Plant’s defence and its benefits for animals and medicine: role of phenolics and terpenoids in avoiding oxygen stress

Land plants have to sustain a wealth of abiotic and biotic impacts such as extreme temperatures or dryness and high light intensities accompanied by oxygen saturation without being able to escape or to switch off the light, which under these conditions is the major reason for their problems. They thus developed a strategy for defence composed of avoidance reactions combined with a set of defence-chemicals. Co-evolution of animals took advantage of this enormous synthesizing capacity of plants. The knowledge about these interrelationships between plants and animals in terms of coping with “oxidative stress” is exponentially increasing and has led to novel insights, especially as far as medical, pharmacological and nutritive aspects are concerned. The biochemistry of oxygen-activation and -detoxification analysed in the past and the identification of similarities between plants and animals opened a new field of research. Biochemical model reactions simulating these common situations allow to predict possible functions of certain chemicals in plants’ defence as well to find new fields of application in human health and to exploit up to date unknown resources. In this report we will specially deal with an underestimated and widely ignored group of chemicals: the terpenoids. We could prove that these substances are effective antioxidants in lipid peroxidation processes. They furthermore are able to prevent carotenoids, another class of secondary plant metabolites, from oxidation.