Inhibition of the autoxidation of ascorbate and norepinephrine by extracts of Clostridium butyricum, Megasphaera elsdenii and Escherichia coli.

ABSTRACT

The autoxidation of ascorbate and of norepinephrine in Krebs Ringer phosphate medium, pH 7.4, was studied. The autoxidation of the two substances was determined spectrophotometrically at 265 and 480 nm respectively. The effect of dialyzed extracts (m.w. greater than 12,000) from Escherichia coli (aerobe), Megasphaera elsdenii, and Clostridium butyricum (obligate anaerobes) was examined and compared to similarly prepared extracts from rat serum and cerebral cortex. The assay medium contained cellular components diluted 10(3)-10(6)-fold. Up to 10(4)-fold dilution there was a substantial reduction in the rate of both autoxidation reactions, but the preparations from M. elsdenii and C. butyricum were conspicuously less effective. After 5 min heat treatment at 100 degrees C the anaerobic preparations produced less than 20% inhibition, while the activity of the other preparations remained unchanged at 75-95% inhibition. These and earlier experiments involving additional mammalian species (Mishra and Kovachich, Neurosci. Lett., 43 103-108, 1983) and plants (Mishra and Kovachich, Life Sci., 34 2207-2212, 1984) suggest that a high level of heat-stable antioxidant activity in one or both of these autoxidation tests (denatured plant extracts only inhibit ascorbate autoxidation) is a general characteristic of organisms that thrive in oxygen-rich atmosphere.