Epicatechin and scopoletin rich Morinda citrifolia (Noni) leaf extract supplementation, mitigated Osteoarthritis via anti‐inflammatory, anti‐oxidative, and anti‐protease pathways

The scopoletin (coumarin) and epicatechin (flavonoid) rich Morinda citrifolia L. (MC) Noni leaves are non‐toxic (unlike the fruits) and consumed as vegetables. The anti‐osteoarthritis effects of the MC leaf extract against joint cartilage degradation and inflammation were investigated through cartilage explant cultures and pre‐clinical animal study. Osteoarthritis were induced by intra‐articular monosodium iodoacetate injection into the right knee. The extract, scopoletin and epicatechin, suppressed glycosaminoglycan and nitric oxide release from the cartilage explant in the presence of Interleukin‐1β. After 28 days, the extract treatment reduced the in vivo serum levels and joint tissues mRNA expressions for joint cartilage degradation, aggrecanase, and collagenase biomarkers. The extract increased the bone formation marker PINP levels, besides improving the articular cartilage structure and chondrocytes cellularity. The extract improved bone formation/repair, subchondral bone structure, strength and integrity, as well as cartilage synthesis by suppressing inflammation, nitric oxide production, joint catabolism by proteases, and oxidative stress. Practical applications The scopoletin (coumarin) and epicatechin (flavonoid) rich Morinda citrifolia (Noni) leaves may be used as vegetables, functional food ingredient, or dietary supplements to suppress osteoarthritis progression against joint cartilage degradation and inflammation. The extract, scopoletin, or epicatechin, suppressed glycosaminoglycan, and nitric oxide release from the cartilage. The Morinda citrifolia leaf extract suppressed inflammation, nitric oxide production, tissues catabolism by proteases and oxidative stress to help reduce joint cartilage degradation, besides improving the articular cartilage structure, chondrocytes health, subchondral bone structure, bone formation/repair, and cartilage synthesis.