Renewed interest in alternative medicine among diabetic individuals prompted us to investigate anti-diabetic effects of Morinda citrifolia (noni) in high-fat diet (HFD)-fed mice. Type 2 diabetes is associated with increased glucose production due to the inability of insulin to suppress hepatic gluconeogenesis and promote glycolysis. Insulin inhibits gluconeogenesis by modulating transcription factors such as forkhead box O (FoxO1). Based on microarray analysis data, we tested the hypothesis that fermented noni fruit juice (fNJ) improves glucose metabolism via FoxO1 phosphorylation. C57BL/6 male mice were fed a HFD and fNJ for 12 weeks. Body weights and food intake were monitored daily. FoxO1 expression was analysed by real-time PCR and Western blotting. Specificity of fNJ-associated FoxO1 regulation of gluconeogenesis was confirmed by small interfering RNA (siRNA) studies using human hepatoma cells, HepG2. Supplementation with fNJ inhibited weight gain and improved glucose and insulin tolerance and fasting glucose in HFD-fed mice. Hypoglycaemic properties of fNJ were associated with the inhibition of hepatic FoxO1 mRNA expression, with a concomitant increase in FoxO1 phosphorylation and nuclear expulsion of the proteins. Gluconeogenic genes, phosphoenolpyruvate C kinase (PEPCK) and glucose-6-phosphatase (G6P), were significantly inhibited in mice fed a HFD+fNJ. HepG2 cells demonstrated more than 80 % inhibition of PEPCK and G6P mRNA expression in cells treated with FoxO1 siRNA and fNJ. These data suggest that fNJ improves glucose metabolism via FoxO1 regulation in HFD-fed mice.

Based on the distribution, molecular similarity and use of Morinda citrifolia L., and occurrence of a wild Morinda species, Southeast Asia and Micronesia have been suggested to be the places where noni originated. The present article discusses the indices used by Vavilov and subsequent authorities on the origin of crop plants to argue that South Asia (Southeast India) has a greater probability of being the centre of domestication/origin for noni than Southeast Asia or Micronesia. The basic reasoning is that economically important plant cannot originate without richness in biodiversity and ingenuity of local people. India with rich floristic diversity, one of the centres of origin of crop plants with a natural distribution of Morinda species, including M. citrifolia L. and its immediate ancestors, has the oldest reference of occurrence, use and cultivation (Vedic literature); therefore, it appears to be the more probable centre of noni's origin. The ancient history of the expansion of Indian culture, religion and trade to Southeast Asian countries corroborate the possible role of Indians in the introduction of noni or knowledge regarding its value to Southeast Asia, from which it was carried to Micronesia and Polynesia, which provided a more favourable environmental niche for perpetuation and use.

Introduction. Noni (Morinda citrifolia) has a long history related to medical uses in Southeast Asian countries. Today, noni grows in the majority of the southern Pacific areas, in India, the Caribbean, South America and the West Indies. One of the challenges of recent years was to process Morinda citrifolia fruit juice, to make a more modern drug from a traditional product. In order to obtain better understanding of the medicinal characteristics of the noni fruit cultivated in Cambodia, the biochemical and mineral compositions of the raw juice extracted from M. citrifolia fruits were determined. Materials and methods. Whole fresh fruits of M. citrifolia which came to France from Cambodia were preserved at –20 °C during the duration of the experimentation. Commercial Tahitian noni juice was bought pasteurized to be used as a reference. The extraction was carried out on two batches of Cambodian fruits using a hydraulic press. Contents in oil, fatty acids, proteins, amino-acids, sugars and minerals of juices were analyzed. Results. Composition of noni juice of different origin was determined, compared, and discussed in relation to the biochemical and mineral composition of other vegetable oils. Conclusion. The biochemical composition of the noni juice, which showed a high content of antioxidant molecules, is not sufficient to explain the famous medicinal effects of noni juice. Certain molecules, in particular alkaloids, still have to be studied.