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Keywords:

  • Bioinorganic chemistry;
  • Vanadates;
  • Alkylation;
  • Hydrolysis;
  • Substituent effects

Abstract

Carcinogens found in cooked foods, tobacco smoke, and vehicle exhaust undergo metabolic activation to pernicious alkylating toxins, yield damaged DNA, and promote cancerous growth. Vanadium has been shown to decrease the occurrence of cancers, possibly by intercepting such toxins before DNA damage can occur. According to recent results, nucleophilic oxido salts of vanadium can prevent this DNA alkylation. Although effective at detoxification and preventing DNA damage, vanadate salts equilibrate in solution to multiple coexisting species and can exhibit toxicity. Ligand-enforced coordination geometries may minimize such equilibrations, thereby decreasing toxicity and providing a means to control reactivity. As part of our efforts to detoxify alkylating agents, here we are studying reactions between oxidovanadium complexes and toxins. Alkylating agents such as diethyl sulfate were treated with a series of new oxidovanadium complexes of the salicylidenehydrazide ligand, [VO2(salhyph(R)2)]. These complexes consumed a collection of alkylating agents and brought about transformation to alcohols. Changing the ligand substituents (R = –OCH3,–CH3, –H, –NO2) yielded a series of compounds with varied degrees of electron density. Kinetic experiments indicated that there may be a correlation between electron density and reactivity with alkylating toxins. The design and reactivity of these compounds indicate that we may be able to exert control over interactions between carcinogens and metal complexes. Such principles may be helpful in developing new compounds for the prevention of cancer. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)