7 research outputs found
Hydrogen Peroxide Formation in a Surrogate Lung Fluid by Transition Metals and Quinones Present in Particulate Matter
Inhaled
ambient particulate matter (PM) causes adverse health effects,
possibly by generating reactive oxygen species (ROS), including hydrogen
peroxide (HOOH), in the lung lining fluid. There are conflicting reports
in the literature as to which chemical components of PM can chemically
generate HOOH in lung fluid mimics. It is also unclear which redox-active
species are most important for HOOH formation at concentrations relevant
to ambient PM. To address this, we use a cell-free, surrogate lung
fluid (SLF) to quantify the initial rate of HOOH formation from 10
transition metals and 4 quinones commonly identified in PM. Copper,
1,2-naphthoquinone, 1,4-naphthoquinone, and phenanthrenequinone
all form HOOH in a SLF, but only copper and 1,2-naphthoquinone
are likely important at ambient concentrations. Iron suppresses HOOH
formation in laboratory solutions, but has a smaller effect in ambient
PM extracts, possibly because organic ligands in the particles reduce
the reactivity of iron. Overall, copper produces the majority of HOOH
chemically generated from typical ambient PM while 1,2-naphthoquinone
generally makes a small contribution. However, measured rates of HOOH
formation in ambient particle extracts are lower than rates calculated
from soluble copper by an average (±1σ) of 44 ± 22%;
this underestimate is likely due to either HOOH destruction by Fe
or a reduction in Cu reactivity due to organic ligands from the PM