Synthesis of 1-O-R-5-deoxy-β-D-ribofuranosides with (CH3)2As and (CH3)2AsO as substituents at the 5-position and a methyl or 2′,3′-dihydroxypropyl group as the aglycone in the 1-position

Six arsenic-containing β-D -ribofuranosides, including the naturally occurring (2′R)-dimethyl[1-O-(2′,3′-dihydroxypropyl)-5-deoxy-β-D -ribofuranos-5-yl]arsine oxide, were prepared in multi-step reactions from D -ribose and tetramethyldiarsine. The synthetic procedure uses the early substitution of the hydroxy group with bromine at C5, subsequent attachment of a chiral three-carbon aglycone at C1, and final delivery of arsenic at C5. The synthesis provides a viable route for the preparation of multigram quantities of the natural product.     

Synthesis and Pharmacological Use of 10H-Phenothiazines,Their Sulfones,and Ribofuranosides

This article describes the synthesis of 10H-phenothiazines from 2-aminobenzenethiol and o-halonitrobenzenes via Smiles rearrangement. Upon refluxing with hydrogen peroxide in glacial acetic acid, these phenothiazines yield the corresponding 10H-phenothiazine-5,5-dioxides. The phenothiazines have also been used as base to prepare ribofuranosides by the reaction with β-D-ribofuranose-1-acetate-2,3,5-tribenzoate. All the synthesized compounds have been characterized by spectral and elemental analysis and have been examined for antioxidant and antimicrobial activity.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

Characterization of organic arsenic compounds in bivalves

Water-soluble arsenic compounds were extracted with methanol/water (1:1, v/v) from various species of bivalves and also from certified reference materials (NIES No. 6, mussel tissue, and NBS 1566, oyster tissue). The extracts were analyzed with a high-performance liquid chromatograph combined with an inductively coupled argon plasma mass spectrometer serving as an arsenic-specific detector. A certified reference material (NIES No. 6) was used to check the reproducibility of the analysis. The relative standard deviations (RSDs) of the peak area of major arsenic compounds among repeated measurements (n = 6) on the same extrct were less than 3.3%, indicating good reproducibility of the technique. The RSDs of some peaks among measurements of independent extracts, on the other hand, were more than 10%, possibly reflecting the heterogeneity of the sample in terms of the chemical species under the present experimental conditions. In many of the samples analyzed in the present study, two arsenic-containing ribofuranosides were detected in addition to arsenobetaine. A compound bearing a glycerophosphoryl glycerol moiety was dominant in such cases. Interestingly, a bivalve living in an estuary (Corbicula japonica) did not contain a detectable amount of arsenobetaine though it had arsenic-containing ribofuranosides. The distribution of arsenic species in the various parts of a clam (Meretrix lusoria) and a mussel (Mytilus coruscum) was also analyzed.     

Arsenic Compounds in Zoo- and Phyto-plankton of Marine Origin

Major water-soluble arsenic compounds accumulated in some zoo- and phyto-plankton were identified. Zooplankton were collected at sampling stations in the Sea of Japan by a Norpac net towed from 600 m depth to the surface. Phytoplankton were cultivated under axenic conditions. Water-soluble arsenic compounds were extracted repeatedly from plankton tissues by aqueous methanol. The arsenic compounds in the extracts were analyzed by HPLC–ICP/MS. Among zooplankton analyzed in the present study, two carnivorous species, i.e. Amphipoda ( Themisto sp.) and Sagittoidea ( Sagitta sp.), contained arsenobetaine as the dominant arsenic species. Arsenobetaine was the major species in Euphausiacea ( Euphausia sp.), also. The most abundant arsenic compound in the herbivorous Copepoda species ( Calanus sp.), on the other hand, was an arsenic-containing ribofuranoside with a sulfate ester group, and arsenobetaine was only a minor component. Phytoplankton contained arsenic-containing ribofuranosides apparently in a species-speific manner. The arsenic compounds in zooplankton seem to reflect their feeding habit; i.e. carnivorous species eating zooplankton or other small animals accumulate arsenobetaine, while herbivorous ones eating phytoplankton accumulate arsenic-containing ribofuranosides as major arsenic compounds.     

Arsenic-containing ribofuranosides and dimethylarsinic acid in green seaweed,Codium fragile

Three water-soluble arsenic compounds were isolated from the green seaweed Codium fragile. These compounds were identified as 1-glycerophosphoryl-2-hydroxy-3-[5′-deoxy-5′-(dimethylarsinoyl)-β-ribofuranosyloxy]propane (1a), 1′ -(1,2-dihydroxypropyl)-5′ -deoxy-5′ -(dimethylarsinoyl)-β-ribofuranoside (1b), and dimethylarsinic acid ((CH₃)₂AsOOH). The structures of these compounds were ascertained by ¹H NMR spectroscopy. Compounds 1a and 1b accounted for 60 % and dimethylarsinic acid for 5% of the water-soluble arsenic.     

SYNTHESIS OF SOME 2-THIOXOPYRIDO[2,3-d]PYRIMIDINE RIBOFURANOSIDES AND THEIR ANTIMICROBIAL ACTIVITY

Abstract

2-Thioxc-3,5,7-trisubstitutcd-I-[2′.3′,5′-tri-O-benzoyl-β-D-ribofuranosyllpyrido [2,3-d]pyri midin-4(IH)-ones have been prepared by the condensation of trimethylsilyl derivative of 2-thioxo-3,5,7-trisubstituted pyrido[2,3-d]pyrimidin-4(IH)-ones with β-D-ribofuranose 1-acetate-2,3,5-tribenzoate in 65%-78% yield. The structure of the synthesized ribofuranosides and their precursors have been established by IR, ¹H NMR and elemental analysis. These derivatives have been screened for their antimicrobial activity.