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    Tough Zoloft Shows Green Catalysts Still Need Fine Tuning
    By Enrico Uva | September 11th 2011 08:48 AM | Print | E-mail | Track Comments
    About Enrico

    I majored in chemistry, worked briefly in the food industry and at Fisheries and Oceans. I then obtained a degree in education. Since then I have...

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    Green catalysts such as iron TAML show great potential. Working at very low concentrations, they speed up H2O2's oxidation of nasty estrogen-imitators and carcinogens like 2,4,6-trichlorophenol. Moreover, the catalysts don't seem to be trouble-makers themselves -- at times one environmental solution spins off a new set of problems. Rather, three TAML activators do not interfere with gene expression in mammals by not binding to their thyroid, androgen, or estrogen hormone receptors.

    But a paper published last month in Environmental Science and Technology suggests that these promising catalysts still need some fine-tuning. Zoloft, Pfizer's trade name for
    sertraline hydrochloride, finds its way into the bodies of almost 30 million Americans alone who suffer from depression or compulsive disorders. But the sertraline molecule is one of those halogenated aromatics, where delocalization of electrons makes it difficult for the molecule to get naturally broken down in the environment. According to an EPA study, even after sewage treatment, most of it ends up intact in sediments.

    This is where TAMLs(
    oxidation catalysts based
    upon tetraamido macrocyclic ligands
    ) come to the partial rescue. Although they quickly begin to break down sertraline into a nonactive pharmaceutical (at least at elevated pH's),  they produce a slow-degrading ketone intermediate . Eventually the ketone does react, but it creates other compounds whose impact on the environment is unknown.

    One line of attack in the research so far has been to modify groups on the TAML molecule, as shown in the diagram for the ones they used to attack Zoloft.


    The authors conclude
    that in general, we need even more reactive TAML activators for advancing water treatment goals.




    References:

    Rapid, Biomimetic Degradation in Water of the Persistent Drug Sertraline by TAML Catalysts and Hydrogen Peroxide. 

    Final report: the Environmental Occurrence, Fate and Ecotoxicity of Selective Inhibitors in Aquatic Environments