Purity of catalase preparations: contamination by endotoxin and its role in the inhibition of airway inflammation

Oxygen radicals, inflammation, and arthritis: pathophysiological considerations and implications for treatment

A vast amount of circumstantial evidence implicates oxygen-derived free radicals, especially superoxide and hydroxyl radical (and to lesser extent, hydrogen peroxide), as mediators of inflammation and/or tissue destruction in inflammatory and arthritic disorders. The substrates for radical generation, namely properly stimulated phagocytic cells, transition metal catalysts, and (to a limited extent) ischemia, are all amply present, although there is no particular rheumatic disease in which a consistent abnormality of radical generation has been identified. These radical species can clearly degrade hyaluronic acid, modify collagen and perhaps proteoglycan structure and/or synthesis, alter and interact with immunoglobulins, activate enzymes and inactivate their inhibitors, and possibly participate in chemotaxis. In most situations, however, there is ample scavenging ability to detoxify these radicals before they hit their target, and many rheumatic disease drugs can decrease their production and/or effects. Despite the apparent sufficiency of natural scavengers and the lack of direct evidence that oxygen radicals are pathogenetically important, substantial pharmaceutical effort is still being made to develop free radical scavengers as therapeutic agents. Although individual free radicals die out quickly, rheumatologic interest in them has been sustained for nearly two decades.

Superoxide dismutase and catalase as therapeutic agents for human diseases. A critical review

The list of human and animal diseases for which oxygen radical scavenging therapy is being recommended continues to grow, based primarily on inferential evidence suggesting a potential role for oxygen-derived free radicals in various types of pathophysiology. Some distinct advances in pharmacologic manipulation of protein scavengers have been made which could ultimately greatly enhance the use of these reagents as drugs, as well as some innovative techniques for drug delivery (direct injection via endoscopy, iontophoresis). Unfortunately, most of the therapeutic reports in the literature, almost all of which are based on usage of standard (native) SOD and/or catalase, are still anecdotal and/or uncontrolled. A review of the human disease/treatment literature suggests that further tightening of the scientific design of such trials is still badly needed; hopefully better experimental design will be applied when products such as PEG conjugates or genetically engineered polymers are ready for testing.