Masakatsu Kaneko

Studies of nucleosides and nucleotides. XXXV. Purine cyclonucleosides. 5. Synthesis of purine cyclonucleoside having 8,2'-O-anhydro linkage and its cleavage reactions.

Abstract Starting from 2′(or 3′)-O- p -toluenesulfonyl-5′-O-acetyl-8-bromoadenosine, introduction of 8-oxy function by the reaction with sodium acetate in acetic acid and cyclization with sodium benzoate in dimethylformamide gave 8,2′-anhydro-8-oxy-9-β- d -arabinofuranosyladenine as the first purine cyclonucleoside having an O-anhydro bond. Configurational similarity of the 8,2′-O- and S-cyclonucleosides was discussed on the basis of UV absorption, NMR and optical rotation studies. Hydrolytic cleavage of the cyclonucleoside with dilute acid gave 8-oxy-9-β- D -arabinofuranosyladenine, showing the attack occurred on the C 8 position. In contrast to this, the reaction with benzoate anion gave 2′-O-benzoyladenosine, which showed the attack by strong nucleophile had occurred on the C 2 position.

Synthesis and antimycobacterial activity of capuramycin analogues. Part 1: substitution of the azepan-2-one moiety of capuramycin

Capuramycin analogues with a variety of substituents in place of the azepan-2-one moiety were synthesized from A-500359E and were tested for their translocase I inhibitory activity and in vitro antimycobacterial activity. Phenyl-type moieties were found to be effective substituents for capuramycin analogues.

Synthesis and antimycobacterial activity of capuramycin analogues. Part 2: acylated derivatives of capuramycin-related compounds.

Acylated derivatives of capuramycin and A-500359A were synthesized and tested for antimycobacterial activity. Compound 20 having a decanoyl group showed very potent activity.

IP3 receptor-ligand. 1: Synthesis of adenophostin A

Abstract Adenophostin A, a potent IP 3 receptor-agonist, was synthesized. The basic skeleton with 3′-O-(α-D-glucosyl)adenosine was constructed by AgClO 4 -γ-collidine-promoted glycosylation employing 2-O-benzyl-3,4,6-tri-O-acetyl-α-D-glucopyranosyl bromide as a glycosyl donor.

Biologically Active Oligodeoxyribonucleotides - II1: Structure Activity Relationships of Anti-HIV-1 Pentadecadeoxyribonucleotides Bearing 5′-End-Modifications

Abstract 5′-End-modified pentadecadeoxyribonucleotides (15mers) with a sequence complementary to the tat 2nd splicing acceptor region of human immunodeficiency virus type 1 (HIV-1) were prepared and evaluated for anti-HIV-1 activity. The structures of modified 15mers were confirmed by negative ion LSI mass spectroscopy, and the anti-HIV-1 activities were evaluated in vitro by MTT assay using MT-4 cells. While the unmodified 15mer had no activity in our assay system, the 15mers bearing modifications with trityl-type substituents at the 5′-end showed potent anti-HIV-1 activities.

Protection of hu-PBL-SCID/beige mice from HIV-1 infection by a 6-mer modified oligonucleotide, R-95288

We analyzed the anti-HIV-1 activity of an oligonucleotide derivative, R-95288, in severe combined immunodeficient (SCID/beige) mice transplanted with normal human peripheral blood leukocytes (PBLs), designated hu-PBL-SCID/beige mice. The human chimeric mice were inoculated with HIV-1(CC1) 3 weeks after the transplantation and sacrificed 2 weeks later. Virus infection was determined by coculture of splenocytes with fresh human PBLs and also by detection of HIV- specific DNA sequences using the polymerase chain reaction. No evidence of infection was observed in mice treated with R-95288 (100 mg/kg/day) using intraperitoneal delivery by osmotic minipumps starting 1 day before virus challenge. In contrast, virus infection was observed in over 80% of the saline-treated control mice. In addition, partial inhibition of HIV-1 infection was obtained in mice treated subcutaneously with R-95288 (100 mg/kg/day). Toxicity towards the engrafted human cells was not observed by flow cytometric analysis. Moreover, R-95288 failed to inhibit lymphocyte proliferation (CC50 > 400 microg/ml), while 90% inhibition of HIV-1 replication was achieved at 3.1 microg/ml in vitro. These results suggest the ability of R-95288 to protect the human chimeric mice against HIV-1 infection.

Biologically Active Oligodeoxyribonucleotides - IV 1 : Anti-HIV-1 Activity of Tgggag Having Hydrophobic Substituent at Its 5′-End via Phosphodiester Linkage §

Abstract Hexadeoxyribonucleotides (6-mers) having a 5′-TGGGAG-3′ sequence bearing hydrophobic substituents at their 5′-ends via phosphodiester linkages were prepared and evaluated for anti-HIV-1 activity in vitro. Some of these modified 6-mers showed weak anti-HIV-1 activities and they were less potent than the 6-mer having a DMTr group directly attached at its 5′-terminus. 1. Part 111: Hotoda, H.; Koizumi, M.; Koga, R.; Momota, K.; Ohmine, T.; Furukawa, H.; Nishigaki, T.; Kinoshita, T.; Kaneko, M.; Kimura, S.; and Shimada, K. (1994) Proceedings of First International Antisense Conjierence of Japan p62 (Pl-24): In print in Antisense Research and Development. §This paper is dedicated to Dr. Yoshihisa Mizuno, Emeritus Professor of Hokkaido University, on the occasion of his 75th birthday.

Biologically Active Oligodeoxyribonucleotides. VII. Anti-HIV-1 Activity of Hexadeoxyribonucleotides Bearing 3′- and 5′-End-Modifications

Abstract It has been determined that hexadeoxyribonucleotides (5′TGGGAG3′), which have modified aromatic groups such as the trityl group at the 5′-end, exhibit anti-HIV-1 activity in vitro. The 6-mer (S-1443) bearing a 3,4-dibenzyloxybenzyl (3,4-DBB) group at the 5′-end and a 2-hydroxyethylphosphate group at the 3′end exhibited the most potent activity and the least cytotoxicity. Moreover, it was found that the S-1443 was the most stable, when the 6-mer analogues were incubated with mouse, rat, or human plasma.

Studies on griseolic acid derivatives. X: Synthesis and phosphodiesterase inhibitory activity of 2-substituted derivatives of griseolic acid

Abstract Griseolic acid derivatives which were modified at the 2-and/or 6-positions were first synthesized from griseolic acid by a ring opening—reclosure reaction of the adenine ring. Among these derivatives, the 2-amino-6-deamino-6-hydroxyl (guanine) derivative showed 3.3 and 45 times stronger inhibitory activity against cAMP and cGMP PDE, respectively, than those of griseolic acid. Structure-activity relationships among these derivatives are also discussed.

Properties of base-substituted and carboxyl-esterified analogues of griseolic acid, a potent cAMP phosphodiesterase inhibitor

Griseolic acid (GA) is a potent cyclic AMP (cAMP) phosphodiesterase (PDE) inhibitor that has an adenine base and two carboxyl groups in its molecule (Nakagawa F, Okazaki T, Naito A, Iijima Y and Yamazaki M, J Antibiot 38: 823-829, 1985). GA analogues were synthesized in which the adenine group was substituted with guanine (6-deamino-2-amino-6-hydroxygriseolic acid, G-GA) or hypoxanthine (6-deamino-6-hydroxygriseolic acid, H-GA). Their inhibitory activities to cyclic GMP (cGMP) PDE and cAMP PDE were compared with GA. For cGMP PDE from rod outer segments of bovine retina, the IC50 values of GA, G-GA and H-GA were 18, 0.040 and 0.12 microM, respectively, with 0.25 microM cGMP as substrate. For type IV PDE isozyme from mouse 3T3 fibroblast cells, the IC50 values of GA, G-GA and H-GA were 0.021, 15 and 11 microM, respectively, with 0.25 microM cAMP as substrate. Thus, GA and G-GA were found to be base-selective inhibitors of type IV PDE of 3T3 cells and type V PDE of bovine retinas, respectively. Esters of carboxylic acids of GA were synthesized in order to increase permeability into cells, and their efficacy was tested by measuring the accumulation of cAMP in 3T3 cells. The dipivaloyloxymethyl ester of GA was found to increase cAMP levels at 0.1 microM, while GA and 3-isobutyl-1-methylxanthine were active only above 100 microM, and the dimethyl ester of GA was inactive. The dipivaloyloxymethyl ester of GA seems to exert its activity after conversion to GA in the cell, since the pivaloyloxymethyl ester was easily hydrolysed by the enzyme action and the dipivaloyloxymethyl ester of GA itself was much less potent an inhibitor of PDE. The dipivaloyloxymethyl ester of GA inhibited thrombin-induced aggregation of platelets and stimulated lipolysis of adipocytes at low concentrations.