Disodium disuccinate astaxanthin ('
rac'-dAST;
Cardax) is a water-dispersible C40
carotenoid derivative under development for oral and parenteral administration for cardioprotection of the at-risk ischemic cardiovascular patient. In experimental
infarction models in animals (rats, rabbits, and dogs), significant myocardial salvage has been obtained, up to 100% at the appropriate dose in dogs. The documented mechanism of action in vitro includes direct scavenging of biologically produced
superoxide anion; in vivo in rabbits, modulation of the
complement activity of serum has also been shown. A direct correlation between administration of the test compound in animals and reductions of multiple, independent markers of oxidative stress in serum was recently obtained in a rat experimental
infarction model. For the current study, it was hypothesized that oral
Cardax administration would inhibit oxidative damage of multiple relevant
biological targets in a representative, well-characterized murine peritoneal
inflammation model. A previously developed mass spectrometry-based (LC/ESI/MS/MS) approach was used to interrogate multiple distinct pathways of oxidation in a black mouse (C57/BL6) model system. In vivo markers of
oxidant stress from peritoneal lavage samples (supernatants) were evaluated in mice on day eight (8)
after treatment with either
Cardax or vehicle (lipophilic
emulsion without
drug) orally by gavage at 500 mg/kg once per day for seven (7) days at five (5) time points: (1) baseline prior to treatment (t=0); (2) 16 h following intraperitoneal (i.p.) injection with thioglycollate to elicit a neutrophilic infiltrate; (3) 4 h following i.p. injection of yeast cell wall (
zymosan; t=16 h/4 h thioglycollate+zymosan); (4) 72 h following i.p. injection with thioglycollate to elicit monocyte/macrophage infiltration; and (5) 72 h/4 h thioglycollate+zymosan. A statistically significant sparing effect on the
arachidonic acid (AA) and
linoleic acid (LA) substrates was observed at time points two and five. When normalized to the concentration of the oxidative substrates, statistically significant reductions of 8-isoprostane-F(2alpha) (8-iso-F(2alpha)) at time point three (maximal neutrophil recruitment/activation), and
5-HETE, 5-oxo-EET,
11-HETE,
9-HODE, and
PGF(2alpha) at time point five (maximal monocyte/macrophage recruitment/activation) were observed. Subsequently, the direct interaction of the optically inactive stereoisomer of
Cardax (meso-
dAST) with human
5-lipoxygenase (5-LOX) was evaluated in vitro with circular dichroism (CD) and electronic absorption (UV/Vis) spectroscopy, and subsequent molecular docking calculations were made using mammalian 15-LOX as a surrogate (for which XRC data has been reported). The results suggested that the meso-compound was capable of interaction with, and binding to, the
solvent-exposed surface of the
enzyme. These preliminary studies provide the foundation for more detailed evaluation of the
therapeutic effects of this compound on the 5-LOX
enzyme, important in
chronic diseases such as
atherosclerosis,
asthma, and
prostate cancer in humans.