Antioxidant Activity of Noni Juice in Vitro and in Human Volunteers

Morinda citrifolia (noni) fruit juice has been found to provide a wide range of potential health benefits. Among these are the reduction of free radicals and protection against lipid peroxide DNA damage in heavy cigarette smokers and athletes who had exercised to the point of exhaustion. These benefits have been observed after drinking a beverage containing a blend of noni juice from French Polynesia, Tahitian Noni® Juice (TNJ). To determine if TNJ exerts more immediate antioxidant effects, and under less extreme conditions, in vitro tests and a trial involving healthy young adult men were conducted. In the human study, volunteers drank 200 mL TNJ, orange juice or water following an overnight fast. Blood samples were collected before and 1 hour following ingestion of the beverages. Plasma and red cell lysate (erythrocyte) samples were measured for antioxidant activity potentiometrically. TNJ exhibited high in vitro antioxidant activity in the 2,2-diphenylpicrylhydrazyl (DPPH) radical scavenging, reducing power and lipid hydroperoxide scavenging assays. TNJ also significantly increased mean antioxidant activity in plasma and erythrocytes of healthy volunteers. The effect of TNJ in erythrocytes was approximately 4.6 times greater than that of orange juice. There were no increases observed in the water group. The results of this study reveal that TNJ can provide antioxidant benefits shortly after ingestion and under more everyday conditions, not only in extreme circumstances or when consumed repeatedly.