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Cancer cells are vulnerable to reactive oxygen species (ROS) due to their abnormal redox environment. Accordingly, combination of chemotherapy and oxidative stress has gained increasing interest for the treatment of cancer. We report a novel seleno-prodrug of gemcitabine (Gem), Se-Gem, and evaluated its activation and biological effects in cancer cells. Se-Gem was prepared by introducing a 1,2-diselenolane (a five-membered cyclic diselenide) moiety into the parent drug Gemvia a carbamate linker. Se-Gem is preferably activated by glutathione (GSH) and displays a remarkably higher potency than Gem (up to a 6-fold increase) to a panel of cancer cell lines. The activation of Se-Gem by GSH releases Gem and a seleno-intermediate nearly quantitatively. Unlike the most ignored side products in prodrug activation, the seleno-intermediate further catalyzes a conversion of GSH and oxygen to GSSG (oxidized GSH) and ROS via redox cycling reactions. Thus Se-Gem may be considered as a suicide agent to deplete GSH and works by a combination of chemotherapy and oxidative stress. This is the first case that employs a cyclic diselenide in prodrug design, and the success of Se-Gem as well as its well-defined action mechanism demonstrates that the 1,2-diselenolane moiety may serve as a general scaffold to advance constructing novel therapeutic molecules with improved potency via a combination of chemotherapy and oxidative stress.

The present invention relates to a process for the preparation of Treosulfan using sodium borohydride and iodine as reducing agent, which is less hazardous and convenient as compared to the reagents used in the prior art. The invention also relates to a novel intermediate to obtain Treosulfan in high yield and high purity.

The two enantiomers of 2,2′-bioxirane were synthesized, and their chiroptical properties were thoroughly investigated in various solvents by polarimetry, vibrational circular dichroism (VCD), and Raman optical activity (ROA). Density functional theory (DFT) calculations at the B3LYP/aug-cc-pVTZ level revealed the presence of three conformers (G+, G?, and cis) with Gibbs populations of 51, 44, and 5% for the isolated molecule, respectively. The population ratios of the two main conformers were modified for solvents exhibiting higher dielectric constants (G? form decreases whereas G+ form increases). The behavior of the specific optical rotation values with the different solvents was correctly reproduced by time-dependent DFT calculations using the polarizable continuum model (PCM), except for the benzene for which explicit solvent model should be necessary. Finally, VCD and ROA spectra were perfectly reproduced by the DFT/PCM calculations for the Boltzmann-averaged G+ and G? conformers.

Phosphomolybdic acid supported on silica gel provides a truly catalytic method for the chemoselective cleavage of benzylidene acetals having sensitive functional groups under mild conditions. It is easy to perform on large scale owing to minimal catalyst loading (0.5 mol-%). Several sensitive functional groups such as TBDPS ether, -OMs, -OAc, allyl ether, N-Boc, N-Fmoc and N-Cbz are stable under the reaction conditions. In addition, benzylidene acetal is selectively cleaved in the presence of isopropylidene ketal. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.

1,2,3,4-Diepoxybutane (DEB) is a bifunctional electrophile capable of forming DNA-DNA and DNA-protein cross-links. DNA alkylation by DEB produces N7-(2′-hydroxy-3′,4′-epoxybut-1′-yl)-guanine monoadducts, which can then form 1,4-bis-(guan-7-yl)-2,3-butanediol (bis-N7G-BD) lesions. All three optical isomers of DEB are produced metabolically from 1,3-butadiene, but S,S-DEB is the most cytotoxic and genotoxic. In the present work, interstrand and intrastrand DNA-DNA cross-linking by individual DEB stereoisomers was investigated by PAGE, mass spectrometry, and stable isotope labeling. S,S-, R,R-, and meso-diepoxides were synthesized from L-dimethyl-2,3-O-isopropylidene-tartrate, D-dimethyl-2,3-O-isopropylidene- tartrate, and meso-erythritol, respectively. Total numbers of bis-N7G-BD lesions (intrastrand and interstrand) in calf thymus DNA treated separately with S,S-, R,R-, or meso-DEB (0.01-0.5 mM) were similar as determined by capillary HPLC-ESI+-MS/MS of DNA hydrolysates. However, denaturing PAGE has revealed that S,S-DEB produced the highest number of interchain cross-links in 5′-GGC-3′/3′-CCG-5′ sequences. Intrastrand adduct formation by DEB was investigated by a novel methodology based on stable isotope labeling HPLC-ESI+-MS/MS. Meso DEB treatment of DNA duplexes containing 5′-[1,7, NH2-15N3,2- 13C-G]GC-3′/3′-CCG-5′ and 5′-GGC-3′/ 3′-CC[15N3,2-13C-G]-5′ trinucleotides gave rise to comparable numbers of 1,2-intrastrand and 1,3-interstrand bis-N7G-BD cross-links, while S,S DEB produced few intrastrand lesions. R,R-DEB treated DNA contained mostly 1,3-interstrand bis-N7G-BD, along with smaller amounts of 1,2-interstrand and 1,2-intrastrand adducts. The effects of DEB stereochemistry on its ability to form DNA-DNA cross-links may be rationalized by the spatial relationships between the epoxy alcohol side chains in stereoisomeric N7-(2′-hydroxy-3′,4′-epoxybut-1′-yl)- guanine adducts and their DNA environment. Different cross-linking specificities of DEB stereoisomers provide a likely structural basis for their distinct biological activities.

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(S,S)-1,2,3,4-diepoxybutane was synthesized from (R,R)-dimethyl tartrate. Nucleophilic opening of this diepoxybutane gave a convenient method for generating a variety of chiral nonracemic diols.

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