Total lignans from Vitex negundo seeds attenuate osteoarthritis and their main component vitedoin A alleviates osteoclast differentiation by suppressing ERK/NFATc1 signaling

The seeds of Vitex negundo have been used for inflammation-related disease treatment in traditional medicine. This study focused on the anti-osteoarthritis (OA) effects of the total lignans of V. negundo seeds (TOV) in monosodium iodoacetate-induced osteoarthritis rats and its pharmacokinetic properties, as well as the effects and potential mechanism of its main components VN1 (6-hydroxy-4-(4-hydroxy-3-methoxy-phenyl)-3-hydro-xymethyl-7-methoxy-3,4-dihydro-2-naphthaldehydeb) and VN2 (vitedoin A) on receptor activator of NF-κB ligand (RANKL)-induced osteoclast differentiation in bone marrow macrophages (BMMs). TOV significantly attenuated osteoarthritis, leading to an increase in pain thresholds, improvement of knee articular cartilages and chondrocytes loss, and decreased total joint scores and serum levels of TNF-α, interleukin-1β (IL-1β), and prostaglandin E2 (PGE2) in osteoarthritis rats. The half-time (T_1/2) was 2.82 h and 1.33 h, and the bioavailability was 15.34%–21.89% and 16.29%–22.11%, for VN1 and VN2, respectively. VN2, rather than VN1, remarkably inhibited tartrate-resistant acid phosphatase (TRAP) activity, reduced the number of TRAP-positive multinuclear cells, diminished the formation of actin ring, and decreased mRNA levels of cathepsin K (CTSK), TRAP, nuclear factor of activated T cell 1 (NFATc1), and osteoclast-associated receptor, as well as downregulated protein levels of p-ERK (phosphorylated extracellular signal-regulated kinase), TRAP, CTSK and NFATc1 in BMMs. These findings suggest TOV has promising therapeutic potential for OA treatment and VN2, in particular, attenuates osteoclast differentiation by suppressing ERK/NFATc1 signaling and actin ring, mainly accounting for the anti-OA efficacy of TOV.