Diuretic activity of some fractions of the epidermis of Poria cocos

ETHNOPHARMACOLOGICAL RELEVANCE

Poria cocos Wolf (Polyporaceae) is a well-known medicinal fungus, the epidermis ("Fu-Ling-Pi" in Chinese) of the sclerotia is used as a diuretic for treating oedema and promoting the diuretic process. In this paper we report on the diuretic activity in rats of petroleum ether, ethyl acetate, n-butanol and the remaining fractions of the ethanol extract from the epidermis of Poria cocos.

MATERIALS AND METHODS

Petroleum ether, ethyl acetate, n-butanol and the remaining fractions of the ethanol extract of Fu-Ling-Pi were orally administered to rats. The urinary excretion rate and the pH and electrolyte excretion were measured in the urine of saline-loaded rats.

RESULTS

In this study, all the tested fractions of Fu-Ling-Pi increased the urinary excretion rate. The three doses of the ethyl acetate fraction all produced remarkable urinary output in 6h, and all produced a remarkable increase in Na(+) excretion and Cl(-) excretion. The Na(+)/K(+) value in the experimental group was significantly enhanced compared with that of the control group, but the three doses of the ethyl acetate fraction had no effect on the K(+) excretion. The 25-mg/kg and 50-mg/kg doses of the n-butanol fraction showed notable urinary output and produced a remarkable increase of Na(+) excretion and Cl(-) excretion, but the two doses did not produce a remarkable effect on the Na(+)/K(+) value. The petroleum ether and remaining fractions did not show remarkable diuretic activities compared with the control group.

CONCLUSIONS

This study confirmed that the ethyl acetate and n-butanol fractions present a remarkable diuretic effect, showing that they are the diuretic bioactive fractions of Fu-Ling-Pi. This finding appears to indicate at least two mechanisms for the observed diuretic activity, and the K(+)-saving diuretic effect may be related to the triterpenoid components of intermediate polarity contained in this fungus, particularly the lanostanes tetracyclic triterpenoids.

Diuretic and anti-diuretic activities of the ethanol and aqueous extracts of Alismatis rhizoma

ETHNOPHARMACOLOGICAL RELEVANCE

Alismatis rhizoma or Alisma orientale (Zexie in Chinese), the dried rhizome of Alisma orientale Juzepzuk (Alismataceae), is a well-known traditional Chinese medicine and is used as an agent for diuresis and for excreting dampness in Asia and Europe. In this paper, we report the diuretic activities of the ethanol extract (EE) and the aqueous extract (AE) of A. rhizoma (AR).

MATERIALS AND METHODS

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

RESULTS

The results showed that EE could increase the urine output at 2.5, 5 and 10mg/kg doses but decrease the urine output at 20, 40 and 80mg/kg doses compared with the control group. The 5 and 10mg/kg doses of EE increased the urine electrolyte excretion, but the effects on Na(+)/K(+) values were too weak to reach statistical significance. The Na(+) excretion and Cl(-) excretion were markedly decreased with the 20, 40 and 80mg/kg doses of EE, but the effect on K(+) excretion was notably slight. All of the tested doses of AE produced an increase in urinary excretion, but the increase did not reach statistical significance.

CONCLUSIONS

This study identified that EE but not AE presents a notable diuretic effect, and EE had diuretic and anti-diuretic effects, which appears to be related to the sodium-chloride co-transporter in the renal distal convoluting tubule. This study demonstrated for the first time that the EE of AR has a dual effect on renal function, including promotion of diuretic activity at lower doses and inhibiting diuretic activity at higher doses, and the AR dose should be given more attention in clinical applications. This study will play a critical and guiding role in the dosing of AR as a diuretic drug in clinical applications.