Effect of sesamin on protection of equine articular cartilage degradation in vitro

Black sesame seed is a potential herbal medicine for osteoarthritis treatment as it contains sesamin, which has antiinflammatory properties and has demonstrated chondroprotective effects in many species. Horses are particularly susceptible to osteoarthritis. Inflammatory mediators and matrix metalloproteinase are important factors causing cartilage degradation. This study aimed to investigate the protective potential of sesamin (0.5-2.0 mu M) against interleukin (IL)-1 beta-induced equine cartilage explant degradation. The cartilage degradation was monitored by measuring the release of cartilage matrix molecules in culture media including sulfated-glycosaminoglycans and hyaluronan by calorimetric assay and EL1SA assay, respectively. The remaining contents of collagen and uronic acid (UA) within the explant tissue were assessed by hydroxyproline assay and UA assay, respectively. Cartilage-degrading enzymes MMP-2 and MMP-3 were evaluated by gelatin zymography and ELISA assay, respectively. The results indicated that sesamin suppressed IL-1 beta-induced equine cartilage degradation by reducing the levels of sulfated-glycosaminoglycans and hyaluronan, and preserving the contents of UA and collagen within the explant tissues. The activity of MMP-2 and the quantity of MMP-3 were also suppressed by sesamin. The chondroprotective efficacy of sesamin was comparable to that of diacerein, an antiarthritic drug. Lactate dehydrogenase assay showed that sesamin at concentrations of up to 2 mM did not cause cytotoxicity to chondrocytes in cartilage explants. These results may lead to new options for osteoarthritis treatment in horses.