Production of high antioxidant activity flavonoid monoglucosides from citrus flavanone with immobilised α‐L‐rhamnosidase in one step

Abstract

Summary The rhamnosyl group of naringin dihydrochalcone, neohesperidin dihydrochalcone, naringin and hesperidin was selectively removed by enzymatic hydrolysis using an immobilised α‐L‐rhamnosidase. Monoglycosylated products, including trilobatin, hesperetin dihydrochalcone‐7‐O‐glucoside, prunin and hesperetin‐7‐O‐glucoside, were isolated and characterised by 1H and 13C NMR and ESI‐MS. To optimise the enzymatic reaction conditions and its process costs, the hydrolysis of neohesperidin dihydrochalcone to produce trilobatin was selected as a model reaction. Using a ratio of neohesperidin dihydrochalcone: immobilised α‐L‐rhamnosidase equal to 1:0.6, the trilobatin yields was over 98%. The recycle of enzyme was also investigated, obtaining trilobatin with a yields of 80% even when the twentieth reaction cycle was conducted. Moreover, antiradical and antimicrobial activities of the obtained flavonoid monoglucosides were examined by DPPH, FRAP and ORAC methods, and compared with the efficacy of parental flavonoid glycosides and their aglycone. The results highlight that some of the obtained flavonoid monoglucosides show significant improvement in the antioxidant activity.

1, 2‐trans‐Stereoselective 7‐O‐Glycosylation of Flavonoids with Unprotected Pyranoses by Mitsunobu Reaction

“…The utility of our methodology was further demonstrated by accessing a wide range of natural flavonoid glycosides (Scheme 2). Thus, flavonoid glycosides such as diosmetin‐7‐ O ‐ β ‐D‐xylopyranoside ( 4 ), [29] naringenin‐7‐ O ‐ β ‐D‐xylopyrano‐side ( 5 ), [30] chrysin‐7‐ O ‐ β ‐D‐glucopyranoside ( 6 ), [31] hesperetin‐7‐ O ‐ β ‐D‐glucopyranoside ( 7 ), [32] phloretin‐4’‐ O ‐ β ‐D‐glucopy‐ranoside (trilobatin) ( 8 ), [33] and naringenin‐7‐ O ‐ β ‐D‐glucoside (prunin) ( 9) [34] were obtained in 42% to 76% yields from commercially available D‐xylose ( 1 d ), D‐glucose ( 1 f ), chrysin ( 2 a ), naringenin ( 2 b ), diosmetin ( 2 c ) hesperetin ( 2 d ), and phloretin ( 2 e ) in one step under Mitsunobu conditions.…”

“…The utility of our methodology was further demonstrated by accessing a wide range of natural flavonoid glycosides (Scheme 2). Thus, flavonoid glycosides such as diosmetin-7-O-β-D-xylopyranoside (4), [29] naringenin-7-O-β-D-xylopyrano-side (5), [30] chrysin-7-O-β-D-glucopyranoside (6), [31] hesperetin-7-O-β-D-glucopyranoside (7), [32] phloretin-4'-O-β-D-glucopy-ranoside (trilobatin) (8), [33] and naringenin-7-O-β-D-glucoside (prunin) (9) [34] were obtained in 42% to 76% yields from commercially Additionally, we also investigated the possibility to achieve regioselectivity among different types of hydroxyl groups on the glycosyl acceptors under Mitsunobu conditions (Scheme 3). Therefore, methyl 3,4-dihydroxybenzoate (10) with adjacent hydroxyl groups was employed as a glycosyl acceptor and…”

Dihydrochalcones: Methods of Acquisition and Pharmacological Properties—A First Systematic Review

“…DPPH and ABTS assays [124] phloretin, phloridzin, trilobatin, naringin dihydrochalcone, neohesperidin dihydrochalcone Some of the flavonoid monoglucosides showed significant improvement in the antioxidant activity. DPPH, FRAP, and ORAC assays [127] flavanones and dihydrochalcones Dihydrochalcones exhibited higher antioxidant activities than the corresponding flavanones. The hydroxyl group at the 2'-position in dihydrochalcone A ring is an essential pharmacophore for its radical scavenging potential.…”

A novel electrochemical sensor based on gold nanobipyramids and poly-l-cysteine for the sensitive determination of trilobatin

“…Recently, numerous analytical techniques have been reported for the determination of trilobatin, such as high-performance liquid chromatography, 10–12 nuclear magnetic resonance spectroscopy, 13 and liquid chromatography-mass spectrometry. 14,15 Nevertheless, most of these traditional techniques have some disadvantages, including the need for large experimental equipment, complex operation, long detection time, and high analysis cost.…”