2′-Fluoro-3-deazaaristeromycin

Enantiomeric 4'-truncated 6'-fluoro-3-deazaneplanocin and its 3-bromo derivative: Synthesis and antiviral properties, including Ebola and Marburg

In seeking to increase the library of fluorine containing adenine-derived carbocyclic nucleoside antiviral candidates, d-like and l-like 6'-fluoro-3-deazaneplanocin and its 3-bromo derivative lacking the 4'-hydroxylmethylene substituent (2/3 and 4/5, respectively) are presented. Their synthesis was accomplished from d-ribose by developing a more facile precursor route than suggested by the literature. The 2/4d-like pair displayed significant anti-filo virial properties while the enantiomeric l-like congeners 3/5 were inactive. Target compounds 2/4 also were active towards measles and norovirus. The effect of 2/4 is further evidence of the role fluoro-derived adenine carbocyclic nucleoside can play in antiviral drug discovery. Furthermore, the simplicity of their synthesis lends them to more efficacious analogs and to scale-up optimization. There were no other relevant antiviral properties for 2/3 and 4/5 (except BK polyomavirus for 3/5).

Enantiomeric 4'-Truncated 3-deaza-1',6'-isoneplanocins: Synthesis and antiviral properties including Ebola

Enantiomeric 3-deaza-1',6'-isoneplanocins (C-3 unsubstituted 7a/7b and C-3 with a bromine 8a/8b) lacking the 4'-hydroxymethyl as mechanistically designed anti-viral targets have been prepared by utilizing the Ullmann reaction. Anti-Ebola properties were found for the D-like 7a and 8a and L-like 8b. All four products showed effects against human cytomegalovirus while D-like 7a/8a affected measles; 7a was effective versus norovirus and 8a inhibited Pichinde. Both 7a and 8a produced SAHase inhibitory effects. However, the anti-EBOV activity of 7a and 8a cannot be readily correlated with this observation due with their contrasting IC₅₀ values (8a > 7a). It is to be noted that 7b showed no effects on this enzyme and 8b was minimally inhibitory. These results offer preliminary insight into the differing mechanisms of action of D- and L- like structures and enlighten structural features to guide additional antiviral agent pursuit in the isoneplanocin series.

Identification of a cytotoxic molecule in heat-modified citrus pectin

Modified forms of citrus pectin possess anticancer properties. However, their mechanism of action and the structural features involved remain unclear. Here, we showed that citrus pectin modified by heat treatment displayed cytotoxic effects in cancer cells. A fractionation approach was used aiming to identify active molecules. Dialysis and ethanol precipitation followed by HPLC analysis evidenced that most of the activity was related to molecules with molecular weight corresponding to low degree of polymerization oligogalacturonic acid. Heat-treatment of galacturonic acid also generated cytotoxic molecules. Furthermore, heat-modified galacturonic acid and heat-fragmented pectin contained the same molecule that induced cell death when isolated by HPLC separation. Mass spectrometry analyses revealed that 4,5-dihydroxy-2-cyclopenten-1-one was one cytotoxic molecule present in heat-treated pectin. Finally, we synthesized the enantiopure (4R,5R)-4,5-dihydroxy-2-cyclopenten-1-one and demonstrated that this molecule was cytotoxic and induced a similar pattern of apoptotic-like features than heat-modified pectin.

Recent progress for the synthesis of selected carbocyclic nucleosides

Nucleoside analogs are extremely useful for the development of therapeutic agents to control viral diseases and cancer. Among the numerous modifications on the nucleoside skeleton, replacement of the oxygen of the furanose ring by a CH2 group resulted in increased flexibility and higher resistance to phosphorylases and led to carbocyclic nucleoside analogs (or carbanucleosides). The broad spectrum of biological activities of carbocyclic nucleosides led to tremendous research interest in their syntheses. The article documents recent strategies for the synthesis of active carbocyclic nucleosides by presenting individual case studies, such as the neplanocins, entecavir and selected fluorinated carbocyclic nucleosides. Furthermore, it provides new insights into new directions for more potent and active carbocyclic nucleoside analogs.