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Phenolic compounds are widely distributed in the plant kingdom. Plant tissues may contain up to several grams per kilogram. External stimuli such as microbial infections, ultraviolet radiation, and chemical stressors induce their synthesis. The phenolic compounds resveratrol, flavonoids, and furanocoumarins have many ecologic functions and affect human health. Ecologic functions include defense against microbial pathogens and herbivorous animals. Phenolic compounds may have both beneficial and toxic effects on human health. Effects on lowdensity lipoproteins and aggregation of platelets are beneficial because they reduce the risk of coronary heart disease. Mutagenic, cancerogenic, and phototoxic effects are risk factors of human health. The synthesis of phenolic compounds in plants can be modulated by the application of herbicides and, to a lesser extent, insecticides and fungicides. The effects on ecosystem functioning and human health are complex and cannot be predicted with great certainty. The consequences of the combined natural and pesticide-induced modulating effects for ecologic functions and human health should be further evaluated. -Environ Health Perspect 1 07(Suppl 1): 109-114 (1999). http://ehpnetl.niehs.nih.gov/docs/1999/Suppl-1/ 109-1 14daniel/abstract.html

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Phenolic compounds are widely distributed in the plant kingdom. Plant tissues may contain up to several grams per kilogram. External stimuli such as microbial infections, ultraviolet radiation, and chemical stressors induce their synthesis. The phenolic compounds resveratrol, flavonoids, and furanocoumarins have many ecologic functions and affect human health. Ecologic functions include defense against microbial pathogens and herbivorous animals. Phenolic compounds may have both beneficial and toxic effects on human health. Effects on low-density lipoproteins and aggregation of platelets are beneficial because they reduce the risk of coronary heart disease. Mutagenic, cancerogenic, and phototoxic effects are risk factors of human health. The synthesis of phenolic compounds in plants can be modulated by the application of herbicides and, to a lesser extent, insecticides and fungicides. The effects on ecosystem functioning and human health are complex and cannot be predicted with great certainty. The consequences of the combined natural and pesticide-induced modulating effects for ecologic functions and human health should be further evaluated.

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The production of the two purine alkaloids theobromine and caffeine has been studied in suspension cultures of Coffea arabica. Maximum formation rate (sum of the two) was found after the exponential phase of growth. The rate of methylation and the biotransformation potency of theobromine to caffeine, studied by the application of [2-I4C]theobromine, wer; highest in the log phase. Although tracer experiments with [2-"Clcaffeine demonstrated a slow degradation of this purine alkaloid, it can be considered as a metabolic end product in this in vitro System. lntroductionTne biosynthetic activities of secondary metabolism vary extremely during a cultivation period caused by internal and external factors [I]. This problem is of great importance with regard to an industrial production of pharmaceutical substances by fermenter techniques [2]. The purpose of the present work was to obtain more basic knowledge in the endogeneous control of secondary metabolism by means of analysing the production of the two purine alkaloids theobromine (3,i-dimethylxanthine) and caffeine (1,3,7-trimethylxanthine) in suspension cultures of Coffea arabica. It is well established that in both the tea [3, 41 and the coffee plant [S, 61 the 3,7-dimethylxanthine is methylated to 1,3,7-trimethylxanthine. Callus tissue cultures of Coffea arabica have a reproducibly high productivity of these purine alkaloids corresponding to that in the living coffee plant [7, 81. Although suspension cultures are less productive than callus cultures, they proved -by reason of easy handling -to be a better tool in the present study in which the kinetics of purine alkaloid metabolism with respect to gro.wth characteristics were analysed. Material and Methods Plant Matcrial und Culture MethodSuspension cultures of Coffea arabica cv Bourbon amarelho derived from primary callus cultures have been cultivated in a commercially available Heruntergeladen von: University of Arizona Library. Urheberrechtlich geschützt.

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