Kurarinone Mitigates LPS-Induced Inflammatory Osteolysis by Inhibiting Osteoclastogenesis Through the Reduction of ROS Levels and Suppression of the PI3K/AKT Signaling Pathway

Inflammatory bone resorption represents a pathological condition marked by an increase in bone loss, commonly associated with chronic inflammatory conditions such as rheumatoid arthritis and periodontitis. Current therapies primarily focus on anti-inflammatory drugs and bisphosphonates; however, these treatments are limited due to side effects, inadequate efficacy, and unpredictable long-term complications. Kurarinone (KR), a bioactive compound isolated from the traditional Chinese herb Sophora flavescens, exhibits a range of biological activities, including anti-inflammatory, anticancer, and cardiovascular protective effects. To address the limitations of existing therapies and enhance drug utilization, this study explores the potential of KR as a therapeutic agent for inflammatory bone resorption and delineates its underlying mechanisms. In vitro experiments reveal that KR notably inhibits osteoclastogenesis and reduces the expression of osteoclastic markers. Additionally, KR decreases the levels of pro-inflammatory cytokines IL-1β, IL-6, and TNF-α, while downregulating NADPH oxidase 1 (NOX1) and Kelch-like ECH-associated protein 1 (Keap1) to diminish ROS production. Furthermore, KR activates the nuclear factor erythroid 2-related factor 2 (Nrf2), which enhances the activity of heme oxygenase-1 (HO-1) and catalase (CAT), facilitating the clearance of excess ROS. The compound also hinders osteoclast formation and functionality by inhibiting the PI3K/AKT/GSK-3β signaling pathway. Lentiviral knockdown of CAT can partially reverse these effects of KR. Meanwhile, in vivo experiments indicate that KR effectively mitigates bone loss in an LPS-induced inflammatory bone resorption model. In summary, KR is a promising new star in breaking through the limitations of previous drugs and treating inflammatory bone resorption.