Fraxin inhibits ovariectomized-induced bone loss and osteoclastogenesis by suppressing ROS activity.

Osteoporosis is characterized by increased osteoclast activity, which is strongly associated with increased levels of reactive oxygen species (ROS). Fraxin, a natural coumarin glycoside, has shown anti-inflammatory and antioxidant properties, but its effects on bone homeostasis are obscure. The effects of fraxin on osteoclast formation and activation were measured via an in vitro osteoclastogenesis assay. Mitochondrial and total ROS production were evaluated with the aid of MitoSOX Red and DCFH-DA, respectively. Osteoclast-related gene expression analysis was performed via qPCR. Key proteins related to osteoclast formation, ROS scavenging, and ROS-regulated signaling, such as mitogen-activated protein kinases (MAPKs), NF-κB pathways, and nuclear factor of activated T cells 1 (NFATc1) signaling, were detected via western blotting. An ovariectomized mouse model was used to evaluate the therapeutic effects of fraxin in vivo. Fraxin inhibited osteoclastogenesis and osteoclast-related gene expression. Mechanistically, fraxin restored the levels of ROS-scavenging enzymes to inhibit ROS accumulation, eventually downregulating ROS-regulated signaling. The measurement of Micro-CT and histological analyses revealed that fraxin treatment significantly reduced OVX-induced bone loss by decreasing the number of osteoclasts. Fraxin shows promise as a novel therapeutic agent for osteoclast-related bone diseases, especially osteoporosis.