Our previous study showed that kaempferitrin, the main flavonoid from Bauhinia forf icata Link leaves, induces diuresis and saluresis when orally given to rats. Since afzelin (AFZ) and kaempferol (KFL) are active compounds from the biometabolism of kaempferitrin, the diuretic and renal protective properties of these two compounds were evaluated. While the acute treatment with AFZ evoked a diuretic action associated with an increase in Cl − excretion and a Ca 2+ -sparing effect, KFL did not present any activity. The pretreatment with a muscarinic receptor blocker or with an inhibitor of the cyclooxygenase fully avoided AFZ-induced diuresis. AFZ also induced a prolonged (7-day treatment) diuretic effect in normotensive (NTR) and hypertensive rats (SHR), with an increase of urinary Na + and Cl − excretion, while it decreased the elimination of Ca 2+ . AFZ was able to decrease ROS and nitrite generation on kidney homogenates in comparison with the SHR group treated with the vehicle, as well as mitigated the changes in the renal corpuscle region (glomerulus and Bowman's capsule). Moreover, AFZ significantly reduced calcium oxalate crystal formation in urine, with inhibition rates of 41% for the NTR and 92% for the SHR group. Taken together, this study shows that AFZ exerts acute and prolonged diuretic effects plus protective renal properties.

Although Bauhinia forficata Link is popularly used in Brazil to induce diuresis, no scientific investigation has focused on demonstrating its efficacy in preclinical trials. For that, normotensive male Wistar and spontaneously hypertensive rats were used to test the effect of extracts and kaempferitrin obtained from Bauhinia forficata leaves in the experimental model of diuresis. Cumulative urine volume, Na and K excretion, calcium, creatinine, prostaglandin E , pH, density, and conductivity were measured at the end of the experiment (after 8 or 24 h). The treatment with aqueous infusion, methanolic extract, trichloromethane, or ethyl acetate-butanolic fractions significantly increase urinary volume and electrolytes levels when orally given to rats, without altering the pH or density parameters. Kaempferitrin induced diuretic, natriuretic, but not kaliuretic effects in both normotensive and hypertensive rats. In addition, kaempferitrin enhanced urinary creatinine and prostaglandin E excretion, without modifying calcium levels. Kaempferitrin-induced diuresis was unaffected by previous treatment with a nonselective inhibitor of nitric oxide synthase and neither with a nonselective muscarinic receptor antagonist. On the other hand, a cyclooxygenase inhibitor was able to decrease its effect when compared with vehicle-treated rats, suggesting that the diuretic and natriuretic properties from kaempferitrin are associated with endogenous prostanoids generation. Copyright © 2017 John Wiley & Sons, Ltd.

This mini review focuses on the ethnopharmacology, phytochemical, and biological/pharmacological activity and toxicology of the medicinal plant, Bauhinia forficata reported during 2012-2016. The results confirmed the continuous use of this plant, especially the leaves, for medicinal purposes, particularly as remedies for the treatment of diabetes and other ailments. Other new biological potential was evidenced, including anti-ulcerogenic, hypocholesterolemic, hepatoprotective and diuretic effects. Clinical and toxicological studies have advanced gradually, requiring more detailed experiments, to ensure the safe use of this plant for medication. Some new flavonoids were detected in this species, but significant differences were observed when comparing the chemical composition of its sub-species.

This study aimed to investigate the possible diuretic effect in rats of two widely distributed bioactive compounds, rosmarinic and caffeic acids, derived from plants used in popular medicine, as well as to demonstrate their effects against in vitro calcium oxalate crystallization. Male Wistar rats were orally treated with vehicle, hydrochlorothiazide, rosmarinic acid, or caffeic acid. The volume and the urinary parameters were evaluated at the end of 8 h. The antiurolithiatic effect of the compounds was verified in vitro. Treatment with rosmarinic acid (3 mg/kg) or caffeic acid (10 mg/kg) significantly increased urine volume when compared with vehicle-treated rats, an effect associated with augmented urinary Na + excretion. Interestingly, while rosmarinic acid showed a K +-sparing effect, caffeic acid significantly increased urinary K + excretion, similarly to the group treated with hydrochlorothiazide (10 mg/kg). The two compounds showed a Ca 2+-sparing effect. Therefore, the in vitro analysis of urinary calculi revealed that rosmarinic acid and caffeic acid, in concentrations ranging from 0.03 to 0.3 mg/ml, reduced the number of monohydrate and dihydrate forms of calcium oxalate crystals formed in the urine, suggesting a potential antiurolithiatic effect of these compounds.

Although diuretics have been widely used to treat hypertension along with others cardiovascular and renal disorders, no scientific data have been recorded to support the diuretic properties of Rubus rosaefolius Sm. (Rosaceae), a plant popularly used in Brazil to treat hypertension. Male Wistar rats were orally treated with: vehicle; hydrochlorothiazide; aqueous (AERR) and methanolic (MERR) extracts; dichloromethane (DCM), hexane (HEX) and ethyl acetate (EA) fractions; and the isolated compounds 2α,3β,19α-trihydroxy-urs-12-en-28-oic acid (TUA) and 5-hydroxy-3,6,7,8,4'-pentamethoxyflavone (PMF). At the end of the experiment (after 8 or 24 h), urine volume and other urine or plasma parameters were measured. AERR and MERR, at 100 and 30 mg/kg, respectively, induced diuretic, natriuretic and kaliuretic effect. Additionally, the DCM and HEX, but not EA, at 10 mg/kg, also increased urine volume and Na and K excretion. Both active constituents, TUA and PMF, at doses of 1 and 3 mg/kg, showed an augmented diuretic and natriuretic index. While TUA revealed a kaliuretic action, PMF did not interfere with potassium excretion. The compounds increased urinary creatinine, but not urea, levels. TUA was able to decrease calcium excretion, as well as HCTZ, while PMF effect was associated with increased urinary prostaglandin E levels. The non-selective muscarinic receptor antagonist (atropine) prevented TUA-induced diuresis. In addition, indomethacin (a cyclooxygenase inhibitor) and atropine, exhibited the ability to block the diuretic effects prompted by PMF. Our study demonstrates the diuretic effect of extracts, fractions and two natural compounds obtained from R. rosaefolius leaves in rats.