Chapter 3: Fractionation and Biological Assays on Whole Organisms

The contrast between complexity and reductionism is explored further in this chapter. An important aspect of determining the biological effects of natural products is knowing how much of the substance can migrate to the site of action in the body – how much is bioavailable. The measurement of the effects of molecules (both isolated and as part of an ingested matrix) is considered using glucosinolates and Brassica vegetables as examples. This is followed by a discussion of selective toxicity and the advantages of using more specific biological targets in the form of receptors rather than whole animal experiments. The principles of health and homeostasis are examined and the chapter concludes with a consideration of some specific examples of receptors that have been used to optimise biological activity. There follows a view of Socratic (Popperian) systems for scientific exposition.