Failure of juice or juice extract from the noni plant (Morinda citrifolia) to protect rats against oxygen toxicity.

Noni juice possesses antioxidant activity and prevents superoxide-mediated tissue injury in laboratory animals. A polysaccharide-rich precipitate of noni juice (noni-ppt) also stimulates tumor necrosis factor (TNF) and interleukin 1 (IL-1) in mice. Endotoxin (lipopolysaccharide) stimulates TNF and IL-1 in rats and protects against superoxide-mediated oxygen toxicity. Accordingly, we hypothesized that noni juice, or noni-ppt, would protect rats against pulmonary oxygen toxicity. Rats were divided into four groups; one received noni-ppt to test for cytokine-induced protection; another received noni juice to test for antioxidant activity; a third received saline as hyperoxia control; a fourth received no treatment in air. Rats were then exposed to either hyperoxia (> 97% oxygen at sea level for 52 or 60 hours) or air and lung injury assessed. Rats receiving saline, noni-ppt or noni juice exhibited typical signs of oxygen toxicity with hemorrhagic lungs, large pleural effusions and increases in protein concentration in bronchoalveolar lavage fluid. They also developed heavy lungs with increases in wet/dry weight ratios, hematocrit values and ratios of effusion protein to plasma protein concentration. These results show that Noni juice and Noni-ppt do not prevent oxygen toxicity in rats when administered according to the protocols used in this study.