RESUMEN
Dimerization of lawsone occurs upon reaction with Co(BF(4))(2)·6H(2)O and N,N'-bis(pyridin-2-ylmethyl)ethylenediamine (py(2)en) to produce the mononuclear complex [Co(III)(bhnq)(py(2)en)]BF(4)·H(2)O (1). This complex has been investigated as a prototype of a bioreductive prodrug, where the bhnq(2-) ligand acts as a model for cytotoxic naphthoquinones. Cyclic voltammetry data in aqueous solution have shown a quasi-reversible Co(III)/Co(II) process at E(1/2) = -0.26 V vs Fc/Fc(+). Reactivity studies revealed the dissociation of bhnq(2-) from the complex upon reduction of 1 with ascorbic acid, and a dependence of the reaction rate on the oxygen concentration suggests the occurrence of redox cycling.
Asunto(s)
Cobalto/química , Naftoquinonas/química , Compuestos Organometálicos/farmacología , Profármacos/síntesis química , Profármacos/farmacología , Saccharomyces cerevisiae/efectos de los fármacos , Proliferación Celular/efectos de los fármacos , Cristalografía por Rayos X , Dimerización , Modelos Moleculares , Estructura Molecular , Compuestos Organometálicos/síntesis química , Compuestos Organometálicos/química , Oxidación-Reducción , Profármacos/química , Saccharomyces cerevisiae/citología , Relación Estructura-ActividadRESUMEN
Propolis is a natural product widely used for humans. Due to its complex composition, a number of applications (antimicrobial, antiinflammatory, anesthetic, cytostatic and antioxidant) have been attributed to this substance. Using Saccharomyces cerevisiae as a eukaryotic model we investigated the mechanisms underlying the antioxidant effect of propolis from Guarapari against oxidative stress. Submitting a wild type (BY4741) and antioxidant deficient strains (ctt1Δ, sod1Δ, gsh1Δ, gtt1Δ and gtt2Δ) either to 15 mM menadione or to 2 mM hydrogen peroxide during 60 min, we observed that all strains, except the mutant sod1Δ, acquired tolerance when previously treated with 25 µg/mL of alcoholic propolis extract. Such a treatment reduced the levels of ROS generation and of lipid peroxidation, after oxidative stress. The increase in Cu/Zn-Sod activity by propolis suggests that the protection might be acting synergistically with Cu/Zn-Sod.