1-3-di-(4-amidinophenoxy)-2-2-bis-(4-amidinophenoxymethyl)propane and propamidine

We have investigated the effects of aromatic polyamidines on HIV-1 transcription. We found a block to Tat-induced HIV-1 transcription assessed by inhibition of CAT activity in HL3T1 cells at a concentration lower than the IC50 value, suggesting that molecules with three (TAPB) and four (TAPP) benzamidine rings could be useful against HIV-1. In contrast, aromatic polyamidines with only two benzamidine rings (DAPP) did not block Tat-induced transcription. We reasoned that this effect could be due to binding of TAPB and TAPP to HIV-1 TAR RNA. By EMSA and filter binding assays, we studied possible interactions of aromatic polyamidines with HIV-1 TAR RNA. Wild-type TAR RNA or TAR RNA with mutations in the stem or bulge sequences, but retaining the stem-loop structure, was used to define the RNA-binding activities of these compounds. Our data suggest that aromatic polyamidines with two (DAPP) and four (TAPP) benzamidine rings, respectively, do not bind to TAR RNA or bind without sequence selectivity. Interestingly, an aromatic polyamidine with three benzamidine rings (TAPB) recognizes the wild-type TAR RNA in a specific manner. Furthermore, we found that introduction of one halogen atom into the benzamidine rings strongly increases the RNA-binding activity of these compounds.

Topics: Anti-HIV Agents; Benzamidines; Cell Line; Drug Design; Electrophoretic Mobility Shift Assay; Gene Expression Regulation, Viral; Gene Products, tat; HIV Long Terminal Repeat; HIV-1; Humans; Jurkat Cells; Nucleic Acid Conformation; RNA, Viral; Structure-Activity Relationship; T-Lymphocytes; tat Gene Products, Human Immunodeficiency Virus; Transcriptional Activation

The inhibitory effect of bis-, tris- and tetra-benzamidine derivatives (DAPP, TAPB and TAPP, respectively) on the catalytic properties of bovine beta-trypsin (beta-trypsin), human alpha-thrombin (alpha-thrombin) and porcine pancreatic beta-kallikrein-B (beta-kallikrein-B) was investigated (between pH 2.0 and 7.0, I = 0.1 M; T = 37.0 +/- 0.5 degrees C), and analyzed in parallel with that of benzamidine, commonly taken as a molecular inhibitor model of serine proteinases. Over the whole pH range explored, benzamidine, DAPP, TAPB and TAPP, show the same value of the association inhibition constant (Ki, M-1) for beta-trypsin; at variance, the affinity of DAPP, TAPB and TAPP for alpha-thrombin and beta-kallikrein-B is higher than that found for benzamidine association around neutrality, but tends to converge in the acidic pH limb. On lowering the pH from 5.5 to 3.0, the decrease in affinity for benzamidine binding to beta-trypsin, alpha-thrombin and beta-kallikrein-B as well as for DAPP, TAPB and TAPP association to beta-trypsin reflects the acidic-pK shift, upon inhibitor binding, of a single ionizing group. Over the same pH range, values of Ki for DAPP, TAPB and TAPP binding to alpha-thrombin and beta-kallikrein-B appear to be modulated by the acidic-pK shift, upon inhibitor association, of two equivalent proton-binding residues. Considering the X-ray three dimensional structures and the computer-generated molecular models of the serine proteinase inhibitor complexes, the observed binding behaviour of benzamidine, DAPP, TAPB and TAPP to beta-trypsin, alpha-thrombin and beta-kallikrein-B has been related to the inferred stereochemistry of the enzyme:inhibitor contact region(s).

Topics: Animals; Benzamidines; Cattle; Humans; Hydrogen-Ion Concentration; Kallikreins; Magnetic Resonance Spectroscopy; Models, Molecular; Pancreas; Serine Proteinase Inhibitors; Swine; Thermodynamics; Thrombin; Trypsin Inhibitors; X-Ray Diffraction

We have synthesized N1-substituted benzamidines and poly-benzamidines with the aim to produce antitumor drugs retaining differential biological properties with respect to unsubstituted compounds. Antiproliferative activity on in vitro cultured human leukemic cells was exhibited by N1-substituted poly-benzamidines, while N1-substituted benzamidines were found to retain very low antitumor effects. Furthermore, our results suggest that N1-substituted benzamidines and some of poly-benzamidines exhibit low activity on trypsin and kallikrein. Taken together these data indicate that some N1-substituted poly-benzamidines could be of interest for experimental antitumor therapy, since are likely to retain low side effects due to alteration of proteinase activity.

Topics: Animals; Antineoplastic Agents; Benzamidines; Cattle; Cell Division; Humans; Kallikreins; Magnetic Resonance Spectroscopy; Protease Inhibitors; Spectrophotometry, Infrared; Structure-Activity Relationship; Trypsin Inhibitors; Tumor Cells, Cultured

In this paper we describe the use of polymerase chain reaction (PCR) to amplify DNA sequences suitable for studies on the activity of DNA-binding drugs of possible interest in anti-tumor as well as anti-viral therapy. To this aim (a) we amplified by PCR two regions of the HIV-1 genome (one localized within the LTR, the other within the env gene), known to bind nuclear factors and (b) we determined whether different aromatic polyamidines are able to differentially affect the electrophoretic mobility of these HIV-1 PCR fragments. We found that aromatic polyamidines differentially affect the electrophoretic migration of PCR-amplified HIV-1 genomic regions. This differential effect, related to a differential DNA-binding activity, could lead to a differential inhibition of protein-DNA interactions.

Topics: Base Sequence; Benzamidines; DNA, Viral; Electrophoresis, Agar Gel; Gene Amplification; Genome, Viral; HIV Long Terminal Repeat; HIV-1; Molecular Sequence Data; Polymerase Chain Reaction