Synthesis of 3-deoxy-3-nucleobase-2,5-anhydro-d-mannitol: a novel class of hydroxymethyl-branched isonucleosides

Synthesis, physicochemical and biological properties of oligonucleotides incorporated with amino-isonucleosides

Antisense oligonucleotides (ASONs) and siRNAs have been applied extensively for the regulation of cellular and viral gene expression, and RNAi is currently one of the most promising new approaches for anti-tumor and anti-viral therapy. In order to improve bioactivity properties and physicochemical properties of siRNA, we synthesized a novel class of ASONs II–VII incorporated with amino-isonucleoside (isoA₁ and isoA₂) for investigation on basic physicochemical properties. Then we designed amino-isonucleoside (isoA₁, isoA₂ and isoT₁) incorporated siRNA 2–7. Some meaningful results have been obtained from the physicochemical property experiments in ASONs. In RNAi potency experiments, we investigated RNAi potency of each strand of the siRNA. These amino-isonucleosides incorporated siRNAs showed promising bioactivity properties and had position specificity. Reduced off target effect from sense strand loading in siRNA application was observed.

D-Arabinose-based synthesis of homo-C-d4T and homo-C-thymidine

2,3,5-Tri-O-benzyl-D-arabinofuranosyl halides (chloride, bromide) were reacted with AllMgBr, MeMgBr, and VinMgBr to furnish anomeric mixtures of the C-glycosyl products. The factors that influenced the beta/alpha ratio are discussed. The alpha,beta-C-vinyl derivative was transformed into 1-deoxy-1-C-hydroxymethyl-beta- and -alpha-D-arabinofuranoses (2,5-anhydro-D-glucitol and -mannitol, respectively), separable after isopropylidenation step. 2,5-Anhydro-1,3-O-isopropylidene-D-glucitol was converted into 2,5-anhydro-6-O-triphenylmethyl-D-erythro-hex-3,4-enitol and 2,5-anhydro-4,6-di-O-benzoyl-3-deoxy-D-ribo-hexitol, which were coupled with N-3-benzoylthymine under the Mitsunobu conditions to furnish two analogs of nucleosides with a -CH(2)- insert between sugar moieties and thymine.

Synthesis of azole nucleoside analogues of d-pinitol as potential antitumor agents

A convenient strategy is reported for the synthesis of azole nucleoside analogues of D-pinitol (=3-O-methyl-D-chiro-inositol). The key intermediate 3-O-methyl-4,5-epoxy-D-chiro-inositol was obtained in excellent yield via an epoxidation from mono-methanesulfonate of D-pinitol. The process of opening of the epoxy ring by azole-bases appeared strongly regioselective in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene. All newly synthesized carbocyclic azole nucleosides were assayed against lung and bladder cancer in vitro. Only the triazole and benzotriazole nucleoside analogues inhibited the growth of human lung cancer cell lines (PG) with EC(50) of 11.3 and 22.6 microM, respectively, and showed much less inhibitory activity against human bladder cell lines (T(24)).

Synthesis and recognition of novel isonucleoside triphosphates by DNA polymerases

Isonucleosides have been attracting a lot of attention in recent years due to the chemical and enzymatic stability and potential anticancer and antiviral activities. We have reported some of the isonucleosides which exhibited significant anticancer activity and found that the oligonucleotide incorporated with isonucleoside could increase the enzymatic stability against the degradation by phosphodiesterase. In this paper, we investigated the recognition of the isonucleoside triphosphates 1-6 by Taq, Vent(exo(-)), DeepVent(exo(-)), 9 degrees Nm, and Therminator DNA polymerases by a non-radioactivity method. We found that most of the isonucleoside triphosphates can be recognized by various DNA polymerase and act as terminators. Isonucleoside triphosphates 2 and 6 can be incorporated as substrates into the primer at 3' terminus to lengthen the chain dependent on a DNA template by Vent(exo(-)) and DeepVent(exo(-)) DNA polymerases.

Synthesis of 4/5-Deoxy-4/5-nucleobase Derivatives of 3-O-Methyl-D-chiro-inositol as Potential Antiviral Agents

Using D-pinitol (= 3-O-methyl-D-chiro-inositol) as starting material, a concise synthesis of 4/5-deoxy-4/5-nucleobase derivatives 11-19 has been achieved. The key intermediate 9 was obtained in good yield via an epoxidation from mono-methanesulfonate of D-pinitol. The process of opening of the epoxide ring in 9 by nucleobases appeared to be regioselective in presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU). All the synthesized carbocyclic nucleosides were assayed against several viruses and tumors such as HIV-1, HSV-1, and HSV-2, and lung and bladder cancer. However, only compounds 14b, 14a, 16a, 16b, and 19 showed mild inhibitory effect against human lung cancer cell lines (PG) with IC50 values ranging from 50 to 100 microM, and the other compounds did not exhibit any significant antiviral activity or cytotoxicity even at concentrations up to 200 microM.

Synthesis of poly-O-sulfated glycosides of 2,5-anhydro-d-mannitol

2,5-Anhydro-3-O-beta-D-glucopyranosyl-; -3-O-alpha-L-idopyranosyl-; -3-O-alpha-D-arabinopyranosyl-; -3-O-alpha-L-arabinopyranosyl-; -3-O-beta-D-maltopyranosyl-; -3-O-beta-D-gentiobiopyranosyl-; -1,6-di-O-beta-D-glucopyranosyl-; -1,6-di-O-alpha-L-idopyranosyl-; -1-O-beta-D-maltopyranosyl-; -1,3,6-tri-O-beta-D-glucopyranosyl-; -1,6-di-O-beta-maltopyranosyl- and -1,6-di-O-beta-D-gentiobiopyranosyl-2,5-anhydro-D-mannitol as well as their poly-O-sulfated derivatives were synthesized. The IP3-IC50 values of their sodium and/or potassium salts were determined for structure-activity studies aiming at the synthesis of new, orally active antiasthmatic compounds.

Synthesis of 2,5-anhydro-(β-d-glucopyranosyluronate)- and (α-l-idopyranosyluronate)-d-mannitol hexa-O-sulfonate hepta sodium salt

Glycosidation of 2,5-anhydro-1,6-di-O-benzoyl-D-mannitol with methyl(2,3,4-tri-O-acetyl-alpha-d-glucopyranosyl-1-O-trichloroacetimidate)uronate in the presence of trimethylsilyl triflate afforded the corresponding 3-O-beta-glycoside, which after deprotection was converted into its hexa-O-sulfate with DMF x SO3 to give after treatment with sodium acetate and subsequent saponification of the methyl ester with sodium hydroxide the hepta sodium salt of 2,5-anhydro-3-O-(beta-d-glucopyranosyl uronate)-D-mannitol hexa-O-sulfate. Glycosidation of the same acceptor with the alpha-thiophenylglycoside of methyl 2,4-di-O-acetyl-3-O-benzyl-L-idopyranosyl uronate in the presence of NIS/TfOH afforded the corresponding 3-O-alpha-glycoside in very low yield, therefore the alpha-thiophenylglycoside of 2-O-acetyl-2,4-O-benzylidene-3-O-benzyl-L-idopyranose was used as donor. The terminal hydroxymethyl group of the obtained disaccharide was subsequently oxidised with NaOCl/TEMPO and the obtained iduronic acid derivative was converted into the hepta sodium salt of 2,5-anhydro-3-O-(-alpha-L-idopyranosyluronate)-D-mannitol hexa-O-sulfonate with DMF x SO3 and subsequent treatment with sodium acetate.