Preclinical evaluation of the diuretic and saluretic effects of (-)-epicatechin and the result of its combination with standard diuretics

Evaluation of the toxicity of the hydroethanolic extract of the stem bark of Virola elongata (Benth.) Warb. in in vitro and in vivo models

ETHNOPHARMACOLOGICAL RELEVANCE

Virola elongata (Benth.) Warb. (Myrsticaceae), referred to as "mucuíba" in Mato Grosso, is a native tree species that can be found in the Amazon Rainforest regions of South America and the Tropical Forests of Central America. The macerated extracts from the stem bark of this tree have been traditionally used to address various health issues, including gastric ulcers, infections, inflammations, and other ailments. In scientific literature, V. elongata has demonstrated pharmacological properties such as antiulcer, gastroprotective, antiproliferative, antimitotic, and psychoactive effects. Nevertheless, it is important to note that the safety profile of V. elongata has not been thoroughly established.

AIM OF THE STUDY

To evaluate the toxicity of the hydroethanolic extract of the stem bark of Virola elongata (HEVe) in experimental models in vivo and in vitro.

MATERIALS AND METHODS

HEVe was obtained by macerating the stem bark powder in 70% hydroethanolic solution (1:10 w/v). The cytotoxicity of HEVe (3.125-200 μg/mL) was evaluated by Alamar blue assay in Chinese hamster ovary epithelial cells (CHO-k1) and human gastric adenocarcinoma (AGS). Genotoxicity assessment of HEVe (10, 30, or 100 μg/mL) was performed in CHO-k1 cells by the micronucleus test. The acute toxicity of HEVe was assessed by single-dose oral administration (2000 mg/kg) in mice of both sexes. The subacute toxicity of HEVe was assessed by oral administration of 300, 600, and 1200 mg/kg of the extract over 30 days in rats. Clinical observations of toxicological parameters were noted and pooled every 6 days. After the treatment period, blood was collected for hematological and biochemical analyses, and some organs were removed for macroscopic and histopathological analyses.

RESULTS

HEVe did not show cytotoxicity in CHO-K1 and AGS cells (IC50 > 200 μg/mL) and did not cause DNA damage in CHO-k1 cells. Oral administration of HEVe in a single dose of 2000 mg/kg did not result in the death of the mice, with a reduction in body weight variation (33.03%, p < 0.05) and an increase in the relative weight of the stomach (12 0.82%, p < 0.05) in male mice, and increased relative weight of the spleen (25.00%, p < 0.01) in female mice. In the assessment of subacute toxicity, HEVe did not result in the death of the animals over the 30 days. A reduction (p < 0.05) in water consumption of 36.65% and 34.12% was observed in the groups treated with 300 and 600 mg/kg, respectively, of HEVe on D6., and the urine excretion of animals treated with 600 mg/kg of HEVe showed an increase (p < 0.05) throughout the experiment, with a maximum value of 46.72% on D12. The blood counts showed that the dose of 300 mg/kg reduced (p < 0.05) the absolute number of lymphocytes, while the doses of 300, 600, or 1200 mg/kg of HEVe reduced the red blood cell count in whole blood by 24.84% (p < 0.01), 16.72% (p < 0.05), and 22.14% (p < 0.01), and the absolute number of monocytes (p < 0.05) in 59.77%, 65.51%, and 79.81%, respectively. As for the biochemical parameters, the glucose level found increased by 22.41% (p < 0.05) only at the highest dose, while creatinine was reduced by 44.71% (p < 0.05) at the dose of 300 mg/kg of HEVe. In animals treated with the three doses tested, plasma levels of AST and alkaline phosphatase showed a reduction (p < 0.05) with the vehicle group. However, the hematological and biochemical changes observed are within the physiological limits for this animal species. No macroscopic and histopathological changes were observed in the organs of the animals treated with the three doses of HEVe within 30 days.

CONCLUSION

The results showed that HEVe did not show cytotoxicity or genotoxicity in vitro. HEVe proved to be safe in rodents in both acute and subacute toxicity tests. In rats, the no-observed-adverse-effect level (NOAEL) dose was greater than 1200 mg/kg p. o. in rats.

The diuretic effect of ethyl acetate fractions of Artocarpus altilis, Artocarpus champeden, and Artocarpus heterophyllus leaves in normotensive Wistar rats

BACKGROUND

Artocarpus altilis, A. Champeden, and Artocarpus heterophylus are popular species in Indonesia, and are commonly used as traditional medicine.

OBJECTIVE

This study aims to evaluate the diuretic effects of the ethyl acetate fraction of these three species on normotensive Wistar rats.

METHODS

The ethyl acetate fraction was prepared by a liquid-liquid extraction method. To evaluate diuretic effects, the sixty rats were divided into normal (distilled water), negative (4.5% NaCl), positive control (furosemide 5 mg/kg), and the testing groups. The testing groups were orally given the ethyl acetate fraction of A. altilis, Artocarpus champeden, and A. heterophylus at three dose levels of 25, 50, and 100 mg/kg. All animals were orally given 4.5% NaCl at a dose of 2 mL/200 g except the normal group; then the animals were given drugs according to group doses. Urine volume and electrolyte levels produced by the testing groups were compared to those of the control group. The concentration and ratio of ions were calculated to determine the natriuretic and carbonic anhydrase activities.

RESULTS

The ethyl acetate fractions of the three Artocarpus species at 100 mg/kg dose were more active than the standard furosemide (p < 0.05) to increase urinary excretion. Furthermore, at doses of 50 and 100 mg/kg, the fraction significantly increased the excretion of Na+, K+, and Cl- ions more than the standard (p < 0.05). The testing groups showed good natriuretic and carbonic anhydrase activities.

CONCLUSIONS

The ethyl acetate fraction of A. altilis, A. champeden, and A. heterophylus leaves performed good diuretic and natriuretic activities. Therefore, the fractions can be considered as potential natural diuretic medicines.

Tagetes erecta L. flowers, a medicinal plant traditionally used to promote diuresis, induced diuretic and natriuretic effects in normotensive and hypertensive rats

ETHNOPHARMACOLOGICAL RELEVANCE

Tagetes erecta L., known as marigold, belongs to the Asteraceae family and is mainly found in South America. Despite reports that T. erecta flowers are used in folk medicine to treat cardiovascular and renal diseases, there is no study regarding its diuretic effect.

AIM

This study aimed to evaluate the chemical composition and the diuretic efficacy of the hydroethanolic extract from T. erecta (HETE) in normotensive (NTR) and hypertensive (SHR) rats.

MATERIAL AND METHODS

The HETE was analyzed by liquid chromatography coupled to diode array detector and mass spectrometry (LC-DAD-MS). Female and male NTR and SHR received the treatment with vehicle, HETE (0.01 mg/kg, 0.1 mg/kg, and 1 mg/kg) or hydrochlorothiazide (HCTZ; 5 mg/kg) orally. The urinary parameters were measured at the end of the 8-h experiment.

RESULTS

From HETE, saccharides and triterpenes were the main annotated compounds, such as erythrodiol and β-amyrin. The urine volume was significantly increased in the groups treated with HETE, in both male and female NTR and SHR rats, compared to the respective vehicle-treated groups. Regarding electrolytes elimination, the treatment with HETE did not reveal significant changes in the urine levels of K⁺ or Cl^-, but it showed a natriuretic and Ca²⁺-sparing effects. The HETE beneficial result in reducing Ca²⁺ excretion was confirmed through the protective effect found in front of the urinary calcium oxalate precipitation and crystallization. The combination with HCTZ, a classic diuretic and saluretic medicine, significantly enhanced HETE-induced diuresis, natriuresis, and the Ca²⁺-sparing effect. On the other hand, the K⁺-sparing action was improved in the combination of HETE with amiloride, a standard K⁺-sparing diuretic. In contrast, the combination of HETE with atropine (a non-selective muscarinic receptor antagonist) and indomethacin (an inhibitor of the cyclooxygenase enzyme), promoted an important reduction in urinary volume, but interestingly the natriuretic effect was maintained.

CONCLUSION

This study contributed to the preclinical validation of the diuretic efficacy of T. erecta, highlighting this species as promising for the development of new pharmacological strategies for the management of kidney disorders.

Mechanisms and management of edema in pediatric nephrotic syndrome

Edema is the abnormal accumulation of fluid in the interstitial compartment of tissues within the body. In nephrotic syndrome, edema is often seen in dependent areas such as the legs, but it can progress to cause significant accumulation in other areas leading to pulmonary edema, ascites, and/or anasarca. In this review, we focus on mechanisms and management of edema in children with nephrotic syndrome. We review the common mechanisms of edema, its burden in pediatric patients, and then present our approach and algorithm for management of edema in pediatric patients. The extensive body of experience accumulated over the last 5 decades means that there are many options, and clinicians may choose among these options based on their experience and careful monitoring of responses in individual patients.

Promising Medicinal Plants with Diuretic Potential Used in Brazil: State of the Art, Challenges, and Prospects

Medicinal plants are used in traditional medicine to treat a wide range of ailments. The knowledge of them is handed down from generation to generation and is described in several pharmacopoeia and in the general literature. The immense biodiversity of the Brazilian flora, covering about 25% of all plant species worldwide, makes Brazil a huge potential source of medicinal plants. Indeed, many of these plant species are already used in the Brazilian ethnopharmacology for their probable effect to induce diuresis, to reduce fluid retention, and to treat cardiovascular and renal disorders. This review article describes and discusses the main native Brazilian medicinal plants (including some of their isolated compounds) used as diuretics. It also gives a comprehensive analysis of the most relevant scientific studies presented to date, as well as addressing a special topic with future prospects for plant species that have not yet been scientifically studied. In brief, several plants can be indicated for more detailed study, with a view to obtain scientific subsidies for a new and effective diuretic medicine in the future. These include Bauhinia forficata, Leandra dasytricha, and Tropaeolum majus. Other species have reputed medicinal properties but lack experimental assays to demonstrate their pharmacological effects (e.g., Mikania hirsutissima, Phyllanthus niruri, and Tagetes minuta). Several active principles are indicated as responsible for the diuretic effects of the plants studied, with emphasis on phenolic compounds as flavonoids, phenolic acids, and xanthones. These results should encourage more detailed preclinical, clinical, and phytochemical investigations on Brazilian plants in the future.

The acute diuretic effects with low-doses of natural prenylated xanthones in rats

The diuretic effect of 3-demethyl-2-geranyl-4-prenylbellidypholine xanthone (DGP) and 1,5,8-trihydroxy-4',5'-dimethyl-2H-pyrano(2,3:3,2)-4-(3-methylbut-2-enyl) xanthone (TDP), two natural prenylated xanthones, was investigated in female normotensive (NTR) and spontaneously hypertensive rats (SHR). The rats received a single treatment with DGP, TDP, hydrochlorothiazide (HCTZ), or vehicle (VEH) after an oral load of physiological saline. The effects of DGP and TDP in combination with diuretics of clinical use, as well as with L-NAME, atropine and indomethacin were also explored. The urinary parameters were measured at the end of the 8-h experiment. When orally given to rats, DGP was able to increase the urine volume, at doses of 0.03-0.3 mg/kg, associated with a K⁺-sparing effect. TDP, in turn, at doses of 0.03-0.3 mg/kg, induced diuresis and saluresis (i.e. augmented urinary levels of Na⁺ and Cl^-) in NTR, while decreased the urinary content of Ca²⁺ in both NTR and SHR. The combination with HCTZ, but not with furosemide or amiloride, significantly enhanced DGP and TDP induced diuresis, which was accompanied by an increase of the electrolytes content in the urine. Instead, amiloride in combination with DGP or TDP enhanced urinary Na⁺ and Cl^- and decreased K⁺ elimination. Furthermore, the effect of DGP and TDP were heightened after pretreatment with L-NAME. While atropine was able to prevent DGP-induced diuresis, the pretreatment with indomethacin precluded TDP-induced diuresis. Besides, TDP exerted protective effects against urinary calcium oxalate crystals formation. Taken together, our data revealed the diuretic effect of two xanthones in rats and their possible underlying mode of action.

Diuretic and Renal Protective Effect of Kaempferol 3-O-Alpha-l-rhamnoside (Afzelin) in Normotensive and Hypertensive Rats

Our previous study showed that kaempferitrin, the main flavonoid from Bauhinia forficata 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 Ca²⁺-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 Ca²⁺. 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.

Nephrotic Syndrome: Oedema Formation and Its Treatment With Diuretics

Oedema is a defining element of the nephrotic syndrome. Its' management varies considerably between clinicians, with no national or international clinical guidelines, and hence variable outcomes. Oedema may have serious sequelae such as immobility, skin breakdown and local or systemic infection. Treatment of nephrotic oedema is often of limited efficacy, with frequent side-effects and interactions with other pharmacotherapy. Here, we describe the current paradigms of oedema in nephrosis, including insights into emerging mechanisms such as the role of the abnormal activation of the epithelial sodium channel in the collecting duct. We then discuss the physiological basis for traditional and novel therapies for the treatment of nephrotic oedema. Despite being the cardinal symptom of nephrosis, few clinical studies guide clinicians to the rational use of therapy. This is reflected in the scarcity of publications in this field; it is time to undertake new clinical trials to direct clinical practice.