Endogenous generation of nitro-fatty acid hybrids having dual nitrate ester (RONO2) and nitroalkene (RNO2) substituents
Marco Fazzari,
Steven R. Woodcock,
Pascal Rowart,
Karina Ricart,
Jack R. Lancaster, Jr.,
Rakesh Patel,
Dario A. Vitturi,
Bruce A. Freeman,
Francisco J. Schopfer
Affiliations
Marco Fazzari
Department of Pharmacology and Chemical Biology, University of Pittsburgh, 200 Lothrop Street, Pittsburgh, 15261, PA, USA; Corresponding author. Dept. of Pharmacology and Chemical Biology, University of Pittsburgh, 200 Lothrop Street, Pittsburgh, 15261, PA, USA
Steven R. Woodcock
Department of Pharmacology and Chemical Biology, University of Pittsburgh, 200 Lothrop Street, Pittsburgh, 15261, PA, USA
Pascal Rowart
Department of Pharmacology and Chemical Biology, University of Pittsburgh, 200 Lothrop Street, Pittsburgh, 15261, PA, USA
Karina Ricart
Department of Pathology, University of Alabama, 901 19th Street South, Birmingham, 35294, AL, USA
Jack R. Lancaster, Jr.
Department of Pharmacology and Chemical Biology, University of Pittsburgh, 200 Lothrop Street, Pittsburgh, 15261, PA, USA; Pittsburgh Heart, Lung, Blood, and Vascular Medicine Institute, Pittsburgh, 15213, PA, USA
Rakesh Patel
Department of Pathology, University of Alabama, 901 19th Street South, Birmingham, 35294, AL, USA
Dario A. Vitturi
Department of Pharmacology and Chemical Biology, University of Pittsburgh, 200 Lothrop Street, Pittsburgh, 15261, PA, USA; Pittsburgh Heart, Lung, Blood, and Vascular Medicine Institute, Pittsburgh, 15213, PA, USA; Center for Critical Care Nephrology, Pittsburgh, 15213, PA, USA
Bruce A. Freeman
Department of Pharmacology and Chemical Biology, University of Pittsburgh, 200 Lothrop Street, Pittsburgh, 15261, PA, USA
Francisco J. Schopfer
Department of Pharmacology and Chemical Biology, University of Pittsburgh, 200 Lothrop Street, Pittsburgh, 15261, PA, USA; Pittsburgh Heart, Lung, Blood, and Vascular Medicine Institute, Pittsburgh, 15213, PA, USA
Organic nitrate esters, long-recognized therapies for cardiovascular disorders, have not been detected biologically. We characterize in rat stomach unsaturated fatty acid nitration reactions that proceed by generation of nitro-nitrate intermediates (NO2–ONO2-FA) via oxygen and nitrite dependent reactions. NO2–ONO2-lipids represent ∼70% of all nitrated lipids in the stomach and they decay in vitro at neutral or basic pH by the loss of the nitrate ester group (-ONO2) from the carbon backbone upon deprotonation of the α-carbon (pKa ∼7), yielding nitrate, nitrite, nitrosative species, and an electrophilic fatty acid nitroalkene product (NO2-FA). Of note, NO2-FA are anti-inflammatory and tissue-protective signaling mediators, which are undergoing Phase II trials for the treatment of kidney and pulmonary diseases. The decay of NO2–ONO2-FA occurs during intestinal transit and absorption, leading to the formation of NO2-FA that were subsequently detected in circulating plasma triglycerides. These observations provide new insight into unsaturated fatty acid nitration mechanisms, identify nitro-nitrate ester-containing lipids as intermediates in the formation of both secondary nitrogen oxides and electrophilic fatty acid nitroalkenes, and expand the scope of endogenous products stemming from metabolic reactions of nitrogen oxides.
