Carbon monoxide (CO) is best known as a silent killer. However, it is also recognized as a low
concentration cell-signaling molecule involved in the regulation of several biological processes.
CO is formed endogenously during the catabolism of hemes by the enzyme heme oxygenase
(HO). There are two isozymes of heme oxygenase known as HO-1 and HO-2. HO-1 is an
inducible enzyme in response to oxidative stress and HO-2 is expressed under homeostatic
conditions and both generate CO in vivo. Recent research has shown that CO plays a therapeutic
role in the promotion of wound healing, in reducing the risk of organ transplant rejection,
protection against ischemia injury, and as an anti-inflammatory. Current therapeutic methods
use direct inhalation of CO gas which presents a risk of asphyxiation. Our research efforts are
directed towards developing compounds that are capable of delivering CO to biological targets
for therapeutic use. Photochemical carbon monoxide releasing molecules (PhotoCORMs) have
the potential for achieving a safe and controlled delivery of CO to specific biological targets.
The research efforts of this project investigate the photochemistry and toxicity of the novel ironbased compound μ-(SCH2CH2OH)2-Fe2(CO)6 in order to study its potential use as a possible
PhotoCORM. The photochemical activity of this compound is studied by irradiating it at
different wavelengths of light. Spectral changes in the optical spectra of μ-(SCH2CH2OH)2Fe2(CO)6 were used to calculate CO released per photon absorbed which is also known as a
quantum yield. Experiments use standard actinometry to determine the power of the light source
and involved irradiations of the μ-(SCH2CH2OH)2-Fe2(CO)6 solutions at different wavelengths.
Quantum yield results are 0.086 and 0.107 for CO release at 365-nm irradiation and 0.327 and
0.320 for CO release at 334-nm irradiation. The toxicity of the compound was studied by
growing Jurkat cells, a human T lymphoma cell line, in RPMI 1640 media supplemented by 10%
fetal bovine serum (FBS). WST-8 assays were performed with varying concentrations of μ(SCH2CH2OH)2-Fe2(CO). Assay results showed that the compound is toxic at increasing
concentrations of μ-(SCH2CH2OH)2-Fe2(CO)6.