Synthesis and Anti-HIV Evaluation of 7-Deaza Analogues of Carbovir

Abstract

Three analogues of Carbovir 1 have been synthesized and evaluated for antiviral activity in vitro. Anti-HIV-1 and anti-HIV-2 activities have been observed with 7-deaza analogues 3 and 5 of 1. Compound 5 was about ten times more potent than 3 against HIV-1 and HIV-2 on different cell lines.     

Synthesis of 7 alpha- and 7 beta-spermidinylcholesterol, squalamine analogues

Stereoselective synthesis of squalamine dessulfates analogues, 7 alpha and 7 beta-N-[3N-(4-aminobutyl) aminopropyl]aminocholesterol are reported, using 7 alpha and 7 beta-aminocholesterol as a key intermediate. It's the first example in which the position of spermidine is modified at the steroid ring. These molecules showed a comparable antibacteria and fungi activities to squalamine. Then, they have a cytotoxic activity on a human non-small cell bronchopulmonary carcinoma line (NSCLC-N6).     

Novel glycosylated [Lys(7)]-dermorphin analogues: synthesis, biological activity and conformational investigations.

Syntheses of the [Lys(7)]- and [Hyp(6),Lys(7)]-dermorphin analogues in which either Tyr(5) or Hyp(6) are O-glucosylated are described. For comparison, the carbohydrate-free peptides have also been prepared. Structural investigations by FT-IR and CD measurements were carried out on the synthetic analogues and some preliminary pharmacological experiments were also performed.The biological potency of the glucosylated analogues was compared with that of the micro-opioid receptor agonist dermorphin in GPI preparations. Glucosylation of either Tyr(5) or Hyp(6) reduces the potency of both [Lys(7)]-dermorphin and [Hyp(6),Lys(7)]-dermorphin. The effect induced by the Tyr(5) glucosylation is quite strong and the potency of both peptides is reduced by about 150 times. A similar but less dramatic effect is induced by the glucosylation of the Hyp(6) residue, and the potency of the parent peptide is reduced by about 15 times. The presence of acetyl groups on the sugar hydroxyl functions further reduces the agonistic potency of the glucosylated analogues. The analgesic potency of [Hyp(6),Lys(7)]-, [Hyp(betaGlc)(6),Lys(7)]- and [Tyr(betaGlc)(5),Lys(7)]-dermorphin were also tested in vivo by the tail-flick test. The glucosylated hydroxyproline-containing analogue is 8-10 times less active than the parent peptide, but its analgesic effect lasts significantly longer.     

Synthesis and cytotoxic activity of N-[(alkylamino)alkyl]carboxamide derivatives of 7-oxo-7H-benz[de]anthracene, 7-oxo-7H-naphtho[1,2,3-de]quinoline, and 7-oxo-7H-benzo[e]perimidine

7-Oxo-7H-naphtho[1,2,3-de]quinoline-11-carboxamides and analogues were prepared and evaluated for in vitro and in vivo antitumor activity. Chromophore variations included 'deaza' (7-oxo-7H-benz[de]anthracene) and 'diaza' (7-oxo-7H-benzo[e]perimidine) analogues, and side chain variations included chiral alpha-methyl compounds. The naphthoquinolines were the most cytotoxic, with IC(50) values of 5-20 nM, and showed the strongest DNA binding, with high selectivity for G-C rich DNA. The chiral alpha-methyl analogues were 10-20-fold more cytotoxic than the parent des-methyl compound. Both enantiomers provided substantial growth delays against s.c. colon 38 tumors in mice, with the R-enantiomer more active than the S (tumor growth delays of >35 and 12 days, respectively).     

Dextran-linked 7-deazaguanine - a polymer-bound inhibitor of xanthine oxidase

Dextran-linked 7-deazaguanine as well as 7-deazahypoxanthine and allopurinol derivatives have been prepared by carbodiimide condensation of the 2-carboxyethyl intermediates 2c and 1c,d with N-(6-aminohexylcarbamoyl-methylated dextran T80. The dextran-linked nucleobases are degradable by endo-dextranase (EC 3.2.1.11) which was demonstrated by time-dependent viscosity measurements. Monomeric as well as polymer-linked purine analogues were tested as inhibitors of xanthine oxidase from cow's milk (EC 1.2.3.1). While the allopurinol- and 7-deazahypoxanthine derivatives (1c,d) do no longer bind to the enzyme the 7-deazaguanine derivates 2c,d are strong competitive inhibitors of xanthine oxidase even in the polymer-linked state.     

Interaction of rat glutathione S-transferases 7-7 and 8-8 with gamma-glutamyl- or glycyl-modified glutathione analogues.

Analogues of GSH in which either the gamma-glutamyl or the glycyl moiety is modified were synthesized and tested as both substrates for and inhibitors of glutathione S-transferases (GSTs) 7-7 and 8-8. Acceptor substrates for GST 7-7 were 1-chloro-2,4-dinitrobenzene (CDNB) and ethacrynic acid (ETA) and for GST 8-8 CDNB, ETA and 4-hydroxynon-trans-2-enal (HNE). The relative ability of each combination of enzyme and GSH analogue to catalyse the conjugation of all acceptor substrates was similar with the exception of the combination of GST 7-7 and gamma-L-Glu-L-Cys-L-Asp, which used CDNB but not ETA as acceptor substrate. In general, GST 7-7 was better than GST 8-8 in utilizing these analogues as substrates, and glycyl analogues were better than gamma-glutamyl analogues as both substrates and inhibitors. These results are compared with those obtained earlier with GSH analogues and GST isoenzymes 1-1, 2-2, 3-3 and 4-4 [Adang, Brussee, Meyer, Coles, Ketterer, van der Gen & Mulder (1988) Biochem. J. 255, 721-724] and the implications with respect to the nature of their active sites are discussed.     

7-Substituted-melatonin and 7-substituted-1-methylmelatonin analogues: effect of substituents on potency and binding affinity

A series of 7-substituted melatonin and 1-methylmelatonin analogues were prepared and tested against human and amphibian melatonin receptors. 7-Substituents reduced the agonist potency of all the analogues in the Xenopus laevis melanophore assay, 7-bromomelatonin (5d) and N-butanoyl 7-bromo-5-methoxytryptamine (5f) being the most active compounds, but both were 42-fold less potent than melatonin (1). Whereas all the analogues bind with lower affinity at the human MT(1) receptor than melatonin, 5d, 5f and N-propanoyl 7-bromo-5-methoxytryptamine (5e) show a similar binding affinity to melatonin at the MT(2) receptor and consequently show some MT(2) selectivity. These results suggest that the receptor pocket around C-7 favours binding by an electronegative group, suggesting an electropositive region in this area of the receptor.     

Preparation and evaluation of deconstruction analogues of 7-deoxykalafungin as AKT kinase inhibitors

The pyranonaphthoquinone (PNQ) lactone natural products, including 7-deoxykalafungin, have been reported to be potent and selective covalent inhibitors of AKT kinase. In this work we seek to identify structural features of the natural product scaffold that are essential for potency and selectivity. Using a deconstruction approach, we designed and prepared simplified analogues of 7-deoxykalafungin. Testing of the compounds for their ability to inhibit AKT and the closely related kinase PKA revealed that the 3,6-dihydro-2H-pyran ring of the PNQ lactones is required for potent and selective inhibition of AKT. We have also unexpectedly identified a new submicromolar inhibitor of PKA.     

Synthesis and 1H NMR studies of 3-(D-erythro-glycerol-1-yl)-1H-pyrazolo[3,4-b]quinoxaline and its 7-chloro and 7-methyl analogues

3-(D-erythro-Glycerol-1-yl)-1H-pyrazolo[3,4-b]quinoxaline and its 7-chloro and 7-methyl analogues (11 and 12) were prepared from the corresponding quinoxalines. The 7-substituted analogues 11 and 12 were obtained as the preponderant isomers, and the 6-substituted analogues as the minor isomers. The structure and position of the substituent were determined by 1H NMR studies. The effect of substitution on the chemical shift of other protons is discussed.     

Synthesis and biological activities of 7-aza rebeccamycin analogues bearing the sugar moiety on the nitrogen of the pyridine ring

The synthesis of a new family of 7-aza-rebeccamycin analogues in which the sugar moiety is attached to the nitrogen of the pyridine ring is described. The capacity of the newly synthesized compounds to bind to DNA and to inhibit topoisomerase I has been evaluated. Their cytotoxicities toward four tumor cell lines, one murine leukemia L1210 and three human tumor cell lines, one prostate carcinoma DU145, one colon carcinoma HT29, and one non-small cell lung carcinoma A549, have been determined. Their abilities to inhibit the checkpoint kinase Chk1 have been evaluated.     

Increased stability of nucleic acids containing 7-deaza-guanosine and 7-deaza-adenosine may enable rapid DNA sequencing by matrix-assisted laser desorption mass spectrometry.

The use of matrix-assisted laser desorption mass spectrometry (MALDI-MS) has been suggested as an ultrafast readout of Sanger DNA sequencing ladders in a manner analogous to that used with sequencing gels. Currently, a serious limitation of MALDI-MS for the analysis of DNA results from the tendency for oligonucleotides to undergo facile fragmentation in the gas phase. The present study was undertaken to gain an understanding of the influence of various chemical structural features of purine bases on the stability of oligodeoxynucleotide ions produced by MALDI. The study focused on the stability of model compounds of the type d(TTTTTTTTTTXTTTTTTTTT TTTT), where T designates deoxythymidine and X a purine-containing 2'-deoxynucleotide. A variety of different purine derivatives were chosen as the base in the nucleotide X. The mass spectra of the model compounds containing 7-deaza analogues of guanine and adenine reveal a significantly increased stability compared to the 7-aza analogues under the conditions of MALDI-MS. The previously reported incorporation of the 7-deaza-2'-deoxy-adenosine triphosphate and the 7-deaza-2'-deoxy-guanosine triphosphate into DNA by polymerases suggests their use in a Sanger dideoxy sequencing experiment. The dideoxy termination products with the 7-deaza-purines instead of the 7-aza-purines might be sufficiently stable to allow separation and detection of the sequencing ladder by MALDI-MS. Thus, an ultrafast (seconds) read-out of DNA sequence may become feasible.     

Biological evaluation of new antitumor taxoids: Alteration of substitution at the C-7 and C-10 of docetaxel

A series of new docetaxol analogues have been designed and synthesized. And their cytotoxicities against cancer cells have been evaluated by MTT method. Most of these compounds showed selective inhibitions on human cancer cell lines. Among them, compound 8 exhibited higher inhibitory activity than Paclitaxel (Taxol) against several cancer cell lines. This work indicated that appropriate modification at C-7 and C-10 of docetaxel might be a promising approach for this unique class of anticancer compounds.     

Synthesis and nicotinic binding of novel phenyl derivatives of UB-165. Identifying factors associated with alpha7 selectivity

Four racemic phenyl-substituted analogues 3-6 of the potent nicotinic agonist UB-165 1 have been synthesised and evaluated against the alpha(4)beta(2), alpha(3)beta(4), and alpha(7) neuronal nicotinic receptors. The 2'-phenyl derivative 3 shows no activity at these major receptor subtypes, while the 4'-phenyl analogue 4 shows an enhanced level of alpha(7) selectivity as compared to UB-165 and deschloro UB-165 2. These results are discussed within the context of recent pharmacophore models.     

The interaction of phosphonate and homophosphonate analogues of 3-deoxy-D-arabino heptulosonate 7-phosphate with 3-dehydroquinate synthetase from Escherichia coli

Phosphonate and homophosphonate analogues of 3-deoxy-D-$\text{arabino}$ heptulosonate 7-phosphate and D-$\text{gluco}$ heptulosonate 7-phosphate behave as competitive inhibitors of 3-dehydroquinate synthetase. Phosphonates have better affinities than homophosphonates and protect efficiently the enzyme against thermal denaturation. No evidence has been obtained for 5-keto phosphonate intermediate formation in the interaction of such analogues with 3-dehydroquinate synthetase and NAD⁺.     

Novel hydroxylamine-containing analogues of 1-guanidino-7-aminoheptane (GC7), an effective inhibitor of deoxyhypusine synthase

Earlier unknown hydroxylamine-containing analogues of 1-guanidino-7-aminohepane (GC7) containing the free aminooxy group (1-aminooxy-6-guanidinohexane), bis-guanyl derivatives of 1-aminooxy-6-aminohexane, and 1-aminooxy-5-aminopentane, and mono-guanidinooxy analogue (1-guanidinooxy-6-aminohexane) were synthesized in high overall yields from commercially available 5-(Boc-amino)1-pentanol and 6-(Boc-amino)-1-hexanol. It was demonstrated that 1,3-di-Boc-2-(trifluoromethylsulfonyl)guanidine is able to specifically amidinate the amino group in the presence of the free aminooxy group. The application of newly synthesized GC7 analogues for the investigation of the peculiarities of their interaction with the active site of deoxyhypusine synthase was discussed.     

Ureido group containing cyclic dermorphin(1-7) analogues: synthesis, biology and conformation.

Six cyclic peptides related to dermorphin(1-7) have been synthesized. The synthesis of linear peptides containing diamino acid residues in positions 2 and 4 was carried out on a 4-methylbenzhydrylamine resin, and cyclization was achieved by treatment with bis-(4-nitrophenyl)carbonate to form a urea unit. The peptides were tested in the guinea-pig ileum (GPI) and mouse vas deferens (MVD) assays. Diverse opioid agonist activities were observed, depending on the size of the ring. The results were compared with those obtained earlier for 1-4 dermorphin analogues. The conformations of all six dermorphin analogues were studied. The conformational space of the peptides was examined using the electrostatically driven Monte Carlo method. On the basis of NMR data, an ensemble of conformations was obtained for each peptide. The opioid activity profiles of the compounds are discussed in the light of the structural data.     

Binding of actinomycin D analogues containing some substituents at position 7 of the antibiotic chromophore to DNA

Spectrophotometric methods are used to study the binding to DNA of Actinomycin D (AMD) and its analogues: 7-nitro-AMD; 7-amino-AMD; 7-(Z-Val-Glo-NH)-AMD; 7-(AcO- . +H2-Val-Glo-NH)-AMD; 7-(AcO- . +H2-Val-Glo-Val-Glo-NH)-AMD. The binding constants are calculated from the binding isotherm of AMD and those of the AMD analogues to calf thymus DNA obtained by spectrophotometric titration. Introduction of smaller substituents such as the nitro or amino groups into position 7 of chromophore influences insignificantly the antibiotic binding to DNA, whereas bulky substituents cause a decrease in the affinity of the AMD analogues for DNA, although the spectral characteristics are not affected.     

Relation between structure and function in some partially synthetic ribonucleases S'. Enzymic and spectroscopic investigation on [Orn10, Asn14]-RNase S' and 1epsilon, 7epsilon, 10delta-triguanidino-[Orn10, Asn14]-RNase S'.

Some analogues have been prepared of S-peptide, the peptide obtained together with S-protein from subtilisn-modified beef pancreatic R Nase A. The syntheses are described of [Orn10, Asn14]-S-peptide and 1epsilon, 7epsilon, 10delta-triguanidino-[Orn10, Asn14]-S-peptide. The S-peptide analogues are able to activate S-protein at the level of the parent [Orn10]-S-peptide and 1epsilon, 7epsilon-diguanidino-S-peptide respectively, although at high peptide-to-protein molar ratios. After their recombination with S-protein the buried character of Tyr-25 was restored, as judged from difference absorption and circular dichroism spectra in the near-ultraviolet region. These findings indicate that the asparaginyl residue is a possible naturally occurring substituent in the R Nase A sequences whose state of amidation in position 14 has not yet been defined.     

A new synthetic analogue of thymidine, 7-(3-bromo-phenoxy)-thymidine, inhibits the proliferation of tumor cells

Modified thymidine analogues have been highlighted as useful agents for the treatment of cancer and viral diseases due to their potent biological activities. In the present study, we synthesized a new thymidine analogue, 7-(3-bromo-phenoxy)-thymidine (4a), as a potential lead for anti-tumor agent. Compound 4a potently inhibits HeLa cell proliferation with an IC(50) of 15 microM.