What is new in non-chromatographic flavonoid purification?

Flavonoids are metabolites occurring in all plant tissues and present different biological activities. They occur in a mixture of similar polarity with laborious separation and purification processes, usually furnishing low yields. Semi-preparative chromatographic methods are universally employed procedures for their isolation. This paper discusses the state-of-the-art in new non-chromatographic techniques for the separation and purification of flavonoids. In the last decades, novel methods for flavonoids purification have been developed to decrease time extraction, reduction of costs, and organic solvent. Herein, we present the state-of-the-art development of ionic liquids, eutectic solvents, chelating agents, and molecular imprinted polymers in greener extractions, enrichments, and the purification of flavonoids. As the main advantage, these proceedings permitted good yields of bioactive flavonoids and biflavonoids, and they are improved when ultrasound, microwave, and mechanical extractors are used in the extraction step. Nevertheless, most of these techniques are not specific to a single molecule’s purification, except MIPs mainly used for analytical purposes. These examples indicate that the development of efficient and straightforward methods for the obtention of different bioactive flavonoids is still incipient but with potential for discovering specific and greener procedures for isolating the target compounds in good yields.