Oligonucleoside phosphorothioates

Deoxyribonucleotides, deoxyribonucleotide phosphorothioates, modified DNA, and analogs have wide applications in molecular biology, antisense applications, antigene therapy, etc. Three methods are available for the synthesis of oligonucleoside phosphorothioates phosphoramidite, H-phosphonate, and phospho-... 

The volume concludes with the preparation of four useful reagents and compounds. Oligonucleoside phosphorothioates may be prepared using... 

In the area of modified intemucleosidic links, the use of the selenium-containing system 186 in the synthesis of oligonucleoside phosphorothioates has been prefmed to the earlier sulfur analogue since the P-Se bond is more labile in reaction with the 5 -OH group of the other... 

Dioxide. The sulfur-transfer reagent 3//-l,2-benzodithiol-3-one 1,1-dioxide (2, eq 1) is widely used in the preparation of oligonucleoside phosphorothioates, which are especially valuable in the development of therapeutic oligonucleotides against various t)q)es of cancer and infectious diseases in humans. ... 

The scope of this report is not to provide an exhaustive list of all oligonucleoside phosphorothioates that have been prepared using 2, but to review those critical issues stemming from the preparation and handling of the reagent along with specific applications of 3H-... 

Purification by B versed-Phase Isolation of 5 -DMT Oligonucleoside Phosphorothioates... 

Fig. 5. (Left) HPLC trace of a mixture of standards used for the base composition assay 1 = dC. 2 = dU. 3 = 1,4 = dl, 5 = dG, 6 = T, 7 = dA (Right) HPLC trace of a typical mixture obtained from digestion of a representative oligonucleoside phosphorothioate sample. The peak identities are referred to by the aforementioned numbers these peaks accounted for ca. 99% of the total integrated signal intensity.

Measurement of Oligonucleoside Phosphorothioate Content by Strong Anion-Exchange (SAX) HPLC... 

The procedure is outlined in Section 3.10. and is predicated on the perhaps surprising observation that, under the specified conditions, an n-mer oligonucleoside phosphorothioate is eluted from an SAX matrix in proportion to the PO PS content, i.e., the higher the PO PS ratio, the faster the elution—completely (or largely) independent of the location of the PO linkage (s) within the n-mer chain (67). The SAX-HPLC profile for a resolution standard is shown in Fig. 6. This 21 -mer phosphorothioate was prepared such that the PO PS content of 3.5 96.5 would lead to accentuated PO-defect species II-IV. 

As a final addendum to the commentary in Section 3., it is worthwhile to discuss briefly two subjects of continual interest in the area of potential pharmaceutical applications of oligonucleoside phosphorothioates scale-up vis-a-vis solid-phase or solution synthesis and stereochemistry. ... 

Up to this time, it has been possible to obtain chemically diastereo-merically pure (or enriched) oligonucleoside phosphorothioates in cases with only one, two, or three phosphorothioate linkages (47,70). This circumstance has therefore precluded potentially important evaluation of whether or not stereorandom and diastereomerically pure oligonucleoside phosphorothioates have significantly different properties with regard to degradation in vivo, distribution, cellular uptake, binding to RNA, antisense potency, and so forth. 

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