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

Received May 24, 2017; Accepted Jun 22, 2017

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1. Introduction

Osteoarthritis (OA) is a degenerative joint disease in the aging population that can cause disability. The functional limitation in the affected 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 metalloproteinases (MMPs) by chondrocytes, which leads to cartilage degradation [3]. Subchondral bone osteoblasts produce proinflammatory cytokines such as interleukin- (IL-) 1, IL-6, and tumor necrosis factor-α (TNF-α). These 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. This leads to bone remodeling. Activation of cyclooxygenase- (COX-) 2 and lipoxygenase (LOX) results in the production of inflammatory 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 herbal medicine. It has been reported that the fruit of this plant has antioxidant [6], anti-inflammatory [7], and antidiabetic effects [8]. It contains various anti-inflammatory and analgesic phytochemicals including hamabiwalactone A and hamabiwalactone B (A) [9].