Sterols, oxidation susceptibility

Serum cholesterol and TG levels were determined by enzymatic methods (28,29). Serum free fatty acid (FFA) level was determined by a colorimetric method (30). Human LDL was obtained by ultracentrifugation. The density range between 1.006-1.063 g/mL was collected as LDL. To determine the oxidative susceptibility in Cu -induced oxidation, LDL was dialyzed in phosphate-buffered saline (PBS) (10 mM, pH 7.4) and subjected to oxidation without prolonged storage (25,31). Hepatic cholesterol contents of hamsters were determined by a modified colorimetric assay after saponification and extraction (32). To avoid interference from plant sterols in the colorimetric assay, fecal cholesterol content was determined by reversed-phase HPLC (mobile phase methanol acetonitrile = 56 44, v/v). 

Steroids and sterols represent an important class of drugs that are susceptible to oxidative degradation through the possession of alkene moieties. The oxidation of phenothiazines forms the sulfoxide moiety. 

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