Biological activity and DNA sequence specificity of synthetic carbamoyl analogues of distamycin

A new penta(N-methylpyrrole carboxamide) analogue of the antibiotic distamycin has been synthesized in which the N-terminal formylamino group was replaced by a carbamoyl moiety. It was substantially more stable than distamycin in aqueous solution and bound to DNA with about the same affinity constant. It had an exemplary margin of selectivity against herpes simplex virus type 1-infected HEp-2 cells in culture compared to uninfected control cells, and was equipotent with distamycin. For comparison, data for analogues containing fewer N-methylpyrrole carboxamide units and/or lacking the carbamoyl replacement are presented. Extensive DNase I footprinting experiments were conducted and revealed that all the distamycin analogues bound to AT-rich nucleotide sequences in three different restriction fragments, irrespective of how many pyrrole rings or which terminal moiety they contained. However, the relative strength of footprints differed significantly among the various compounds, though the apparent size of the binding site did not. With semi-synthetic DNA containing inosine and 2,6-diaminopurine residues in place of guanosine and adenine, respectively, the compounds recognized new binding sites composed of IC-rich clusters and were excluded from binding to their canonical sites. This showed that the process of specific sequence recognition was critically dominated by the placement of the purine 2-amino group in the minor groove of the double helix. </jats:p

Interaction between double helix DNA fragments and the new antitumor agent sabarubicin, Men10755

Amongthe disaccharide derivatives of the antitumor anthracycline doxorubicin, sabarubicin (Men10755) is more active and less cytotoxic than doxorubicin. It showed a strong in vivo antitumor activity in all preclinical models examined, in conjunction with a better tolerability, and is now in phase II clinical trials. The interaction of sabarubicin andMen10749(a similar disaccharidewith a different configuration at C-40 of the proximal sugar) with the hexanucleotides d(CGTACG)2 and d(CGATCG)2 was studied by a combined use of 2D-1Hand 31PNMRtechniques. Both 1Hand 31P chemical shifts of imino protons and phosphates allowed to established the intercalation sites between the CG base pairs, as it occurs for other anthracyclines of the series. The dissociation rate constants (koff) of the slow step of the intercalation process were measured for Men10755 and Men10749, by NMR NOE-exchange experiments. The increase of koff , with respect of doxorubicin, showed that the intercalation process is significantly faster for both drugs, leading to an average residence time for sabarubicin into d(CGTACG)2 sixfold shorter than for doxorubicin. This could give account of both higher cytoplasmic/nuclear ratio and lower cellular uptake of sabarubicin in comparison with doxorubicin and accordingly of the lower cytotoxicity of these disaccharide analogues. A relevant number of NOE interactions allowed the structure of the complexes in solution to be derived through restrained MD calculations. NMR-DOSY experiments were performed with several drug/oligonucleotide mixtures in order to determine the structure and the dimension of the aggregates

Funzionalizzazione del C-3’ delle cefalosporine Δ2 e Δ3

Viene descritta la reazione dei Δ3 – C3’ bromo derivati della cefalosporine con alcooli. Si ottengono 3’-acilossimetilcefalosporine con buone rese e senza isomerizzazione del doppio legame; la reazione è più lenta rispetto all'analoga trasformazione descritta per i derivati Δ2

Studies related to cephalosporins. Part1. Solvolytic reactions of 3-bromomethyl cephems with alcohols and phenols

3-Bromomethyl-3 cephems are solvolysed by alcohols, similarly to the Δ2 isomers. The yields are fairly good and this reaction represents a straightforward route to obntain 3-alcoxymethyl-3-cephems. Both 3-bromomethyl-2-cephems and 3-bromomethyl-3-isomers reactr with a variety of phenols under solvolytic conditions, giving only C-substitution products. This reaction represent the sole example of c-alkylation of phenols by an allylic bromide under such mild conditions

Binding of Epstein-Barr virus nuclear antigen 1 to DNA: inhibition by distamycin and two novel distamycin analogues

Modulation of the interaction between cellular or viral transcription factors and target DNA sequences may represent a potential experimental strategy to control proliferation of neoplastic cells as well as virus DNA replication. Distamycin represents a likely candidate to mediate such modulation by pharmacological means. In order to obtain more detailed information on structure-activity relationships of these compounds, we have analysed the effects of distamycin and two distamycin analogues on the binding of a recombinant protein, the Epstein-Barr virus nuclear antigen 1 (EBNA-1) to its target sequence of Epstein-Barr virus, containing the 12 bp palindromic consensus TAGCATATGCTA. The sequence selectivity in the binding of distamycin to DNA was evaluated by footprinting experiments, while the effects of distamycins on DNA-protein interactions was analysed by means of electrophoretic mobility shift assay. The data presented in this paper suggest that distamycin and its analogues differentially inhibit the interaction between DNA-binding proteins and target DNA sequences

Croton macrostachys, a plant used in traditional medicine: purgative and inflammatory activity

Croton macrostachys seeds are widely used in Somalia as a purgative. in the present study, pharmacologic and chemical investigations confirm the laxative effect of the seeds and indicate the presence of phorbolesters. There appears to be no direct correlation between the phorbolester content and laxative effect

Distamycin analogues with improved sequence-specific DNA binding activities

none9In the present study we have investigated the effect of unprecedented chemical modifications introduced in the distamycin molecule, with the aim of assessing their ability to interfere with sequence-specific DNA-protein interactions in vitro. By using an electrophoretic mobility shift assay, we have been able to identify novel distamycin analogues with improved displacing abilities on the binding of octamer nuclear factors to their target DNA sequence. While variations in the number of pyrrole rings and/or reversion of an internal amide bond result in distamycin-like compounds with identical or very similar properties, the reversion of the formamido into a carboxyamido group or its replacement with the charged formimidoyl moiety significantly improves the ability of the resulting novel distamycin derivatives to compete with OCT-1 (octamer 1 nuclear factor) for its target DNA sequence. Tissue-specific octamer-dependent in vitro transcription is similarly affected by these chemical modifications, suggesting that the ability of distamycins to bind octamer sequences has a direct influence on the functional state of octamer-containing promoters. These data represent an initial, successful attempt to rationalize the design of DNA binding drugs, using distamycins as a model.noneCIUCCI A; FERIOTTO G; MISCHIATI C; GAMBARI R; ANIMATI F; LOMBARDI P; NATALI PG; ARCAMONE F; GIACOMINI PCiucci, A; Feriotto, Giordana; Mischiati, Carlo; Gambari, Roberto; Animati, F; Lombardi, P; Natali, Pg; Arcamone, F; Giacomini, P