# An Analysis of Commercial Noni Juice: LC-MS/MS Phenolic Profiles and Cytotoxic Activity
## 3 Results and Discussion
### Cytotoxic Activity  
The various Noni juice crystals showed significantly different (\(p\) < 0.05) activity against the HeLa cells (Figure 3). The CIN extracts showed the highest potency (cell viability of 63 \(\pm\) 1%), significantly different to the negative control, whereas the FN, LHN and DHN showed lower potency (76-90% cell viability). Aside from CIN, the effects of all extracts on the HeLa cells were not significantly different from that of the negative control; hence deeming them to have no or low cytotoxicity. It is possible that longer cell exposure times (>48 h) to the Noni juice extracts would have resulted in a greater reduction in cell viability. Nevertheless, these results suggest that commercial samples of noni juice do not appear to have very high cytotoxic activity against the tested cell lines.  
\begin{table}
\begin{tabular}{c c c} \hline
**Compound** & **TPC** & **FRAP** \\ \hline Gallic acid & 1 & - \\ Trolox & - & 1 \\ Rutin & 0.44 & 0.95 \\ Gentisic acid & 1.10 & 7.40 \\
4-hydroxybenzoic acid & 0.75 & 0 \\ \hline \end{tabular}
\end{table}
Table 7: The slope of the TPC and FRAP calibrations for the main phenolic compounds identified in noni juice samples, relative to the respective standards (gallic acid for TPC or Trolox for FRAP).  
Previously, [PERSON] et al. [38] reported that Noni juice and cisplatin either alone or in combination were able to induce apoptosis in HeLa cells through the mitochondrial pathway. Their findings also reported that cisplatin showed higher cell potency compared to Noni juice, comparative to the results of this study. However, the combination of Noni juice and cisplatin showed additive effects, suggesting that it can be used as a chemo adjuvant in the treatment of cervical cancer [38; 39]. Another study suggested that in vitro, a 'concentrated component' in Noni juice and not the pure Noni juice may firstly stimulate the immune system to 'possibly' assist the body fight the cancer and then kill a small percentage (0-36%) of cancer depending on the type [2]. This may explain the low potency of the Noni juice extracts (0-30%) (Figure 3) obtained in this study. Further fractionation and isolation of Noni juice is required to identify the 'component' responsible for the cytotoxic activity.  
To further investigate the cytotoxic activity, colon cancer cell lines (HT29 cells) were treated with the Noni juice extracts, with the findings shown in Figure 4. Cell viability decreased to 70-89% upon treatment with the Noni juice extracts, which was lower than the negative control (100% cell viability). This indicated that Noni extracts to some degree induced a cytotoxic effect on HT29 cell lines. There were no significant differences found between the various sources of Noni juice extracts, hence a comparison of their cytotoxicity is inconclusive.  
Figure 3: The percentage cell viability of HeLa cells treated with different sources of Noni juice extracts at 500 \(\upmu\)g/mL. Different letters on the bar indicate significant difference between the different sources of Noni crude extracts (\(p<0.05\)). Negative control: cells without treatment; positive control: cells treated with 10 \(\upmu\)g/mL cisplatin (chemotherapy drug). Abbreviations: FN = Fijian Noni; LHN = Life Health Noni; DHN = Dynamic Health Noni; TON = Tahitian Organic Noni; CIN = Cook Island Noni.  
In general, the HeLa cell line was more susceptible to the TON, CIN and DHN, whereas FN and LHN were found to be more potent against HT29. Furthermore, although some correlation between the phytochemistry and cytotoxic activity of the five sources of Noni juice was noted in this study, comparison in terms of TPC and cytotoxic activity against the HT29 cell line was inconclusive.