Nucleoside synthesis from 3-alkylated sugars: role of 3beta-oxy substituents in directing nucleoside formation

Toward the synthesis of the hypoxia selective anticancer agent BE-43547 A2

A short and enantioselective synthesis of the 19-epi-BE-43547 A2 chiral framework has been achieved in a high yield. The challenging key C15 tertiary stereocenter was derived from D-glucose. The synthetic strategy involves a Julia-Kocienski olefination to install the lipophilic side chain. An efficient protocol for Z to E isomerization of olefin was developed using a novel UV flow reactor. In addition, an unprecedented oxygen mediated hydroboration and the Krapcho decarboxylation of β-keto lactone were observed.

Mycotoxins from Fusarium proliferatum: new inhibitors of papain-like cysteine proteases

Papain-like cysteine proteases (PLCPs) in plants are essential to prevent phytopathogen invasion. In order to search for cysteine protease inhibitors and to investigate compounds that could be associated to pineapple Fusarium disease, a chemistry investigation was performed on Fusarium proliferatum isolated from Ananas comosus (pineapple) and cultivated in Czapek medium. From F. proliferatum extracts, nine secondary metabolites were isolated and characterized by nuclear magnetic resonance spectroscopy and mass spectrometry experiments: beauvericin (1), fusaric acid (2), N-ethyl-3-phenylacetamide (3), N-acetyltryptamine (4), cyclo(L-Val-L-Pro) cyclodipeptide (5), cyclo(L-Leu-L-Pro) cyclodipeptide (6), cyclo(L-Leu-L-Pro) diketopiperazine (7), 2,4-dihydroxypyrimidine (8), and 1H-indole-3-carbaldehyde (9). Compounds 1, 3, and 6 showed significant inhibition of papain, with IC50 values of 25.3 ± 1.9, 39.4 ± 2.5, and 7.4 ± 0.5 μM, respectively. Compound 1 also showed significant inhibition against human cathepsins V and B with IC50 of 46.0 ± 3.0 and 6.8 ± 0.7 μM, respectively. The inhibition of papain by mycotoxins (fusaric acid and beauvericin) may indicate a mechanism of Fusarium in the roles of infection process.