An evaluation of diuretic activity of Morinda citrifolia (Linn) (Noni) fruit juice in normal rats

Morinda citrifolia (Noni fruit) juice, a proven antioxidant when evaluated for nephroprotective effects in a murine model was noted to produce a high volume of urine formation. Hence it was evaluated for its diuretic potential in normal rats. The study was conducted in saline primed Wistar albino rats (n=6) using frusemide (10 mg/kg) as the reference diuretic drug with two oral doses, 5mg/kg and 10mg/kg respectively. Urine volume and electrolytes (Sodium, Potassium and Chloride) excretion was estimated at the end of 24 hours and data was analyzed by Kruskall Wallis and Mann Whitney tests. P<0.05 was considered as statistically significant. Noni fruit juice statistically increased the volume of urine (6.82 ±1.18ml/100g/24hr and 7.87±1.15ml/100gm/24hr) in a dose dependent manner increasing the diuretic index to 2.04 and 2.36 for 5ml.kg and 10ml/kg dose ranges respectively. However, there was a statistical significant decrease in sodium ion excretion (70.1±14.3 m.mol/L at 5ml/kg and 41.97±9.3 m.mol/L at 10ml/kg) when compared to the control (107±5.18 m.mol/L). Though there was a similar decrease in potassium excretion it was not statistically significant. These findings indicate that the probable increase in urine formation might be due an aquaretic action of Noni fruit rather than a natruretic effect and further studies with larger doses and longer duration are warranted.