Eicosanoids, also known as eicosanoic acids, are a family of signaling molecules produced and secreted by many types of cells under normal and pathophysiological conditions. In the human body, these metabolites are excreted into body fluids such as plasma and urine. The precursors of eicosanoids are 20-carbon polyunsaturated fatty acids (PUFAs) esterified in cell membrane phospholipids, such as arachidonic acid (C20:4). Before being further metabolized into eicosanoids, fatty acids (FAs) are enzymatically cleaved from phospholipids by phospholipase A2. Thus, fatty acids as membrane components (i.e., PUFA content) are specific to cell types, crucial for cell function, and influenced by nutrients.
Eicosanoids have a variety of physiological effects. The n-6 fatty acid arachidonic acid (C20:4) is an eicosanoid precursor, primarily producing pro-inflammatory eicosanoids, including prostaglandins (PGs) (two series), thromboxanes (TXs) (two series), leukotrienes (LTs) (four series), and hydroxyeicosatetraenoic acid (HETE) derivatives. The concentration of eicosanoids increases under various diseases and pathophysiological conditions, including type 1/2 diabetes, cardiovascular diseases, obesity, multiple sclerosis, cystic fibrosis, intestinal and pulmonary diseases, neurodegenerative diseases, and several cancers.
Key eicosanoid metabolites in urine, derived from arachidonic acid and related to oxidative stress or pro-inflammatory states, include:
a) Tetranor PGE-M, a stable metabolite of PGE2 synthesized by cyclooxygenase (COX)-1 and COX-2 (present in plasma, relatively unstable). Elevated levels are found in the urine of cancer patients, such as those with lung cancer.
b) 8-iso-PGF2α (also known as 8-epi-PGF2α, 8-isoprostaglandin, or iPF2α-III) is the most commonly used eicosanoid molecule as a biomarker for oxidative stress. 8-iso-PGF2α is produced through free radical-mediated oxidation of arachidonic acid, rather than enzymatically. It is present in plasma but is relatively unstable. Levels are elevated in patients with neurodegenerative diseases or type 1/2 diabetes.
c) 2,3-dinor-8-iso-PGF2α, a β-oxidation product of 8-iso-PGF2.
d) 2,3-dinor-TXB2
e) 11-dehydro-TXB2, a stable urinary metabolite of TXA2 produced by COX-1. Elevated levels are found in diabetic patients and are thought to reflect platelet activation.
f) LTE4, a metabolite of LTD4 formed from LTC4; the synthesis of leukotrienes is regulated by 5-lipoxygenase. LTE4 is used as a biomarker to predict asthma and is considered to reflect systemic LT status.
g) 12-HETE, produced by 12-lipoxygenase. Its concentration increases in female diabetic and hypertensive patients. Similar to 11-dehydro-TXB2, increased levels of 12-HETE may be associated with platelet activation.
Analysis of Eicosanoid Metabolites in Urine
Urinary eicosanoid metabolites are typically measured by GC-MS or LC-MS/MS, usually requiring complex and time-consuming sample extraction and derivatization. Although methods exist for spectral analysis of individual urinary eicosanoids, there are few methods for quantifying eicosanoids from different pathways in urine. Baipai Biotechnologies provides reliable, rapid, and cost-effective eicosanoid metabolite analysis services based on highly stable, repeatable, and highly sensitive systems for separation, characterization, identification, and quantification, combined with LC-MS/MS.
Baipai Biotechnologies offers analysis of the following eicosanoid metabolites
