Maria Novella Romanelli

Design and Study of Piracetam-like Nootropics, Controversial Members of the Problematic Class of Cognition-Enhancing Drugs

Cognition enhancers are drugs able to facilitate attentional abilities and acquisition, storage and retrieval of information, and to attenuate the impairment of cognitive functions associated with head traumas, stroke, age and age-related pathologies. Development of cognition enhancers is still a difficult task because of complexity of the brain functions, poor predictivity of animal tests and lengthy and expensive clinical trials. After the early serendipitous discovery of first generation cognition enhancers, current research is based on a variety of working hypotheses, derived from the progress of knowledge in the neurobiopathology of cognitive processes. Among other classes of drugs, piracetam-like cognition enhancers (nootropics) have never reached general acceptance, in spite of their excellent tolerability and safety. In the present review, after a general discussion of the problems connected with the design and development of cognition enhancers, the class is examined in more detail. Reasons for the problems encountered by nootropics, compounds therapeutically available and those in development, their structure activity relationships and mechanisms of action are discussed. Recent developments which hopefully will lead to a revival of the class are reviewed.

N,N-bis(cyclohexanol)amine aryl esters: a new class of highly potent transporter-dependent multidrug resistance inhibitors.

A new series of Pgp-dependent MDR inhibitors having a N,N-bis(cyclohexanol)amine scaffold was designed on the basis of the frozen analogue approach. The scaffold chosen gives origin to different geometrical isomers. The new compounds showed a wide range of potencies and efficacies on doxorubicin-resistant erythroleukemia K562 cells in the pirarubicin uptake assay. The most interesting compounds (isomers of 3) were studied further evaluating their action on the ATPase activity present in rat small intestine membrane vesicles and doxorubicin cytotoxicity potentiation on K562 cells. The latter assay was performed also on the isomers of 4. The four isomers of each set present different behavior in each of these tests. Compound 3d shows the most promising properties as it was able to completely reverse Pgp-dependent pirarubicin extrusion at low nanomolar concentration, inhibited ATPase activity at 5 x 10(-9) and increased the cytotoxicity of doxorubicin with a reversal fold (RF) of 36.4 at 3 microM concentration.

Hybridized and isosteric analogues of N1-acetyl-N4-dimethyl-piperazinium iodide (ADMP) and N1-phenyl-N4-dimethyl-piperazinium iodide (DMPP) with central nicotinic action

A series of piperazine derivatives, obtained by hybridization of N1-acetyl-N4-dimethyl-piperazinium iodide (1, ADMP) and N1-phenyl-N4-dimethyl-piperazinium iodide (3, DMPP) or of the corresponding tertiary bases (2, 4) with arecoline (5) and arecolone (6) or by isosteric substitution of the phenyl ring of DMPP, has been synthesized. Hybridization afforded compounds that, both as tertiary bases and as iodomethylates, have no affinity for the nicotinic receptor. On the contrary, isosteric substitution gave compounds that maintain affinity for the receptor; among them, two tertiary bases (37, 38), show affinity in the nanomolar range for the nicotinic receptor. The pharmacological profile of these isomeric compounds is quite interesting as they present differences in their peripheral and central effects, suggesting that they interact with different subtypes of the nicotinic receptor.

4-Aminopiperidine derivatives as a new class of potent cognition enhancing drugs.

Extrusion of one of the nitrogens of the piperazine ring of potent nootropic drugs previously described gave 4-aminopiperidine analogues that maintained high cognition enhancing activity in the mouse passive avoidance test. One of the new compounds (9, active at 0.01 mg/kg ip) may represent a new lead for the development of cognition enhancers useful to treat the cognitive deficit produced by neurodegenerative pathologies like Alzheimers disease.

Presynaptic auto- and hetero-receptors in the cholinergic regulation of pain

Abstract By modulating central acetylcholine release, presynaptic autoreceptor (M 2 ) and heteroreceptors (D 2 and A 1 ) can regulate the pain threshold through postsynaptic M 1 muscarinic receptors which were thus seen to be ultimately responsible for cholinergic antinociception. As regards antinociception, muscarinic autoreceptors belong to the M 2 receptor subtype. Antinociception is obtained by either antagonizing M 2 , D 2 and A 1 receptors or activating M 1 receptors. The two types of receptors were found to have opposite stereochemical requirements, since autoreceptors were blocked by (R)-(+)-hyoscyamine only, while postsynaptic receptors were preferentially inhibited by the (S)-(-) enantiomer. This observation was confirmed with other antimuscarinic compounds, since only the enantiomers having the same absolute configuration as (R)-(+)-hyoscyamine were active.

Novel blockers of hyperpolarization-activated current with isoform selectivity in recombinant cells and native tissue

BACKGROUND AND PURPOSE Selective hyperpolarization activated, cyclic nucleotide‐gated channel (HCN) blockers represent an important therapeutic goal due to the wide distribution and multiple functions of these proteins, representing the molecular correlate of f‐ and h‐current (If or Ih). Recently, new compounds able to block differentially the homomeric HCN isoforms expressed in HEK293 have been synthesized. In the present work, the electrophysiological and pharmacological properties of these new HCN blockers were characterized and their activities evaluated on native channels.

Design, Synthesis, and Preliminary Biological Evaluation of New Isoform-Selective f-Current Blockers

New I(f) blockers have been designed and tested on HEK293 cells stably expressing the HCN1, HCN2, and HCN4 channels to find compounds able to discriminate among the channel isoforms. Among the synthesized compounds, the cis-butene derivative (R)-5 shows some preference for HCN2 while the pseudodimeric product (R)-6 shows selectivity for HCN1. These compounds can be important pharmacological tools to study the channels in native tissues and may be useful to design safe drugs.

Design, synthesis and preliminary biological evaluation of new hydroxamate histone deacetylase inhibitors as potential antileukemic agents

This study concerns the synthesis of new histone deacetylase inhibitors (HDACi) characterized by a 1,4-benzodiazepine ring used as the cap, joined through an amide function or a triple bond as connection units, to a linear alkyl chain bearing the hydroxamate function as Zn2+-chelating group. Biological tests performed in human acute promyelocytic leukemia NB4 cells showed that new hybrids can induce histone H3/H4 acetylation, growth arrest, and also apoptosis. Notably, chiral compounds exhibit stereoselective activity.

Effectiveness of the Histone Deacetylase Inhibitor (S)-2 against LNCaP and PC3 Human Prostate Cancer Cells

Histone deacetylase inhibitors (HDACi) represent a promising class of epigenetic agents with anticancer properties. Here, we report that (S)-2, a novel hydroxamate-based HDACi, shown previously to be effective against acute myeloid leukemia cells, was also a potent inducer of apoptosis/differentiation in human prostate LNCaP and PC3 cancer cells. In LNCaP cells (S)-2 was capable of triggering H3/H4 histone acetylation, H2AX phosphorylation as a marker of DNA damage and producing G0/G1 cell cycle arrest. Consistently, (S)-2 led to enhanced expression of both the protein and mRNA p21 levels in LNCaP cells but, contrary to SAHA, not in normal non-tumorigenic prostate PNT1A cells. Mechanistic studies demonstrated that (S)-2-induced apoptosis in LNCaP cells developed through the cleavage of pro-caspase 9 and 3 and of poly(ADP-ribose)-polymerase accompanied by the dose-dependent loss of mitochondrial membrane potential. Indeed, the addition of the pan-caspase inhibitor Z-VAD-fmk greatly reduced drug-mediated apoptosis while the antioxidant N-acetyl-cysteine was virtually ineffective. Importantly, preliminary data with nude mice xenografted with LNCaP cells showed that (S)-2 prompted a decrease in the tumor volume and an increase in H2AX phosphorylation within the cancer cells. Moreover, the highly metastatic prostate cancer PC3 cells were also sensitive to (S)-2 that: i) induced growth arrest and moderate apoptosis; ii) steered cells towards differentiation and neutral lipid accumulation; iii) reduced cell invasiveness potential by decreasing the amount of MMP-9 activity and up-regulating TIMP-1 expression; and iv) inhibited cell motility and migration through the Matrigel. Overall, (S)-2 has proven to be a powerful HDACi capable of inducing growth arrest, cell death and/or differentiation of LNCaP and PC3 prostate cancer cells and, due to its low toxicity and efficacy in vivo, might also be of clinical interest to support conventional prostate cancer therapy.

Structure-Activity Relationships Studies in a Series of N,N-Bis(alkanol)amine Aryl Esters as P-Glycoprotein (Pgp) Dependent Multidrug Resistance (MDR) Inhibitors

As a continuation of a previous research, a series of N,N-bis(alkanol)amine aryl esters, as Pgp-dependent MDR inhibitors, was designed and synthesized. The aromatic ester portions are suitably modulated, and new aryl rings (Ar(1) and Ar(2)) were combined with trans-3-(3,4,5-trimethoxyphenyl)vinyl, 3,4,5-trimethoxybenzyl and anthracene moieties that were present in the most potent previously studied compounds. The new compounds showed a wide range of potencies and efficacies on doxorubicin-resistant erythroleukemia K562 cells (K562/DOX) in the pirarubicin uptake assay. Selected compounds (5, 6, 8, 9, and 21) were further studied, evaluating their action on doxorubicin cytotoxicity potentiation on K562 cells; they significantly enhanced doxorubicin cytotoxicity on K562/DOX cells, confirming the results obtained with pirarubicin. Compound 9 shows the most promising properties as it was able to nearly completely reverse Pgp-dependent pirarubicin extrusion at nanomolar doses and increased the cytotoxicity of doxorubicin with a reversal fold (RF) of 19.1 at 3 microM dose.