Lawsone dimerization in cobalt(III) complexes toward the design of new prototypes of bioreductive prodrugs.
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.
Instituto de Química, Universidade Federal Fluminense, Outeiro S. João Batista S/N, 24020-141 Niterói, RJ, Brazil.
Francisco L S
FL
Bustamante
Julia M
JM
Metello
Frederico A V
FA
de Castro
Carlos B
CB
Pinheiro
Marcos D
MD
Pereira
Mauricio
M
Lanznaster
D049109:Cell Proliferation / Q000187:drug effects; D003035:Cobalt / Q000737:chemistry*; D018360:Crystallography, X-Ray; D019281:Dimerization; D008958:Models, Molecular; D015394:Molecular Structure; D009285:Naphthoquinones / Q000737:chemistry*; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D010084:Oxidation-Reduction; D011355:Prodrugs / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology*; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000187:drug effects*; D013329:Structure-Activity Relationship
D009285:Naphthoquinones; D009942:Organometallic Compounds; D011355:Prodrugs; D003035:Cobalt; C005090:lawsone