Bio-Normalizer modulates interferon-γ-induced nitric oxide production in the mouse macrophage cell line RAW 264.7

Bio-Normalizer, a natural health food supplement prepared from Carica papaya and some other medicinal plants was investigated to determine its effects on cellular nitric oxide (nitrogen monoxide, NO) production and inducible nitric oxide synthase (iNOS) expression. Bio-Normalizer upregulated interferon (IFN)-γ-induced NO production by macrophages in a dose-dependent manner. Such an effect of Bio-Normalizer on NO production was not due to changes in the activity of iNOS. Reverse transcription-polymerase chain reaction analysis revealed that the levels of iNOS mRNA were augmented by treatment of the cells with Bio-Normalizer and IFN-γ. The ability of Bio-Normalizer to augment IFN-γ-induced iNOS mRNA expression was independent of any changes on the mRNA stability. Treatment of cells with Bio-Normalizer alone did not affect NO production by macrophages. Tumor necrosis factor-α and interleukin-1β are involved in the induction of iNOS gene as well as the immune system. Bio-Normalizer augmented the mRNA expression of these cytokines in the presence of IFN-γ. This suggests that Bio-Normalizer is not directly involved in the expression of iNOS, but shows synergistic interaction with IFN-γ to induce NO synthesis.