The Function of Natural Colorants: The Biochromes

Abstract

The colors of nature belong undoubtedly to the beautiful part of our environment. Colors always fascinated humans and left them wonderstruck. But the trivial question as to the practical application of natural colorants led soon and consequently to coloring and dyeing of objects and humans. Aesthetical, ritual and similar aspects prevailed. This function of dyes and pigments is widespread in nature. The importance of such visual-effective dyes is obvious: they support communication between organisms with the aid of conspicuous optical signals and they conceal revealing ones, when inconspicuosness can mean survival. But the purpose of natural pigments and biochromes is broader. Emergence and development of life on earth is inseparably associated with the radiating energy source, the sun. This led to the evolution of biochromes with various functions: collection and harvesting of light, transduction into chemical energy, transport of electrons or gases, photoreceptor processing of information and color discrimination, to mention only a few. Without these pigments – with their photobiological, biochemical, and physiological reactions – life, as we know it, would not have been possible. Color is essential. Several times during the evolution protecting devices and mechanisms had to be invented against the destructive and damaging influence of reactive oxygen, light and UV radiation. To this end nature employed accessory pigments as carotenoids and flavonoids. It is notable and interesting to recognize that human epidemiology and animal studies have indicated that cancer risk may be modified by changes in dietary habits or dietary components. Recent studies indicate that phytochemicals, among them the carotenoids and flavonoids, can inhibit tumor genesis at one or several stages.