The Phytochemistry and Anticarcinogenic Activity of Noni Juice †

Abstract

Noni juice, obtained from the fruit of the noni tree (Morinda citrifolia L.), is a popular commodity in the market, particularly in the South Pacific. It is widely used by consumers for the prevention of several lifestyle diseases. Although there is increasing interest in the potential therapeutic use of noni plants, there are no comparative studies on the various commercialized noni fruit juices available to decipher their phytochemical composition and properties against carcinomas. The present study, therefore, aims to fill this research gap and investigate the juice’s anecdotal use as complementary alternative medicine to manage cancer. Five commercial brands of noni juice were included in this study, namely, Tahitian Organic Noni (TON), Cook Island Noni (CIN), Dynamic Health Noni (DHN), Fijian Noni (FN), and Life Health Noni (LHN). The juice samples were vacuum-filtered and freeze-dried to obtain crystal products for methanolic extraction. Total phenolic content (TPC) and antioxidant capacity (FRAP—ferric reducing antioxidant power) were determined on the methanolic extracts. The cytotoxicity of the noni juices was also tested on human cervical adenocarcinoma (HeLa cell lines) by dissolving 2 mg of the crystal product in sterile deionized water and diluting to 1000 μg/mL in the media culture. The final concentration of the extracts in the well plate was 500 μg/mL. The MTS cell viability assay was performed after the cells were incubated with the extracts for 48 h at 37 °C with 5% CO2. The DHN and FN extracts were found to have the highest TPC of 5393 ± 298 and 5060 ± 23 mg gallic acid equivalent /100 g dry weight (DW), respectively, whereas the highest antioxidant capacity was seen in the CIN extract (6389 ± 49 mg Trolox equivalent/100 g DW). The CIN extract also showed the most promising effect with only 63 ± 1% cell viability, whilst the other extracts showed lower cytotoxic effects (76–90% cell viability) on the HeLa cell line. It is possible that greater cytotoxicity could be observed over long exposure times. The noni juice samples contain high levels of TP and antioxidant capacity and appear to show some level of cytotoxic activity, which were statistically different from the negative control. Further work involving more extensive in vitro and in vivo studies are necessary to elucidate its anticarcinogenic activities.