The quantification of free radicals (FR) in serum calls for a sensitive, and not expensive method of FR-detection, particularly in view of their short-time existence on the one hand, but the continuous origin in living biological systems, on the other hand. The current state of FR assessment in blood is represented by the series of indirect methods for detection of changes resulting as the consequence of pathological activity of free radicals, or by very specific ions-transfer detection methods, which cannot be used under routine conditions of clinical chemistry. The principle of our method which is the first one applicable for common use in all laboratories is based on the ability of chlorophyllin (sodium magnesium chlorophyllin) to transfer electrons due to its p electron-rich structure. Thus the aim of the presented paper was to examine all conditions under which this compound should serve as the acceptor or donor of electrons and therefore be the strongest antioxidant among others, present in individual serum samples. The special form of calibration used in this work, ensues from basic knowledge of an easy and massive oxidation of Fe 2+ into Fe 3+ ions in alkaline solutions. By our method we studied various groups of probands, suffering from atherosclerotic changes of lipid metabolism. The obtained results support the suggestion that pathologically increased concentrations of FR can be expected above all in persons with hypercholesterolaemia only, respecti- vely with the hypercholesterolaemia combined with hypertriacylglycerolaemia. In cases of medium increased triacylglycerol levels only, and especially if they are raised by esters of polyunsaturated fatty acids, a false antioxidant effect of triacylglycerols was observed. This discovery makes our method suitable also for studies of food antioxidant protection effects during prevention and antioxidant therapy. Our method was compared with the absolute standard method, the electron paramagnetic resonance, and no statistically important differences were found. The regression analysis gives a r-coefficient value of 0.922.

        Key words: free radicals, method for estimation, chlorophyllin lipids.