Conventional and Emerging Extraction Processes of Flavonoids

Abstract

Flavonoids are a group of plant constituents called phenolic compounds and correspond to the nonenergy part of the human diet. Flavonoids are found in vegetables, seeds, fruits, and beverages such as wine and beer. Over 7000 flavonoids have been identified and they have been considered substances with a beneficial action on human health, particularly of multiple positive effects because of their antioxidant and free radical scavenging action. Although several studies indicate that some flavonoids have provident actions, they occur only at high doses, confirming in most investigations the existence of anti-inflammatory effects, antiviral or anti-allergic, and their protective role against cardiovascular disease, cancer, and various pathologies. Flavonoids are generally removed by chemical methods using solvents and traditional processes, which besides being expensive, involve long periods of time and affect the bioactivity of such compounds. Recently, efforts to develop biotechnological strategies to reduce or eliminate the use of toxic solvents have been reported, reducing processing time and maintaining the bioactivity of the compounds. In this paper, we review, analyze, and discuss methodologies for biotechnological recovery/extraction of flavonoids from agro-industrial residues, describing the advances and challenges in the topic.

Sephadex® LH-20, Isolation, and Purification of Flavonoids from Plant Species: A Comprehensive Review

“…Moreover, 5 isoflavone derivatives have been isolated by SLH as the last separation procedure. Formononetin-7- O -β- d -glucosy1 [ 1 , 2 , 3 , 4 , 5 , 6 ] glucoside ( 94 ) and tectoridin ( 95 ) have been purified from ethyl acetate extract of Maackia amurensis bark (eluent: methanol‒water 6:4) [ 69 ], whilst formononetin ( 93 ) was extracted from Aquilaria sinensis stem ethyl acetate extract (eluent: methanol) [ 57 ]. Sphaerobioside ( 96 ) and a well-known isoflavone genistein ( 97 ) have been previously isolated by SLH eluting with methanol‒water (1:1) and methanol, respectively, from aqueous root fractions of Cudrania tricuspidata [ 25 ].…”

“…The ability of polyamide to make hydrogen bonds with hydroxyl groups of flavonoids, depending on the numbers and positions of this groups, are the basis of the isolation process in this technique. The recent advanced techniques, including High-performance liquid chromatography (HPLC), high-speed counter current chromatography (HSCCC), molecular imprinting technology (MIT), droplet counter-current chromatography (DCCC), along with older methods medium pressure liquid chromatography (MPLC), circular liquid chromatography (CLC), and centrifugal preparative thin layer chromatography (CPTLC), are the applied techniques to isolate flavonoids [ 2 , 4 , 5 ]. However, GC-MS, HPLC-ESI-Q-TOF-MS, HPLC-PdAD-ESI-MS/MS, LC-MS, LC-MS/MS, and ultra-HPLC (UHPLC), have mostly been employed to analytical analysis of flavonoids from plant species [ 5 ].…”

“…The recent advanced techniques, including High-performance liquid chromatography (HPLC), high-speed counter current chromatography (HSCCC), molecular imprinting technology (MIT), droplet counter-current chromatography (DCCC), along with older methods medium pressure liquid chromatography (MPLC), circular liquid chromatography (CLC), and centrifugal preparative thin layer chromatography (CPTLC), are the applied techniques to isolate flavonoids [ 2 , 4 , 5 ]. However, GC-MS, HPLC-ESI-Q-TOF-MS, HPLC-PdAD-ESI-MS/MS, LC-MS, LC-MS/MS, and ultra-HPLC (UHPLC), have mostly been employed to analytical analysis of flavonoids from plant species [ 5 ]. The acidity of the extraction solvents have been reported a direct correlation with flavonoid contents, whereas in a study on Vitis vinifera , total flavonoid contents enhanced (from 20.63 to 46.77 mg/g) by addition of HCl (from 0 to 1%) [ 6 ].…”

“…Nuclear magnetic resonance (NMR), mass spectrometry (MS), spectrophotometric ultra-violet (UV), and infrared (IR) techniques providing spectroscopic spectra of flavonoids, have been exploited to elucidate the flavonoid structures. Moreover, their physical characteristics such as melting point (mp), circular dichroism (CD), and optical rotatory power ([α] D ) can be applied to identify the flavonoids [ 5 ].…”

A High-Yield Process for Production of Biosugars and Hesperidin from Mandarin Peel Wastes

“…The development of an effective and selective method for bioactive compound extraction would be beneficial. Recent extraction methods have largely focused on finding a green method that minimizes the use of solvent and energy, and reduces wastes, such as subcritical water extraction, ultrasound extraction, microwave extraction, supercritical fluids extraction, and pressurized hot water extraction (PHWE) [ 26 , 27 , 28 , 29 , 30 , 31 , 32 ]. More recently, the enzyme-assisted extraction method has shown faster extraction, higher recovery, reduced solvent usage and lower energy consumption when compared to non-enzymatic methods [ 33 , 34 ].…”