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

Aim of the studyOrthosiphon 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 methodsThe diuretic effect of different methanol extracts was examined by treating different groups of Sprague–Dawley rats with single (2 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-HPLC at 280 nm.ResultsSodium and potassium excretion increased significantly (p < 0.05 and <0.01) in the first 8 h of treatment with a single dose (2 g/kg) of the extracts in a pattern comparable to that of the known diuretic hydrochlorothiazide. Meanwhile, repeated administration of 0.5 g/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 2 g/kg of methanol:water (1:1) extract and the standard allopurinol reduced the serum urate level in hyperuricemic rats at hour 6.ConclusionThese results provided an evidence of the high tendency of methanol:water (1:1) extract of Orthosiphon stamineus towards diuretic and hypouricemic effects in rats.