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Daniela Barlocco

Publications and source records attributed to Daniela Barlocco.

8 recordsLinked to original sources
PubMed2003

ortho-Halogen naphthaleins as specific inhibitors of Lactobacillus casei thymidylate synthase. Conformational properties and biological activity.

Thymidylate synthase (TS) (EC 2.1.1.45), an enzyme involved in the DNA synthesis of both prokaryotic and eukaryotic cells, is a potential target for the development of anticancer and antinfective agents. Recently, we described a series of phthalein and naphthalein derivatives as TS inhibitors. These compounds have structures unrelated to the folate (Non-Analogue Antifolate Inhibitors, NAAIs) and were selective for the bacterial versus the human TS (hTS). In particular, halogen-substituted molecules were the most interesting. In the present paper the halogen derivatives of variously substituted 3,3-bis(4-hydroxyphenyl)-1H,3H-naphtho[2,3-c]furan-1-one (1-5) and 3,3-bis(4-hydroxyphenyl)-1H,3H-naphtho[1,8-c,d]pyran-1-one (6-14) were synthesized to investigate the biological effect of halogen substitution on the inhibition and selectivity for the TS enzymes. Conformational properties of the naphthalein series were explored in order to highlight possible differences between molecules that show species-specific biological profile with respect to non species-specific ones. With this aim, the conformational properties of the synthesized compounds were investigated by NMR, in various solvents and at different temperatures, and by computational analysis. The apparent inhibition constants (K(i)) for Lactobacillus casei TS (LcTS) were found to range from 0.7 to 7.0 microM, with the exception of the weakly active iodo-derivatives (4, 10, 13); all] the compounds were poorly active against hTS. The di-halogenated compounds 7, 8, 14 showed the highest specificity towards LcTS, their specificity index (SI) ranging between 40 and >558. The di-halogenated 1,8-naphthalein derivatives (7-10) exhibited different conformational properties with respect to the tetra-haloderivatives. Though a clear explanation for the observed specificity by means of conformational analysis is difficult to find, some interesting conformational effects are discussed in the context of selective recognition of the compounds investigated by the LcTS enzyme.

Crystallography, X-Ray↗
PubMed2003

Isolation and pharmacological activities of the Tecoma stans alkaloids.

Tecoma stans is a plant traditionally used in Mexico for the control of diabetes. Amongst the alkaloids isolated from the plant harvested in Egypt, Tecomine was shown to be one of the compounds responsible for the hypoglycemic action. Given the interest in substances able to treat type II diabetes, we isolated the main alkaloids present in the plant growing in Egypt and Brazil and tested them in vivo on db/db mice. Contrary to previous literature reports on different animal models, Tecomine was unable to modify glycemia; the only effect seen being a decrease in plasma cholesterol levels. On the contrary, when tested in vitro on glucose uptake in white adipocytes, the compound showed a marked effect. The two other alkaloids isolated, namely 5beta-Hydroxyskitanthine, early called Base C, and Boschniakine were inactive both in vivo and in vitro assays.

Adipocytes↗
PubMed2003

Congo red analogues as potential anti-prion agents.

'Transmissible Spongiform Encephalopathies' (TSE) are a group of degenerative, progressive and fatal disorders of CNS which affect both humans and animals, characterised by a long incubation time. The pathogenetic mechanism in TSE is the conversion of normal prion protein (PrP(sen)) to an altered protease resistant isoform (PrP(res)) that accumulates in amyloid deposits into the brain; therefore, PrP(res) is the primary target for therapeutic strategies. The discovery that the sulphonated azo dye Congo red (CR) is able to inhibit the replications of TSE agents and the accumulation of PrP(res) in animals and in scrapie infected mouse neuroblastoma cells induced us to designe molecules structurally related to CR (1a-f, 2f,g). The compounds were tested in vitro to evaluate their interaction with 263K PrP(res). Six of the tested compounds were found to interact with PrP(res) molecules and to over-stabilise the PrP(res) aggregates, as CR does. However, none of them induced the reversion of PrP(res) to PrP(sen).

Animals↗
PubMed2003

Insulin detemir. Novo Nordisk.

Insulin detemir (NN-304) is a soluble, long-acting insulin analog being developed by Novo Nordisk for the potential treatment of type 1 and 2 diabetes. As of February 2003, Novo Nordisk was expecting both US and EU approval in the first half of 2004. In December 2002, Novo Nordisk submitted an NDA to the FDA and an NDS to the Canadian Biologics & Genetics Therapeutic Directorate for the approval of insulin detemir for the treatment of diabetes mellitus.

Animals↗
PubMed2002

6-Chloropyridazin-3-yl derivatives active as nicotinic agents: synthesis, binding, and modeling studies.

3,8-Diazabicyclo[3.2.1]octane (1), 2,5-diazabicyclo[2.2.1]heptane (2), piperazine (3), and homopiperazine (4) derivatives, substituted at one nitrogen atom with the 6-chloro-3-pyridazinyl group while the other nitrogen atom was either unsubstituted or mono- or dimethylated, were synthesized and tested for their affinity toward the neuronal nicotinic acetylcholine receptors (nAChRs). All of the compounds had K(i) values in the nanomolar range. A molecular modeling study allowed location of their preferred conformations, the energies of which were recalculated in water with a continuum solvent model. Some of the compounds showed, in their populated conformations, only pharmacophoric distances longer than the values taken into consideration by the Sheridan model for nAChRs receptors. Thus, this SAR study gives support to the hypothesis that these longer distances are still compatible with affinity for alpha4beta2 receptors in the nanomolar range.

Animals↗
PubMed2002

Structure-based studies on species-specific inhibition of thymidylate synthase.

Thymidylate synthase (TS) is a well-recognized target for anticancer chemotherapy. Due to its key role in the sole de novo pathway for thymidylate synthesis and, hence, DNA synthesis, it is an essential enzyme in all life forms. As such, it has been recently recognized as a valuable new target against infectious diseases. There is also a pressing need for new antimicrobial agents that are able to target strains that are drug resistant toward currently used drugs. In this context, species specificity is of crucial importance to distinguish between the invading microorganism and the human host, yet thymidylate synthase is among the most highly conserved enzymes. We combine structure-based drug design with rapid synthetic techniques and mutagenesis, in an iterative fashion, to develop novel antifolates that are not derived from the substrate and cofactor, and to understand the molecular basis for the observed species specificity. The role of structural and computational studies in the discovery of nonanalog antifolate inhibitors of bacterial TS, naphthalein and dansyl derivatives, and in the understanding of their biological activity profile, are discussed.

Crystallography, X-Ray↗
PubMed2002

Novel 3-arylamino- and 3-cycloalkylamino-5, 6-diphenyl-pyridazines active as ACAT inhibitors.

A new series of pyridazine derivatives, structurally related to the previously reported ACAT inhibitors 3-(cyclo)alkylamino-5, 6-diphenyl-pyridazines, were synthesized and tested for their inhibitory properties. Substitution of the 3-alkylamino chain with a phenylamino group maintains activity. In contrast, the presence of either substituents on the phenylamino group or aliphatic rings having more or less than six carbon atoms lowers it.

Animals↗