Studies on diuretic and hypouricemic effects of Orthosiphon stamineus methanol extracts in rats

Aim of the study: Orthosiphon stamineus (Labiatae) is a traditional folk medicine widely used in Southeast Asia for the treatment of several kidney disorders, gout and as a diuretic. This study was conducted to examine the diuretic and hypouricemic effects of orthosiphon stamineus leaf extracts. Materials and methods: The diuretic effect of different methanol extracts was examined by treating different groups of Sprague-Dawley rats with single (2 mic effects in rats. (c) 2008 Elsevier Ireland Ltd. All rights reserved.g/kg) oral doses of methanol and methanol:water (1: 1) extracts. Hydrochlorothiazide (10 mg/kg) was used as positive control in acute study. Methanol and methanol water (1: 1) extracts at 0.5 g/kg were administered for a period of 7 consecutive days. Cumulative urine volume and electrolytes (Na+ and K+) concentrations at different time intervals were measured. On the other hand, hypouricemic activity of methanol:water extract (1:1) was experimented using different oral single doses (0.25, 0.5, 1 and 2 g/kg). Allopurinol was used as positive control. Uric acid concentration in serum was analyzed by using RP-H PLC at 280 nm. Results: Sodium and potassium excretion increased significantly (p < 0.05 and < 0.01) in the first 8 h of treatment with a single dose (2g/kg) of the extracts in a pattern comparable to that of the known diuretic hydrochlorothiazide. Meanwhile. repeated administration of 0.5g/kg methanol:water (1:1) extract showed a significant increase in urine volume (from day 3 to day 7) (p < 0.01) and electrolytes excretion (Na+ and K+) from day 2 to day 7 (p < 0.05 and < 0.01). On the other hand, 0.5, 1 and 2g/kg of methanol:water (1:1) extract and the standard allopurinol reduced the serum urate level in hyperuricemic rats at hour 6. Conclusion: These results provided an evidence of the high tendency of methanol:water (1: 1) extract of Orthosiphon stamineus towards diuretic and hypouricemic effects in rats. (c) 2008 Elsevier Ireland Ltd. All rights reserved.