Chemical protection against aging

Translational research involving oxidative stress and diseases of aging

There is ample mounting evidence that reactive oxidant species are exacerbated in inflammatory processes, many pathological conditions, and underlying processes of chronic age-related diseases. Therefore there is increased expectation that therapeutics can be developed that act in some fashion to suppress reactive oxidant species and ameliorate the condition. This has turned out to be more difficult than at first expected. Developing therapeutics for indications in which reactive oxidant species are an important consideration presents some unique challenges. We discuss important questions including whether reactive oxidant species should be a therapeutic target, the need to recognize the fact that an antioxidant in a defined chemical system may be a poor antioxidant operationally in a biological system, and the importance of considering that reactive oxidant species may accompany the disease or pathological system rather than being a causative factor. We also discuss the value of having preclinical models to determine if the processes that are important in causing the disease under study are critically dependent on reactive oxidant species events and if the therapeutic under consideration quells these processes. In addition we discuss measures of success that must be met in commercial research and development and in preclinical and clinical trials and discuss as examples our translational research effort in developing nitrones for the treatment of acute ischemic stroke and as anti-cancer agents.

Prostaglandins, platelets, and atherosclerosis

Metabolism of arachidonic acid (AA) in blood platelets and in vascular endothelium does not lead to prostaglandins, but thromboxane A2 and prostacyclin are generated. These labile metabolites of AA antagonize each other: thromboxane A2 is a vasoconstrictor and proaggregatory agent, whereas prostacyclin dilates arteries, prevents platelets from aggregation, and dissipates the preformed platelet clumps. Prostacyclin is a powerful stimulator of adenylate cyclase in platelets and therefore its antiplatelet action is potentiated by phosphodiesterase inhibitors such as theophylline or dipyridamole. Cyclo-oxygenase of AA is inhibited by aspirin, thromboxane synthetase by analogues of prostaglandin endoperoxides, and prostacyclin synthetase by linear lipid peroxides. A hypothesis is put forward that atherosclerosis develops because of pathological, nonenzymic lipid peroxides. A hypothesis is put forward that atherosclerosis develops because of pathological, nonenzymic lipid peroxydation in the body and the subsequent molecular damage to prostacyclin synthetase in the rheologically determined areas of arterial walls. Endothelium deprived of prostacyclin is the basis for microthrombi formation, and follows a sequence of events described by Rokitansky and later by Ross. Prostacyclin is also a circulating hormone which is generated by the lungs. Thereby a damage of this "endocrine gland" by respiratory disorders, air pollution, or tobacco smoking are likely to contribute to pathogenesis of atherosclerosis, myocardial infarction, and arterial thromboembolism. Pharmacological treatment and prevention of these diseases should logically include antioxydants, prostacyclin and its analogues, thromboxane synthetase inhibitors and perhaps cyclooxygenase inhibitors (aspirin ?). Prostacyclin was already infused intravenously to men and its powerful antiaggregatory and deaggregatory actions were demonstrated. These properties of prostacyclin along with its vasodilator and positive inotropic actions destine this hormone to be a new type of antithrombotic drug in acute myocardial infarction.

Cytogenetic activity of some common antioxidants and their interaction with x-rays

Experiments were designed to investigate the cytogenetic activity of some commonly used phenolic antioxidants, namely BHA, BHT, BMP and PG, all used widely to preserve and stablize food products rich in fats and oils. Barley and onion were used as test systems. The treatments reduced seed germination and induced a significant amount of seedling injury. Only PMP treatments produced a moderate amount of chromosomal aberrations while others failed to do so. Being strong antioxidants it was expected that these compounds would reduce the cytogenetic damage caused by the radiations. Contrary to expectations, however, a significant increase was observed in the radiation damage measured as seed and seedling lethality and chromosomal aberrations. Chemical post-treatments also increased the radiation damage. The damage was, however, reduced with ATP post-irradiation treatment.