Gallic acid, a phenolic compound isolated from Mimosa bimucronata (DC.) Kuntze leaves, induces diuresis and saluresis in rats.

Although present in the leaves of Mimosa bimucronata (DC.) and many other medicinal plants commonly used to augment urinary volume excretion, the effects of gallic acid as a diuretic agent remain to be studied. Wistar rats were orally treated with vehicle, hydrochlorothiazide, or gallic acid. The effects of gallic acid in the presence of hydrochlorothiazide, furosemide, amiloride, L-NAME, atropine, and indomethacin were also investigated. Diuretic index, pH, conductivity, and electrolyte excretion were evaluated at the end of the experiment (after 8 or 24 h). Gallic acid induced diuretic and saluretic (Na+ and Cl-) effects, without interfering with K+ excretion, when orally given to female and male rats at a dose of 3 mg/kg. These effects were associated with increased creatinine and conductivity values while pH was unaffected by any of the treatments. Plasma Na+, K+, and Cl- levels were not affected by any of the acute treatments. The combination with hydrochlorothiazide or furosemide was unable to intensify the effects of gallic acid when compared with the response obtained with each drug alone. On the other hand, the treatment with amiloride plus gallic acid amplified both diuresis and saluresis, besides to a marked potassium-sparing effect. Its diuretic action was significantly prevented in the presence of indomethacin, a cyclooxygenase inhibitor, but not with the pretreatments with L-NAME or atropine. Although several biological activities have already been described for gallic acid, this is the first study demonstrating its potential as a diuretic agent.

Chemical composition and diuretic, natriuretic and kaliuretic effects of extracts of Mimosa bimucronata (DC.) Kuntze leaves and its majority constituent methyl gallate in rats.

OBJECTIVES: Some species of the genus Mimosa showed promising results in previous investigations, which include diuretic effect; however, no chemical analyses or animal model has been conducted so far to evaluate the biological properties of M. bimucronata. METHODS: Male Wistar rats received the oral treatment with vehicle; hydrochlorothiazide; methanolic extract from M. bimucronata (MEMB), dichloromethane (DCM) and ethyl acetate (EA) fractions or methyl gallate (MG). The cumulative urine volume, electrolytes excretion, pH and osmolality were determined at the end of the experiment. KEY FINDINGS: The chemical studies demonstrated that the phenolic compounds are the majorities in the plant, with the MG being the main substance identified. We showed that MEMB and EA fraction, but not DCM, exhibited diuretic and saluretic effects. Similarly, the MG also revealed diuretic, natriuretic and kaliuretic properties to both normotensive and spontaneously hypertensive rats. Atropine, a muscarinic receptor antagonist, fully prevented MG-induced diuresis and saluresis. In addition, MG did not alter the viability of A7r5 and L929 cell lines and neither stimulated nitric oxide generation. CONCLUSIONS: These findings suggest that M. bimucronata extracts and its majority compound MG present diuretic, natriuretic and kaliuretic properties, which was dependent on the activation of muscarinic acetylcholine receptor.

Gastroprotective bio-guiding study of fruits from Mimusops balata.

Mimusops spp. is used as plant-based antiulcer drugs in Indian traditional medicine. In this study, a bio-guiding study of methanolic extracts of Mimusops balata edible fruits was performed to identify an antiulcer gastric compound. The gastric lesions induced by HCl/ethanol in mice were significantly improved by methanolic extract from seed (MESe, 300 mg/kg), but not by methanolic extract from peel (MEPe, 300 mg/kg) or pulp (MEPu, 300 mg/kg), when compared to the vehicle group. Treatment with MESe also decreased gastric ulceration induced by indomethacin. The antiulcerogenic activity of MESe appears to involve the maintainance of GSH levels, reduction of LPO content, inhibition of neutrophil migration (as evidenced by a decrease in the MPO activity) and a potent free radical scavenger activity (IC50 = 3.4 µg/ml). Moreover, MESe decrease the gastric volume, pH, total acidity, and pepsin activity in the gastric juice. Exceptionally, MESe showed a high content of phenolic compound, identified by layer chromatography and Folin-Ciocalteu reagent. Considering the better pharmacological and phytochemical profile, MESe was successively partitioned and resulted in isolation and identification of a constituent, the flavonoid taxifolin, identified by spectroscopic methods ((1)H, (13)C NMR, and HPLC). Taxifolin also inhibited the ulcerogenic effect of HCl/ethanol at a low dose of 1.14 mg/kg and inhibited in vitro H+/K(+)-ATPase activity by 41% at a concentration of 100 µg/ml. Taken together, these results evidenced the gastroprotective potential of fruits from M. balata and showed that this effect is exclusive to the seeds.