Suppressive Effect of the n-Hexane Extract of Litsea japonica Fruit Flesh on Monosodium-Iodoacetate-Induced Osteoarthritis in Rats

Abstract EN

We examined the antiosteoarthritic effect of the n-hexane extract of Litsea japonica fruit flesh (LJF-HE) in a rat model of monosodium-iodoacetate- (MIA-) induced osteoarthritis.

LJF-HE significantly reduced the difference in weight-bearing capabilities of the hind paws between healthy and MIA-treated rats.

Histological examination of the knee joints indicated that LJF-HE suppressed cartilage and bone destruction.

Additionally, there were decreases in the expression of matrix metalloproteinase-2 and metalloproteinase-9 and cyclooxygenase-2 in the joints.

The serum levels of deoxypyridinoline (DPD) and osteocalcin, which are markers of bone metabolism, also decreased.

Furthermore, LJF-HE significantly suppressed infiltration of inflammatory cells into the synovium and inhibited the expression of proinflammatory cytokines such as tumor necrosis factor- (TNF-) α, interleukin- (IL-) 1, and IL-6 in the joints and serum.

The serum levels of leukotriene B4 and lipoxygenase were also significantly lowered by LJF-HE.

Finally, LJF-HE inhibited the production of nitric oxide, prostaglandin E2, IL-6, and TNF-α in lipopolysaccharide-activated macrophages, which might be associated with inhibited phosphorylation of p38 mitogen-activated protein kinase and c-Jun N-terminal kinase.

Our data suggest that LJF-HE has an anti-inflammatory effect and may have potential as an antiosteoarthritic agent.