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Novel adenosine antagonists, 2-alkynyl-8-aryl-9-methyladenine derivatives, were synthesized as candidate hypoglycemic agents. These analogues were evaluated for inhibitory activity on N-ethylcarboxamidoadenosine (NECA)-induced glucose production in primary cultured rat hepatocytes. In general, aromatic moieties at the 8-position and alkynyl groups at the 2-position had significantly increased activity compared to unsubstituted compounds. The preferred substituents at the 8-position of adenine were the 2-furyl and 3-fluorophenyl groups. In modifying the alkynyl side chain, change of the ring size, cleavage of the ring, and removal of the hydroxyl group were well tolerated. The order of the stimulatory effects of adenosine agonists on rat hepatocytes was NECA > CPA > CGS21680, which is consistent with involvement of the A2B receptor. In Chinese hamster ovary cells stably transfected with human A2B receptor cDNA, one of the compounds potent in hepatocytes, 15o (IC50 = 0.42 μM), antagonized NECA-induced stimulation of cyclic AMP production (IC50 = 0.063 μM). This inhibitory effect was much more potent than those of FK453, KF17837, and L249313 which have been reported to be respectively A1, A2A, and A3 selective antagonists. These findings agree very well with the result that, compared to 15o, these selective antagonists for each receptor subtype showed only marginal effects in rat hepatocytes. These results suggest that adenosine agonist-induced glucose production in rat hepatocytes is mediated through the A2B receptor. Furthermore, 15o showed hypoglycemic activity in an animal model of noninsulin-dependent diabetes mellitus, the KK-A^y mice. It is possible that inhibition of hepatic glucose production via the A2B receptor could be at least one of the mechanisms by which 15o exerts its in vivo effects. Further elaboration of this group of compounds may afford novel antidiabetic agents.

We synthesized various 4-(3-chloro-4-methoxybenzyl)aminophthalazines substituted at the 1- and 6-positions and evaluated their inhibitory activity toward phosphodiesterase 5 (PDE5) and their vasorelaxant activity in isolated porcine coronary arteries precontracted with prostaglandin F2α (10^-5 M). The preferred substituents at the 1-position of the phthalazine were 4-hydroxypiperidino, 4-hydroxymethylpiperidino, 4-(2-hydroxyethyl)piperidino, and 4-oxopiperidino. Among these compounds, [4-(3-chloro-4-methoxybenzyl)amino-1-(4-hydroxy)piperidino]-6-phthalazinecarbonitrile monohydrochloride (13) exhibited potent PDE5 inhibitory activity (IC50 = 0.56 nM) with >1700-fold high selectivity over other PDE isozymes (PDE1−4). Compound 13 exhibited the most potent vasorelaxant action (EC50 = 13 nM) in this series of compounds. Compound 13 reduced mean pulmonary arterial pressure by 29.9 ± 3.1% when administered intravenously at 30 μg/kg to the chronically hypoxic rats and had an apparent oral bioavailability of about 19.5% in rats and was selected for further biological evaluation.

Although several antiretroviral compounds are already known, almost no acyclic nucleoside derivatives lacking an oxacyclopentane have been reported to exert significant inhibition against human immunodeficiency virus type 1 (HIV-1) in vitro. We found two unsaturated acyclic nucleoside derivatives, adenallene [9-(4'-hydroxy-1',2'-butadienyl)adenine] and cytallene [1-(4'-hydroxy-1',2'-butadienyl)cytosine], that protect various CD4+ T-cell lines from the infectivity and cytopathic effect of HIV-1. These compounds inhibit the expression of HIV-1 gag-encoded protein and suppress viral DNA synthesis at concentrations that do not affect functions of normal T cells in vitro. They also inhibit the in vitro infectivity of another human retrovirus, HIV-2. Further in vitro analyses of the anti-HIV-1 activity revealed that the presence of two cumulated double bonds between the 1' and 2' carbons and between the 2' and 3' carbons confers antiretroviral activity in certain pyrimidine or purine derivatives containing a four-carbon chain. We have also found that the 4'-hydroxyl group is critical for the in vitro anti-HIV activity of adenallene. Our observations may provide structure-activity relationships for acyclic nucleoside analogues and may be of value in developing a new class of experimental drugs for the therapy of HIV-related diseases.

We synthesized various 4-benzylamino-1-chloro-6-substituted phthalazines (15) and 4-benzylamino-1-chloro-7-substituted phthalazines (16) and evaluated their inhibitory activity toward phosphodiesterase 5 (PDE5) purified from porcine platelets. The PDE5-inhibitory activities of 15 were greater than those of the isomers (16). The preferred substituent at the 4-position of phthalazine was a (3-chloro-4-methoxybenzyl)amino group, and those at the 6-position were cyano, nitro, and trifluoromethyl groups. Compounds 15a (IC50 = 4.8 nM), 15f (3.5 nM), and 15i (5.3 nM) were more potent inhibitors than E4021 (8.6 nM). Compounds 15a and 15f also showed vasorelaxant activity in isolated porcine coronary arteries precontracted with prostaglandin F2α (10^-5 M). The EC50 values for vasorelaxant action of 15a, 15f, and E4021 were 150, 160, and 980 nM, respectively. These results show that novel PDE5 inhibitors possessing a potent vasorelaxant effect may exist among phthalazine derivatives.

In this report, we demonstrate the sequence-specific suppression of viral expression in T cells chronically infected with human immunodeficiency virus 1 (HIV-1), using antisense phosphorothioate oligodeoxynucleotides. As a target for antisense intervention, we used the HIV-1 gene rev, which is essential for viral replication and regulates the expression of virion proteins, in part, by affecting the splicing of the viral mRNA. A phosphorothioate oligomer complementary to the initiation sequence of HIV-1 rev had a significant and selective inhibitory effect on the production of several viral proteins in chronically HIV-1-infected T cells and drastically reduced the unspliced (genomic) viral mRNA transcripts, with relative sparing of smaller (spliced) transcripts. By contrast, the antisense sequence with unmodified normal phosphodiester linkages as well as phosphorothioate oligomers containing sense, random, homopolymeric sequences, or antisense sequence with N3-methylthymidine residues did not have an inhibitory effect on viral expression. Thus, sequence specificity and nuclease resistance were critical for the anti-viral-gene regulatory effect of the antisense molecules. The altered HIV-1 mRNA profile induced by the antisense phosphorothioate oligomer suggests that the mechanism for the inhibition of viral expression is due to an interference with the regulatory gene, rev, by translation arrest.

Nuclease-resistant phosphorothioate analogs of certain oligodeoxynucleotides have been tested in vitro as antiviral agents against human immunodeficiency virus (HIV) in human T cells. Phosphorothioate analogs complementary to HIV sequences, as well as noncomplementary analogs including homooligomers, exhibited potent antiviral activity. The antiviral activity was related to the base composition of the analogs, and longer phosphorothioates were more effective than shorter ones. A 28-mer phosphorothioate oligodeoxycytidine (S-dC28) at a concentration of 1 microM exhibited potent antiviral activity and inhibited de novo viral DNA synthesis as shown by Southern blot analysis. However, S-dC28 failed to inhibit gag expression in chronically infected T cells assessed by immunofluorescent assay at concentrations up to 25 microM. An N3-methylthymidine-containing phosphorothioate analog, which does not hybridize efficiently in vitro to complementary normal DNA, showed no antiviral activity. A 14-mer phosphorothioate oligodeoxycytidine (S-dC14) synergistically enhanced the antiviral activity of 2',3'-dideoxyadenosine, an anti-HIV nucleoside. Therefore, phosphorothioate analogs of oligodeoxynucleotides could represent a unique class of experimental therapeutic agents against the acquired immunodeficiency syndrome and related diseases. However, their mechanism of action is likely to be complex.

We report that 2',3'-dideoxyadenosine and 2',3'-dideoxycytidine inhibit retroviral DNA synthesis and mRNA expression in T cells exposed to the virus that causes acquired immunodeficiency syndrome, and afford such cells long-term protection in vitro under conditions of substantial viral excess. Both 2',3'-dideoxyadenosine and 2',3'-dideoxycytidine appear to completely block reverse transcription from viral RNA to viral DNA. Viral mRNA expression is also not detected in cells protected by the drugs throughout 30 days of culture following exposure to the virus. Purine and pyrimidine analogues as 2',3'-dideoxynucleoside-5'-triphosphate serve as substrates for the human T-lymphotropic virus type III/lymphadenopathy-associated virus reverse transcriptase to elongate a DNA chain by one residue, after which the chain is terminated. Cloned normal helper/inducer T cells exposed to a cytopathic dose of the virus, but protected by the drugs, respond normally to specific antigen in vitro. These results suggest that the drugs could be promising agents for further studies in the experimental treatment of patients infected with retroviruses.

A patient suffering from acute lymphoblastic leukemia in the third progressive phase, refractory to the majority of available treatments, was given total-body irradiation of 800 r. dosage, after administration of methyl-nitro-imidazolyl-mercaptopurine (300 mg. daily for 4 days). One week after irradiation, he received an infusion of a mixture of equal parts of bone marrow from six donors (mother, sister, father and three brothers), a total of 5.8 x 1010 nucleated cells. Myeloid restoration began 2 weeks after the infusion and continued to progress rapidly. The reality of the graft was demonstrated by study of the erythrocytic antigens. Nearly all the erythrocytes found in the blood after 6 months belonged to the phenotype of one of the male donors. Studies of chromosomes and leukocyte sex chromatin suggested that a small proportion of leukocytes were being produced by the cells of one of the female donors. The patient was found to produce beta 2A, beta 2M and gamma globulins of the Inv type of the donors, suggesting that lymphoid cells may also have been successfully grafted. A skin graft from the male donor whose marrow graft had apparently been accepted was still perfectly intact 7 months after grafting, whereas the grafts from other donors were rejected, indicating a specific tolerance to tissues from this donor. Previous studies of compatibility between the recipient and the various donors by a histocompatibility test described by us, or by means of similarities in leukocyte antigens, indicated that the accepted donor had been antigenically more nearly compatible than the others. What appeared to be a secondary syndrome became manifest 1 week after marrow transfusion; it consisted of weight loss, digestive disorders (anorexia, nausea, vomiting, diarrhea), hepatic disturbances (hepatomegaly, increased serum concentrations of various enzymes), transient polyadenopathy (histologically composed of histiocytic proliferation and lymphocytic aplasia), desquamative erythrodermia, eosinophilia exceeding 50 per cent, and superinfection (including a probable miliary tuberculosis). The syndrome was controlled by careful symptomatic treatment; its intensity gradually abated. Reactivation of the secondary syndrome was accomplished by reinjection of leukocytes from the donor whose graft had been tolerated. This was controlled by Δ-1-cortisone and symptomatic treatment. The patient was still alive and in apparently complete hematologic remission from the leukemia 12 months after the treatment described above. Particular reasons for this success possibly include the absence of previous blood transfusions and the use of multiple marrow donors.