Plant Biotechnology for Health: From Secondary Metabolites to Molecular Farming

Abstract

There is a continuous search of new drugs and molecules for being used in health care. Plants offer a huge variety of those bioactive molecules, some of which are still unknown. The use of plants in popular medicine is the source of in-formation for ethnobotanists and pharmacobotanists, which in general are the first link in the chain that leads to the taxonomical, chemical and pharmacological de-scription of a species. Chapter 2 summarizes the classical strategy employed to analyze the occurrence of bioactive principles in plants, since their collection in the field to the analytical and biological assays. It also refers to new technologies (e.g.: systems biology, synthetic biology) and their contribution to the knowledge about medicinal plants and their active principles. Chapter 3 exposes the classification and main characteristics of plant secondary metabolites, giving some examples of their applications for health. The pharmaceutical industry profits from those bioactive molecules to elaborate or, taking plant compounds as starting point or model, to synthesize drugs with known or novel pharmacological activities. The traditional sources of raw material are plants in the field. However, in the second half of the XX century the in vitro culture technology arise bringing the possibility of maintaining plant cultures in controlled environmental conditions, free from the risks of pathogen and predator attack, from weather variations, and from geopolitical circumstances. Chapter 4 describe the characteristics and prospective of in vitro cultures. Chapter 5 reports the strategy employed to analyze the production of a solasodine, a steroidal glycoalkaloid, as an example of the approaches used to develop a productive process of a secondary metabolite. By the end of the XX century the production of recombinant proteins in plants, named molecular farming, appeared as a new strategy for obtaining biopharmaceuticals. Numerous proteins were expressed (antibodies, antigens, blood proteins, growth factors, etc.) but the attained yields were not competitive to the traditional production platforms in most of the cases. Chapter 6 describes the basics of molecular farming and some of their applications. Chapter 7 deals with the expression of a whole antibody in plants, the catalytic antibody 14D9 that was taken as an experimental model to produce a recombinant protein in in vitro cultures. C Chapter 8 refers to the potential application of a recombinant immunogen, transiently expressed in plants, to trigger a specific immune response and eventually to be used to formulate an experimental vaccine. Finally, chapter 9 gives a general view of the subject of mathematical modeling for producing recombinant protein in in vitro cultures under Good Manufacturing Practices.