Paola Nieri

The role of nitric oxide in anthracycline toxicity and prospects for pharmacologic prevention of cardiac damage

Anthracycline antibiotics are potent antitumor agents whose activity is severely limited by a cumulative dose‐dependent chronic cardiotoxicity that results from the summation of multiple biochemical pathways of cellular damage, which ultimately yields to disruption of myocardiocyte integrity and loss of cardiac function. Nitric oxide (NO) is a key molecule involved in the pathophysiology of heart; dysregulation of activity of NO synthases (NOSs) and of NO metabolism seems to be a common feature in various cardiac diseases. The contribution of NO to anthracycline cardiac damage is suggested by evidence demonstrating anthracycline‐mediated induction of NOS expression and NO release in heart and the ability of NOSs to promote anthracycline redox cycling to produce reactive oxygen species (ROS), including O2− and H2O2. Overproduction of ROS and NO yields to reactive nitrogen species, particularly the powerful oxidant molecule peroxynitrite (ONOO−), which may produce the marked reduction of cardiac contractility. This review focuses on the anthracycline‐mediated deregulation of NO network and presents an unifying viewpoint of the main molecular mechanisms involved in the pathogenesis of anthracycline cardiotoxicity, including iron, free radicals, and novel mechanistic notions on cardiac ceramide signaling and apoptosis. The data presented in the literature encourage the development of strategies of pharmacological manipulation of NO metabolism to be used as a novel approach to the prevention of cardiotoxicity induced by anthracyclines.—Fogli, S., Nieri, P., Breschi, M. C. The role of nitric oxide in anthracycline toxicity and prospects for pharmacologic prevention of cardiac damage. FASEB J. 18, 664–675 (2004)

Cardiovascular effects of Urtica dioica L. (Urticaceae) roots extracts: in vitro and in vivo pharmacological studies

Urtica dioica (Urticaceae) is a plant principally used in the traditional medicine of oriental Marocco as antihypertensive remedy (J. Ethnopharmacol., 58 (1997), 45). The aim of this work was to evaluate a possible direct cardiovascular action of the plant and to investigate its mechanism of action. In aortic preparations with intact and functional endothelial layer, pre-contracted with KCl 20 mM or norepinephrine 3 microM, the crude aqueous and methanolic extracts of the plant roots, as well as purified fractions elicited a vasodilator action. Nevertheless, the vasodilator activity was not present in aortic rings without endothelial layer. In aortic rings with intact endothelial layer, the vasorelaxing effect was abolished by L-NAME, a NO-biosynthesis inhibitor, and ODQ, a guanylate cyclase inhibitor. Furthermore, potassium channel blockers (TEA, 4-aminopyridine, quinine, but not glybenclamide) antagonized the vasodilator action of the purified fraction F1W of U. dioica. The same fraction produced a marked decrease of inotropic activity, in spontaneously beating atria of guinea-pig, and a marked, but transient, hypotensive activity on the blood pressure of anaesthetized rats. It is concluded that U. dioica can produce hypotensive responses, through a vasorelaxing effect mediated by the release of endothelial nitric oxide and the opening of potassium channels, and through a negative inotropic action.

Synthesis and β-blocking activity of (R, S)-(E)-oximeethers of 2,3-dihydro-1,8-naphthyridine and 2,3-dihydrothiopyrano[2,3-b]pyridine : potential antihypertensive agents - Part IX

The synthesis of oximeethers of 2,3-dihydro-1,8-naphthyridine and 2, 3-dihydrothiopyrano[2,3-b]pyridine is described. These compounds exhibit a selective beta-blocking activity, with a selectivity towards beta(2)-receptors. Groups in the N(1) position giving rise to a considerable steric hindrance led to a higher beta(2)-blocking selectivity, whereas groups creating a moderate hindrance caused a weak but significant decrease in beta(2)-antagonist potency. Substitution of the N(1)-R group with a sulfur atom led to compounds possessing beta(1)-, beta(2)- and beta(3)-blocking properties. Compounds 9c(1) and 10a(1) showed a beta(3)-antagonist activity slightly lower than that of propranolol.

Synthesis of 1,8-naphthyridine derivatives: potential antihypertensive agents – Part VIII

A series of 2-(carbethoxypiperazinyl)- and 2-piperazinyl-1,8-naphthyridine derivatives, variously substituted, have been synthesized and pharmacologically investigated for their antihypertensive activity. Some of them exhibited a significant and prolonged decrease of the mean arterial pressure (MAP) on spontaneously hypertensive rats. For this series of compounds, on the basis of the pharmacological results obtained, no structure-activity relationship can be deduced at this time. Moreover, the most active and representative compounds 11b, 12a and 16b were investigated by means of in vitro pharmacological functional studies and in vivo, as diuretic agents, to determine a possible mechanism of the antihypertensive activity, which is unknown for the moment.

Cytotoxic activity of polyacetylenes and polyenes isolated from roots of Echinacea pallida

The n‐hexane extracts of the roots of three medicinally used Echinacea species exhibited cytotoxic activity on human cancer cell lines, with Echinacea pallida found to be the most cytotoxic. Acetylenes are present in E. pallida lipophilic extracts but essentially absent in extracts from the other two species. In the present study, the cytotoxic effects of five compounds, two polyacetylenes (namely, 8‐hydroxy‐pentadeca‐(9E)‐ene‐11,13‐diyn‐2‐one (1) and pentadeca‐(9E)‐ene‐11,13‐diyne‐2,8‐dione (3)) and three polyenes (namely, 8‐hydroxy‐pentadeca‐(9E,13Z)‐dien‐11‐yn‐2‐one (2), pentadeca‐(9E,13Z)‐dien‐11‐yne‐2,8‐dione (4) and pentadeca‐(8Z,13Z)‐dien‐11‐yn‐2‐one (5)), isolated from the n‐hexane extract of E. pallida roots by bioassay‐guided fractionation, were investigated and the potential bioavailability of these compounds in the extract was studied.

Cannabinoid derivatives induce cell death in pancreatic MIA PaCa-2 cells via a receptor-independent mechanism

Cannabinoids (CBs) are implicated in the control of cell survival in different types of tumors, but little is known about the role of CB system in pancreatic cancer. Herein, we investigated the in vitro antitumor activity of CBs and the potential role of their receptors in human pancreatic cancer cells MIA PaCa‐2. Characterization tools used for this study included growth inhibition/cell viability analyses, caspase 3/7 induction, DNA fragmentation, microarray analysis and combination index‐isobologram method. Our results demonstrate that CBs produce a significant cytotoxic effect via a receptor‐independent mechanism. The CB1 antagonist N‐(piperidin‐1‐1yl)‐5‐(4‐iodophenyl)‐1‐(2,4‐dichlorophenyl)‐4‐methyl‐1H‐pyrazole‐3‐carboxamide (AM251) was the most active compound with an IC50 of 8.6 ± 1.3 μM after 72 h. AM251 induces apoptosis, causes transcriptional changes of genes in janus kinase/signal transducers and activators of transcription signaling network and synergistically interacts with the pyrimidine analogue, 5‐fluorouracil. These findings exclude the involvement of CB receptors in the regulation of MIA PaCa‐2 cell growth and put AM251 forward as a candidate for the development of novel compounds worthy to be tested in this type of neoplasia.

Modulation of P-glycoprotein activity by cannabinoid molecules in HK-2 renal cells

1 Endogenous and synthetic cannabinoid molecules have been investigated as possible MDR‐1/P‐glycoprotein (P‐gp) modulators in HK‐2‐immortalized renal cells, using calcein acetoxymethylester (calcein‐AM) as a P‐gp substrate. 2 Among the endocannabinoid molecules tested, anandamide (AEA), but not 2‐arachidonoyl‐glycerol (2‐AG) or palmitoyl‐ethanolamide (PEA), increased the intracellular fluorescence emitted by calcein, a metabolic derivative of the P‐gp substrate calcein‐AM, indicative of a reduction in transport capacity. 3 All the three synthetic cannabimimetics tested, that is, R‐(+)‐methanandamide (R(+)‐MET), AM 251 and CP55,940 significantly increased calcein accumulation in the cytosol. 4 RT–PCR demonstrated that HK‐2 cells do not express CB1 or CB2 cannabinoid receptors. 5 R(+)‐MET, AM251 and CP55,940 were also evaluated as modulators of P‐gp expression, by Western blot analysis. Only AM251 weakly enhanced the protein levels (by 1.2‐fold) after a 4‐day‐long incubation with the noncytotoxic drug concentration 2 μM. 6 The present data provide the first evidence that the endocannabinoid AEA and different synthetic cannabinoids may inhibit the P‐gp activity in vitro via a cannabinoid receptor‐independent mechanism.

Synthesis and β-blocking activity of (E)- and (Z)-iminoethers of 1,8-naphthyridine. Potential antihypertensive agents. 4

Abstract A series of substituted (E)-and (Z)-iminoethers of 1,8-naphthyridine was synthesized from corresponding ketones. The pharmacological activity of these compounds was evaluated on isolated preparations to assess the eventual interaction with α and β adrenoceptors. All the compounds exhibited β2 stimulating and β1 blocking properties, while on α receptors neither stimulating nor blocking activity was observed.

P-Glycoprotein inhibitory activity of lipophilic constituents of Echinacea pallida roots in a human proximal tubular cell line.

The N-hexane root extracts from Echinacea pallida, Echinacea angustifolia and Echinacea purpurea were evaluated for inhibition of the multidrug transporter P-glycoprotein (Pgp) activity, the product of the ABCB1 gene, involved in cancer multidrug resistance (MDR) and in herb-drug or drug-drug interactions. The biological assay was performed using the human proximal tubule HK-2 cell line that constitutively expresses ABCB1. The N-hexane extracts of all three species reduced the efflux of the Pgp probe calcein-AM from HK-2 cells two-fold in a concentration-dependent manner, and E. pallida was found to be the most active species. For the first time, two polyacetylenes and three polyenes, isolated from the N-hexane extract of E. pallida roots by a bioassay-guided fractionation, were found to be able to reduce Pgp activity. Pentadeca-(8 Z,13 Z)-dien-11-yn-2-one was the most efficient compound, being able to decrease the calcein-AM efflux about three-fold with respect to the control at 30 microg/mL.

Rational design, synthesis, and pharmacological properties of new 1,8-naphthyridin-2(1H)-on-3-carboxamide derivatives as highly selective cannabinoid-2 receptor agonists.

The CB(2) receptor activation can be exploited for the treatment of diseases such as chronic pain and tumors of immune origin, devoid of psychotropic activity. On the basis of our already reported 1,8-naphthyridin-4(1H)-on-3-carboxamide derivatives, new 1,8-naphthyridin-2(1H)-on-3-carboxamide derivatives were designed, synthesized, and tested for their affinities toward the human CB(1) and CB(2) cannabinoid receptors. Some of the reported compounds showed a subnanomolar CB(2) affinity with a CB(1)/CB(2) selectivity ratio greater than 200 (compounds 6, 12, cis-12, 13, and cis-13). Further studies revealed that compound 12, which presented benzyl and carboxy-4-methylcyclohexylamide substituents bound in the 1 and 3 positions, exerted a CB(2)-mediated inhibitory action on immunological human basophil activation. On the human T cell leukemia line Jurkat the same derivative induced a concentration-dependent decrease of cell viability. The obtained results suggest that 1,8-naphthyridin-2(1H)-on-3-carboxamides represent a new scaffold very suitable for the development of new promising CB(2) agonists.