Pentane as an index of in vitro lipid peroxidation via microsomal NADPH-P-450 enzyme systems

Pentane was measured in a mixture of guinea pig liver microsomes and carbontetrachloride (CCl4) in the presence of nicotineamide adenine dinucleotide phosphate (NADPH) and under anaerobic conditions by gas chromatography. Pentane of 0.2 pmol/mg protein/min was formed in the presence of NADPH without CCl4. Pentane formation increased to 2.0 pmol/mg protein/min in the presence of CCl4 and NADPH. This reaction required an anaerobic atmosphere, 2.1 mmol/litter of NADPH and 13.4 mmol/litter of CCl4 under optimal conditions. The formation was reduced in the presence of oxygen, glutathione, vitamin E and metyrapone. These results clearly show that pentane is formed by lipid peroxidation initiated by the free radical cleavage products of CCl4, which are anaerobically produced by NADPH-dependent microsomal enzymes. We conclude that pentane is a good index of in vitro lipid peroxidation via microsomal NADPH-P-450 enzyme systems.