity (DTH). Its effects on humoral immune responses were evaluated by determining the serum levels of lysozyme and ceruloplasmin, and immunoglobulins (IgG and IgM).
RESULTS: Phyllanthin dose-dependently inhibited CD11b/CD18 adhesion, the engulfment of E. coli by peritoneal macrophages molecules, NO and MPO release in treated mice. Phyllanthin caused significant and dose-dependent inhibition of T and B lymphocytes proliferation and down-regulation of the Th1 (IL-2 and IFN-γ) and Th2 (IL-4) cytokines. Phyllanthin at 100mg/kg caused a significant reduction in the percentage expression of CD4(+) and CD8(+) in splenocytes and the inhibition was comparable to that of cyclosporin A at 50mg/kg. At 100mg/kg, phyllanthin also dose-dependently exhibited strong inhibition on the sheep red blood cell (sRBC)-induced swelling rate of mice paw in DTH. Significant inhibition of serum levels of ceruloplasmin and lysozyme were observed in mice fed with higher doses (40 and 100mg/kg) of phyllanthin. Anti-sRBC immunoglobulins (IgM and IgG) antibody titer was down-regulated in immunized and phyllanthin-treated mice in a dose-dependent manner with maximum inhibition being observed at 100mg/kg.
CONCLUSION: The strong inhibitory effects of phyllanthin on the cellular and humoral immune responses suggest that phyllanthin may be a good candidate for development into an effective immunosuppressive agent.
Methods: Seeds of T. ammi were extracted using three different solvents n-hexane, chloroform, and methanol by using soxhlet apparatus. To assess the immunomodulatory effect, delayed-type hypersensitivity (DTH) assay method was used and by the DTH assay, the effect of T. ammi on the skin thickness of rats was estimated. To find the exact dose for administration, acute toxicity test was performed using crude methanolic extract at a dose of 400, 800, 1600, and 3200mg/kg. After acute toxicity test, 500mg/kg dose was determined as safe for therapeutic effect and immunomodulatory effect was evaluated at this dose. Dose of 500mg/kg was administered to Wistar rats daily for 14 days and skin thickness of rats was measured at 24, 48, and 72h.
Results: Results were obtained from six groups of rats, which were positive control group, negative control group, and the groups receiving the test drugs. Standard drug was the combination of sodium selenite, vitamin E, and sodium chloride and it showed more positive results as compared to that of test drug. Furthermore, among the three extracts, methanol extract showed more effectiveness on skin thickness.
Conclusion: There was a meaningful difference was observed between the skin thickness of rats which shows that T. ammi have good immunomodulatory as well as immunostimulant activity.