An Analysis of Commercial Noni Juice: LC-MS/MS Phenolic Profiles and Cytotoxic Activity

Fermented juice from the noni tree (Morinda citrifolia) is a traditional medicinal product used by South Pacific Islanders to treat a wide range of ailments, including cancer, inflammation and obesity, as well as improving overall wellbeing. Many of its bioactive properties have been suggested to arise from the high antioxidant capacity and phenolic content found in the juice. However, there have been limited investigations into the phenolic profiles of noni juice produced locally in the Pacific. This study aimed to investigate the chemical composition and bioactive properties of noni juice. The first phase of this study used liquid chromatography with tandem mass spectrometry (LC-MS/MS) to characterise the phenolic composition of five brands of commercial noni juice produced in the South Pacific region. A total of 21 phenolic compounds were putatively identified, with the most abundant generally being rutin, 4-hydroxybenzoic acid and gentisic acid. Vastly differing phenolic profiles were found between the noni juice brands. Significant differences were also found in their antioxidant capacities and total phenolic contents. Of the three major phenolic compounds identified, gentisic acid showed the highest antioxidant activity (640% higher than Trolox). Additionally, the noni juice showed no significant anti-acetylcholinesterase activity and no to moderate cytotoxicity against two cancer cell lines (HeLa and HT29). These results indicate that the phytochemical profiles—and hence, the expected bioactive properties—are likely to vary significantly between different noni juice brands. Furthermore, the anti-cancer activity of non-concentrated noni juice appears to be relatively low.