Extracts of Oldenlandia diffusa protects chondrocytes via inhibiting apoptosis and associated inflammatory response in osteoarthritis

Osteoarthritis (OA) is a type of joint disorder that is marked by the gradual breakdown of cartilage and persistent inflammation of the synovial membrane, and is a leading cause of disability among elderly people worldwide. Oldenlandia diffusa (OD) is a member of the Rubiaceae family, and various researches have revealed that it possesses antioxidant, anti-inflammatory, and anti-tumor properties. Extracts of Oldenlandia diffusa is commonly used in traditional oriental medicine to treat various illnesses, including inflammation and cancer. This study is aimed at investigating the anti-inflammatory and anti-apoptosis effects of OD and its potential mechanisms on IL-1β-induced mouse chondrocytes, as well as its characteristics in a mouse osteoarthritis model. In this study, the key targets and potential pathways of OD were determined through network pharmacology analysis and molecular docking. The potential mechanism of OD in osteoarthritis was verified by in vitro and in vivo studies. The results of network pharmacology showed that Bax, Bcl2, CASP3, and JUN are key candidate targets of OD for the treatment of osteoarthritis. There is a strong correlation between apoptosis and both OA and OD. Additionally, molecular docking results show that β-sitosterol in OD can strongly bind with CASP3 and PTGS2. In vitro experiments showed that OD pretreatment inhibited the expression of pro-inflammatory factors induced by IL-1β, such as COX2, iNOS, IL-6, TNF-α, and PGE2. Furthermore, OD reversed IL-1β-mediated degradation of collagen II and aggrecan within the extracellular matrix (ECM). The protective effect of OD can be attributed to its inhibition of the MAPK pathway and inhibition of chondrocyte apoptosis. Additionally, it was found that OD can alleviate cartilage degradation in a mouse model of knee osteoarthritis. Our study showed that β-sitosterol, one of the active components of OD, could alleviate the inflammation and cartilage degeneration of OA by inhibiting chondrocyte apoptosis and MAPK pathway.