Phenolic Antioxidant Biosynthesis in Plants for Functional Food Application: Integration of Systems Biology and Biotechnological Approaches

Abstract

We are applying a dynamic systems biology approach to the development of several phenolic phytochemicals in food-grade plants as ingredients for functional food applications. Phenolic antioxidant phytochemicals from food-grade plants will be an important part of a healthy diet in a global population that is projected to reach 9 billion in the next 50 years. Such phytochemicals are being targeted for designing conventional foods with added health benefits (functional foods). Such value-added foods are needed for dietary support to manage major oxidation-linked diseases, such as diabetes, cardiovascular disease, arthritis, cognition diseases and cancer. Plants produce phenolic metabolites as a part of growth, developmental and stress-adaptation response. These stress and developmental-modulated phenolic phytochemicals can be targeted for the design of functional foods. In order to design consistent food-grade phytochemical profiles for safety and clinical relevancy, novel tissue culture and bioprocessing technologies have been developed. The strategy for designing these phenolic phytochemicals is based on the model that phenolic metabolites in plants are efficiently produced through an alternative mode of metabolism that links proline synthesis to activity of the pentose–phosphate pathway. Using the proline-linked pentose–phosphate pathway model, techniques have been developed to isolate high phenolic clonal lines of food-grade plants from single heterozygous seeds. Further, using the same model, elicitation concepts and techniques have been applied to over-produce phenolic metabolites in seeds and sprouts. In both clonal and seed sprout systems, exogenous treatment of phenolic phytochemicals from a non-target species elicited endogenous stimulation of phenolic synthesis and, potentially, an antioxidant response. From these investigations, a hypothetical model has been proposed in which the proline-linked pentose–phosphate pathway is critical for modulating protective antioxidant response pathways in diverse biological systems, including humans. This model, when confirmed precisely, may provide a mechanism for understanding the mode of action of phenolic phytochemicals in modulating antioxidant pathways in relation to human health. An understanding of the interconnection of the proline-linked pentose–phosphate pathway and antioxidant response pathway can provide dietary and nutritional mechanisms as well as new strategies to manage oxidation-linked diseases through improvement of host physiological response. In this review we have focused on clonal herbs, fava bean sprouts and cranberry bioprocessing as 3 model systems for understanding biosynthesis of phenolic metabolites for functional food application.