Prolonged diuretic and saluretic effect of nothofagin isolated from Leandra dasytricha (A. Gray) Cogn. leaves in normotensive and hypertensive rats: Role of antioxidant system and renal protection.

Although the acute diuretic effect of nothofagin has been recently demonstrated, its effects after dose-repeated treatment have not yet been explored. For that, male Wistar normotensive (NTR) and spontaneously hypertensive rats (SHR) were orally treated, once a day, with vehicle (VEH: distilled water; 1 ml/kg), hydrochlorothiazide (HCTZ; 10 mg/kg) or nothofagin (NOT; 1 mg/kg). The cumulative diuretic index and urinary electrolytes excretion were measured each 24 h. On the last day of the experiment (7th day), urine, blood and kidney samples were collected for biochemical and molecular analyzes. The urinary volume of both NTR and SHR were significantly increased with the treatment with NOT (from the second to the seventh day of treatment), with final values reaching an increase of 56% and 82%, respectively, when compared with VEH-treated group. This effect was associated with increased levels of urinary excretion of Na+ and Cl-, without any changes on K+ excretion. None of the treatments modified urinary pH or density values. Importantly, neither the NOT nor the HCTZ caused any change in body weight following the dose-repeated treatment, and also did not provoke an electrolytic disturbance. Regarding the renal analyzes, when compared with the vehicle-treated NTR group, the activity of superoxide dismutase (SOD) and the reduced glutathione (GSH) levels in kidney homogenates of the SHR group were decreased, while the generation of lipid hydroperoxides were significantly increased. The daily treatment with NOT was able to restore the GSH levels and SOD activity, as well as reduced the lipoperoxidation in the kidney homogenates obtained from SHR animals. Finally, NOT significantly augmented the levels of nitrite, a marker of nitric oxide production, in the plasma obtained from SHR group when compared with the vehicle-treated only NTR. This study revealed the prolonged diuretic and saluretic effect of nothofagin in normotensive and hypertensive rats. Our data also showed the renal protective effects of nothofagin by the improvement of antioxidative capacity, as well as by the augmented bioavailability of plasma nitric oxide in the hypertensive group.

Diuretic, natriuretic and potassium-sparing effect of nothofagin isolated from Leandra dasytricha (A. Gray) Cogn. leaves in normotensive and hypertensive rats.

Active constituents from natural origin have long been used for the treatment of patients suffering from cardiovascular and renal diseases. This study therefore aimed to investigate the diuretic and natriuretic properties of nothofagin, a dihydrochalcone isolated from Leandra dasytricha (A. Gray) Cogn. leaves in normotensive and hypertensive rats. Male Wistar normotensive rats were orally treated with vehicle (1 ml/kg); hydrochlorothiazide (HCTZ; 25 mg/kg); ethyl acetate fraction from L. dasytricha (EALD; 3-30 mg/kg) and nothofagin (NOT; 0.3-3 mg/kg). Spontaneously hypertensive rats (SHR) received NOT (1 mg/kg), HCTZ (25 mg/kg) or vehicle. The cumulative diuretic index, urinary electrolytes excretion (Na+ and K+), pH, density and conductivity were measured at the end of the experiment (after 8 h). A7r5 and L929 cell lines were used to measure cell viability after exposure to NOT. Nitric oxide generation was quantified in A7r5 cell supernatant, and DPPH assay was used for evaluating the antioxidant properties of NOT. The urinary volume of normotensive rats were increased after the treatment with EALD, without any changes in Na+ or K+ excretion. NOT was able to induce diuresis and natriuresis, but not kaliuresis, in both normotensive and hypertensive rats. The reduction in prostanoids generation through cyclooxygenase inhibition, as well as the muscarinic receptor antagonism, fully avoided NOT-induced increases in diuretic index. NOT, which did not interfere with L929 or A7r5 cell viability, was able to stimulate nitric oxide generation in A7r5 cell, besides showing an antioxidant effect in scavenging the free-radical DPPH. Taken together, our study shows, for the first time, the diuretic, natriuretic and potassium-sparing effect of nothofagin in rats, which was associated with prostanoids generation, muscarinic receptor activation and antioxidant properties.