Diuretic activity of the ethanol and aqueous extracts of the surface layer of Poria cocos in rat

Ethnopharmacological relevance: Poria cocos Wolf (Polyporaceae) is a well-known traditional East-Asian medicinal fungus. the epidermis ("Fu-Ling-Pi" in Chinese) of the sclerotia is used as a diuretic. This study was conducted to evaluate of ethanol extract (EE) and aqueous extract (AE) of the diuretic activity of Fu-Ling-Pi in saline-loaded rats.

Material and methods: The EE and AE were orally administered to rats. Urinary excretion rate, pH and electrolyte excretion were measured in the urine of saline-loaded rats.

Results: Urinary excretion rates were significantly increased by the EE. The three doses of AE only produced a slight increase urinary output. The EE had little or no effect on K(+) excretion, but did indeed induce a notable excretion of Na(+), that was in agreement with the urinary excretion. The three doses of AE produced an increase Na(+) and K(+) excretion, but did not arrive at statistical significance.

Conclusions: The present study confirmed that the not aqueous but ethanol extracts of the epidermis of Poria cocos presents a remarkable diuretic effect.