Phytosterols as growth regulators.

: Starting from squalen and gonan structures, nature produces by enzymatic transformation a great variety of P--and subsequently also of "animal" sterols. This wonderful chain of biosyntheses comprises a number of provitamins such as beta-carotene and ergosterol and has an endpoint in the vitamin D compounds ergocalciferol (ercalciol, vit D2) and cholecalciferol (calciol, vit D3). On the other hand, we have has an endpoint the most important compound cholesterol and its derivatives, like androsterone, testosterone and 17 beta-estradiol. The members of this family of chemical compounds perform the most diverse biological functions, if properly "directed" or transported to their respective sites of action. Since all of these compounds are hardly soluble in water, we concentrated our research work on their solubilization and thus on enhancing their bioavailability and bioreactivity. The bioreactivity of P was taken as guiding principle for an investigation into understanding the ways of nature as closely as possible-and, at same time-to interpret the findings in comprehensive context. An effort at integrated system's thinking was made throughout.