Effect of polyamines and synthetic polyamine-analogues on the expression of antizyme (AtoC) and its regulatory genes

BACKGROUND: In bacteria, the biosynthesis of polyamines is modulated at the level of transcription as well as post-translationally. Antizyme (Az) has long been identified as a non-competitive protein inhibitor of polyamine biosynthesis in E. coli. Az was also revealed to be the product of the atoC gene. AtoC is the response regulator of the AtoS-AtoC two-component system and it functions as the positive transcriptional regulator of the atoDAEB operon genes, encoding enzymes involved in short chain fatty acid metabolism. The antizyme is referred to as AtoC/Az, to indicate its dual function as both a transcriptional and post-translational regulator. RESULTS: The roles of polyamines on the transcription of atoS and atoC genes as well as that of atoDAEB(ato) operon were studied. Polyamine-mediated induction was tested both in atoSC positive and negative E. coli backgrounds by using β-galactosidase reporter constructs carrying the appropriate promoters patoDAEB, patoS, patoC. In addition, a selection of synthetic polyamine analogues have been synthesized and tested for their effectiveness in inducing the expression of atoC/Az, the product of which plays a pivotal role in the feedback inhibition of putrescine biosynthesis and the transcriptional regulation of the ato operon. The effects of these compounds were also determined on the ato operon expression. The polyamine analogues were also tested for their effect on the activity of ornithine decarboxylase (ODC), the key enzyme of polyamine biosynthesis and on the growth of polyamine-deficient E. coli. CONCLUSION: Polyamines, which have been reported to induce the protein levels of AtoC/Az in E. coli, act at the transcriptional level, since they cause activation of the atoC transcription. In addition, a series of polyamine analogues were studied on the transcription of atoC gene and ODC activity

Syntheses of novel polyamine analogs and polymine conjugates with natural products and synthetic derivatives with medicinal interest

The present thesis describes the syntheses of a series of novel polyamine analogs and polyamine conjugates with natural products and synthetic derivatives. These compounds will be evaluated for their biological properties against a variety of cellular targets: A) Efficient guanylation of aliphatic and aromatic polyamine analogs at their secondary amino functions. B) Efficient syntheses of polyamines incorporating tetrazole rings in their skeleton. C) Syntheses of polyamine analogs N-substituted with tetrazoles rings. D) Coupling reactions of polyamine analogs, with free primary amino functions, with cinnamic acid derivatives. E) Synthesis of polyamine conjugates with chloramphenicol, F) Synthesis of polyamine conjugates with C₆₀-fullerene.Στο πλαίσιο της παρούσας διδακτορικής διατριβής πραγματοποιήθηκαν οι συνοέσεις πρωτότυπων πολυαμινικών αναλόγων και συζευγμάτων πολυαμινών με φυσικά προϊόντα και συνοετικά τους ανάλογα. Απώτερος στόχος είναι όλες οι ενώσεις που συντέθηκαν να μελετηθούν για τη βιολογική τους δράση σε μια πληθώρα κυτταρικών στόχων προκειμένου να εξεταστεί η πιθανότητα να δρουν ως αντιοξειδωτική ή αντιπαρασιτικοί ή αντιβακτηριδιακή ή αντικαρκινικοί παράγοντες. Συγκεκριμένα πραγματοποιήθηκαν οι παρακάτω συνοέσεις: Α) Αποτελεσματικές γουανιδυλιώσεις αλειφατικών και αρωματικών πολυαμινικών αναλόγων, στις δευτεροταγείς αμινομάδες τους. Β) Συνθέσεις πολυαμινικών αναλόγων που ενσωματώνουν στο σκελετό τους τετραζολικούς δακτυλίους, Γ) Συνοέσεις πολυαμινικών αναλόγων Ν-Υποκατεστημένων με τετραζολικούς δακτυλίους. Δ) Αντιδράσεις σύζευξης πολυαμινικών αναλόγων, με ελεύθερες τις πρωτοταγείς αμινομάδες τους, με παράγωγα του κινναμικού οξέος. Ε) Σύνθεση συζευγμάτων πολυαμινών της χλωραμφαινικόλης. ΣΤ) Σύνθεση συζευγμάτων πολυαμινών με C₆₀-φουλλερένιο

Conjugation with polyamines enhances the antibacterial and anticancer activity of chloramphenicol

Chloramphenicol (CAM) is a broad-spectrum antibiotic, limited to occasional only use in developed countries because of its potential toxicity. To explore the influence of polyamines on the uptake and activity of CAM into cells, a series of polyamine-CAM conjugates were synthesized. Both polyamine architecture and the position of CAM-scaffold substitution were crucial in augmenting the antibacterial and anticancer potency of the synthesized conjugates. Compounds 4 and 5, prepared by replacement of dichloro-acetyl group of CAM with succinic acid attached to N4 and N1 positions of N-8,N-8-dibenzylspermidine, respectively, exhibited higher activity than CAM in inhibiting the puromycin reaction in a bacterial cell-free system. Kinetic and footprinting analysis revealed that whereas the CAM-scaffold preserved its role in competing with the binding of aminoacyl-tRNA 3'-terminus to ribosomal A-site, the polyamine-tail could interfere with the rotatory motion of aminoacyl-tRNA 3'-terminus toward the P-site. Compared to CAM, compounds 4 and 5 exhibited comparable or improved antibacterial activity, particularly against CAM-resistant strains. Compound 4 also possessed enhanced toxicity against human cancer cells, and lower toxicity against healthy human cells. Thus, the designed conjugates proved to be suitable tools in investigating the ribosomal catalytic center plasticity and some of them exhibited greater efficacy than CAM itself