Design, Biological Evaluation, and Molecular Modeling of Tetrahydroisoquinoline Derivatives: Discovery of A Potent P-Glycoprotein Ligand Overcoming Multidrug Resistance in Cancer Stem Cells.

P-Glycoprotein is a well-known membrane transporter responsible for the efflux of an ample spectrum of anticancer drugs. Its relevance in the management of cancer chemotherapy is increased in view of its high expression in cancer stem cells, a population of cancer cells with strong tumor-promoting ability. In the present study, a series of compounds were synthesized through structure modulation of [4'-(6,7-dimethoxy-3,4-dihydro-1 H-isoquinolin-2-ylmethyl)biphenyl-4-ol] (MC70), modifying the phenolic group of the lead compound. Among them, compound 5b emerged for its activity against the transporter (EC50 = 15 nM) and was capable of restoring doxorubicin antiproliferative activity at nontoxic concentration. Its behavior was rationalized through a molecular modeling study consisting of a well-tempered metadynamics simulation, which allowed one to identify the most favorable binding pose, and of a subsequent molecular dynamics run, which indicated a peculiar effect of the compound on the motion pattern of the transporter.

Vascular Toxicity Risk Assessment of MC18 and MC70, Novel Potential Diagnostic Tools for In Vivo PET Studies.

The P-glicoprotein (P-gp) inhibitor MC18 has been recently proposed as a valuable PET tracer to measure P-gp expression in vivo. The aim of this study was to evaluate the toxic hazard towards the vasculature of MC18 along with the structurally related and more potent P-gp inhibitor MC70. Their effects on A7r5 and EA.hy926 cells viability, on the mechanical activity of fresh and cultured rat aorta rings as well as on Cav 1.2 channel current (ICa1.2 ) of A7r5 cells were studied. At concentrations >10 µM, MC18 and MC70 decreased cell viability causing evident morphological changes. In fresh rat aorta rings, both compounds (0.1-100 µM) antagonized phenylephrine-induced contraction in a concentration-dependent manner, with IC50 values in the range of 1.67-14.49 µM, whereas only MC18 caused a concentration-dependent decrease of the 60 mM K+ (K60)-induced responses. In rings cultured for 7 days with both compounds (1-10 µM), 10 µM MC70 significantly reduced, while 10 µM MC18 completely prevented the contractile response to both phenylephrine and K60. MC18 and MC70 (0.1-100 µM) inhibited ICa1.2 in a concentration-dependent manner with IC50 values of 16.81 and 32.13 µM, respectively. These findings demonstrate that MC18-induced vascular effects took place at concentrations that are at least three orders of magnitude higher than those (≤10 nM) allowing in vivo measurement of P-gp expression. Thus, MC18, and possibly MC70, can be considered promising PET tools for in vivo P-gp quantification.

Structure-Activity Relationship Studies on Tetrahydroisoquinoline Derivatives: [4'-(6,7-Dimethoxy-3,4-dihydro-1H-isoquinolin-2-ylmethyl)biphenyl-4-ol] (MC70) Conjugated through Flexible Alkyl Chains with Furazan Moieties Gives Rise to Potent and Selective Ligands of P-glycoprotein.

P-glycoprotein (P-gp) is a well-known membrane transporter expressed in a number of strategic biological barriers, where it exerts a protective effect of paramount importance. Conversely it is one of the main causes of multidrug resistance (MDR), being capable of effluxing many chemotherapeutics. In a development of previous research, a small library of compounds was created conjugating diversely substituted furazan rings with MC70, a well-known P-gp inhibitor. These compounds were assessed for their potency against P-gp and another transporter (MRP1), for their apparent permeability (Papp) and for their ability to induce ATPase activity, thus delineating a complete functional profile. They displayed a substrate mechanism of action and high selectivity toward P-gp, unlike the lead compound. Data relating to their activity range from low micromolar to sub-nanomolar EC50, the most interesting compounds being 15 (0.97 nM), 19 (1.3 nM), 25 (0.60 nM), and 27 (0.90 nM).

Functionalized Coumarine Fragment to Obtain Fluorescent and Selective P-Glycoprotein Ligands.

Starting from our lead compound MC70 displaying high P-glycoprotein (P-gp) inhibition activity but low selectivity, a new class of coumarine derivatives was studied to develop selective and fluorescent P-gp ligands. In this series, the biphenyl moiety of MC70 was replaced with the coumarine fluorophore as a bioisostere of the biphenyl nucleus in order to improve the selectivity toward P-gp and the fluorescent properties for in vitro studies. Moreover, the presence and position of substituents on the coumarine nucleus were probed to develop suitable fluorescent probes to study the expression and activity of P-gp in living cells. The best result was found for compound 4c, which exerts a good P-gp activity profile (EC50 = 13 µM) as substrate and a high selectivity toward the pump since it is inactive toward MRP1.

Stereoselective Modulation of P-Glycoprotein by Chiral Small Molecules.

Inhibition of drug efflux pumps such as P-glycoprotein (P-gp) is an approach toward combating multidrug resistance, which is a significant hurdle in current cancer treatments. To address this, N-substituted aryloxymethyl pyrrolidines were designed and synthesized in their homochiral forms in order to investigate the stereochemical requirements for the binding site of P-gp. Our study provides evidence that the chiral property of molecules could be a strategy for improving the capacity for interacting with P-gp, as the most active compounds of the series stereoselectively modulated this efflux pump. The naphthalene-1-yl analogue (R)-2-[(2,3-dichlorophenoxy)methyl]-1-(naphthalen-1-ylmethyl)pyrrolidine) [(R)-7 a] emerged foremost for its potency and stereoselectivity toward P-gp, with the S enantiomer being nearly inactive. The modulation of P-gp by (R)-7 a involved consumption of ATP, thus demonstrating that the compound behaves as a P-gp substrate.

Aerosol corrosion prevention and energy-saving strategies in the design of green data centers.

The energy demands of data centers (DCs) worldwide are rapidly increasing, as are their environmental and economic costs. This paper presents a study conducted at Sannazzaro de' Burgondi (Po Valley), Italy, specifically aimed at optimizing the operating conditions of a DC designed for the Italian Oil and Gas Company (Eni) (5200 m(2) of Information Technology installed, 30 MW) and based on a direct free cooling (DFC) system. The aim of the study was to save the largest possible quantity of energy, while at the same time preventing aerosol corrosion. The aerosol properties (number size distribution, chemical composition, deliquescence relative humidity (DRH), acidity) and meteorological parameters were monitored and utilized to determine the potential levels of aerosol entering the DC (equivalent ISO class), together with its DRH. These data enabled us both to select the DC's filtering system (MERV13 filters) and to optimize the cooling cycle through calculation of the most reliable humidity cycle (60% of maximum allowed RH) applicable to the DFC. A potential energy saving of 81%, compared to a traditional air conditioning cooling system, was estimated: in one year, for 1 kW of installed information technology, the estimated energy saving is 7.4 MWh, resulting in 2.7 fewer tons of CO2 being emitted, and a financial saving of € 1100.

In-vivo administration of CLC-K kidney chloride channels inhibitors increases water diuresis in rats: a new drug target for hypertension?

OBJECTIVE: The human kidney-specific chloride channels ClC-Ka (rodent ClC-K1) and ClC-Kb (rodent ClC-K2) are important determinants of renal function, participating to urine concentration and blood pressure regulation mechanisms. Here we tested the hypothesis that these chloride channels could represent new drug targets for inducing diuretic and antihypertensive effects. METHODS: To this purpose, the CLC-K blockers benzofuran derivatives MT-189 and RT-93 (10, 50, 100 mg/kg), were acutely administered by gavage in Wistar rats, and pharmacodynamic and pharmacokinetic parameters determined by functional, bioanalytical, biochemical and molecular biology assays. RESULTS: Plasma concentration values for MT-189 and RT-93 were indicative of good bioavailability. Both MT-189 and RT-93 dose-dependently increased urine volume without affecting electrolyte balance. A comparable reduction of SBP was observed in rats after MT-189, RT-93 or furosemide administration. Benzofuran derivatives treatment did not affect kidney CLC-K mRNA level or inner medulla osmolality, whereas a significant vasopressin-independent down-regulation of aquaporin water channel type 2 was observed at protein and transcriptional levels. In rats treated with benzofuran derivatives, the observed polyuria was mainly water diuresis; this finding indirectly supports a cross-talk between chloride and water transport in nephron. Moreover, preliminary in-vitro evaluation of the drugs capability to cross the blood-inner ear barrier suggests that these compounds have a limited ability to induce potential auditory side effects. CONCLUSION: CLC-K blockers may represent a new class of drugs for the treatment of conditions associated with expanded extracellular volume, with a hopeful high therapeutic potential for hypertensive patients carrying ClC-K gain-of-function polymorphisms.