Aqueous extract of Rhodiola imbricata rhizome stimulates proinflammatory mediators via phosphorylated IkappaB and transcription factor nuclear factor-kappaB.

Modulation of immune response to alleviate diseases has long since been of interest. Plant extracts have been widely investigated for their possible immunomodulatory properties. We have evaluated the immunomodulatory activity of aqueous extract of Rhodiola rhizome in human peripheral blood mononuclear cells (PBMCs) and mouse macrophage cell line RAW 264.7. The Rhodiola extract was found to stimulate production of interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-alpha) in human PBMCs as well as RAW 264.7 cell line. It also increased production of nitric oxide synergistically in combination with lipopolysaccharide (LPS) in RAW 264.7. Rhodiola at 250 microg/ml increased the p-IkappaB expression in human PBMCs. Aqueous extract of Rhodiola (250 microg/ml) also activated the nuclear translocation of NF-kappaB in human PBMCs, which is comparable to the positive stimulant LPS. Thus, our present study suggests that Rhodiola most likely activates proinflammatory mediators via phosphorylated inhibitory kB and transcription factor NF-kB. Our study demonstrates immunostimulatory potential of aqueous extract of Rhodiola rhizome, that can be used for upregulation of immune response in patients with inadequate functioning of the immune system.