The effect of Menyanthes trifoliata L. on acute renal failure might be due to PAF-inhibition.

The influence of oral administration of a water decoction made from the rhizomes of Menyanthes trifoliata L. (MtL) was studied in rats, before and after exposure of 45 min of renal ischemia. Under normal conditions (preischemia) MtL treated kidneys behave similarly to untreated kidneys, measured as glomerular filtration rate (GFR), urine flow and the ability of the kidneys to concentrate urine. After ischemia, the MtL animals, showed much more preserved renal function, demonstrating a glomerular filtration rate (GFR) that was more than 3 times higher than in untreated animals. An in vitro model of platelet activating factor (PAF)-induced exocytosis in human neutrophils, was used to investigate PAF-inhibiting activity of MtL. The standard PAF antagonists WEB 2086, WEB 2170 and SRI 63-441 were used and compared to MtL. All PAF antagonists showed a concentration-dependent inhibition of the exocytosis of activated neutrophils, the PAF-inhibitor WEB 2170 being the most potent, with an IC(50) = 0.2 μg/ml while MtL showed an IC(50) = 160 μg/ml. It is concluded that the higher GFR seen after acute renal failure and treatment with MtL, could, in part, be due to a PAF-antagonistic effect.