A novel quinolinone diuretic, M12285, and its activation mechanism through sulfate conjugation

Heterocycles in Breast Cancer Treatment: The Use of Pyrazole Derivatives

Among the aromatic heterocycle rings, pyrazole -a five-membered ring with two adjacent nitrogen atoms in its structure has been postulated as a potent candidate in the pharmacological context. This moiety is an interesting therapeutic target covering a broad spectrum of biological activities due to its presence in many natural substances. Hence, the potential of the pyrazole derivatives as antitumor agents has been explored in many investigations, showing promising results in some cases. In this sense, breast cancer, which is already the leading cause of cancer mortality in women in some countries, has been the topic selected for this review, which covers a range of different research from the earliest studies published in 2003 to the most recent ones in 2021.

Reaction of pregnenolone with cyanoacetylhydrazine: novel synthesis of hydrazide-hydrazone, pyrazole, pyridine, thiazole, thiophene derivatives and their cytotoxicity evaluations

Pregnenolone (1) was used as a template to develop new anticancer compounds. Ring D modification of 1 through its reaction with cyanoacetylhydrazine (2) gave the hydrazide-hydrazone derivative 3. The latter compound underwent heterocyclization reactions to give the pyrazole, pyridine, thiazole and thiophene derivatives of pregnenolone. The cytotoxicity of the newly synthesized heterocyclic steroids against three human tumor cell lines namely breast adenocarcinoma (MCF-7), non-small cell lung cancer (NCI-H460) and CNS cancer (SF-268) were studied. Some of tested compounds were found to exhibit much higher inhibitory effects towards the three tumor cell lines than the reference drug, doxorubicin.

Studies on the Metabolic Fate of M17055, a Novel Diuretic (5): Pharmacokinetics and Pharmacodynamics of Unchanged Drug in Rat and Dog After Intravenous Administration of M17055

The pharmacokinetics and pharamacodynamics of M17055, a novel diuretic were studied after a single intravenous administration to rats and dogs, the two species used in the pharmacological and toxicological studies. No gender dependent response to systemic exposure was observed at the high dose level in rats, in agreement with the determined LD(50). A gender difference in urinary excretion of M17055, however, was clearly observed in rats. The slower elimination and the lower total body clearance (CLtot) values of M17055 in dogs reflect the difference of the no-effect level (NOEL) between rats (0.1 mg/kg) and dogs (0.03 mg/kg) well. The diuretic response was well correlated with the urinary M17055 excretion rate by fitting to a sigmoid E(max) model in both rats and dogs. The derived ER(50) value of M17055 in dogs was approximately 10 times less than that reported for furosemide, suggesting that the intrinsic potency of M17055 is equal to or higher than those of other powerful loop diuretics. Although diuretic sensitivity was considered to be lower in dogs than in rats, the higher amount of M17055 reaching the dog kidney is likely to compensate for this. The diuretic response in female rats was predictable by using the pharmacodynamic parameters derived from male rats. These results show that the apparent high diuretic potency and the other pivotal observations for M17055 found in the pharmacological and toxicological studies can be rationalized by the pharmacokinetic and pharmacodynamic properties of the unchanged compound.

Studies on the Metabolic Fate of M17055 a Novel Diuretic (4): Species Difference in Metabolic Pathway and Identification of Human CYP Isoform Responsible for the Metabolism of M17055

The metabolic profile of M17055, a novel diuretic, after administration to experimental animals and after incubation with human liver microsomes was investigated. 1. Extensive metabolism was observed in rats and monkeys and the structures of six metabolites (RU1, RU2, and RU3 from rat urine or liver perfusate; MU1, MU2 and MU3 from monkey urine) were assumed or identified. The clear species difference of metabolism was revealed between rats and a monkey with different structures of the isolated metabolites. 2. When these metabolites were quantified using radioactive material, RU3, RU1 and MU3 were considered to be major metabolites in rat urine, rat bile and monkey urine respectively, while in a dog, unchanged drug was observed as the major component indicating only little metabolism occurred in dog, when administered intravenously. 3. RU1 and RU2 were also generated from [(14)C]M17055 after incubation with human liver microsomes, suggesting that the metabolic pathway of M17055 in humans involves that observed in rats. 4. [(14)C]M17055 metabolism in human liver microsomes was inhibited by CYP2C8/9 and CYP3A4/5 inhibitors, and also by the antibodies that recognize CYP2C8/9/19 and CYP3A4. Significant correlations were observed between the rate of [(14)C]M17055 metabolism and the activity of testosterone 6beta-hydroxylation or tolbutamide methyl-hydroxylation. cDNA-expressed CYP3A4 and CYP2C9 could catalyze the metabolism of [(14)C]M17055. These results suggest that the metabolism of M17055 in human liver microsomes is catalyzed mainly by CYP3A4 and CYP2C9.

Evidence for (+)-cicletanine sulfate as an active natriuretic metabolite of cicletanine in the rat

It was previously shown that the urinary sulfo-conjugate metabolite of cicletanine (cicletanine sulfate), and not free cicletanine, is salidiuretic in rats. Here we investigated potential differences between the resolved (+/-) enantiomers of cicletanine sulfate. Two groups of rats (n = 10) received either (+)- or (-)-cicletanine p.o. High performance capillary electrophoresis revealed that the 24-h urinary excretion of (+)-cicletanine sulfate was 5 times higher than that of (-)-cicletanine sulfate (18.9% vs. 3.8% of the oral dose). The same relative trend was observed after 5 and 10 days of oral administration. Following direct administration into the renal artery of anesthetized rats, (+)-cicletanine sulfate was 3-4 times more potent, in terms of active doses, than (-)-cicletanine sulfate to increase sodium excretion (ED50 = 1.86 +/- 0.28 mg/kg vs. 6.1 +/- 1.0 mg/kg, mean +/- S.E.M., n = 4). The maximal natriuretic potency of (+)-cicletanine sulfate was intermediate between that of furosemide and DIDS (4,4'-diisothiocyanostilbene-2,2'-disulfonate). In rat erythrocytes, (+)-cicletanine sulfate was between 2 and 3 times more potent to inhibit the Na(+)-dependent Cl-/HCO3- anion exchanger than (-)-cicletanine sulfate (IC50 = 61 +/- 3 microM vs. 142 +/- 31 microM, n = 4). In conclusion, (+)-cicletanine was more sulfo-conjugated and more potent natriuretic agent in rats than (-)-cicletanine. These results strongly suggest that (+)-cicletanine sulfate is the active natriuretic metabolite of racemic cicletanine in rats. This compound may probably act by inhibiting the Na(+)-dependent Cl-/HCO3- anion exchanger at the cortical diluting segment.

Beneficial effect of a novel diuretic, M17055, on blood pressure and cardiovascular hypertrophy in spontaneously hypertensive rats

We investigated the effects of a novel diuretic, M17055, on blood pressure and cardiovascular hypertrophy in spontaneously hypertensive rats (SHR). M17055 was orally administered once a day for 24 consecutive days to 14-week-old male SHR. M17055 at doses of 1.25, 2.5 and 5 mg/kg/day exerted a dose-related diuretic and antihypertensive effect during the treatment. The weight of the left ventricle normalized by body weight on the following day of the last dosage was significantly (P < 0.01) reduced by M17055 at doses of 2.5 and 5 mg/kg/day in a dose-dependent manner. The effect of M17055 on cardiac hypertrophy was more potent (P < 0.01) than that of captopril, when the comparison was performed at the doses of M17055 and captopril inducing the same extent of blood-pressure decrement. Vascular hypertrophy was evaluated by the media/lumen ratio (M/L) in the thoracic aorta and the first branch of the superior mesenteric artery. In the aorta, M/L was slightly, but not significantly, decreased by M17055 at doses of 2.5 and 5 mg/kg/day, whereas it was decreased significantly (P < 0.01) by captopril. In the mesenteric artery, the ratio was significantly (P < 0.05) reduced by M17055 at a dose of 5 mg/kg/day. These results suggest that M17055 possesses beneficial properties for the clinical treatment of hypertension.

Loop and distal actions of a novel diuretic, M17055

We investigated the mechanism of action of a novel 'high ceiling' diuretic, M17055, in in vivo clearance studies with anesthetized dogs during water diuresis and in vitro microperfusion studies of isolated rabbit renal tubules. In the clearance study, intravenous infusion of M17055 (1 mg/kg per h) decreased free water clearance and increased urinary excretion of Na+ and Cl- to a greater extent than did a maximum dose of furosemide (30 mg/kg per h). With the maximum dose of furosemide, an additional dose of M17055 or hydrochlorothiazide resulted in additional suppression of free water clearance. These results indicate that M17055 has some additional mechanisms of action in the distal nephron. In isolated rabbit cortical thick ascending limb of Henle's loop, M17055 applied to the lumen decreased the lumen positive transepithelial voltage at concentrations over 10(-6) M and suppressed the lumen-to-bath 36Cl- flux at 10(-5) M. In the connecting tubule, M17055 added to the lumen suppressed lumen negative transepithelial voltage in a concentration-dependent manner in a range from 10(-4) to 10(-3) M. The effect of M17055 on transepithelial voltage was also observed in the distal convoluted tubule and cortical collecting duct. Moreover, 10(-3) M of M17055 in the lumen significantly decreased the lumen-to-bath 22Na+ flux in the cortical collecting duct. From these observations, it appears that M17055 acts not only on the thick ascending limb of Henle's loop but also on the distal segments via inhibition of electrogenic Na+ transport.