Verification of the folkloric diuretic claim of <i>Hibiscus sabdariffa</i> L. petal extract

Abstract

The folklorically acclaimed diuretic activity of the petal extract of Hibiscus sabdariffa was verified in saline-loaded albino rats (80 – 220 g; n=5) according to the method of De la Peurta Vazquez et al, 1989. A methanolic extract of the dried petals was prepared, and, upon lethal toxicity testing, was found to be very safe – LD₅₀ >5,000 mg/kg, i.p. A metabolic assay was conducted using graded doses (5 mg/kg – 160 mg/kg) The urine produced over a period of six hours was collected per animal and its volume, density, pH, and electrolyte concentrations (Na⁺, K⁺ and C^-) were determined using standard techniques. The effect of the most active dose level was compared to those of frusemide 3 mg/kg, mannitol 200 mg/kg, hydrochlorothiazide 10 mg/kg, and spironolactone 3 mg/kg. The extract was found to cause a dose-dependent increase in urine mobilization, which peaked at a dose of 40 mg/kg. At this dose level, .the extract showed a significant (p<0.05) aquaretic action characterized by a 300-fold increase in urine production, a slight fall in density and a fall in urine pH, relative to the control group. Although the extract did not increase the mobilization of the urinary electrolytes assayed, as did the standard diuretics used, the observed effects somewhat justify its ethnomedicinal use in the management of oedematous conditions.

Key words: Folk medicine; Hibiscus sabdariffa; Petals; Diuretics; Aquaretic; Urinary electrolytes; Rats.

Nig. J. Pharm. Res. 3(1) 2004: 1-8