Chemical or medicinal “oxygen” is never just one homogeneous substance. Apart from impurities found in commercial-grade preparations—welder’s oxygen is “purer” than medicinal oxygen—there are at least ten reactive forms to be reckoned with when considering “generic” oxygen. These can be classed as subtypes of atomic oxygen, O; molecular oxygen (dioxygen), O2; and ozone, O3.
The importance of oxygen subtypes or forms is illustrated by ozone and superoxide. Other reactive forms maybe as—or more—important at sub-molecular levels. When it comes to understanding oxygen in biological systems much remains to be learned about how the whole spectrum of oxygen forms behave for good and ill.
Ozone—present in the ambient air from which much medicinal oxygen is derived—plays a dual role in the biosphere. It contributes to earth’s upper atmospheric shield against harmful cosmic radiation while helping to trap climate-altering carbon dioxide. As a reactive ground-level oxygen form, it exerts trans-species, physical adverse effects on respiratory functions and subcellular structural integrity. Think asthma, inflammation, and lipid membrane damage.
But there are also non-biological macro-level effects. For example, ozonolysis of unsaturated bonds, through ambient exposure, produces compounds with oxygen double bonds that alter some structural substances’ compositions and functional integrity. This is illustrated by the elastic deterioration of rubber bands and the cracking of rubber tires exposed to “normal” ozone-containing atmospheres. Concentrated exposures are more deleterious.
Superoxide—formed when molecular oxygen (dioxygen) gains an electron in its outer shell—is a second oxygen form with great importance. Its role in biological electron transfer reactions warrants a page all its own, something I will write about in next month’s installment of Oxygenologist.
