Tokumi Maruyama

One‐Handed Helical Screw Direction of Homopeptide Foldamer Exclusively Induced by Cyclic α‐Amino Acid Side‐Chain Chiral Centers

Chiral cyclic α,α-disubstituted amino acids, (3S,4S)- and (3R,4R)-1-amino-3,4-(dialkoxy)cyclopentanecarboxylic acids ((S,S)- and (R,R)-Ac(5)c(dOR); R: methyl, methoxymethyl), were synthesized from dimethyl L-(+)- or D-(-)-tartrate, and their homochiral homoligomers were prepared by solution-phase methods. The preferred secondary structure of the (S,S)-Ac(5)c(dOMe) hexapeptide was a left-handed (M) 3(10) helix, whereas those of the (S,S)-Ac(5)c(dOMe) octa- and decapeptides were left-handed (M) α helices, both in solution and in the crystal state. The octa- and decapeptides can be well dissolved in pure water and are more α helical in water than in 2,2,2-trifluoroethanol solution. The left-handed (M) helices of the (S,S)-Ac(5)c(dOMe) homochiral homopeptides were exclusively controlled by the side-chain chiral centers, because the cyclic amino acid (S,S)-Ac(5)c(dOMe) does not have an α-carbon chiral center but has side-chain γ-carbon chiral centers.

Deamination of 9-(Hydroxymethylated cycloalkyl)-9H-adenines (Carbocyclic Adenine Nucleosides) by Adenosine Deaminase: Effect of High-Pressure Upon Deamination Rate and Enantioselectivity 1) #

Abstract The deamination of eight kinds of racemic carbocyclic adenine nucleosides by adenosine deaminase under high-pressure (400 MPa) was examined and the result was compared with that obtained from the reaction under atmospheric pressure. The deamination of all carbocyclic nucleosides irrespective to their ring size of carbocycles was facilitated remarkably high-pressure. The reaction of three and five membered carbocyclic nucleosides resulted in the very high enantioselectivity both under high- and atmospheric Plessure whereas the enantioselectivity of six membered carbocyclic nucleosides was suppressed under high-pressure. However, the enantioselectivity of four membered nucleosides was low under both conditions. 1. Part 38 in the series “Synthesis of Nucleosides and Related Compounds”. For Part 37, see Katagiri, N.; Makino, S.; Kaneko, C. Chem. Pharm. Bid., 1995, 43, 884. #This paper is dedicated to the celebration of the 75th birthday of Dr. Yoshihisa Mizuno, Emeritus Professor of Hokkaido University.

Synthesis and biological evaluation of nucleoside analogues having 6-chloropurine as anti-SARS-CoV agents

Abstract Nucleoside analogues that have 6-chloropurine as the nucleobase were synthesized and evaluated for anti-SARS-CoV activity by plaque reduction and yield reduction assays in order to develop novel anti-SARS-CoV agents. Among these analogues, two compounds, namely, 1 and 11, exhibited promising anti-SARS-CoV activity that was comparable to those of mizoribine and ribavirin, which are known anti-SARS-CoV agents. Moreover, we observed several SAR trends such as the antiviral effects of the 6-chloropurine moiety, unprotected 5′-hydroxyl group and benzoylated 5′-hydroxyl group.

Improved synthesis of 9-(2,3-dideoxy-2-fluoro-β-d-threo-pentofuranosyl)adenine (FddA) using triethylamine trihydrofluoride

Abstract An improved synthesis of 9-(2,3-dideoxy-2-fluoro-β- d - threo -pentofuranosyl)adenine ( 1 , FddA) via a fluorination of 3′- O -benzoyl-5′- O -tritylriboside ( 4a ) using noncorrosive triethylamine trihydrofluoride (Et 3 N·3HF) is described. The method is suitable for large-scale synthesis. In particular, the synthesis of the pivotal intermediate 4a was much improved in avoidance of the use of toxic tin reagent. Radical deoxygenation with several silanes was also studied. The total yield of FddA from 6-chloropurine riboside ( 2 ) in this study was greater than that we reported previously.

Sumoylation of CoREST modulates its function as a transcriptional repressor

It is emerging that covalent modifications of many transcription factors and co-factors by the small ubiquitin-like modifier (SUMO) can have a key role in modulating their transcriptional regulation. As SUMO modification is often associated with transcriptional repression, we studied whether it was involved in modulating the repressive activity of CoREST. We showed that CoREST can be modified by SUMO-1 at lysine 294. PIASxbeta interacted with CoREST in vitro and in vivo, and functions as an E3-ligase to mediate its sumoylation. Furthermore, SENP1 mediated the desumoylation of CoREST. Interestingly, mutation of the CoREST sumoylation site compromised its ability as a corepressor. These results demonstrate that SUMO-1 modification modulates the transcriptional repression by CoREST and is needed for its full repressive activity.

Synthetic Nucleosides and Nucleotides. 43. Inhibition of Vertebrate Telomerases by Carbocyclic Oxetanocin G (C.OXT-G) Triphosphate Analogues and Influence of C.OXT-G Treatment on Telomere Length in Human HL60 Cells

Telomerase, responsible for telomere synthesis, is expressed in ∼ 90% of human tumor cells but seldom in normal somatic cells. In this study, inhibition by carbocyclic oxetanocin G triphosphate (C.OXT-GTP) and its analogues was investigated in order to clarify the susceptibility of telomerase to various nucleotide analogues. C.OXT-GTP competitively inhibited telomerase activity with respect to dGTP. However, C.OXT-GTP had a potent inhibitory effect on DNA polymerase α. It was examined whether the nucleoside (C.OXT-G) was able to alter telomere length in cultured human HL60 cells. Contrary to expectation, long-term treatment with 10 μM C.OXT-G was found to cause telomere lengthening.

Synthesis and antiviral activity of 1,3-disubstituted uracils against HIV-1 and HCMV.

The development of new non-nucleoside reverse transcriptase inhibitors (NNRTIs) is an efficient strategy for finding new therapeutic agents against human immunodeficiency virus (HIV). A large number of 6-substituted uracil derivatives have been prepared in order to explore new NNRTIs. However, there are few approaches to anti-HIV agents from 1,3-disubstituted uracil derivatives. Therefore, we tried to prepare several 1,3-disubstituted uracils, which were easily obtainable from uracil by preparation under alkali and Mitsunobu conditions, and examined their antiviral activity against HIV-1 and human cytomegalovirus (HCMV). We found that 1-benzyl-3-(3,5-dimethylbenzyl)uracil and 1-cyanomethyl-3-(3,5-dimethylbenzyl)-4-thiouracil showed powerful inhibition against HCMV and HIV-1, respectively.

Synthesis of uracil-5- and adenine-8-phosphonic acids

Abstract Successive treatments of 5-bromo-2,4-dimethyoxypyrimidine (I) with n-butyllithium and diethyl chlorophosphonate followed by dealkylation afforded uracil-5-phosphonic acid (V). Adenine-8-phosphonic acid (IX) was also prepared by a similar method, starting from 6-chloro-9-(tetrahdyro-2-pyranyl)purine (VI).

A novel nucleic acid analogue shows strong angiogenic activity

A novel nucleic acid analogue (2Cl-C.OXT-A) significantly stimulated tube formation of human umbilical endothelial cells (HUVEC). Its maximum potency at 100muM was stronger than that of vascular endothelial growth factor (VEGF), a positive control. At this concentration, 2Cl-C.OXT-A moderately stimulated proliferation as well as migration of HUVEC. To gain mechanistic insights how 2Cl-C.OXT-A promotes angiogenic responses in HUVEC, we performed immunoblot analyses using phospho-specific antibodies as probes. 2Cl-C.OXT-A induced robust phosphorylation/activation of MAP kinase ERK1/2 and an upstream MAP kinase kinase MEK. Conversely, a MEK inhibitor PD98059 abolished ERK1/2 activation and tube formation both enhanced by 2Cl-C.OXT-A. In contrast, MAP kinase responses elicited by 2Cl-C.OXT-A were not inhibited by SU5416, a specific inhibitor of VEGF receptor tyrosine kinase. Collectively these results suggest that 2Cl-C.OXT-A-induces angiogenic responses in HUVEC mediated by a MAP kinase cascade comprising MEK and ERK1/2, but independently of VEGF receptor tyrosine kinase. In vivo assay using chicken chorioallantoic membrane (CAM) and rabbit cornea also suggested the angiogenic potency of 2Cl-C.OXT-A.

Practical synthesis of 9-(2,3-dideoxy-2-fluoro-β-d-threo-pentofuranosyl)adenine (FddA) via a purine 3′-deoxynucleoside

Abstract A practical synthesis of 9-(2,3-dideoxy-2-fluoro-β- d - threo -pentofuranosyl)adenine ( 1 , FddA) via a 6-chloro-9-(3-deoxy-β- d - erythro -pentofuranosyl)-9 H -purine ( 6 ) is described. Fluorination at the C2′-β position of the purine 3′-deoxynucleoside was improved by the introduction of 6-chloro group, and proceeded in moderate yield. The total yield of FddA from readily available starting material 6 was 35%.