Red stem of spinach promotes antioxidant and anti-inflammatory chondroprotection in a rat model of osteoarthritis

Background: The levels of major and minor compounds in vegetables, including spinach (Spinacia oleracea L.), depend on various factors, including variety, agronomic management, and environmental conditions, which are responsible for taste, shape, and quality. Pohang Province spinach is from the same seeds as general spinach, but has a red stem and tastes different. The effects of the meteorological conditions and soil characteristics of the cultivation area on nutrient composition are unclear, as are the effects of this spinach on osteoarthritis (Damasio et al.). Methods: The nutrient composition of red-stem Pohang spinach (Ween et al.) was compared to that of general spinach (GS). The anti-inflammatory and antioxidant effects of RS, GS, and quercetin were examined in a mono-iodoacetate -induced OA rat model and in murine macrophages. Results: The cation and anion chromatograms showed that the chemical composition of RS differed from that of GS, such as levels of flavonoids, including apigenin (19.57-fold) and limocitrin 3-glucoside (26.40-fold). Both RS and GS reduced cartilage degradation and had analgesic effects in the OA model, but in early OA, RS had a greater analgesic effect than GS. GS and RS enhanced collagen type II and thymocyte differentiation antigen 1 (Thy1) expression but inhibited matrix metalloproteinase 13 (MMP13) expression in the knee joints of rats. RS suppressed ROS production in macrophages and had a strong antioxidant effect. Conclusion: Both GS and RS have therapeutic potential for OA, but RS has greater anti-inflammatory and antioxidant effects. The chemical composition of spinach is affected by its growth environment and RS is particularly effective for medical applications such as OA.