Flavonoids of Passiflora: isolation, structure elucidation, and biotechnological application

Abstract The genus Passiflora is native to the tropical and semitropical countries of the Americas although species are growing in Asia and Australia. Brazil is considered a center of diversity of the genus. Some species are listed as official plant drugs in the pharmacopoeias of many countries. They are traditionally used for therapeutic purposes such as sedatives and tranquilizers. The Passiflora species and its flavonoids are important natural products with a broad spectrum of biological activities and nutraceutical properties. Flavonoids comprise a class of structurally diverse and complex compounds which possess several functions in plants including ultraviolet protection, defense against pathogen infection, signaling during nodulation, regulating auxin transport, as well as being responsible for the coloration of flowers, fruits, and leaves. Moreover, these compounds display some interesting pharmacological properties that have been explored by the pharmaceutical industry. The phytochemical aspects regarding the Passiflora species have been studied extensively. The flavonoids are the main secondary metabolites, being, therefore, considered by their chemical markers. This chapter provides an overview of some aspects related to the flavonoid biosynthesis, isolation, and structure elucidation using spectroscopic methods such as mass spectrometry, nuclear magnetic resonance, and chromatographic-spectroscopic hyphenated techniques. In addition, we hope to address a few strategies and achievements through a biotechnological approach to the in vitro production of flavonoids. Overall, the Passiflora genus and its flavonoids offer a remarkable potential for research mainly within the interfaces of chemistry/biotechnology/pharmacology. This chapter intends to assemble the most important literature concerning the value of the Passiflora species as a source of bioactive flavonoids.