The synthesis, characterization, NO donor properties, and in vitro vas
odilating activity of a series of water soluble furoxans (5-14a,b) are
described. AU of the compounds released NO when treated with a large
excess of cysteine under physiological conditions (pH 7.4; 37 degrees
C). The amount of NO produced after 1 h of incubation was evaluated by
detecting nitrites, via the Griess reaction. Derivatives 5b, 7b, and
14b were able to release nitric oxide also in the absence of the thiol
cofactor. The initial rates of NO release were determined at differen
t concentrations, using a spectrophotometric technique based on the NO
-induced oxidation of oxyhemoglobin (HbO(2)) to methemoglobin (MetHb).
The initial rates of NO release were Linearly dependent on the concen
trations of the single compounds. The vasodilating potency (EC(50)) of
all the derivatives was assessed on rat aortic. strips precontracted
with noradrenaline. Correlation between potency and initial NO release
rate is discussed.