Zinc increases vulnerability of rat thymic lymphocytes to arachidonic acid under in vitro conditions.

Previous studies on the cytotoxicity of arachidonic acid (ARA) elucidated the involvement of oxidative stress and Ca(2+). In the present study, the Zn(2+)-related cytotoxicity of ARA was studied by a flow cytometric technique with appropriate fluorescent probes in rat thymocytes. Addition of 10 µM ZnCl2 enhanced the increase in cell lethality induced by 10 µM ARA. The removal of Zn(2+) by Zn(2+) chelators attenuated the ARA-induced increase in cell lethality. Thus, Zn(2+) is suggested to be involved in ARA cytotoxicity. ARA at 3-10 µM elevated intracellular Zn(2+) level. The Zn(2+) chelators attenuated the ARA-induced increase in intracellular Zn(2+) level while ARA significantly increased intracellular Zn(2+) level in the presence of 3 µM ZnCl2, suggesting the involvement of external Zn(2+). Zn(2+) reportedly exerts cytotoxic action under oxidative stress induced by hydrogen peroxide, via an excessive increase in intracellular Zn(2+) levels. Since ARA induces oxidative stress, the simultaneous administration of zinc and ARA may be harmful.

Thermal and transport properties of ionic liquids based on benzyl-substituted phosphonium cations.

The physicochemical properties of two novel ionic liquids based on benzyltriethylphosphonium and benzyltributylphosphonium cations are described in this report. It was found that both benzyl-substituted phosphonium cations gave low-melting salts in combination with a bis(trifluoromethylsulfonyl)amide anion. The thermogravimetric analysis suggested that the benzyl-substituted phosphonium ionic liquids showed higher thermal stability than those of not only the alkyl-substituted phosphonium ILs but also the corresponding benzyl-substituted ammonium compounds. The benzyl-substituted phosphonium ionic liquids also exhibited relatively high conductivities when compared to those of the corresponding ammonium compounds. These results indicate an improving effect of introducing a benzyl group into the phosphonium cations on both the thermal stability and the conductivity.