Alkylation of Inorganic Oxo Compounds and Insights on Preventing DNA Damage

Metabolism of food- and tobacco-borne procarcinogens results in the exposure of DNA to toxic alkylating agents. These assaults can bring about DNA alkylation damage, mutations, and cancer. Dietary inorganic compounds such as selenium and vanadium are known to prevent cancer, possibly by reacting directly with alkylating agents, thereby preventing DNA damage. To understand potential interactions between oxo species and alkylating toxins, we reacted a series of alkylating agents with varied classes of oxo compounds (i.e., vanadates, selenate, phosphate, sulfate, acetate, nitrate, and nitrite). A new organic-soluble selenate, [(C6H5)4P]3(O3SeOCH2OSeO3)(HSeO4), was synthesized and characterized for these studies. Vanadates were found to convert ethylating agents into ethanol, whereas other anions formed esters upon alkylation. General trends show that oxo anions of the greatest charge density were the most reactive. These studies suggest that the design of new compounds for cancer prevention should incorporate reactive oxo groups with high anionic charge density

The Elusive Vanadate (V₃O₉)^3-: Isolation, Crystal Structure, and Nonaqueous Solution Behavior

The isolation, crystal structure, and nonaqueous solution characteristics of the first trinuclear vanadate are presented. The crystal structure reveals a six-membered cyclic arrangement of alternating vanadium and oxygen atoms for the anion of [(C4H9)4N]3(V3O9). The 51V NMR spectrum of this compound in CD3CN exhibits multiple peaks. The relative intensities of each resonance can be altered by concentration and temperature changes, the later of which are reversible. Addition of [(C4H9)4N]Br and NaClO4 also perturbs the equilibria between species observed. Conductivity data for [(C4H9)4N]3(V3O9) in CH3CN as a function of concentration display pronounced curvature and indicate formation of a neutral species in solution at the highest concentrations studied. Stoichiometric mixtures of [(C4H9)4N]3(V3O9) with the known vanadates [(C4H9)4N]3(HV4O12), [(C4H9)4N]3(V5O14), and [(C4H9)4N]3(H3V10O28) are prepared and examined by 51V NMR. Equilibration between the various vanadates is observed and characterized. Resonances for these known vanadates, however, cannot be used to identify the peaks found for [(C4H9)4N]3(V3O9), alone, in solution. The existence of ion pairs in acetonitrile is the only interpretation for the solution behavior of [(C4H9)4N]3(V3O9) consistent with all data. As such, we can directly observe each possible ion pairing state by 51V NMR:  (V3O9)3- at −555 ppm, {[(C4H9)4N](V3O9)}2- at −569 ppm, {[(C4H9)4N]2(V3O9)}- at −576 ppm, and [(C4H9)4N]3(V3O9) at −628 ppm. To the best of our knowledge, [(C4H9)4N]3(V3O9) presents the first case in which every possible ion paired state can be observed directly from a parent polyion. Isolation and characterization of this simple metal oxo moiety may now facilitate efforts to design functional polyoxometalates

Alkylation of Inorganic Oxo Compounds and Insights on Preventing DNA Damage

Metabolism of food- and tobacco-borne procarcinogens results in the exposure of DNA to toxic alkylating agents. These assaults can bring about DNA alkylation damage, mutations, and cancer. Dietary inorganic compounds such as selenium and vanadium are known to prevent cancer, possibly by reacting directly with alkylating agents, thereby preventing DNA damage. To understand potential interactions between oxo species and alkylating toxins, we reacted a series of alkylating agents with varied classes of oxo compounds (i.e., vanadates, selenate, phosphate, sulfate, acetate, nitrate, and nitrite). A new organic-soluble selenate, [(C6H5)4P]3(O3SeOCH2OSeO3)(HSeO4), was synthesized and characterized for these studies. Vanadates were found to convert ethylating agents into ethanol, whereas other anions formed esters upon alkylation. General trends show that oxo anions of the greatest charge density were the most reactive. These studies suggest that the design of new compounds for cancer prevention should incorporate reactive oxo groups with high anionic charge density