Various Analytical Techniques for the Isolation and Identification of Flavonoid Compounds: A Descriptive Review

Abstract

Flavonoids are phytochemical compounds that can be found in a wide range of plants, including vegetables, fruits, and leaves. This vast set of phenolic plant elements can be split into numerous classes based on their diverse structures, including Flavanones, Flavanols, Flavonols, Flavones, Isoflavones, and Anthocyanins. Interestingly, they possess various applications such as natural dyes, medicinal uses, and food sources. Flavonoids have been shown to have anti-cancer, antioxidant, anti-inflammatory, and anti-viral properties in clinical studies. They also have cardio-protective and neuroprotective effects. In addition, they are responsible for the presence of different colors and flavors in various fruits, flowers, and food sources. Multiple spectroscopic techniques, including Infrared spectroscopy (IR), Ultraviolet spectroscopy (UV), and Nuclear magnetic resonance (NMR) spectroscopy, are being used to identify the structure of flavonoids. UV-Vis spectroscopy data can be used to estimate the position, type, and number of substituents present in a conjugated system. IR spectroscopy is primarily used to determine the type of functional groups and aromatic ring substitutions. The structure of Flavonoids, their type, number of protons, and carbons can be determined by NMR spectroscopy. The current review was based on searches of the Scopus, Web of Science, and Google Scholar databases for literature reviews. The purpose of this review article is to demonstrate the structure, function, and different extraction methods of flavonoids. It also summarizes the isolation and analytical identification techniques for flavonoids.