Lipoperoxide plasma levels in patients with liver cirrhosis

Oxygen free radicals might play a role in the pathogenesis of tissue damage in many pathological conditions, including liver diseases where antioxidant tissue systems are reduced. The leading mechanism of free radical toxicity is the peroxidation of membrane phospholipids. Lipoperoxide hydrolysis produces aldehydes -the most represented being malondialdehyde-which reacts with thiobarbituric acid and whose concentration is considered a marker of lipid peroxidation.

We developed a fast and cheap HPLC method for measuring malondialdehyde concentration in plasma using a 3 mm C18 Baker column (4.6 x 50 mm). Thiobarbituric acid-reacting substances were eluted isocratically with a mobile phase containing methanol/KH2PO4 (35/65), and detected fluorometrically. The whole analysis lasts 2.5 minutes. The fasting levels of thiobarbituric acid-reactive substances were measured in 30 non-smoking blood donors and in 45 patients with liver cirrhosis.

In control subjects they were on average 0.84 [SD 0.41] mumol/L and were increased to 1.59 [SD 1.23] mumol/L in patients with cirrhosis, where they inversely correlated with hepatocellular function.

The method compares favorably with previous techniques in terms of cost and analytical time. It can be used for serial measurement of plasma lipoperoxide concentrations in response to oxidative stress or following drug administration. Our preliminary data confirms the presence of an oxidative stress in cirrhotic patients. Normal lipoperoxide levels in subjects with very advanced disease may be due to polyunsaturated fatty acid deficiency and/or enzyme defects.