Research Article Suppressive Effect of the n-Hexane Extract of Litsea japonica Fruit Flesh on Monosodium-Iodoacetate-Induced Osteoarthritis in Rats Seung-Hyung Kim, 1 Hye-Jin Choi, 2 Won-Kyung Yang, 1 Ji-Eun Lee, 1 Ju-Hyun Cho, 3 In-Jae Park, 3 Sunyoung Park, 4 Bo-Kyung Park, 5 and Mirim Jin 4 1 Institute of Traditional Medicine and Bioscience, Daejeon University, Daejeon 34520, Republic of Korea 2 Laboratory of Molecular Medicine, College of Korean Medicine, Daejeon University, Daejeon 34520, Republic of Korea 3 Hurum Central Research Institute, Hurum Co., Ltd., Chungcheongbuk-do, Cheongju-si 28116, Republic of Korea 4 College of Medicine, Gachon University, Incheon 21999, Republic of Korea 5 KM Convergence Research Division, Korea Institute of Oriental Medicine, Daejeon 34054, Republic of Korea Correspondence should be addressed to Mirim Jin; mirimj@gachon.ac.kr Received 24 May 2017; Accepted 22 June 2017; Published 22 August 2017 Academic Editor: Antonella Fioravanti Copyright © 2017 Seung-Hyung Kim et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. We examined the antiosteoarthritic efect of the n-hexane extract of Litsea japonica fruit fesh (LJF-HE) in a rat model of monosodium-iodoacetate- (MIA-) induced osteoarthritis. LJF-HE signifcantly reduced the diference 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. Te serum levels of deoxypyridinoline (DPD) and osteocalcin, which are markers of bone metabolism, also decreased. Furthermore, LJF-HE signifcantly suppressed infltration of infammatory cells into the synovium and inhibited the expression of proinfammatory cytokines such as tumor necrosis factor- (TNF-) , interleukin- (IL-) 1, and IL-6 in the joints and serum. Te serum levels of leukotriene B4 and lipoxygenase were also signifcantly lowered by LJF- HE. Finally, LJF-HE inhibited the production of nitric oxide, prostaglandin E2, IL-6, and TNF- 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-infammatory efect and may have potential as an antiosteoarthritic agent. 1. Introduction Osteoarthritis (OA) is a degenerative joint disease in the aging population that can cause disability. Te functional limitation in the afected joint, which is caused by progressive degradation of cartilage and subchondral tissue remodeling, leads to bone deformity [1]. It is reported that metabolic interactions between cartilage and bones play pivotal roles in the pathogenesis of OA [2]. During OA progression, activated osteoblasts induce the production of matrix metal- loproteinases (MMPs) by chondrocytes, which leads to carti- lage degradation [3]. Subchondral bone osteoblasts produce proinfammatory cytokines such as interleukin- (IL-) 1, IL-6, and tumor necrosis factor- (TNF-). Tese trigger osteoclast activity, which leads to bone resorption [4] and an imbalance in bone metabolism. As a result, catabolism is favored while there is a decrease in anabolism. Tis leads to bone remodeling. Activation of cyclooxygenase- (COX-) 2 and lipoxygenase (LOX) results in the produc- tion of infammatory mediators such as prostaglandins and leukotrienes from arachidonic acid, which also contributes to the development and progression of OA [5]. Litsea japonica (L. japonica) Jussieu (Lauraceae) is grown in the southern areas of Korea and Japan and used as a Hindawi Evidence-Based Complementary and Alternative Medicine Volume 2017, Article ID 1791403, 10 pages https://doi.org/10.1155/2017/1791403