A report on green extraction procedures for separation of flavonoids and its bio activities

This paper provides an overview of the development of novel extraction techniques using choline chloride-based natural deep eutectic solvents for the extraction of the group of secondary plant metabolites, flavonoids. It also reviews studies on the structural characterisation and applications of extracted flavonoids for the treatment of various types of infections. A comprehensive literature survey was carried out using databases such as Scopus, PubMed, Google Scholar, and Science Direct. More than 4000 types of flavonoids were documented, and these fascinating natural products display a broad range of potential clinical properties. They are characterised by varying polyphenol structures and possess numerous therapeutic properties, such as antioxidant, anti-inflammatory, antiproliferative, photoprotective, antipigmentation, and anti-aging. The finest defined property of every flavonoid is its antioxidant effect, which defends the body against reactive oxygen species. For example. quercetin has been reported to be extremely efficient against intracellular replication and infectivity of polio-virus type 1, herpes simplex virus type 1, respiratory syncytial virus, and parainfluenza virus type 3. Natural deep eutectic solvents prepared specifically using choline chloride and lactic acid serve as sustainable and promising solvents in the extraction of important secondary metabolites, with extraction percentage higher than 70%. After the extraction of flavonoids, structural characterisation is conducted using different spectroscopic techniques. The comprehensive study of flavonoids is stimulating because of their diverse molecular structure, with significant developments in the field improving knowledge about of their therapeutic potential.