Implications of notoginsenoside R1 in osteoclastogenesis and bone remodeling via nitric oxide modulation.

BACKGROUND

Bone remodeling depends on the balance between osteoblast-mediated formation and osteoclast-mediated resorption, with disruption contributing to osteoporosis and other osteolytic diseases. Nitric oxide (NO) serves as a critical regulator of skeletal homeostasis and inflammatory signaling. Panax notoginseng, traditionally used in bone trauma, contains notoginsenoside R1 (NGR1) as a principal bioactive component. However, the mechanisms by which NGR1 modulates osteoclastogenesis remain unclear.

METHODS

A network pharmacology approach was employed to predict NGR1 targets and their intersection with NO regulation and osteoclastogenesis. Protein-protein interaction (PPI) analysis, GO/KEGG enrichment, and molecular docking were conducted to identify hub genes and pathways. Experimental validation was performed using CD14⁺ monocytes differentiated into osteoclasts under RANKL and M-CSF stimulation. TRAP staining, cathepsin K expression, and NO production assays were used to assess osteoclast formation, functionality, and signaling modulation.

RESULTS

Network analysis identified 79 overlapping targets between NGR1, NO regulation, and osteoporosis, highlighting hub genes involved in inflammatory signaling (IL-1β, IL-6, TNF, PTGS2), apoptosis (AKT1, CASP3, BCL2, ESR1), and signal transduction (STAT3, MAPK3). Docking studies indicated strong binding potential of NGR1 to AKT1, PTGS2, MAPK3, and CASP3. Experimentally, NGR1 inhibited osteoclastogenesis in a dose-dependent manner, with significant suppression at ≥ 50 μM. NGR1 and the NO scavenger PTIO showed comparable inhibitory effects, in contrast to the pro-osteoclastogenic effects of the NO donor SNP. NGR1 treatment also reduced NO production and impaired osteoclast function, as demonstrated by decreased TRAP and cathepsin K expression.

CONCLUSION

This study provides the first comprehensive evidence that NGR1 acts as a multi-target regulator of osteoclastogenesis through NO-dependent mechanisms. By integrating the suppression of NO levels with predicted modulation of inflammatory, apoptotic, and signal transduction pathways, NGR1 suppresses osteoclast differentiation and function. These findings advance the molecular understanding of Panax notoginseng in bone health and support NGR1 as a promising therapeutic candidate for pathological bone loss, warranting further in vivo and translational investigation.