Inhibition of nitric oxide production in the macrophage-like RAW 264.7 cell line by protein from the rhizomes of Zingiberaceae plants.

Nitric oxide (NO) plays a key role in the pathogenesis of inflammation and has been implicated in endotoxin-induced tissue injury. Zingiberaceae is a family of indigenous plants of tropical regions, many of which have traditionally been used as anti-inflammatory agents. Here, the ability of crude protein extracts from the rhizomes of 15 Zingiberaceae species to inhibit NO production in the RAW 264.7 cell line after co-stimulation with lipopolysaccharide (LPS) and interferon-gamma (IFN-γ) was evaluated. The crude protein extract of Zingiber ottensii Valeton exhibited the highest inhibitory activity, with an IC(50) value of 38.6 ± 0.34 µg protein/mL, and also suppressed the LPS- and rm-interferon (IFN)-γ-mediated increase in the inducible nitric oxide synthase (iNOS), interleukin (IL)-6, and tumor necrosis factor (TNF)-α mRNA transcript expression levels, suggesting the interference was mediated at the transcriptional level. This strong anti-inflammatory activity may have the potential to be developed as a therapeutic compound. Analytical sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and mass spectrometry revealed four main protein bands, including a likely lectin, superoxide dismutase, and cysteine protease, in the fractions related to the antioxidant activity.