The Role of Endophytic Fungi in the Anticancer Activity of Morinda citrifolia Linn. (Noni)

We hypothesize that the fungal endophytes of noni may possibly play a role in its overall pharmacological repertoire, especially since the perceived efficacy of the fruit in ethnomedicinal use is associated with the fermented juice. The foremost goal of this study is to explore the role of endophyte-derived secondary metabolites in the purported anticancer properties of noni. To that end, culturable endophytic fungi resident within the healthy leaves and fruit of the plant were isolated and identified by molecular sequence analysis of the 5.8S gene and internal transcribed spacers (ITS). Purified organisms were subjected to in vitro fermentation in malt extract broth for 8 weeks under anaerobic conditions at room temperature (25 degrees C), in order to simulate the conditions under which traditional fermented noni juice is prepared. The cytotoxic potential of organic extracts derived from the fermented broths of individual endophytes was then tested against three major cancers that afflict humans. Twelve distinct endophytic fungal species were obtained from the leaves and 3 from the fruit. Three of the leaf endophytes inhibited the growth of human carcinoma cell lines LU-1 (lung), PC-3 (prostate), and MCF-7 (breast) with IC50 values of <= 10 mu g/mL.