ABSTRACT
Flavonoids are a class of natural substances from plants with a variable structure derived as secondary metabolites with benzo--pyrone polyphenolic nuclear structure. Research and development interests in flavonoids are rising due to their proven versatile health benefits. Over six classes and multiple subclasses of flavonoids related to structure have been discovered. The metabolism, bioavailability, and biological activity of flavonoids depend on the configuration, the total number of hydroxyl groups, and the substitution of functional groups around their molecular structure. Major sources of flavonoids to humans are fruits, vegetables, grains, barks, roots, stems, flowers, tea, and wine. Since the structure is directly related to the biological system’s function, the different flavonoids’ health benefits as dietary ingredients continue to be widely evaluated. Flavonoids have been shown to help in combating oxidative stress and function as growth regulators in plants. Many extracts of the flavonoids and some synthesized samples in the laboratory have been shown to have a significant effect in mitigating diseases related to aging. They have been shown to possess strong antioxidative activity, free radical scavenging capacity, coronary heart disease prevention, hepatoprotective, anti-inflammatory, and anticancer activities, as well as potential antiviral activities. The demand for flavonoid-rich nutraceuticals is soaring. Grapes and green tea have been reported to harbor significant amounts of this polyphenolic phytochemical. Different research techniques are being investigated to escalate isolation, identification, characterization, function, and application as nutraceuticals for human health benefits. To meet the demand for highly sorted flavonoid-rich nutraceuticals with the supply of flavonoids, the current research trend in the nutraceutical industries is focusing on how to enhance flavonoid synthesis in plant system and microbial biotechnology methods that would maximize the synthesis of flavonoids in the laboratory. However, to further boost confidence and reliability in flavonoid-rich nutraceuticals, there must be standard, well-established strict, and comprehensive regulations worldwide to ensure the health benefits and safety of nutraceuticals. In this chapter, we attempt to discuss the classifications of flavonoids, their application as nutraceuticals for health benefits, and the future of flavonoid-rich nutraceuticals.
